Joints are provided in cement concrete pavements to control transverse and longitudinal cracking that occur due to restrained deformations caused by moisture and temperature variations in the slab. But the construction of joints reduces the load-carrying capacity of the pavement at the joints, and pavements have beem deteriorated by cracks at the slab edges along the joints due to traffic loads. Therefore, it is important to analyze the behavior of joints accurately in the design of cement concrete pavements. In this study, the mechanical behavior of cement concrete pavement slabs is analyzed by the plate-finite element model, and Winkler foundation model is adopted to analyze the subgrades. The load transfer mechanism of joints are composed of dowel action, aggregate interlocking, and tied-key action, and the analytical program is developed using these joint models.

This paper presents an equation for balanced-steel ratio in longitudinal and transverse direction throughout analysis based on a space truss model introducing the concept of concrete softening effect. This paper also presents as equation for postcracking torisonal stiffness throughout analysis considering the equilibrium conditions and compatibility conditions based on shear panel. Correlation between predicted postcracking torsional stiffness, and experimental results was good, not only for beams tested in this paper but also for others in the literature.

This paper introduced truss model and one-way slab elastic Model to analyse flexure of unbonded prestressed concrete member. After cracking, we could determine concrete membrane depth, deflection and stress. In order to do that, an numerical example of simply supported one way slab which has non-external membrane support(s=0) is analysed. The analytical results using the analytical model were compared with several experimental results and were generally satisfied.

Based on the design concept of a "Strong Column - Weak Beam" in the design of reinforced concrete, recently, a design method which moves the plastic hinging zone of a specific length away from the column face, has been proposed for reducing the degradation of stiffness and strength in the beam-column joint. To analyze reinforced concrete structures designed by this method. It is necessary to establish the analytical model which can simulate the hysteretic behavior depended on the initial positions and enlargements of plastic hinges. In this paper, by the numerical assumptions and the regression of experimental results, an analytical model is proposed. To estimate the accuracy of this model, some example analyses are conducted and compared with experimental results. From these comparision. It is shown that the proposed model is a good to predict the behavior of members subjected go cyclic loads.lic loads.

지진하중에 의한 콘크리트의 손상 및 파괴의 적절한 평가를 위한 많은 연구가 수행되고 있지만 현재까지 손상을 당한 부재의 잔여강도를 예측할 수 있는 적절한 손상 모델이 없는 실정이다. 본 논문은 콘크리트의 손상에 관한 기본적인 현상들을 면밀히 조사 연구한 후 콘크리트의 low-cycle 피로현상을 해석모델링하여 반복하중 하에서의 손상모델을 제안하였다. 제안된 모델은 콘크리트가 파괴에 도달할 시 싸이클 수 대신에 부재의 흡수에너지 능력을 주요변수로 택하였다. 특히 본 손상모델으 정확성은 기 제안한바 있는 반복하중 작용시의 콘크리트 부재의 해석적인 이력모델[3]을 사용하여 예증하였다.

Based on the recent developments of the reliability-based structural analysis and design as well as the extending knowledge on the probabilistic characteristics of loadings and resistances, the probability based design criteria have been successfully developed for many standards. Since the probabilistic characteristics depend highly on the local environments(loadings) and workmanship resistances), it is recognized to develop the design creterion compatible with domestic requirements. In this study, therefore, the proper probability based design criterion(load and resistance factor design formats) has been developed based on the safaty levels observed from calibration with existing standards, which applies to the ultimate limit states of reinforced concrete members.

Because of the inherent random nature of most manmade and environmental loadings and materials as well as the emperfect structural analysis, the reliability-based structural design has been recognized as a rational approach and the probability-based design criteria has been successfully developed for many standards. In order to do this it is necessary to establish target reliability levels, for which the reliability levels inherent in present design practice will be used as a rational guide. In this study the reliability levels implied in current practices, therefore, are investigated using the load and resistance models developed for domestic uses.

There is the need to balance safety, economy and serviceability in all phases of society proboems. This is especially true in structural code formulation, where a framework is established by which practicing structural enginers can be assured of designing structures that reasonably meet the above three objectives. The existeing design codes, which are generally based on the structural theory and certain engineering experience, do not realistically consider the uncertainties of loads and resistances and the basic reliability concepts. The purpose of the present study is therefore to develop the realistic reliablility-based design criteria to secure adequate safety and reliability, and to derive the models for partial and combined resistance factor formats.

