The amount of coal ash has been increasing and development of effective use is urgently needed. Various by-products and waste are expected to be used as resources from the point of reduction in environmental load. This is an experimental study to compare the properties of high volume coal ash concrete using the reclaimed coal ash. For this purpose, the mix proportion of concrete according to the content ratio of below 5mm reclaimed coal ash (0.65, 0.70, 0.75 and 0.80). And then air content, slump, compressive strength test were performed. According to test results, it was found that the compressive strength of reclaimed coal ash concrete was similar to the content ratio of below 5mm reclaimed coal ash. And the slump of reclaimed coal ash concrete decreased as the content ratio of below 5mm.

The purpose of this paper is to offer a base data of specification, so that the strength information of concrete in the structure for irrigation can be rationally determined the coefficient of variation of an existing irrigation structure and the best fit the ready-mixed concrete strength to specified strength $f_ck$. From analysis of concrete cylinders from about 30 numbers in southern Korea, it was concluded that the coefficient of variation of cylinder strength were approximately 5.9%. On the basis of the core strength test data, it was appeared that the average coefficient of variation for the existing irrigation structure can be taken as 17.8% for strength level 21MPa.

Development of the construction industry generally exhausts natural aggregate. Hence it is problem to the lack of supply and quality deterioration, so the resource saving and protection of environment is made an effort through recycling by-product. This study presents that fundamental properties of concrete which used cooper slag as alternate sand of low fineness modulus and plan of cooper slag as concrete aggregate. Testing factors are concrete's slump, air contents, unit weight and compressive strength. The results of this study are as follows; (1) Concrete slump is generally satisfied with the condition but is inferior to the others in substitution rates 30%. Also air contents are 3.1-4.1% and go up according to increase substitution rate. (2) Unit weight increase in 1.1% as the mixing ratio of cooper slag argument 10%. (3) compressive strength of cooper slag concrete is similar to plain and especially higher 11-15% in W/C 45%, 50%. So it seems that aggregate mixed cooper slag is suitable to low water-cement ratio mixture.

This study is carried out (1) checking the development of compressive strength of high flowing concrete at early age, changing water-binder ratio, curing temperature, and type of aggregate, and (2) suggesting basic date that helping cost and schedule plan in future construction. As the result of this study, we find that high curing temperature is effective for the development of compressive strength of concrete at early age on the condition of each water-binder ratio, and after making the compressive prediction formula related to the curing temperature by maturity, the result of the formular is similar to the temperature-compressive strength-age measured data

Metakaolin is a cementitious material for producing high-strength concrete. This material is now used as substitute for silica-fume. In this paper, we studied the properties of fresh concrete such as slump-flow, air content, and the feature of strength of hardened concrete according to the substitute ratio of metakaolin, silica-fume. In the fresh concrete test, the time depend loss of slump-flow & air content is good to 10-15% substitute ratio of metakaolin. And, in the strength test, 10-15% substitute ratio of metakaolin is good for producing high-strength concrete also. But, allowing for economical efficiency, we concluded that 10% is a adequate substitute ratio for producing high performance concrete.

This study is investigated the various properties and drying shrinkage of concrete according to water content under the condition proper fluidity is adjusted, in order to suggest the method for reduction of crack by drying shrinkage. According to the results, though water content varies, slump and air content are satisfied to the planed values, but shear slump and separation happen at water content of 120 and 140kg/$m^3$ due to the overuse of superplasticizer(SP). As water content is diminished, setting time is retarded by an increase of the using amount of SP, and compressive and tensile strength increase in the range of 160-180kg/㎥ of water content, but decrease significantly at 120 and 140kg/$m^3$. Length change by drying shrinkage decrease with a decrease of water content. Therefore, considering not only drying shrinkage but also fluidity, setting time and strength, it proves that the most appropriate water content of concrete is 160kg/$m^3$ in the condition of this experiment.

High-Flowability Concrete has many advanced properties and been focused on their workability. Because of the difficulty in understanding of the quality of High-Flowablity Concrete just using slump properties, many studies have been carried out rheological properties influenced on concrete fluidity. In this paper, for the purpose of expecting some level of rheological properties, the change of rheological properties of High-Flowability Concrete with dosages and types of superplasticizer, and various addition amounts addictives were investigated.

In this study, we made the high strength light weight concrete which was composed of the garnet minute powder to be the industry by-product in the YoungJoo region and the artificial light weight aggregate which the high temperature(1100℃) plastic process. The characteristic of the autogenous shrinkage had been considered about strength characteristic and the age passage In the following addition: The concrete's each unit quantity was determined 145,160,175㎏f/㎥.w/b and s/a was determined 30%, 43%, 45%. the each garnet's substitution ratio was determined 0, 10%. In this results, the compressive strength appeared greatly as the unit joining discretion grew bigger. The autogenous shrinkage ratio was increased rapidly until 7th day but it was reduced after 7th day regardless of the mixed factor. The autogenous shrinkage ratio which follows the change of the unit quantity and s/a increased together as the unit quantity and the s/a increases.

This study was performed to verify the effect of workability in construction site using by high strength concrete with granulated blast furnace slag. For the satisfaction of the target strength, the optimized mixing ratio was drawn from the replacement ratio of granulated blast furnace slag and fly-ash. Results from the experiment and the application showed the outstanding quality of concrete and the effects of cost-down.

High flowing concrete has not spread whole in the normal concrete structure, because it requires special quality control technique. Recently owing to the lack of natural resources and reinforcement of environmental standard, the construction cost of cement is rapidly increased. Also ready mixed concrete industry has gone through various economical difficulty as the manufacture cost of concrete is increased. So, the purpose of this study is to evaluate the qualities of middle fluidity concrete using the fly-ash and portland blast-furnace slag cement in order to decrease the amount of cement and resolve the problem of the quality control of high flowing concrete and the manufacture cost. The results of this study show that it reduces the amount of addition of superplasticizer and develope properties of concrete to the use the fly-ash and portland blast-furnace slag cement.

The steel slag, a by-product which is produced on the process of manufacturing steel by refining pig iron is mainly used as road materials after aging it. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the volume expanded. Due to this reason it prevents steel slag from being used as aggregate of concrete. But steel slag used in this study is controled by a air-jet method which rapidly cools substance melted at a high temperature. Rapid cooling prevents from generating of free-CaO in steel slag. In this study, it was investigated that steel slag manufactured by air-jet method affects on concrete in the freezing and thawing. As results of this study, concrete mixed with steel slag was worse in the freezing and thawing than concrete mixed with sand in spite of using air entraining agent. To obtain durability of concrete in the freezing and thawing, it is desirable to mix 50% of steel slag in concrete per unit weight of volume.

Scaling deterioration of port concrete structures due to the combined effects of chemical actions by seawater and the freeze-thaw action is also a problem which has not yet been fundamentally solved. Furthermore, deterioration of concrete surface was considered as accelerate factor of concrete durability tended to decrease. Therefore, we considered the scaling measuring method and decreasing influence of durability of concrete according to kind of binders, such as OPC, Slag, Slag+Fa, due to freeze and haw of sea water. As a results of this study, it was effective method of scaling deterioration of concrete, and confirmed the salt deterioration resistance effect to use slag binder against to sea water.

This paper investigated the chloride invasion resistance properties of concrete containing mineral admixtures(pozzolanic materials such as fly-ash, ground granulated blast-furnace slage, silica fume and meta kaolin) for each replacement ratios under W/B ratios ranged from 40% to 55%. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a result, the migration coefficients of chloride ion of concrete containing mineral admixtures were shown reducing with the use of mineral admixtures, and the compressive strength was shown related to the migration coefficient. From the correlation between compressive strengths and migration coefficients, the kind and replacement ratio of mineral admixtures have a great effect on migration coefficients below 50㎫.

In this study, to confirm corrosion of reinforced concrete affected by carbonation, chloride ion diffusion, absorption ratio, air permeability, measured carbonation velocity coefficient, chloride ion diffusion coefficient, absorption coefficient, air permeability coefficient. Corrosion velocity under environment of complex deterioration. And than compared corrosion velocity with these coefficients. As the results of this study, the correlation coefficient between chloride ion diffusion coefficients and absorption coefficient was revealed that it is very high. As well, an increase in carbonation, chloride ion diffusion also increases corrosion velocity. It showed that corrosion velocity was affected by the carbonation, chloride ion diffusion, absorption ratio, air permeability. Generally, data on the development of these coefficient made with none, organic B, organic A, inorganic B, and inorganic A is shown. It showed that coating of surface prevent steel bar from deteriorating.

Chloride ingress into concrete followed by reinforcement corrosion and deterioration of concrete structures is a major problem for many structures under chloride attacks. It is necessary to investigate the environmental conditions of concrete structures exposed to chloride attacks. In this study, the air-borne chloride contents in domestic marine environment were investigated.

Although there has been an upcoming recognition in the repairing reinforcement and remodeling of currently existing buildings with a regard to economic and resource saving effects of buildings roughly exposed to the open air for a long-term period, followed by a number of problems with the construction business operations that support economy-oriented projects within the limits of their short-term period durability, it is true that reasonable decisions of concrete performance are insufficient owing to the lack of proper history management for those existing buildings. This research attempted to comparatively analyze the compression strength together with investigation of carbonization depth and alkali concentration according to the passage of years on the subjects of aged buildings, and to provide basic data for remodeling and/or reconstruction of future construction structures by indirectly estimating durability lifetime expectancy according to carbonization phenomenon.

This paper investigated the apparent chloride diffusivity of various concretes. Ten mixtures of concrete were initially prepared and tested to estimate diffusion property. The penetration depth and concentration of chloride ion were examined at the same water-binder ration. The binders were composed of normal portland cement, fly ash, ground granulated blast-furnace slag, and silica fume. From the results, it was concluded that using the mineral admixtures had a filling effect on the pore structure of cements matrix due to those pozzoanic reaction with the hydrates of cement, which increases the tortuosity of pore and makes large pore finer. And diffusivity of chloride is following: NPC100 > F10N90 > F30N70 > F20N80 > F20S05 > G30N70 > F10S05 > G30S05 > G30F15 > G50N50.

Recently, physical properties of concrete containing ternary blended cement were actively researching to develop durability, mobility, and atc. as well as strength increase of concrete. In this study, durability of concrete such as the resistance against chloride ion penetration, rebar corrosion, freeze and thaw, and sulfate were researched for concrete containing ordinary portland cement(OPC) and ternary blended cement(TBC), respectively. For this purpose, concrete specimens containing OPC and TBC, respectively, were made for 37.5% of W/C, and then various durability experiments described above were carried out. As a result, it was observed from the test that concrete containing TBC showed excellent durability than concrete containing OPC.

This study is to investigate durability in concrete containing slag powder and limestone power. The variables are the substitution ratio of slag powder and limestone powder. In order to study the effect of slag powder and limestone powder, all mixtures were prepared at a fixed water/cement ratio, slump, and entrained air quantity. When concrete containing slag powder is mixing rate 40%, durability appeared the highest in general. When concrete containing limestone powder is mixing rate 10% in all experiments, the most suitable result appeared.

