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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea Concrete Institute
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Korea Concrete Institute
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Volume & Issues
Volume 11, Issue 6 - Dec 1999
Volume 11, Issue 5 - Oct 1999
Volume 11, Issue 4 - Aug 1999
Volume 11, Issue 3 - Jun 1999
Volume 11, Issue 2 - 00 1999
Volume 11, Issue 1 - 00 1999
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Nonlinear Analysis of Prestressed Concrete Box Girder Bridges Using Macro Element
Oh, Byung-Hwan ; Lee, Myung-Kue ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 77~77
The conventional design of prestressed concrete box girder bridges has been based on the linear elastic analyses using simplified geometric models. To overcome the restriction involved in the simplifications, a macro element for the rational analysis of prestressed concrete box girder bridges with variable cross sections is incorporated in the present analysis. Through the adoption of nonlinear material models, the behaviour of prestressed box bridges up to ultimate loading stage can be examined. The time dependent material models included in the present macro element code enable to predict the long term behaviour of prestressed concrete box girder bridges. The proposed macro element code with the nonlinear material models and time dependent routines can be efficiently used for the realistic analysis of prestressed concrete box girder bridges with arbitrary shapes.
Effects of Shear Reinforcements on the Reinforced High-Strength Lightweight Concrete Beams
Shin, Sung-Woo ; Lee, Kwang-Soo ; Ahn, Jong-Mun ; Choi, Myung-Shin ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 89~89
In this study, fifteen reinforced high-strength lightweight concrete(HLC)beams were tested to investigate shear behavior of specimens according to shear reinforcement ratio. Test variables are shear span to effective depth ratio(a/d=2.5, 3.5, 4.5) and shear reinforcement ratio(0~1.0
). Concrete compressive strength and tensile steel reinforcement ratio are constantly 439kg/
and 0.0203, respectively. Test results for the HLC beams showed that ACI code equation underestimates the shear strength of concrete(
), and overestimates the shear strength of shear reinforcements(
). It is revealed that the effectivenesses of shear reinforcements of reinforced HLC beams are lower than those of normal weight concrete beams. Then, the shear strengths of shear reinforcements are increased in proportion not to first degree of shear reinforcement ration but to square root of them.
Prediction of Differential Column Shortening for Reinforced Concrete Tall Buildings
Lee, Tae-Gyu ; Kim, Jin-Keun ; Song, Jin-Gyu ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 99~99
In this paper, the prediction method of the differential column shortening for cracked reinforced concrete tall buildings due to the construction sequence is presented. The cracked sectional properties from the strain and curvature of the sectional centroid is directly used. And the stiffness matrix of concrete elements considering the axial strain-curvature interaction effect is adopted. The creep and shrinkage properties used in the predictions were calculated in accordance with ACI 209, CEB-FIP 1990, and B3 model code. In order to demonstrate the validity of this algorithm, the prediction by the proposed method are compared with both the results of the in-situ test and the results by other simplified method. The proposed method is in good agreement with experimental results, and better than the simplified method.
Behavior of Non-seismic Detailed Low-Rise R/C Exterior Beam-to-Column Joints Subjected to Cyclic Loading
Sur, Man-Sik ; Chang, Chun-Ho ; Kim, Young-Moon ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 109~109
Seismic design code has been performed since 1988 in Korea, so it has not been applied to low-rise reinforced concrete buildings which had been built before 1988. Those building have been designed only for gravity loads based on non-seismic code, Therefore, even minor earthquake occurred, those buildings might have serious damages. In this paper, to investigate the behavior of low-rise reinforced concrete moment resisting frame which had been built in according to the building code of Korea that had been published before 1988, two type of 1/2 scaled exterior beam-column subassemblies which have non-seismic detailing based on the building code of Korea were constructed and tested with reversed cycling loading under the displacement control method. The special features of joint with non-seismic detailing is that there is no transverse reinforcement in the joint. In tests, cracks pattern, strength degradation, loss of stiffness, energy dissipation and the slippage of beam and column bars were investigated. Cracks did not occurred in the joint even seismic loading of 0.12g which is considered as peak ground acceleration in Korea was applied. And increasing seismic loading above 0.12g shear crack happened in the joint which have not transverse beam.