This study develops practical models and methods for the assessment of safety and capacity rating of existing P.C. girder bridges based on the reliability methods. One of the main objectives of the study is to propose a practical but realistic limit state model for safety assessment and LRFR rating criteria, which explicitly incorporates the degree of deterioration and damage as well as actual condition of P.C. girder bridges in terms of the damage factor and the response ratio. The damage factor proposed in the paper is defined as the ratio of the current estimated stiffness to the intact base-line stiffness of a member. Based on the observation and the results of applications to existing bridges, it may be concluded that the proposed methods for the assessment and capacity rating models, which explicitly account for the uncertainties and effects of degree of deterioration or damage, provide more realistic and consistent safety-assessment and capacity rating.

Six small-scale reinforced concrete beam-column joint specimens subjected to monotonic and cyclic loading were tested to investigate the effects of strength of concrete. Variables are 1)compressive strength of concrete(f' c=300, 700kg/㎠), 2)shear span to depth ratio (a/d=4.7, 2.0). The major results of this test were: 1)flexural strength of high strength concrete beam-column joint was not affected too much by the compressive strength of concrete, 2) flexural cracks emerge to inside of beam deeply for high strength concrete member.

This paper is to study the effect of rectilinear confinement in high-strength concrete subjected to a monotonically increasing compressive axial loads. To investigate behavior of columns rectilinearly confined with lateral ties and longitudinal rebars, twelve specimens including two plain concrete specimens were tested. The main variables in this study are volumetric ratio of lateral ties, cistribution of lateral ties, yield strength of logitudinal steel, ratio of area of longitudinal steel to the area of cross section. The test results were not only compared with an empirical model for the stress-strain curve of rectilinearly confined high-strength concrete but also the existing model. The empirical model used calculating column capacity shows better agreement with the test results tham the existing model.

The purpose of this study was to investigate the effects of flexural strength ratio(Mr=$\Sigma$Mc/$\Sigma$Mb) with High-Strength Concrete up to 800Kg/$\textrm{cm}^2$. Five specimens were tested under reversed cyclic loadings. The primary variables were flexural strength ratio of the beam-column, compressive strength of concrete and loading patterns. The results showed that the failure at the beam-column joint in case of high strength concrete was severe more than in case of normal strength concrete when flexural strength ratio 1.4. Thus the part for low limit of flexural strength ratio(Mr=1.4) should be revised for high strengthconcrete.

This research is related to the experimental investigation of the inelastic behavior of reinforced concrete columns. A total of 12 specimens have been cast with different span ratios, steel reinforcements and load applications. Through the tests axial forces have been kept constantly at 40 tons while the bending moments were applied incremently and careful observations were given to the initial crack formation, crack pattern and propagation.

Large panel building systems are composed of vertical wall panels which support horizontal roof and floor panels to form a box like structure. The simplecity of the connections, which makes precast concrete economically viable, causes a lack of continuity in stiffness, strength and ductility. This precast concrete large panel systems typically have weak connection regions. Three types of 2-story full-scale precast concrete subassemblages were tested under reversed cyclic loading. The seismic resistance capacity and failure mode of each system are compared in connection with the characteristics of joint connection details.

The results of a large-scale study to determine the effects of epoxy coating on the bond strength between deformed reinforcement and concrete are descrebed. Tests include beam-end specimens containing No. 5(16mm), No. 6 (19mm), No. 8(25mm), No. 11(32mm) bars with average coating thicknesses ranging from 3 to 17 mils(0.08-0.43mm). Three deformation patterns are evaluated. Specimens with covers of 1, 2, and 3 bar deameters are studied. Both top-cast and bottom-cast bars are tested. Epoxy coatings are found to significantly reduce bond strength. The severity of that reduction is a function of deformation pattern, bar size, and coating thickness. Design recommendations based on these observations differ from the modifications to the 1989 ACI Building Code.

The effect of concrete strength on shear cracking strength in reinforced concrete beams is investigated analytically. The quantitative response of reinforced concrete beam-end-part with varing concrete stiffness, which is a function of concrete compressive strength, is examined utilizing a finite element mothod. The result indicates that the severer shear stress localization/concentration takes place in the beam having higher concrete strength. Thus the increase ratio of shear cracking strength with respect to concrete compressive strength decreases as the concrete strength becoms higher.