It is recognized that reinforcement corrosion is the main distress behind the present concern regarding concrete durability. In this study, to confirm corrosion of reinforced concrete affected by thickness of cover, kinds of surface coating, measured electric potential, ratio of corrosion area, weight reduction, corrosion velocity of steel bar under environment of complex deterioration. The results showed that an increase in age also increases corrosion of steel bar. Ratio of corrosion area is largely related to ratio of weight reduction. as well, corrosion of steel bar by thickness of cover is superior to l0mm thick than 20mm thick. It showed that an increase in thickness of cover prevent steel bar from deteriorating. The results of this study showed that corrosion velocity was affected by thickness of cover, kinds of surface coating. data on the development of corrosion velocity made with none, organic B, organic A, inorganic B, and inorganic A is shown.

The most common deteriorating processes of concrete structures in the world-wide are carbonation and chloride ion. In this paper, chloride profiles of carbonated concrete is predicted to considering two layer composite model, which is based on Fick's 2nd law. From the experimental result on combined deterioration of chloride and carbonation, it was examined that high chloride concentration was built up to 3-5㎜ over depth from carbonation depth. The analytical modeling of chloride diffusion, which was based on the Fick's 2nd law of diffusion, was suggested to depict the relative influence of the carbonation depth.

Recently, owing to the deterioration of reconstruction and the construction, much of the construction waste is discharged in our construction field, and the amount of construction waste are rapidly increased. These waste are raised to financial and environmental problems, so the method of reusing waste concretes has been studied and carried out many direction. Especially being want of resources, if waste concrete could be recycled as aggregate for concrete, it will contribute to solve the exhaustion of natural aggregate, in terms of saving resources and protecting environment. This study is that the floating properties of concrete with recycled coarse aggregate were investigated for the substitution of recycled coarse aggregate. The result of this study, in case of water reducing, the property of harden concrete for the substitution ratio of recycled coarse aggregate was increased. The Quality of recycled coarse aggregate concrete was improved by water reducing.

The Alkali-Aggregate Reaction (AAR) may cause a serious failure in the concrete structures. Several researchers in some nations have performed the continuous studies to prevent failure of a concrete structures by the AAR distress as well as the studies to manifest the mechanism. The ASTM Standards to prevent failure by potential AAR aggregates were established in 1950. The KS F2545 and KS F 2546 were established to test the susceptibility of aggregate to potential AAR in 1982. But the researches on the AAR have not been performed affluently in Korea because the distress due to AAR has seldom been reported officially. In this study, the Chemical Method and Scanning Electron Microscopy (SEM) were used to verifying the cause of the pattern crack on the surface and internal crack in the plain concrete pavement. It can be concluded that the distress of a specific site in plain concrete pavement was mainly due to AAR, and the chemical method and SEM may be the effective tools for verifying the cause of AAR distresses.

The purpose of this study is to examine the influence of the flowability and the compressive strength of concrete after the improving of grain shape of the coarse aggregate and fine aggregate fineness modulus. According to the experimental results, the coarse aggregate after improvement of grain shape it lead to be down by 6% fine aggregate ratio, from 47% to 41%. The 0.5% increase of fine aggregate fineness modulus lead to 3% increase of concrete slump, and 1% reduction of concrete air content. While compressive strength on fine aggregate fineness modulus, it was increased until fineness modulus 3.0, but after it reached by 3.5 it was decreased. The compressive strength of the coarse aggregate after improving the grain shape was decreased by 6% due to loss of the adhesion of cement paste.

This paper is to investigate the characteristics of a concrete in which river sand is partially substituted with crushed sand. Since river sand has a relatively small fineness modulus, there is a need to increase the fineness modulus of sand used in the manufacture of concrete. In an experiment, it was observed that when river sand had a fineness modulus of 2.0~2.4 and crushed sand had a fineness modulus of 2.8~3.5, the substitution rate of the crushed sand was preferably within the range of 25~50%. The experimental results also revealed that as the substitution rate of the crushed sand increased, the flowability of the concrete tended to increase. However, when the substitution rate of the crushed sand reached 75% or more, the workability of the concrete was considerably poor. Further, as the substitution rate of the crushed sand increased, the air content and the bleeding rate of the concrete were low.

Aggregate may limit the strength of concrete, and aggregate with undesirable properties cannot produces strong concrete. Also, the properties of aggregate greatly affect the durability and structural performance of concrete. Recently, it has increased the using of crushed aggregate for concrete due to the exhaustion of good natural aggregate. In case of Korea, in 2002, the using ration of crushed stone occupies about 97% of whole coarse aggregate, and ratio of crushed sand occupies about 18.3% of whole fine aggregate. This is a study to compare and analyze the properties of crushed aggregate for concrete to do mix proportion and improve the concrete quality. According to results, it was found that nearly all the properties of crushed aggregate satisfied with the value recommended by KS.

The Natural aggregate will be faced with serious shortage problem within 10 years due to the great amount of consumption in domestic. In order to reserve our natural resources, the construction waste has to be reused as an alternative material. Especially, It is more imminent to find alternative material in case of fine aggregate. This paper presents and experimental results on the fundamental property of concrete using recycled fine aggregate. As a result, it was found that the property of concrete using recycled fine aggregate substituted for 25% of a natural sand was similar in that of crushed fine aggregate.

In order to evaluate the applicability of steel slag aggregates for tetrapod concrete, the properties of concrete as structural material were investigated. The biochemical research of marine concrete using steel slag aggregates was also carried out. The tested concrete properties are slump, air content, compressive strength, splitting tensile strength, elastic modulus, carbonation, hydration heat, freezing and thawing, sulfate attack, drying shrinkage, etc. The biochemical experiments are carried to research the propagation and reproduction of seaweeds and survival of bottom dwelling species. According to the experimental results, the steel slag aggregate content did not have a significant effect on compressive strength, splitting tensile strength and elastic modulus. The durability of concrete was not influenced by the steel slag aggregate content. From the biochemical research, steel slag aggregate can be evaluated as the material that is ideally suited for promoting propagation and reproduction of seaweeds and survival of bottom dwelling species.

Sewage sludge and clay used as raw materials in the study. Green aggregates contain different contents by dried weight of the sewage sludge, up to 80 percent is manufactured and burning conditions of soak temperature, soak time and rate of temperature increase. influence of burning condition and mixing ratio on specific gravity of burned aggregate are discussed. The appropriate burning condition to all aggregates is evaluated. Aggregates result form the thermal treatment get specific gravity under 0.8, water absorption fewer than 7.5 percent, and aggregate crushing value from 28 to 53. As the result, aggregates can be available as the lightweight aggregate for non-structural concrete.

In a design of LNG storage tank, one of the major loading conditions that significantly affects liquid tightness of the outer concrete wall is the cryogenic temperature of LNG under the emergency condition of LNG leakage. Proposed in this study are the more consistent procedures to ensure the liquid tightness of LNG tank focusing on the design of prestressing tendon. It is expected that the proposed schemes lead to a more effective serviceability design of LNG tank that satisfies various requirements for the liquid tightness in an efficient manner.

Mechanical anchorage can substitute a standard hook. To enhance the workability and economical benefit of mechanical anchorage, the size of anchor plate should be optimized. In this paper, the pull-out behaviors such as strength, failure mode, and crack patterns of mechanically anchored reinforcement in concrete are investigated using nonlinear finite element analysis. The nonlinear finite element analysis results are consistent with the experimental results. These results show that the optimal anchor plates can be designed using the nonlinear finite element analysis.

The re-bar work in the construction of nuclear power plants is difficult, due to the large diameter and the congestion of reinforcements. The mechanical anchorage offers a potential solution for this problem. However, the requirements or the standards for the shape of anchor plate of mechanical anchor has not been clearly established up to now. In this paper, the required performance of the mechanical anchorage for large diameter reinforcements in nuclear power plants are proposed, and the anchor plates are designed through nonlinear finite element analysis. The diameters of anchor plate are determined to be $\sqrt{5}$ times of reinforcement diameter for longitudinal reinforcements and $\sqrt{10}$ for shear reinforcements. The thickness of anchor plates is optimized as 0.3-0.35 times of reinforcement diameter for longitudinal reinforcements and 0.5~0.56 times for shear reinforcements.

Recently, many high-rise reinforced concrete (RC) bearing wall structures of multiple occupancy have been constructed, which have the irregularities of weak (or soft) story and torsion at the lower stories simultaneously. The study compared the eccentricity of such a building predicted by design codes, EC 8, IBC 2000 and UBC 97, and by the test results through a series of shaking table tests of 1:12 model. Based on the comparison of the predicted eccentricity and the test result, the conclusions are drawn as follow: Accidental torsion due to the uncertainty on the properties of structure can be reasonably predicted by using the dynamic analysis with the center of mass being shifted by 5 percent of the dimension of the building perpendicular to the direction of the excitations than by using equivalent lateral force procedure

This paper presents a nonlinear finite element analysis procedure for the seismic performance assessment of reinforced concrete bridge piers using damage indices. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Damage indices aim to provide a means of quantifying numerically the damage reinforced concrete bridge piers sustained under earthquake loading. The proposed numerical method for the seismic performance assessment of reinforced concrete bridge piers is verified by comparison with the reliable experimental results.

This paper concerns the seismic performance index of highrise reinforced concrete shear wall buildings assessed by FEMA 273 and ATC-40 provisions. The applied buildings are 10 to 35 stories and the evaluation level is life safety level. The seismic performance index results of $1^{st}$ and $2^{nd}$ evaluations are as follows; (equation omitted)

The design process of concrete retaining walls includes multiple procedures such as structural analysis, member design, the production of calculation sheets, CAD, and itemized statements of Quantities and costs. The objective of this study is to develope an integrated design system that includes all the steps needed for concrete retaining wall design, and as a result, to improve the quality and efficiency of the design process. In this study, the design steps are divided into structural modules and database, and each module and database is systematically combined for the complete design process. The developed design system is based on Web environment. Therefore it can be used in real time and reduces the design work time and space.

Large amount of binders and high-range AE water-reducing (HRWR) agent are required for self-consolidating concrete in order to achieve flowability and segregation resistance. In this study, the initial permeability of SSC(self-consolidating concrete) until the age of 28 days is measured and compared with those of other SSCs, in which some parts of cement are substituted with fly ash or blast furnace slag. The strengths of SSC samples are also examined along with the permeability change.

This experimental investigation was conducted to examine the seismic performance of reinforced concrete bridge columns. The columns were subjected to a constant axial load and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement ($P_s$ =0.96, 1.44 per cent) and axial load ratio (0.05, 0.1, 0.2 P/$P_o$). Test results show that bridge columns with 50 per cent higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour. For bridge columns with axial load ratio(P/$P_o$) less than 0.2, the ratio of $M_{max}$ over $M_{aci}$, nominal moment capacity predicted by ACI 318-02 provisions, is consistently greater than 1 with approximately a 20 percent margin of safty.

The objective of this paper is to investigate the effective width of wide beam. Three specimens were designed to have different depths of wide beam and to simulate exterior beam-column joint including spandrel beam. Load reversals were applied to the end of wide beam to model behaviors under seismic situation. From the test, it was shown that the strength and effective width of specimens were improved when the depth of specimens increased. The effective width of wide beam depended on the depth of it. Formulas in ACI 318-02 underestimated the effective width of wide beam even though these reflected the contribution of the depth of beam.