Fracture Behavior of a Stacked Concrete Structure Based on the Fracture Mechanics
Kim, Sang-Chul ; Kim, Yeon-Tae ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 119~119
The objective of this study is to simulate the fracture behavior of composite structure bonded with more than 2 different cementitious materials. For this, concrete and cement were stacked and bonded in a direction perpendicular to loading and specimens were tested. Each constituent material of concrete and cement was fabricated independently also, and three point bending and indirect tensile tests were carried out for the acquisition of measured values applicable to the proposed model. As a result of comparing theoretical results and experimental ones, it was found that the proposed model derived from fictitious crack theory can be used to predict the fracture behavior of composite structures on the vases of well agreement with experimental results. It was also noted that the degree of improvement of fracture energies and strengths is greatly dependent on the stacking sequence of layers composing of a composite structure. Thus, it can be concluded that brittleness or ductility of a composite structure can be accomplished by a proper arrangement of layers on one's purpose throughout the proposed analysis.
A Study to Improve Bonding Strength of Strengthening Plate with Notches
Han, Man-Yop ; Song, Byeong-Pyo ; Lee, Kwang-Myong ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 129~129
Recently, many strengthening methods are developed and used to rehabilitate existing structures. One of the old and popular methods is strengthening with bonding steel plate. However, steel plate bonding method has a defect, which is debonding failure of steel plate before yielding of the plate due to stress concentration at the of the bonded plate. The objective of this study is the experimental verification of the improved bonding properties of a strengthening plate with notches. Two normal beams and ten strengthened beams with steel plate, which have several different notches, are tested and showed their effectiveness. Test results show that the notches of strengthening plate significantly improve post-yielding behavior, compared to normally strengthened beams. It is proved that the notches of strengthening plate increases ultimate strength 14% more than normal strengthened beam after yield strength. As for the shape of notches, arc notch is the best. and triangle notch and trapezoidal notch are the next and end welding method has no effect.
A Study on the Properties of High Performance Concrete Using CSA Expansive Additives and Inorganic Admixtures
Han, Cheon-Goo ; Bahn, Ho-Yong ; Jun, Byung-Chea ; Hong, Sang-Hee ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 141~141
Recently, high performance concrete developed has a good quality at fresh and hardened state, but high binder contents results in spending much money on manufacturing and many cracks by drying and autogenous shrinkage, Therefore, in this paper, not only prevention of cracks caused by drying and autogenous shrinkage, but improvement of quality and accomplishment of economy by applying F.A(fly ash), S.F(silica fume) and CSA(calcium sulfa aluminate) expansive additives as an inorganic admixtures in W/B 35% are discussed. According to the experimental results, when 5% of CSA expansive additives and 15:5(F.A:S.F)are replaced at unit cement content, high performance concrete with both good fluidity at fresh state and high compressive strength, compensation of drying and autogenous shrinkage at hardened state are accomplished.
Experiment and Strength Analysis of High-Strength RC Columns
Son, Hyeok-Soo ; Kim, Jun-Beom ; Lee, Jae-Hoon ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 149~149
This paper is a part of a research aimed at the verification of basic design rules of high-strength concrete columns. A total of 32 column specimens were tested to investigate structural behavior and strength of eccentrically loaded reinforced concrete tied columns. Main variables included in this test program were concrete compressive strength. steel amount, eccentricity, and slenderness ratio. The concrete compressive strength varied from 356 kg/
to 951 kg/
and the longitudinal steel ratios were between 1.13 % and 5.51 %. Test results of column sectional strength are compared with the results of analyses by ACI rectangular stress block, trapezoidal stress block, and modified rectangular stress block. Axial force-moment-curvature analysis is also performed for predicting axial load-moment strength and compared with the test results. The ACI rectangular stress block provides over-estimated column strengths for the lightly reinforced high strength column specimens. The calculated strengths by moment-curvature analyses are highly affected by
values of the concrete stress-strain curve. Observed failure mode. concrete ultimate strain, and stress block parameters are discussed.
Analysis of Vibration Modes of Small and Large Concrete Blocks Containing Flaws by Impact Resonance Method
Park, Seok-Kyun ; Yoon, Seok-Soo ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 161~161
Impact resonance testing was carried out on small and large concrete blocks containing several types of artificial flaws respectively. Quantitative analysis of the observed peak frequencies in the impact resonance tests identifies the possible normal modes of concrete blocks containing flaws. and enables to determine the depth and size of the flaws in concrete blocks. In this study, concrete can be treated as a homogeneous and isotropic material. The flaw size and location at each section of artificial flaw series in small and large concrete blocks, determined through two-dimensional scanning of impact point and real-time fast Fourier transform, are in good agreement with real size location, respectively. Consequently, quantitative analysis method of vibration modes in the impact resonance tests, which can be applied for homogeneous and isotropic material, can be useful for the detection of flaws in any case of small and large concrete blocks in this study.