This study was performed to verify the behavior of channel type PC bridge through the full scale model test. It is well known that the behavior of connection is especially important in case of precast multi-beam bridges. In this study, the lateral load distribution capacity was found satisfactory and influenced little either by the type or strength of connections. Analysis results agreed well with test results. Parameter studies were performed based on the test and analysis results.

The behavior of short span filled spandrel arch bridge of 10 and 21 m span with various axis line, rise and backill height were investigated under the design loads(self weight, earth pressure, temperature load, live load, etc). Even though the behaviors of arch were known as relatively complicated, the followings can be concluded within the limits of this study. The design value of arch bridge increase as the rise decreases, the effects of temperature load become dominant for the design of arch bridge, and governing design factors are occured at springing.

To estimate the concrete strength at fresh state is very important problem in quality control. So, this study is designed for analyzing the quality control application of practical use Re-Mi-Con with the early estimation method of concrete strength using the test of solution heat of hydrochloric acid.

Chromatograms of asphalt cements were observed using high pressure - gel permeation chromatography (HP-GPC). The chromatogram characterzed profile of molecular size distribution of asphalt cements. Bituminous concretes using the asphalt cements were prepared in laboratory to measure mechanical properties, tensile strength (TS) and resilient modulus (MR), in dry and wet conditions. Three sources of AC-20 Asphalt cements and one aggregates were used for GPC test and strength test. Results of mechanical property tests and GPC tests were analyzed to evaluate correlation between those two results. Regression analysis showed strong correlation between a mechanical property and sliced percent areas of GPC profile. Mathematical models were developed for estimating mechanical properties of asphalt cement concrete based on HP-GPC data.

This study is designed to analyze the variation of grading and shape of aggregate with the number of rotations of Los-Angeles abrasion machine, and is aimed to analyze the effect of slump and compressive strength of strength of concrete with the shape of coarse aggregate by the abrasion act.

This is the study on the feature of workability and engineering properties of flowing concrete using the superplasticizing agents which is using to effect considerable reductions in water contents in the same level of consistemcy and workability. It is the aim of this study to compare workabili쇼 and engineering properties of flowing concrete according to the addition time and method of superplasticizing agents. In this experimental study, 2cm slump of concrete, 18cm slump of conventional concrete, two kinds of aggregates and addition time and method of superplasticizing agents of 0, 15, 30, 45, 60 and 90 minutes were included to analyze and investigate the workability and engineering properties of flowing concrete.

Seaside concrete structure is deteriorated by chloride-ion, sulphate and salt cristalization in concrete pore. Therefore the amount of these chemical substance should be analyzed for evaluating the durability of seaside concrete structure. In this study, the amount of chloride-ion in concrete was surveyed in order to estimate the damage state of concrete structure within am influence of seawater.

Fly Ash in concrete is known to be effective in improving workability, the reduction of heat of hydration, increasing the long-term compressive strength, and improving durability. Recently, fly ash is consedered an essential material for the high-strength concrete. In this paper, investigations for the strength and workability characteristics was carried out when fly ash was used in the high-strength concrete. As the result, fly ash was effective in increasing the long-term compressive strength, but the short-term compressive strength was gradually decreased with increating fly ash contents. And also the use of superplasticzers was required for providing the proper workability when fly ash contents were increased. The optimum content of fly ash was about 10%.

Many papers have been published on drying shrinkage of hardened cement paste and cement mortar. The causes of drying shrinkage in cement mortar may be attributed to its mechanical properties, temperature, curing time and the evaporation of water from cement mortar. This paper deals only with drying shrinkage in cement mortar. In particular, the relationships between water evaporation and drying shrinkage are discussed.

일반적으로 플라이애쉬는 콘크리트의 여러 가지 물성을 크게 개선시키는 것으로 알려져 있으나, 플라이애쉬 자체의 함유 성분에 따라서는 이러한 개선 효과가 감소하는 경우도 있다. 본 연구에서는, 플라이애쉬에 함유된 미연탄소가 공기연행 콘크리트의 물성에 미치는 영향을 규명하고, 품질관리면에서 사용상의 주의점을 지적한다.