Time dependent deflections of double composite box girders are investigated based on the on going laboratory experiments scheduled for 3months long. Two of 2-span double composite box girders with 2.5m each span length are cast and time dependent behaviors are measured using 30 strain gages and 2 LVDTs after 5 days' curing. The measured experimental results are compared with the numerical predictions performed based on the one dimensional finite element method adopting beam element. The FEM formulation adopts the time dependent concrete constitutive model which is derived in an incremental format by expanding the total form of stress-strain relation by the first order Taylor series with respect to the reference time. A good agreement between the measured and predicted results are observed and the effects of the bottom concrete placed at the negative moment region of the bridge girder are discussed.

Progressive failure analysis of steel composite double T-beam is performed to investigate the mechanical effects of steel composite fabricated in the webs of double-T beam to replace concrete placing forms. The analysis is based on nonlinear finite element scheme considering material nonlinearities of concrete, reinforcing bar and PS steel. Four-parameter strength envelope defines the hardening and softening phenomena of concrete with consideration of the various levels of confining pressures. Rankine maximum strength criterion defines the elasto-plasticity of PS steel and reinforcing bar, and Von Mises $J_2$ failure criterion for steel plate which wraps the concrete webs of double T-beam. A 6m long two-span steel composite double T-beam is analyzed and compared with the experimental results.

I-beam composite hollow slabs were proposed for long-span slabs and long-span bridges due to their higher stiffness and strength. However, the behavior of the composite slab is quite complicate and allowable stress design method is used for the design of the slab. In this paper, static tests on the composite hollow slabs were performed and their inelastic behavior was investigated. Ultimate strength of the composite slabs were evaluated and the contribution of each I-beam to the flexural strength of the slab was also estimated using the measured strain distribution. From the results of these experiments, I-beam composite hollow slabs can be designed by strength design method.

The composite structural system with reinforced concrete column and steel beam has some advantages in the structural efficiency by complementing the shortcomings between the two systems. The system, however, has also a lot of problems in earthquake-proof capacity and construction process because it is wet method of construction. So, this paper proposed PCS(Precast Concrete Column and Steel Beam) structural system with dry method of construction. Purpose of this study is to enhance merit and control failure mechanism by installing Dog-Bone on H-beam.

Precast Segmental method was developed in germany 1950s. This method has been adoptted in long span girder mainly owing to easy construction effect. But, so far, The limit exists that this method is constructed in a portion of span and hard conveyance and foundation. This study was performed to analysis behavior difference of two rectanglar section girder, spliced girder that was jointed 5-sliced 0.8m segment and monolithic girder that was produced in one body 4m span

Flexural-torsional behaviors of the typical architectural precast beam sections - inverted tee and rectangular - were compared. The inverted-tee beams were designed with a parking live load - 500kgf/$\textrm{m}^2$ and a market-1,200kgf/$\textrm{m}^2$ according to the currently used typical shape in the domestic market building site. The rectangular beams were also designed as the same bottom dimension and area, and reinforced for similar strength as in the cases of inverted tee beams. Two rectangular and two inverted precast pretensioned concrete beams were tested and analyzed

The stress-strain curve of concrete confined with both lateral ties and carbon fiber sheet(CFS) is different to that of concrete confined with only lateral ties or CFS. The objective of this study is to investigate the stress-strain relation of reinforced concrete columns confined by composite material. The main variable of the specimens was the content rate of lateral ties to CFS. In the test a total 24 rectangular specimens, which are all 148$\times$148$\times$300mm size. The test results indicated that while the compressive strength of specimens confined with both lateral ties and CFS increased proportionally to the aided amount of two materials, the maximum strain of specimens depended on the larger strain of lateral ties or CFS.

The R.C Building will be superannuated as time passes. This program is generated by propagation of cracks. In order to manage such cracks, time and efforts, expense, etc. are required. In this study, glass sensors were embedding in a model beam and column and leakage of fluorescence and adhesive material was investigated. Further, currents in glass pipe were observed to find the leakage of liquid in glass pipes. Progressive cracks generated by cause the fracture of glass pipes. Therefore, the liquid become to flow and electric current stops, and the cracked part of the member can be found easily. Moreover, the adhesive delays progressive cracking system that responds in air, and the life of a structure can be made to extend. The purpose of this research is to develop of low price sensors that can perform of self-diagnosis in addition to ability of concrete repair concrete to damage.

The purpose of this experimental study is to understand the flexural Behavior of structural deck plate continuous slabs (power deck plate slabs). The main variables considered in this test are thickness of the slab and the deck plate. Five specimens that have length of 600cm and width of 60cm were manufactured. Test results indicated that the ultimate flexural strength of power deck plate slabs was conservative compared to ACI flexural provisions. But, suitable arrangement of bar of top reinforcement is needed for crack control.

As reviewing of current trend on PC connection details, owing to effective stress transfer in the connection, it grow to increase that use of mechanical splices, reinforcements or welded splices, and prestressing. However such devices as reinforcement, mechanical splices entail not only more cost resulted from materials but also extra construction process so as to cause PC used method to lower competition against conventional method. Therefore more enhanced connection details which help working process simplified and construction cost reduced. In this research, as replace 9.3mm 7strand for reinforcement, it is attempt to devise connection detail which makes workability improve and confirm effective stress transfer in the region of connection. The experimental research is proceeded by partial tension test of specimen. The splice lengths of 7strand is decided to be variations. The flexural capability is verified to depend on spice length. An an appropriate splice length could be also determined as a precedent research on improving PC connection detail.

Evaluation of bond strength of a fire-damaged reinforced concrete structure for determining whether to reuse, reinforced, or abandon the structure is very important. Recently, calculating method for changes in bond strength of rebars is proposed by C. Chiang. The equation is relating the ratio of residual bond strength, R, to temperature, T, and exposure time, t. This study presented and verified a general process for evaluating damage to bond strength of RC structure arising from high temperature.

To analyze a bond stress-slip behavior between a reinforcing bar and concrete under repeated loading, pull-out fatigue test was performed. Major variables were repeated stress levels and cycle numbers. Test specimen was taken repeated constant amplitude loading before it was fractured by pull-out test. Increments of bond strength and slip according to repeated stress level and cycle numbers were analyzed. On the basis of test results, Local bond stress-slip relationship under repeated loading were formulated

Substantial experimental and theoretical work exists on the bond characteristics of FRP-concrete adhesive joints. Experimental studies show that the bond strength cannot always increase with an increase in the bond length, and that the ultimate strength is strongly influenced by the concrete strength. To solve this feature, analytic solutions based on fracture mechanics are widely used, and the local shear stress-slip curve with a softening branch is known as more rational model. The analytic solution, however, cannot describe various shapes of model curve. In this study, numerical method using interface element is introduced to express various shapes of model curve. Characteristics of adhesive joint is investigated for the shapes of the model curve and their parameters. And the numerical solutions are compared with the test results of CFRP sheet adhesive joints.

Results of 61 framed reinforced concrete shear walls with openings were reviewed to evaluate the current design provisions for nominal shear strength. Provisions for ACI 318-02 and AIJ Code pertaining to shear design of shear walls evaluated the applicability of shear walls with openings subjected to lateral and vertical loads. Evaluation of test results indicates that the nominal unit shear strength($\Psi$=1.0) calculated using the provisions of ACI and AIJ does not represent the observed shear strength well. Based on the limited database considered in this study, A reasonable lower bound to the shear strength of high-strength concrete shear walls is found to be $1.09\sqrt{f_{cu}}$ kgf/$\textrm{cm}^2$.

This paper describes a practical formulation of Non-Bernoulli-Compatibility Truss Model. Not only equilibrium conditions but also some approximations are employed to solve for the unknowns included in the proposed model. By assuming that the ratio of $V_a$ to V remains to be constant along the shear span, the relationship between $\alpha$ and z is mathematically established as an arch shape function. $V_m$ is also approximated to be an empirical value that is equal to the least membrane shear strength. The coefficient a is made utilizing a nonlinear finite element analysis. The adequacy of the model is examined by test results available in literatures, and the predicted values are shown to be in excellent agreement with the experimental results.

Previous researches about headed reinforcement have not been concerned about bond failure which is quite important is some cases. In this paper, failure mechanism including bond failure was presented in order to define the contribution of bond stress at the time failure occurs. Examined with design codes and test results, it is proved to be rational to consider the contribution of bond stress in determining the ultimate pull-out capacity of headed reinforcement. Direct adaptation of design code for anchor bolt without modification for the contribution of bond stress will lead to underestimate the capacity of headed reinforcement.

A reducing bearing angle theory for bond of ribbed reinforcing bars to concrete is proposed to simulate experimental observation. Analytical expressions to determine bond strength for splitting and pullout failure are derived, where the bearing angle is a key variable. As bearing angle is reduced, splitting strength decreases and shearing strength increases. The proposed reducing bearing angle theory is effective to simulate damage of the deformed bar-concrete interface and understand bond mechanism of ribbed reinforcing steel in concrete structures.

Recently, construction materials have been quickly advancing. Especially, the rate of development of cement based construction materials is much quicker than steel or composite materials. In order to optimize the ductility and strength of cement based materials, Micro-Mechanics based fiber concrete called Engineered Cement Composite (ECC) has been developed and studied extensively by many researchers in the field due to ECC's remarkable flexural strain and strength capacities, many leading nation (i.e., US, Japan and European countries have reached the point of being able to use ECC in actual constructions. But, due to the belated interest in the field, Korea is lagging behind the leading countries. ECC's ability to use its short fibers to bridge micro-cracks (50-80㎛ in width) allows great ductility and strength. In this study, it is confirmed excellency of ECC through the test of tensile strength.

The ACI 318 stress block parameters have been closely examined for validity of their values in evaluation of flexural strength and deformability. For this the conventional definition of stress block has been used. The comparison of parameter values between ACI stress blocks and the exact approach implies that an alternative idealization other than the rectangular stress block may be required.

Recently, there is a growing trend in the United States toward replacing latex additives in polymer-modified cement mortars with redispersible polymer powders. This movement is relatively new in the U.S. but is further advanced in Europe due to the more extensive use of cement and concrete in residential construction. Hitherto, in Korea - there is a very diminutive movement towards this growing trend. Thus, there is limited availability of data on redispersible polymer powders. This study investigates the effectiveness of redispersible polymer powder on improvement of the mechanical properties of modified mortar. It was concluded from the results of the experiments that the size of the dispersed polymer particles, variations in glass transition points (Tg), and variations in minimum film formation temperature (MFT) influenced the strength development of the modified mortars, and optimum strength in modified mortars using redispersible powders can be achieved when the Tg which accounts for the degree of powder flexibility is considered.

This study discusses the properties of shrinkage of high performance concrete with W/B and water content. According to results, drying shrinkage decrease of water content due to the influence of autogenous shrinkage. And drying shrinkage is reduced with a decrease of water content. As W/B decreases, autogenous shrinkage increases because shrinkage by hydration is generated greatly due to an increase of binder content. Also, as water content decreases, it is reduced because of a decrease of cement paste by cement content.

Cold weather can lead to many problems in mixing, placing, setting time, and curing of concrete that can have harmful effects on its properties and service life. Korean Concrete Institute (KCI) defines cold weather as a period when the average daily air temperature is less $4^{\circ}C$ and recommends to cast concrete with special care such as shielding, heating and so on. The use of high early strength cements may improve the rate of hardening characteristics of concrete in cold weather by making it possible to achieve faster setting time and evolving more hydration heat than ordinary Portland cement. Higher early strength can be achieved using Type III cement especially during the first 7 days. The strength increase property of Type III cement at low temperature was studied. As a conclusion the heat or heat insulation curing period can be reduced to 50~75%. So, it can be used for cold weather concreting to reduce construction cost and extend the construction season.

This study discusses the fundamental properties of high performance concrete and autogenous drying shrinkage with the kinds and the adding amount of superplasticizer. According to results, drying shrinkage hardly shows differences by the kinds of superplasticizer, and is reduced with an increase of the adding ratio. Autogenous shrinkage is reduced in order of HP>HN>HM, but does not make a big difference. As the adding amount of superplasticizer increases, autogenous shrinkage is reduced due to a decrease of cement content which influences on autogenous shrinkage seriously.

This study is intended to investigate the properties of concrete using AE Water Reducing Agent of Early-Strength Type. According to the results, as for the replacing method of mineral admixture, setting time is shortened faster in order of replacement for fine aggregate, combination and replacement for cement, and when AE Water Reducing Agent of Early-Strength Type is used, it is shortened by about 4 hours, compared with normal AE Water Reducing Agent Compressive strength is lower in the case of replacement for fine aggregate, but higher in the other case than that of plain concrete. And When AE Water Reducing Agent of Early-Strength Type is used, early compressive strength is very high in comparison to normal AE Water Reducing Agent. Early strength development is very favorable by the use of AE Water Reducing Agent of Early-Strength Type regardless of the replacing method of mineral admixture at $20^{\circ}C$, but at $l0^{\circ}C$, it is effective for Early strength development that W/B is lowered to below 45%, BS of 20% is replaced for fine aggregate, and AE Water Reducing Agent of Early-Strength Type is used.

The non-evaporable water and calcium hydroxides were measured by TG/DTA for studying the temperature effect on hydration of concrete mixture. The experimental parameters introduced in this study were the curing temperatures, ages and W/C ratios. The mixing temperature was also controlled to improve the efficiency of experimental work. While the mixture cured at high temperature showed the large quantity of non-evaporable water and calcium hydroxides at early age, the production rate of these hydration products was decreased as increasing the curing age, and the quantity of hydration product became smaller than that of the corresponding mixture cured at lower temperature at later age.

The purpose of this study is for the active use of the fly ash, which is a by-product of the combustion pulverizes coal thermal power plants, to compensate for the lack of landfill and for conservation of energy, by using fly ash as the supplementary cementitious material, and to prove its possibility as the related products of the cement. First of all, we examined strength development of Micro grinding fly ash by elevating its fineness and using $Na_{2}SO_{4}$ as an activator to elevate pozzolanic reaction of fly ash. Following fly ash replacement ratio and curing temperature we hope to prove its properties to suggest its possibility in the concrete and cement industry. In case of water curing, the more fineness and higher annexing of activator is, the higher strength is, and the higher curing temperature is the more pozzolanic reaction happens.

When concrete structures are exposed under marine condition for a long time, the steel in concrete is corroded due to the ingression of chlorides in the sea water. Because the damages of corrosion resulting from the chloride ion are very serious, many research have been performed. In this study, it was experimentally investigated that the mechanical and diffusion characteristics of concrete substituted with ordinary portland cement, silica fume and blast furnace slag to investigate the chloride ingress characteristics with concrete quality. Chloride diffusion coefficients in concrete shows increasing tendency as w/c ratio increase. Also test results indicate that blend of admixture become lower chloride diffusion coefficients in concrete as compared with normal concrete.

The compressive strength of concrete is used as the most fundamental and important material property when reinforced concrete structures are designed. It has been problem to use this value, however, because the control specimen sizes and shapes are different from every country. In this study, the effect of specimen shapes and sizes on compressive strength of concrete members was experimentally investigated based on fracture mechanics. Experiments for the mode I failure was earned out by using cylinder, cube, and prism specimens. The test results are curve fitted using least square method(LSM) to obtain the new parameters for the modified size effect law(MSEL). The analysis results show that the effect of specimen sizes and shapes on ultimate strength is apparent. The results also show stronger size effect in member when the casting direction is perpendicular to loading direction

CFRD face slab concrete has a much capability to occur crack due to drying shrinkage and vibrator compaction etc. Because crack of concrete induces structural problem and decrease durability of concrete, it is need to reduce crack of concrete. In the experimental study it was analyzed that the effect of curing of concrete and compaction on CFRD face slab concrete. As a results, it was found that control of construction condition into curing of concrete and compaction improved on construction efficiency of face slab concrete.

The purpose of this study is to examine the effect of aluminium sulfate on setting time and compressive strength of cement mortar as focused on formation of ettringite by the reaction between aluminium sulfate and calcium hydrate. The specific parameter was the addition ratio of aluminium sulfate to cement mortar. After specimens made by admixing aluminium of 0~7% by weight of cement, respectively, to cement mixtures, the experimental items such as setting time, compressive strength and heat of hydration in this study were carried out. As a result of this study, it is possible that aluminium sulfate could be added into cement mixture from a standpoint of increasing early compressive strength as considering the setting time and heat of hydration.

A chloride is an important deteriorating factor which governs the durability of the reinforced-concrete structures under marine environments. Also, the main penetration mechanism of chloride ion into concrete is a diffusion phenomenon. In this study, It is evaluated the diffusion coefficient of chloride ion in non-steady state by Fick's second law. Submergence method in salt water carried out in this experiment. Two types of cement which is different in mineral composition were used. In addition, the effect of mineral admixtures of blast-furnace slag and meta-kaolin was studied. In conclusion, the diffusion coefficient of chloride ion is much affected according to cement type and mineral admixtures, also, it is proved that meta-kaolin as well as blast-furnace slag is effective in preventing penetration of chloride ion.

Nowadays, hydration heat analysis using FEM is common in thermal crack control of concrete structure. Many kinds of general FEM programs for hydration heat analysis are used in practice. But there are some problems in this using. In this study hydration heat analysis of wall according to placement length are performed. In this results we could get two conclusions. First, general structures like wall having general geometry and construction condition have similar behavior. So it is not necessary to analysis thermal crack in every case. Second, the results of 2D analysis is possible to be applied instead of those of 3D analysis because the results of 2D analysis is similar to 3D analysis in long wall having about 15~18m or over length at 3m height.

Recently, a structure has been large and high under the improvement of construction technique. So, mass concrete constructions that a mat foundation thickness of structure is over 80cm have been many. Also, in the reason of high strength of concrete, a matter of thermal crack became an important task to be solved. In this study, we executed temperature and stress analysis of mat foundation. And we evaluated quantitatively about the possibility of thermal crack by using hydration heat analysis program. Because of this analysis technique, we could control skilfully the quality of mat foundation in a construction.

Quasi-instanteneously performed creep loading is probably one way to seperate the viscous and the plastic creep from the elastic deformation. For mature concrete no differences seem to exist depending on whether the loading is rapidly applied or not. At early age the plastic deformations probably dominate the deformation. A series of test have been done to measure the quasi-instanteneous deformation in concrete specimens according to loading durations and concrete ages. The present study indicates that even very short-term loading contains creep deformation. As concrete is younger and load duration is longer, the proportion of creep deformation in quasi-instanteneous deformation is increased.

The study is the results of accelerated tests and the specimens, mortars, are submerged in a 5% sulfuric acid solution. The deterioration of specimens is followed up by investigating the change in weight and compressive strength of the specimens and techniques such as XRD and XRF are used to examine the chemical changes. Sulfuric acid is a very aggressive acid that reacts with the free lime [$Ca(OH)_2$] in the concrete forming gypsum($CaSO_{4}.2H_{2}O$). This reaction is associated with an increase in volume of the concrete, and the corroded surface becomes soft and white. The results showed that the OPC mortar caused an decrease in weight above 18% and strength loss about 57%. On the other hand, AASC(alkali-activated slag composites) did not cause any decrease in weight and in the case of strength caused an decrease below 10%. In addition, this mechanical results was verified to XRD and XRF.

Steel slag is produced during steel making process. Compared with the blast furnace slag, converter slag has the expansibility due to the reaction with water and free CaO. Therefore it is specified in Standard Specification for Concrete in Korea that steel slag aggregate must not be used in concrete. In this study, atomized steel slag aggregate is conducted from converter slag by the atomizing method. Atomized steel slag and conventional converter slag are same in its composite by nature in the converter but compounds of the composite become different because of different method of slag treatment. Especially atomized steel slag aggregate overcomes expansibility that is the weak point for usage. It is researched whether it has the possibility, suitability for fine aggregate in concrete. Slump and air content are measured in fresh concrete, compressive and bending strength in hardened concrete. These is compared with control concrete with washed sand.

Recently, as quality river aggregates like sands and gravels become scarce, use of crushed stones and sands, seashore sands, and seashore gravels is increasing abruptly. And, aggregates recycled from slags and waste concretes are used. However, since the converter slag easily expands and breaks due to free lime, differently from the blast-furnace slag, it is not suitable for use as concrete aggregates. Since the atomized steel slag aggregate has slippery surface and spherical shape, the mortar flowing characteristics improved as the atomized steel slag content increases, without regard to the aggregates coarseness and water/cement ratio. The flow characteristics loss rate of the mortar manufactured from steel slag aggregates was similar to that of the mortar manufactured from washed sand only. The compact strength of the mortar manufactured from coarse PS Ball were larger than that manufactured from washing sand only.

In practice, recycled aggregate is not used for a structural member due to its high absorbability and abrasion. It is, however, highly expected that the usage of recycled aggregate increases as the processing technique of the recycled aggregate progresses. In this study herein, the compressive strength of the recycled aggregate concrete was investigated. Coarse aggregate was replaced with 100% of the recycled aggregate, and cement and fine aggregate was replaced with various amount. The specimen was steam-cured at $80^{\circ}C$. It was shown that the concrete can obtain desirable strength when fine aggregate was replaced with up to 60% of recycled fine aggregate, and when cement was replaced with up to 15% of fly ash.

Since regulation or specification for the reinforcing method are quite ambiguous, structural design for the reinforcement can be subjectively and arbitrarily conducted. Thus, reasonable limitation and guide for the quantity of the reinforcement are required for the safe use of the structure after repair. In order to guarantee the safety of the structural member several items should be considered; reinforcing limit to avoid the brittle failure, least required strength of the existing member before reinforcement in order not to fail under the new serviceability load condition when reinforcing steel plates or CFRP sheets are harmed or subjected to fire.