In recently, the interest of high strength and flowing concrete, to improve quality and workability of concrete, is gradually increased. In order to make high strength and flowing concrete, many processes may be considered, the water reducing technique using superplasticizer seems to be the most practical, but domestic superplsticizers are not widely used because of economical efficiency, low quality and lack of understanding in construction field. The purpose of this report is to analyze the consumption structure and behavior of domastic acmixtures containing superplasticizer, and to examine about, dessemination of superplasticizer.

In order to discuss the freeze-thaw durability of FRC and mechanical properties by the fiber types of FRC, experimental studies of FRC were carried out. The kinds of fiber used which are in CFRC are PAN-based and Pitch-based carbon fiber and in GFRC are alkali-resistance glass fiber. To examine the effects of the kinds, types (continuous fiber and Tow, Belt, Cloth) and contents of fiber and matrices, the following three methods CFRC and GFRC, Air cured, Water cured and Autoclaved CFRC and GFRC were tested. According to the test results, the flexural, tensile strength and toughness of FRC were remarkably influenced by types of fiber and addition of condensed silica fume. Also, freeze-thaw resistance of FRC was considerably improved in comparision to conventional mortar.

This is an experimental study to investigate chante of early strength of polymer concrete due to curing temperature change. Polymer binders that were used in the experiment include 2 types of epoxy system and 4 types of polyester system which are commercially producer in Korea. The study result showed that there was a difference in early strength by curing temperature. At $35^{\circ}C$ which is a higher than normal curing temperature, higher strengths were developed in polymer concretes prepared with KB-Clear and YD-128 of epoxy system, and G-550 and H-660 of polyester system. However, at the same temperature, reduced strengths were obtained for FH-103 and TR-132 of polyester system. Further study under various curing conditions with humidity and temperature change will warrant more generalized result.

Recently, the multistory building construction of reinforced concrete has increased year by year, trended to be high rise in the view of effective land use planning, costing down of building construction and residential conditions. For this urgent need in construction industry, research and development of workability and engineering properties of high strength concrete has been closed up as one of the big world wide problems to be solved reasonably. It is aim of this study to provide the fundamental data the workability and engineering properties of steel-fiber reinforced high strength concrete containing silica-fume and fly-ash comparing with plain concrete for the practical use and research data accumulation in the side of development of new material in the building construction.

This study shows both through experiment and based on theory the reinforcement effectiveness when using FRP(Fiber Reinforced Plastics) as a means of reinforcing the concrete of the deteriorated concrete. Non-deteriorated concrete and deteriorated concrete which is deteriorated by freezing and thawing are made three type specimens (non-reinforced) concrete beam, one layer FRP reinforced concrete beam, two layer FRP reinforced concrete beam) for this purpose. Bending strength and cracking load ratio is measured by bending test.

Fracture tests were carried out in order to investigate the flexural behavior of SFRC (Steel Fiber Reinforced Concrete) structures. Sixty three SFRC beams were used in the tests, the fracture mode, the relationships between loading and strains, and the relationships between loading and mid-span deflections of the beams were observed under the three point bending loading. From the test results, the effects of steel fiber contents and a/h ratio on the concrete flexural behavior were studied, and the stress intensity factors and the flexural strength of SFRC beams were calculated. According to the results of regression analysis, predicting formulas for the flexural strength of SFRC beams are also suggested.

Recently, a growing attention is paid to development of new construction materials. The fiber reinforced Concrete is recognized as one of the most promising new construction materials. A comprehensive experimental study was conducted to explore the mechanical behavior of steel fiber reinforced concrete. The major variables in the experiment were the fiber contents and the lengths of steel fibers. The flexural, tensile, and compressive behavior of steel fiber reinforced concrete were investigated. The present study shows that the strength and ductility are remarkably increased with the increase of fiber content. The rate of strength increase due to steel fibers was found to be the highest in tension, the middle in flexure and the lowest in compression. This indicates that the steel fibers play a major role in increasing the tensile capacity.

This paper presents the recent repair and maintenance techniques of R/C structures in Korea. This paper consists of four parts : the first part introduces the current diagmosis techniques, the second one includes the repair methods and the third one classifies the repair material. Finally a repair case of the R/C structure in a chemical plant in Korea was introduced.