Flexural test and parametric study by FEM analysis on 6.0m long reinforced concrete beams strengthened by GFRP are reported in these tests. The selected variables are strengthened plate length, plate thickness. The effects of these variables are discussed. The results generally indicate that the flexural strength of strengthened beams is increased. The results of FEM analysis show that the more strengthening GFRP is the more stress of GFRP is decrease when failure mode is peeling failure.

The bridge columns with lap-splice reinforcements in earthquake suffered a brittle bond-slip failure due to deterioration of the lap-spliced longitudinal reinforcements without developing its flexural capacity or ductility. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP wrapping. The retrofitted columns using FRP wrapping showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the circumferential confinement effect of existing circular bridge pier strengthened with FRP wrapping for poor lap-splice details. The effects on the confinement of FRP wrapping, such as gap lengths between footing and FRP, fiber orientations, and thicknesses of FRP, were investigated by quasi-static experiments.

Confirmation of a damage degree and repair about a damage part are very hard for an underwater structure. And quality control of a construction is very complicated even if repair work is carried out on a damaged structure because repair work is carried out in water. If repair work is carried out while a defect part of the structure which there is in water keeps dry state, a efficient of repair is maximized. However, as for the repair technology about an underwater structure, a systematic researcher is not enough because of the environmental trouble. And, as for the effect about repair method to be applied to a currently underwater structure, it is not certainly proved. In this study The repair work of an underwater structure damaged applied the method that used a fiber panel form work. And a efficient of structure repaired was evaluated.

Fractal has the self-similar. It's character is used to explain the nature. The crack of the concrete is the nature appearance. So, we use the Fractal explain the character of crack of concrete. Many researchers study the Fractal. I study the many researcher's works and explain possibility of these works. We conducted a function that is the fractal fracture stress and finded some conclusions.

Triaxial behavior of concrete cylinders wrapped with FRP material has been investigated for the increase of concrete strength by lateral confinement. Using the model by Richart et al., a modified empirical equation was proposed to estimate the strength of concrete cylinders with FRP confinement based on the linear relationship between the concrete strength and lateral confining pressure. From the experimental stress-strain result of the cylinder specimens having similar confining pressure, less ductility was observed for higher strength concrete. But the compressive strength of the specimen was linearly increased by lateral confinement. The confinement effectiveness coefficient for the strength enhancement of the cylinders by FRP wrap was obtained as 2.27 from the regression analysis.

The strengthening method with CFS(Carbon Fiber Sheet) to reinforced concrete structures has a fatal defect. Strengthened beams have been almost failed far below their ultimate strength due to interface debonding failure between the surface of concrete and CFS. The purpose of this study is to investigate the failure mechanism and failure behavior of strengthened RC beam using CFS.

Carbon fiber sheet is attractive due to its good tensile strength, resistance to corrosion, and low weight. The strengthening of concrete structures with externally bonded carbon fiber sheets is increasingly being used for repair and rehabilitation of existing structures. However CFS strengthened beams break down under the service loads. As rupture strain is not reached ultimate value, reduction of the tensile strength is recommended. This study evaluate CFS tensile strength reduction factor which is required to analyze bending moment.

This study is to develop a strengthening method for RC slab bridges and rigid-frame bridges with external prestressing. In this study, we design the slab specimen that have a strengthening of the DB-13 and set up the longitudinal tendons placed on both side of slab strengthens the whole bridge, and lateral tendons placed under the slab strengthens the middle of slab, and conveys the load at middle slab to both sides. Structural analysis for the tensile force for strengthening were analysed and we know that displacement and strain was improved from this test. This method has no upward roof work, so it is very convenient for installing. And no spaces under the slab are need, so it is good for shallow slabs which has less space inder the slab.

This study was carried out to suggest the effective reinforcing method which can evaluate the tensile capacity of cast-in-place anchor with cracks. Currently, cast-in-place anchor is used widely for the fastening of equipment in Korean NPPs. 26 test specimens with a single anchor under 4 cracked conditions are prepared using plain concrete. The distance between crack and anchor and reinforcing materials were selected as the main test variable. The tensile force was applied using a actuator with a capacity of 100 tonf using a displacement control method of 0.5 mm/min velocity. Test results from this result show the combination of carbon plate and epoxy will be more available for repair and reinforcement of equipment foundation system in NPPs. Further experimental work is indeed involving the epoxy injection effect and adjustment of reinforcing location of carbon sheet.

The degree of changes in mechanical properties of fire-damaged reinforced concrete column depends mostly on sectional geometry, duration exposed to fire, and moisture containment. In order to reasonably assess the deterioration of structural capacity of fire-damaged reinforced concrete column, it is necessary to develop a theoretical model predicting column behavior based on nonlinear heat transfer equation in addition to the traditional mechanics. This research focuses on the development of theoretical model to predict moment-curvature relations of fire-damaged reinforced column. The model is used for the assessment of structural capacity of fire-damaged column in terms of moment-curvature relations and PM interaction curves.

In this paper, the linear and nonlinear strut-tie model approaches for the analysis and design of concrete structures are suggested. The validity of the approaches are examined through the strength analysis of four dapped-end beams tested to failure. According to the analysis results, the nonlinear strut-tie model approach which takes the various characteristics of nonlinear behaviors into account in the analysis and design of structural concrete and predicts the strength of structural concrete proven to be an effective method for structural analysis and design.

Deep pile caps usually contain no transverse shear reinforcement and only small percentages of longitudinal reinforcement. The current design procedures including ACI 318-02 for the pile caps do not provide engineers with a clear understanding of the physical behavior of deep pile caps. In this study, the failure strengths of nine pile cap specimens tested to failure were evaluated using 3-dimensional strut-tie models. The analysis results obtained from the present study were compared with those obtained from several design methods, and the validity of the present method implementing 3-dimensional strut-tie models was examined.

A new Direct Nonlinear Strut-Tie Model design method performing iterative calculations using secant stiffness was developed. Since basically the proposed design method uses elastic analysis, it has the advantages of convenience and stability in numerical analysis. At the same time, the proposed design method can accurately estimate the strength and ductility demands on the members because it analyzes the inelastic behavior of structure using iterative calculation. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. The proposed design method, as an integrated method of analysis and design, can address the earthquake design strategy devised by the engineer, such as ductility limit on each member. Through iterative calculations on the structure preliminary designed with member sizes, the strength and ductility demands of each member can be estimated so that they satisfy the given design strategy, and as the result economical and safe design is achieved.

In this study, the experimental results were simulated by using a nonlinear analysis programs IDARC 2D and RUAUMOKO 2D. These programs use a global Takeda-like model. The objectives of this study is to verify the correlation between the experimental and analytical responses of reinforced concrete (RC) frame and to provide the calibration to the available static inelastic analysis techniques. The evaluation of the accuracy of analytical simulation by IDARC 2D and RUAUMOKO 2D leads to the conclusion that the global behaviors can be, in general, simulated with limited accuracy in the linear analysis as detailing.

In this study was compared with result of instrumentation and numeral analysis of non-weir of concrete dam to prepare a plan for total safety estimation method such as reliability estimation of numerical analysis result, characteristics of dam behavior and etc. The results of instrument analysis of displacement and stress on N.H.W.L was similar to that of numeral analysis.

For a realistic and reasonable determination of condition and status, assessment system should include load modeling for the loads acting on slab bridges due to traffic loads, evaluation system for fatigue, and determination of remaining service life. The purpose of the present study is to develop a realistic expert system which can estimate reasonably the fatigue and service life of slab bridges, based on the load models that are derived from the traffic loads.

In case to look at considering affects of skew angles into the curved bridges, this study mainly focalized to compare and analyze of the influence of skew angles to curved bridges along with analysis of the behavior of entire construction in accordance with changes of skew angles and curvature. With explanation of macroscophic behavior of curved bridges with skew angles through this study, it is mostly to grasp with characteristics and structural weaknesses of skew curved bridges compared with straight skew bridges.

In a slender column under sustained eccentric compression, the deformations caused by creep and shrinkage can lead to an increase in the loads on the structure and a reduction in strength. This study presents a methodlogy and improved computer program for the analysis of time-dependent long column in considering slender effects and nonlinear behaviors. In this result, when slenderness ratio is greater than 80, we know that magnified moment methods may be not applied in long columns.

ACI design code is not capable of evaluating the inter-effects between concrete and torsional reinforcement on the torsional resistance of the reinforced concrete beams. In this study, the failure strengths of the ten reinforced concrete beams subjected to pure torsion were evaluated using 3-dimensional strut-tie models. The analysis results obtained from the present study were compared with those obtained from the ACI design code. The comparison showed that the accuracy and performance of the present method were better than the ACI design code. Thus, the method implementing a 3-dimensional strut-tie model can be possibly applied to the analysis and design of the reinforced concrete beams subjected to pure torsion as a rational design method.

Experimental tests on the high strength self-compacting concrete with light-weight fine aggregate and light-weight coarse aggregate(LHSSC) were performed with slump-flow, reaching time to the slump-flow of 500mm, V-funnel dropping time and U-box difference level and compressive strength. LHSCC with light-weight fine aggregate of 75% and light-weight coarse aggregate of 100% was only satisfied with the property conditions of second self-compacting concrete(SCC), like as flowability, resistance to segregation and filling ability. The 28-day compressive strength of LHSCC indicated above 300kgf/$\textrm{cm}^2$ in all concrete mixtures, and it was increased to increase the replacement ratio of light-weight fine aggregate or to decrease the replacement ratio of light-weight coarse aggregate. Therefore, for satisfying the properties of fresh SCC and hardened concrete with above 350kgf/$\textrm{cm}^2$, it would expected that the replacement ratio of light-weight fine aggregate and light-weight coarse aggregate will be determined with 50~75% and 25~50%, respectively.

Concrete with low water to binder ratio (W/B) is prone to large autogenous shrinkage. Early age cracking of concrete would be caused by tensile stress induced by large autogenous shrinkage under restrained condition. Therefore, it is necessary to measure autogenous shrinkage to control the early age cracking of concrete. An objective of this study is to investigate the effects of W/B and blast furnace slag (BFS) on autogenous shrinkage of concrete. Autogenous shrinkage of concrete with various W/B ranging from 0.42 to 0.27 and BFS contents of 0, 30 and 50% were measured. Test results show that the autogenous shrinkage of concrete increases as the W/B decreases, and all BFS concretes showed larger autogenous shrinkage than OPC concretes with the same W/B. Moreover, the higher BFS content, the larger autogenous shrinkage.

The purpose of this study is to clarify the effect of the emulsifier ratio on strength properties of the polymer-modified mortars using methylmethacrylate-ethyl acrylate(MMA/EA) latexes, and to obtain basic data necessary to develope appropriate latexes for cement modifiers. Polymer-modified mortars using MMA/EA latexes are prepared with various monomer ratios, and tested for air content, flexural and compressive strengths. From the test results, we knew that the water-cement ratio is decreased and the air content is increased with an increase in the amount of emulsifier. In general, the superior flexural and compressive strengths of polymer-modified mortars using MMA/EA latexes is obtained at a bound MMA content of 60 percent and a emulsifier ratio of 6 percent.

This study deals with the mechanical properties of polymethyl methacrylate(PMMA) mortars without crosslinking agent. Waste expanded polystyrene(EPS) is used as a multifunctional admixture such as a thickener, a extender, a shrinkage reducing agent, a assistant to polymerization. PMMA mortars are prepared with various EPS contents of binder and subjected to a dry and a dry/heat combined curing, and tested for working life, flexural and compressive strengths. From the test results, the working life of PMMA mortars without crosslinking agent is shortened with raising EPS content of binder. The flexural and compressive strengths of the PMMA Mortars are decreased somewhat with increase in the EPS content. PMMA mortars with good mechanical properties could be manufactured without any crosslinking agent and their properties would be controled by adjusting EPS content of binder.

MMA-modified fiberglass-reinforced plastic composite pipe was produced by using the binder of MMA-modified unsaturated polyester resin in which low viscosity MMA was added to unsaturated polyester resin. Sixteen specimens were made of polymer mortar and fiberglass-reinforced plastic by the centrifugal method. For these specimens the external strength tests were carried out by taking the core thickness consisting of polymer mortar and the fiberglass content per unit area as experimental variables to figure out the effect of variations of these variables influencing on flexural rigidity that is an important property for the composite pipe. Results of this study are believed to provide the basic data for more economical and practical design of MMA-modified fiberglass-reinforced plastic composite pipe.

This paper proposes rheological creep and shrinkage model of FCM bridges made for HPC about 40Mpa. The proposed model separates time dependent part with characteristic material part and regards main variable as elastic modulus, which represents material characteristic and history. To find parameters of the model, we had creep, shrinkage and basic material tests about four FCM bridges. All specimens were tested with same condition, after 3days, 28days and 90days of curing. Also, exposed condition and closed condition were separately given to compare the data of each bridge. Finally, all creep data of four FCM bridges were compared to proposed rheological model and other proposed world code models, AASHTO, ACI, CEB-FIP, JSCE and etc.

This study has focused on the possibility for recycling of tailings from the Sangdong tungsten mine as powder of self-compacting concrete(SCC). The experimental tests for slump-flow, reaching time to the slump-flow of 500mm, V-funnel and U-box were carried out in accordance with the specified by the Japanese Society of Civil Engineering(JSCE). The result of this study, in case of SCC mixed with tailings, slump-flow was decreased with increasing mixing ratio. But reaching time slump-flow of 500mm, V-funnel and U-box were satisfied a prescribed range. The mechanical properties including compressive strength, splitting tensile strength and static modulus of elasticity were checked with the requirements specified by Korean Industrial Standard(KS). The compressive strength of SCC was decreased with increasing replacement, splitting tensile strength and static modulus were similar to those of normal concrete.

Polymer concrete has more useful than cement concrete in the strength and durability. So, it is widely utilizing as panel for wall, manhole for communication, foundation and underground connection box, etc. But polymer concrete is a defect that is disadvantageous in economical aspect because cost of resin is expensive. Polymer concrete (PC) using unsaturated polyester resins based on recycled polyethylene terephthalate(PET) plastic waste were used in our study for grasping its mechanical properties such as compressive strength, tensile strength, flexural strength and chemical resistance was tested by dealing with 20% HCl, 30% NaOH. As a result of it, compressive, tensile and flexural strength of PC indicated 752kgf/$\textrm{cm}^2$, 80kgf/$\textrm{cm}^2$ and 243kgf/$\textrm{cm}^2$ kind of satisfaction successively. Also, properties of chemical resistance are superior to those of cement concrete.

Polymer concrete using wastes PET recycled resin that is, in general, more excellent mechanical properties than portland cement concrete. A lot of works are carried out about short-term properties of polymer concrete, however, little work has done to define their long-term properties, that is, sustain load such as creep. In this study will show the data that can long-term behavior of polymer concrete by short term creep test of polymer concrete that was affect to the temperature and the time to predict to long-term creep behavior. Then prediction equation was similar tendency that was comparing to short-term creep test and long-term creep test.

The objective of this study is to investigate the basic properties of polyester mortars using ground calcium carbonate(GCC), blast furance slag(BFS), fly ash(FA), ordinary portland cement(OPC) as fillers. Particle size distribution, particle shape and resin absorption of GCC, BFS, FA and OPC are checked. Polyester mortars with GCC, BFS, FA and OPC are prepared with various MEKPO content and tested for working life. The flexural and compressive strengths of the polyester mortars with MEKPO content of 0.5phr are evaluated. As a test result, the average sizes of GCC, BFS, FA and OPC are 9.7$\mu\textrm{m}$, 11.6$\mu\textrm{m}$, 21.2$\mu\textrm{m}$, 29.9$\mu\textrm{m}$. Resin absorption of FA is 1.5times larger than other fillers. The polyester mortar with FA at a MEKPO content of 0.5phr has the longest working life and the maximum flexural and compressive strengths.

This research is to evaluate the seismic performance of reinforced concrete bridge piers with lap-spliced longitudinal reinforcement steels in the plastic hinge region, and to develop the enhancement scheme of their seismic capacity. Six circular columns of 0.6m diameter and 1.5m height were made with two confinement steel ratios. They were damaged under series of artificial earthquakes that could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading simultaneously under an axial load, P=$0.1f_{ck}A_{g}$, and residual seismic performance of damaged columns was evaluated. Test results show that RC bridge piers with lap-spliced longitudinal steels behaved with minor damage even under artificial earthquakes with 0.22g PGA, but failed at low ductility subjected to the subsequent quasi-static load test. This failure was due to the debonding of the lap splice. The specimens externally wrapped with composite FRP straps in the potential plastic hinge region showed significant improvement both in flexural strength and displacement ductility.

This paper discusses laboratory evaluations to assess the physical properties of antiwashout underwater concrete (AWC) containing pozzolanic materials such as fly ash (FA), blast furnace slag (SG) and metakaolin(MK). For the experiments, pH value, suspended solids, slump flow, efflux time and compressive strength were tested. According to the results from compressive strength test, MK10 showed the very high compressive strength characteristic during the entire curing days, but the rate of strength development was decreased as time goes by.

Portland Cement Concrete (PCC) pavements have the advantage of durability and superior surface friction when compared to most dense-graded asphalt. However, data collected to date generally show PCC pavements to create more noise than asphaltic surfaces. As the results of research, surfaces of exposed aggregate, tining and grooving concrete pavements appear to provide better noise quality characteristics as well as good frictional characteristics and durability. In this paper, several methods of texturing were considered to reduce tire/pavement noise. As the results of this paper, PCC pavements with special texturing have superior surface friction as well as noise reductions when compared to conventional PCC pavement. Especially, Exposed Aggregate Concrete (EAC) surface appears to provide better noise quality characteristics. Conclusively, if overall noise and safety are considered simultaneously, EAC pavement that provides satisfactory friction as well as better noise reductions is suggested.

Creep Poisson's ratio reported by previous experimental studies on multiaxial creep of concrete was controversial. The Poisson's ratio is very sensitive to small experimental error that is inevitably induced, and the sensitivity may cause the controversy. It is difficulty to find out the properties on multiaxial creep of concrete. Therefore, a new approach method to analyze the test results is needed to precisely understand the properties on multiaxial creep of concrete. In this study, microplane model is used as a new approach method in analyzing the multiaxial creep test data. The six data sets extracted from the literature are fitted from regression analysis. Double-power law as a model representing volumetric and deviatoric creep evolutions on microplane is used, and six parameters in volumetric and deviatoric compliances are determined on the assumption that the volumetric and deviatoric creep strains are linearly proportional to corresponding stresses. The optimum fits give very accurate description of the test data. The Poisson's ratio calculated from the optimum fits varies with time and does not depends on the stress states, namely, uniaxial, biaxial, and triaxial stress states. Regression analysis is also performed on the assumption that the Poisson's ratio remains constant with titre. The constant Poisson's ratio can be use in practice without serious error.

This study discusses the use of anti-shrinkage agent as the method to reduce autogenous and drying shrinkage. According to results, as for the fundamental properties of high performance concrete, fluidity and strength decrease with an increase of the adding ratio of anti-shrinkage agent, but air content increases. Compared with plain concrete, autogenous and drying shrinkage are reduced by 12~52% and 4~22% respectively upto the adding rario of anti-shrinkage agent of 2.0%. When expansive additive is added by 5.0%, they are also reduced by 38~95% and 15~50% respectively. Therefore, as expansive additive of 5.0% and anti-shrinkage agent of 1.0% are added to high performance concrete of around W/B 30%, it is considered that fluidity and strength are hardly influenced, and in addition, crack by shrinkage can be prevented effectively.

This study discusses the fundamental properties of cement mortar with the kinds and adding ratio of stabilizing agent of recycled water. According to the results, fluidity and air content hardly make difference by the kinds and adding ratio of stabilizing agent. When recycled water is used, setting time is shortened slightly in comparison with plain mortar because of an increase of fine particle. And it is similar to the use of recycled water in the case of A, Band D(stabilizing agent), but shortened significantly in the case of C. Also, it does not show difference with variation of the adding ratio, but as the adding ratio increases, it approach to the value of plain mortar. When recycled water is used, compressive strength is similar to plain concrete, and it shows the larger value in order of D, C and A. As the adding ratio of stabilizing agent increases, it decreases at 3days, but increases at 7 and 28days. However, at the adding ratio of 0.5%, it decreases, instead. Length change ratio by drying shrinkage increases in the case of B in comparison with plain mortar, but is similar to plain mortar in the other stabilizing agent. As the adding ratio of stabilizing agent increases, it decreases, however, increases at the adding ratio of 0.5%

This study is intended to investigate application of mica waste(MS) to fine aggregate for mortar by comparing it with cement mortar in which crushed sand(CS) and river sand(NS) are used. According to the results, as the physical properties of aggregate, specific gravity is large in order of MS, NS and CS, absorption ratio in order of MS, CS and NS, and unit weight and solid volume percentage in order of NS, CS and MS. In the case of MS mortar, mechanical properties, drying shrinkage and heat conduction ratio are reduced, but the radiative amount of infrared light is excellent compared with NS mortar. Fluidity and unit weight of MS mortar is larger than those of CS mortar, and strength does not make differences. Length change by drying shrinkage is larger, but heat conduction ratio and radiative amount of infrared light are smaller than CS mortar. Thus, it proves that MS can be used in place of NS and CS, but its quality is deteriorated slightly.

The results of an experiment on the sound absorption of the porous concrete using recycled aggregates and its influence on the compressive strength are reported in this paper. The content of recycled aggregate of 0, 10, 30, 50 and 70%, and the design void ratio of 30 percent for a given size of aggregate were used. In the compressive strength, an aggregate of the size of 5~13mm is much higher strength than that of the 13~20mm, In sound absorption experiment, the sound absorption ratio was is subjected to decreased as the content of recycled aggregates was increased. As a result, Porous concrete using recycled aggregates and by-products sufficiently have the performance of sound absorption.

The results of an experiment on the sound absorption of the porous concrete and its influence on the compressive strength are reported in this paper. Two different sizes of coarse aggregate of 5~13, 13~20mm, and the design void ratio of 20, 25 and 30 percent for a given size of aggregate were used. In the compressive strength, an aggregate of the size of 5~13mm is much higher strength than that of the 13~20mm, In the sound absorption experiment, the size of aggregate of 5~l0mm is much higher sound absorption than that of the 13~20mm. The sound absorption ratio was increased as the design void ratio. As a result, Porous concrete sufficiently have the performance of sound absorption.

Most concrete is recently made of an aggregate which is properly absorbed, and carried in it in order to do capability at every fields. We have been close to demand new capability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high quality aggregate. Therefore, for solving the problems we apply to a packing method for using dried materials. That is to say it is a kind of making into an instant. In this study, There is a purpose to present fundamental data, comparing and analyzing a phenomenon about aggregate absorption following the rate of adding water, for using existing materials.

The propose of this study is to discover the extrusion lightweight concrete panel mixing by admixture. The standard of water ratio 50% and weight substitution 0%, 10% by Fly-ash. When the products are manufactured, it is used to maintain its form weight substitution and addition among the viscosity agent each Silica-fume and Hydroxy propyl methyl cellulose. The study is basic properties and performances of extrusion lightweight concrete panels. Testing methods was specific gravity, water absorption, resistance to impact, thermal conductivity, and sound insulation.

The purpose of this work is to introduce some fundamental stereological concepts to quantify damage parameters using X-ray CT(Computed Tomography) in the scope of CDM(Continuum Damage Mechanics). X-ray CT is a completely nondestructive technique for visualizing features in the interior of opaque solid objects, and for obtaining digital information on their 3D geometries and properties. Many researchers have introduced lots of damage parameters to model the mechanical behavior of deteriorated materials. Those damage parameters can be represented in many forms such as specific void or crack surfaces, the spacing between cracks, the specific damaged surface area, the specific damaged surface area tensor, the mean solid path among the damaged surfaces and the mean solid path tensor. Despite of many accomplishments in CDM since there is no the systematic experiment, it have limitations in application. In this situation, X-ray computed tomography is highlited by many researchers and applied in a wide range of materials including rock, bone, ceramic, metal, soft tissue and concrete.

The rheological properties of cement paste system mixed with mineral admixture for the purpose of increasing the strength and improving durability and rheology of concrete were investigated. The results were as follows: The rheological properties of one-ingredient paste system were improved with increasing the dosage of superplasticizer. For two-ingredients paste system, increasing the replacement rate of BFS(blast furnace slag) and FA(fly ash), the yield value and plastic viscosity were decreased compared with non-replacement. In the OPC(ordinary portland cement)-SF(silica fume) system, increasing the replacement rate of SF, the plastic viscosity and yield value increased linearly. In three-ingredients paste system, both OPC-BFS-SF and OPC-FA-SF system, the rheological properties were improved compared with the only replacement of SF. Both two- and three- ingredients paste system, the rheological properties using BFS were improved more than FA.

Dehydration and micro crack thermal expansion occur in cement hydrates of concrete structure heated by fire for a long time. The characteristic of concrete exposed to high temperature can be analyzed from distribution of porosity and pore size. Porosity showed a tendency to increase irrespective of specimen types. This is due to both the outbreak of collapse of gel comprising the cement and a micro crack by heating. Porosity did not affect the variety of specimen and increased with the same tendency throughout every specimen. In addition, the deteriorate of compressive strength resulted from increase in porosity

Recently, advanced systems for water treatment are introduced for water quality improvement. One of those systems is water treatment method using ozone($O_3$). For it has strong oxidizing energy, it is necessary to have materisl stability against $O_3$. In this paper, epoxy resin specimens using as anticorrosive material of concrete structure for drink water are used to serve as a material of deterioration evaluation. It is to be studied weight loss, surface corrosion of specimens, ingredient analysis of floating particle, a solute of chemical ingredient by way of accelerated ozone testing. As the results of experiment, specimen weight is decreased. The surface of specimen is eroded heavily and showed a loss of gloss and floating particle, and in the stability for drinking water, harmful ingredient is not detected in the water.

In this study, we encapsulate the core materials which have long term resisting properties to the bacteria. We also try to apply those capsules to the mortar and concrete which is using for the structures and ornament materials. Various wall thickness, shape, and membrane structure of microcapsule are tested and construction properties of the mortar and concrete which contain microcapsules are examined. Finally the microcapsules with anti-bacteria which can be used for mortar and concrete are developed.

Functions of the building structures are recently expended, because the structures are getting larger and people's indoor staying times are getting longer. Therefore, various functional materials such as yellow mud, carbon soot, and jade are widely used. But functions of those materials have not permanent and continued an effect. Specially, the development of construction materials containing anti-insect is highly important to delight the environment of residence. This research try to examine to develop the mortar and concrete which contain microcapsules with long-term effect of anti-insect.

When fresh concrete is exposed to sufficiently low temperature, the free water in the concrete is cooled below its freezing point and transforms into ice, which causes decrease in compressive strength of concrete. Of the many influencing factors on the loss of compressive strength, the age of concrete at the beginning of freezing, water-cement ratio, and cement-type are significantly important. The objective of this study is to examine how the these factors affect the compressive strength of concrete frozen at early ages. The results from the tests showed that as age at the beginning of freezing is delayed and water-cement ratio is low, the loss of compressive strength decreases. In addition, concrete made with high-early-strength cement is less susceptible to frost damage than concrete made with ordinary portland cement.

The objective of in this study makes investigation into the characteristics of antiwashout underwater concrete as to mix proportion, casting and curing water through experimental researches. in this study, sea sand is blended with river sand, crushed sand is blended with river sand and sea sand as to investigate the quality change and characteristics of antiwashout underwater concrete with variation of blend ratio of sea sand and crushed sand(0, 20, 40, 60, 80, 100%). Higher compressive strength is measured following the order of river sand, sea sand, crushed sand regardless of age and casting condition. Except for case of using river sand, blended ratio of 40% is appeared on most compressive strength.

The effects of substituting cement with fly ash(10%, 15%, 20%) and different fiber addition(polypropylene, cellulose, poly vinyl alcohol), on the control of microcrack and enhanced durability performance of face slab concrete in CFRD was studied experimentally It was conducted experiments of plastic shrinkage of mortar and concrete, and drying shrinkage of concrete. Also, durability test were carried out the chloride permeability, abrasion resistance and freeze-thaw repetition. Through the experimental results, it was concluded that ploy vinyl alcohol fiber containing concrete was the most effective mixture in control of cracking and durability.

Chloride diffusivity is one of the important properties of concrete affecting the durability of a structure. The diffusivity for porous materials is determined conventionally by immersion in a solution. However, this method is complicate and time-consuming, often requiring months or years to obtain results. Thus, the application of colorimetric method to estimate the apparent diffusivity of chloride ion was verified in this study. The result reveals that the apparent diffusivity of chloride ion can be predicted to use colorimetric method. Additionally the colorimetric method is capable to predict the profile of chloride ion.

The purpose of this study is measures vulcanization properties of matter by time of room temperature vulcanization synthetic rubber sheet and the evaluation adhesive properties tested by concrete surface moisture. Also, Its estimated reaction mechanism and adhesion performance between protection mortar and waterproofing layer. The results showed that vulcanization progressed in room temperature and adhesion intensity increased regardless of moisture condition.

User's demand, as a maintenance for durability of construction and a comfortable life, and an incentive systems for new waterproofing system incite waterproofing company to evolve new waterproofing system that is upgraded waterproofing quality by getting advantages for the existing waterproofing systems. There are seven new waterproofing systems for building roof to be authorized from Ministry of construction & transportation. Those are multi-layers waterproofing system, and five of those are the insulation type. A trend of new waterproofing systems for building roof is multi-layers waterproofing system insulated.

This study is analyzed about the factor of adhesive strength characteristics, curing time, asphalt application, test temperature which are liquid waterproofing membrane of rubber-asphalt and chloroprene-rubber type for concrete bridge deck. According to the results, curing time is shorter, adhesive strength is less in chloroprene-rubber type. And also chloroprene-rubber and rubber-asphalt type are showed high adhesive strength in low temperature.

This study deals with the method of test for waterproof agent and admixture of cement, and especially, the effect on bond strength between waterproofing layer and mortar or concrete substrate in building construction. Quality of that has been managed according to it of construction standard manual, housing construction manual, 건, and Q until performance of that is specified by law as KS F 4923. Therefore this study focus on the quality and trend for a fatty system and PCM(Polymer Cement Mortar)

One of the most important reasons that CFT is used in many conditions is by using that we can achieve the effect, which reduce the section of the member. This research purpose to find the most ideal composition, which is achieved by the investigation in the concrete's property of matter like ability of Slump, Slump Flow, Air content, Bleeding, and Settlement when the high strength of concrete which is over 80㎫ is used in the CFT column.

Contemporary, architecture calls for a wide range of surface textures and treatments. A surface compatible with the architecture's design may vary from a glass-smooth finish to one requiring special sculptured ornamentation. These surfaces require many different types of form sheathing and lining. The purpose of study development new design form and made elaborateness shape. Easy to used in field that architecture finish material not used expect effective reduce of working hours, personnel expenses, architecture finish material, cost. though this study, we have figured out the best mix proportion for durability and glossability of glossing exposure concrete.

In many countries a considerable amount of demolition wastes is generated and wastes concrete constitutes a significant proportion of the construction waste. Therefore, the necessity for the use of recycled aggregate in concrete arise and the reuse of a waste concrete may solve the problems of environmental pollution and shortage of natural aggregate. According to this study is to examine the possibility of site adoption microwave-use early strength estimation method. Based on the existed study related the plain concrete, the interrelation between recycled aggregate concrte and microwave-use early strength estimation method is required.

We have developed and applied the super high early strength concrete overlay pavements for repairing asphalts pavements within 24hours. This pavements repairing method by the super high early strength concrete have already applied in U.S.A, japan, England, etc. The super high early strength concrete developed by Ssangyong cement co. for repairing pavements speedily have replaced at No. 2, 17 pavements in managing by Sunchoen national pavements management office. In the results, all of works have finished within 16~24hours after intercepting traffics and all of traffics was opened to be hamonious. In present, this pavements is sound and strong

Problem of repairing by boring is that it deteriorates stabelety and durability of structure by permeation of seawater from underneath after damage and repair of reinforcing rod regarding of spot. The purpose of this study is to improve the porblem by using the repair method of general boring to mend the of large mat basis. Direction of thes experiment is to apply the new repair material and the method to control the blazing fire factor caused by the crack from the foundation of large mat and also to estimate it's integrity. New method of construction is method of contruction that do speace scurity in vertical drilling and bottom useing water jet. New material used bantonite and rubberized asphalt. Test result existent repair method of construction large size mat basis perforation is difficult and reinforcing rod can be damaged coule there were a lot of problems with re-water leakage of crack repair region, but overcomes existent short coming by method that apply in this study.

The objective of this study is to evaluate the injection performance of crack repair method in concrete structure. To improve the quality of the concrete structure caulking material was injected into the crack of building that were planned to be demolished and injection properties of various repair method were compared and assessed according to type of crack. Results from the test showed that when cracks and injection port were integrated and the injection port wasn't blocked repair material was able to be injected even below around 40㎏/㎠ pressure. Moreover, effective pressure each type of packer showed wide range varying from 200-400㎏/㎠. As for drill method for injection port, core drill method has shown to be more effective compared to the air pump method

In flat-plate floors, slab-column connections are broken down with a brittle shear failure. And it can cause the collapse of the whole structures. Thus, the proper method of shear reinforcement in flat plate-column connections must be required. The objective of this study is to compare shear reinforcement specimens using lattice bars to no shear reinforcement specimens in view of shear strength and ductility of the flat plate-column connections. The test results have shown that shear reinforcement specimens varying $\rho$, $b_0$/d and $C_1$/$C_2$ increase in shear strength by 36.85% and in ductility by 9.16 for no shear reinforcement specimens on the average. This results confirm the effectiveness of this type of shear reinforcement in improving shear strength and ductility.

It is reported that the amount of reinforcements for domestic PSC box girder bridges is used two times more that those for foreign PSC box girder bridges, which is considered to be irrational and uneconomical. Therefore, we have come to the conclusion through this study that the advanced design direction can reduce the amount of reinforcements under the condition that the static load test and the nonlinear analysis for the specimen of the PSC box girder bridge with reduced reinforcements which is designed by advanced design direction was carried out in order to verify the validity of the advanced design direction.

For implementation of the strut-tie model approach to the practical analysis and design of structural concrete, the effective strengths of concrete struts in a strut-tie model, which have a crucial effect on the determination of strut and tie forces and the validity verification of strut-tie model's geometric compatibility condition, have to be determined accurately. In this study, the validity of the methods for determining the effective strengths of concrete struts was evaluated by conducting the strut-tie model analyses of the three reinforced concrete deep beams tested to failure with the effective strengths of concrete struts obtained from the suggested determination methods.

The floor thickness in residential buildings may not satisfy the floor vibration criteria even though the thickness is determined by the serviceability requirements in current design provisons. Thus it is necessary to develop the procedure to determine slab thickness that satisfies the floor vibration criteria. In this study provide the methods to determine the slab thickness that satisfies the vertical floor vibration criteria for several sizes of flat plate floor system. Randomness inherent in young modulus of concrete and heel drop intensity was accounted. For this purpose Monte Carlo simulation procedure was adopted.

Recently, hybrid concrete structures such as a concrete-filled steel tubular(CFT), a steel reinforced concrete(SRC) and a composite material are popular in structure applications. They also have merit of high strength, high ductility, and large energy absorption capacity. But the analysis of hybrid concrete structures is very difficult owing to the complex behavior of concrete under passive confinement. This paper has analyzed CFT, which receives passive confinement using Tri-Surface concrete model for three dimension finite element analysis. By the result of that, the proposed model was properly forecasted a concrete behavior that receives passive restraint as well as non-linear analysis of concrete which receive uniaxial stress and high active confinement of 400Mpa. If the model through the steady study is set up especially on the factor of concrete under passive confinement, the proposed concrete model will be surely useful for analysis of the hybrid concrete structures.

In the seismic response analysis, the artificial earthquake time history is generated to do the exact seismic analysis for the complex structural system like as containment building. In the present study the several simulated earthquakes are generated by use of SIMQKE program and the time history dynamic analysis of containment building is performed. Also, the seismic responses are statistically analyzed. The seismic response uncertainty arisen from the simulation of earthquakes is one of major uncertainties and the statistical description is needed to account for the random nature of earthquake.

Steel-concrete composite columns are used extensively in modern buildings. Extensive research on composite columns in which structural steel are in concrete have been carried out. In-filled composite columns, however have received limited attention compared to encased columns. In this paper, interrelationship of parameters is examined into analyzing and comparing with data through ABAQUS program and experiment on concrete filled tubular column under axial load and propriety of model is checked out by FEM analysis. The main variations of this paper are width-thickness ratio of the section(B/t =33.3, 38.9, 44.4), concrete strength($f_{ck}$=240, 360kgf/$\textrm{cm}^2$), and width-length ratio($L_o$/B=8.0, 10.0, 12.0, 15.0, 20.0). The ultimate value obtained through analysis is compared with test value and calculated by design code of other countries and previous studies.

This paper presents the confinement effect of transverse reinforcement and cross-tie in hollow rectangular sectional columns. 20 analytical models with different amounts of transverse reinforcement and cross-tie in a plastic hinge region were analyzed by 3D nonlinear FEM. The analytical results show that the higher ductility can be achieved by the resonable combination of transverse re-bar and cross-tie providing sufficient lateral confinement.

The columns with large widths in out-of-plane direction fail showing the high nonlinearity of strain distribution. In order to predict the nonlinear behavior with reasonable accuracy in 2 dimensional analysis the material models taking this characteristic into account are indispensible. In this study equivalent softening model is developed which releases the same amount of energy at failure as that of 3-D analysis. Its validity is confirmed by comparing the analysis result with that of 3-D.

This paper presents the behaviors of reinforced concrete columns under high temperature. When columns are exposed high temperature, temperature distribution of a section becomes nonlinear and it is calculated by using finite difference method(F.D.M). The interaction curves show the strength of columns at various exposure times. The strength of columns decreases according to the increase of the exposure time and the decrease of concrete cover.

The cement-based composites have relatively low tensile strength and toughness. The fiber addition is one of the most important ways of increasing the toughness of concrete. The steel fibers have been used conventionally in the shotcrete of tunnel lining. Recently, the structural synthetic fibers were developed and used frequently in some actual tunnel shotcreting in foreign countries. There are so many method to evaluate a toughness; ASTM, JCI, EFNARC, etc. But these methods contain a few defects. So most researchers are studying to develope a new toughness evaluation method. A RTA is one of these methods. The purpose of this study is to explore the strength and toughness characteristic of the fiber reinforced concrete panel according to the geometry; diameter, thickness. The result were compared with those of steel fiber reinforced concrete.

This paper deals with structural behavior of reinforced concrete beams with high strength under fire and fire damaged condition. The main purpose of this study is to evaluate the residual strength of flexural members by exposure time to fire. For this purpose, six beam specimens are fabricated and experimented. Among the specimens, four specimens are exposed to the fire for 60 and 90 minutes and two specimens are control beam that is not exposed to fire. After being cooled in room temperature, the specimens are loaded to the failure. The research result shows that the main variables of the test, concrete cover and exposure time to fire are much influenced on the structural behavior and the residual strength.

In this paper, fatigue behavior of concrete slab tracks under railway loads by experimental method is discussed. The addition of steel fibers to concrete mix has been receiving more attention as a way of improving the crack behavior of concrete beams an slabs tacks. This study two objectives: 1) to observe the fatigue behavior of fiber reinforced concrete slab in labor, and 2) to present crack propagation and deflection of fiber reinforced concrete slab track under railway loads in the Waghauser test line. Nine beams, two slabs and one test track were experimentally tested.

This study concerns the new estimated strength equation of concrete by penetration test. There are not only few estimate strength equations of concrete, but also many problems to apply them because of time, cost, easiness, structural damage, reliability and so on. In this study, there performed a series of test for one year and estimated strength equation of concrete as follows; Linear: fck =3.38d - 95.1 ($$r^2$$=88.6%) Quadratic: fck =0.188$$d^2$$- 10.76d + 166.3 ($$r^2$$=96.7%) here, fck : estimated compressive strength of concrete by Mpa d: exposed probe length by mm.

Under sustained loads, the deformation of a structure gradually increase with time and eventually may be much greater than its instantaneous value, This inelastic and time-dependent deformation causes increase in deflection and curvature, redistribution of stress and internal action, In this paper, time-dependent analysis with creep and shrinkage of uncracked and cracked partially prestressed concrete flexural members is presented.

Non-destructive testing is essential in the inspection of alteration, repair and new construction in construction industry. This paper is to evaluate the strength variation of fire damaged concrete by non-destructive testing. Furthermore, It is to infer the recovery degree of residual strength of fire-damaged concrete. For this purpose, researchers are exploring the performance of non-destructive testing method using ultrasonic testing and Schmidt hammer in concrete specimens. Testing is performed four-times: before fire test, directly after fire test, after 20 days and after 60 days.

The crack of concrete structure plays an important role in the durability and safety of structure. Therefore, the features such as width, length, and direction of that must be measured periodically. The conventional method of measurement of cracks is manually sketched, however. it takes a fairly long time and lacks quantitative objectivity. This study proposes the algorithm to extract and analyze cracks automatically. The proposed algorithm is composed of two sub-algorithms. The extraction algorithm includes elimination of effect due to light, binarization. and noise reduction. The analysis algorithm includes thinning process, labeling, and calculation of crack width, length, and direction. The test to demonstrate the algorithm is fulfilled using the images of cracks on real concrete surface.

Recently, the floor thickness in residence may not be satisfied with the floor vibration criteria although the thickness is evaluated by the serviceability requirements in current design provisions. Thus it is necessary to develop the procedure to determine slab thickness satisfied with the floor vibration criteria. In this study, We proposed the methods to determine the slab thickness satisfied with the vertical floor vibration criteria for several concrete compressive strength of flat plate floor systems. For this purpose Monte Carlo simulation procedure was adopted and both randomness inherent in young modulus of concrete and heel drop intensity were accounted.

Using numerical analysis modeling of Multi-electrode Array that could be applied to the corrosion state measurement of a reinforcing steel bar in concrete, the steel bar location inside concrete can be probed by the investigation of the change of the measured impedance from concrete surface determined by the electrical impedance of interface between the steel bar and concrete, the electrical resistivity of concrete, the array of electrodes and the relative location and diameter of the steel bar.

The purpose of this study is to present data for the reusing, reinforcement and estimation of safety of the RC structure damaged by fire, and for the prevention of explosive spalling by checking the character of explosive spalling according to kinds of fine aggregate, admixture and water-cement ratios. The materials used fine aggregates were sea sand, crushed sand and recycled sand, and the admixtures were fly ash and blast-furnace slag. Also the water-cement ratios was 55% and 30.5%. After those were heated respectively for 30 and 60 minutes in accordance with Standard Time-Temperature Curve. And then conditions of explosive spalling were divided into five grades, and characters of explosive spalling were investigated.

Generally, $TiO_2$ powders absorb ultraviolet rays and make oxidation/reduction reactions on its surface. Hydroxide radical(OH), a product of photocatalyst reactions, has so strong oxidation/reduction electric potential that it can oxidize noxious gas like NOx. In this study, $TiO_2$ was substituted for cement to investigate the purifying degree of NOx. Rutile and anatase types of $TiO_2$ were used as photocatalyst. The sun rays and the ultraviolet were used as a light source. Anatase type $TiO_2$ was better than rutile type in purifying performance. The sunray showed the best purifying performance among the light sources. 3% substitution of TiO$_2$ with the sunray was enough to purify NOx efficiently.

Experimental results for variation of concrete strength according to vibration time control for fresh concrete were given. Vibration velocity, time before vibration and vibrating time were used as experimental parameters. Compressive strength, split tensile strength, ana bond strength were investigated and then fracture surfaces of split tensile strength specimen were observed. From the experimental results, it could be concluded that there may be no decrease in concrete strengths if time before vibration will be sustained at least for more than 3 hours.