Behaviour of Beams Without Transverse Reinforcement
Cho, Soon-Ho ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 173~173
To deepen the understanding of shear behaviour in beams without transverse reinforcement, the relative importance of five contributing factors to concrete shear resistance(
), which are i)flexural compression zone, ii)friction at crack faces, iii)dowel action, iv)arch action and recently identified, v)residual tensile stresses across cracks, was explained physically using two analytical methods based on the truss concept. One is called "Modified Compression Field Theory(MCFT)" considering ii) and v) explicitly, and the other "Crack Friction Truss Model(CFTM)" more dominantly ii) in determining concrete resistance. To verify their effectiveness, the predictions using MCFT and CFTM were also made for twenty KAIST beam tests(
=53.7Mpa), designated more likely to the development of the size effect law based on the fracture mechanics concept. Experimental findings with varying of a/d, longitudinal reinforcement ratios, and obtained from MCFT enabled additional explanations for some phenomena which were difficult to measure in tests. However, MCFT seemed somewhat conservative for beams with higher longitudinal reinforcement, while somewhat unsafe for beams with larger depths. More tests are necessary leading to firm conclusions in these areas.
The Fundamental Study on Properties of Concrete Using the Garnet with Industrial Wastes
Lim, Byoung-Ho ; Park, Jung-Min ; Kim, Tae-Gon ; Kim, Wha-Jung ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 183~183
This paper investigated the possibility of appling to concrete through fundamental experiment for garnet, which was industrial wastes generated in kyung pook region, in aspects of development of new materials and recycling of industrial wastes due to shortage of natural resources. Consequently, garnet powder showed the possibility of admixture as showed in the chemical composition because the content of silica and alumina in relation to pozzolanic activity was about 50%. The time of setting was more or less diminished as the increasing of replacement ratio of garnet. In flow test, flow values tended to increase to some degree as the increasing of replacement ratio of garnet. Therefore, application of garnet was expected to improve the workability of concrete. The compressive strength of mortar replaced by garnet was respectively increased as compared with plain mortar and the maximum strength was showed in replaced by 10%, however a little different to the change of W/B ratio. Also, the possibility of admixture to reduce the amount of cement and to improve the property of concrete was showed as the strength of mortar replaced by garnet was comparable to that by existing admixture(silica fume, fly-ash).
An Experimental Study on the Shear Behavior of Reinforced Concrete Deep Beams Subject to Concentrated Loads
Lee, Jin-Seop ; Kim, Sang-Sik ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 191~191
The shear behavior of simply supported reinforced concrete deep beams subject to concentrated loads has been scrutinized experimentally to verify the influence of the structural parameters such as concrete strength, shear span-depth ratio, and web reinforcements. A total of 42 reinforced concrete deep beams with compressive strengths of 250 kg/
and 500 kg/
has been tested at the laboratory under one or two-point top loading. The shear span-depth ratio have been taken as three types of 0.4, 0.8 and 1.2, and the horizontal and vertical shear reinforcements ratio, ranging from 0.0 to 0.57 percent respectively. In the tests, the effects of the shear span-depth ratio, concrete strength and web reinforcements on the shear strength and crack initiation and propagation have been carefully checked and analyzed. From the tests, it has been observed that the failures of all specimens were due to shear and the shear behaviors of specimens were greatly affected by inclined cracks from the load application points to the supports in shear span. The load bearing capacities have changed significantly depending on the shear span ratio, and the efficiency of horizontal shear reinforcements were increased as the shear span-depth ratio decreased. The test results have been analyzed and compared with the formulas proposed by previous researchers and the design equation from the code. While the shear strengths obtained from the tests showed around 1.4 and 1.9 times higher than the values calculated by CIRIA guide and the domestic code, they were closely coincident with the formulas given by de Paiva's equation.
Structural Behavior of Pre-loaded RC Beams Strengthened by SP, CFS, and CFL
Chung, Lan ; Lee, Young-Jea ; Moon, Heui-Jeung ; Lee, Kyung-Un ; Jung, Sang-Jin ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 201~201
In recent years, strengthening by steel plate, carbon fiber sheets, and carbon fiber laminate is spotlighted in order to repair and rehabilitation of R/C structures. In this study, 3 methods of rehabilitation technique were analyzed from the test results. Test parameters were the width of cracks, the method of repair and rehabilitation, the magnitude of pre-load. Deflections, failure loads, strains of reinforcing bar, strains of carbon fiber sheet, carbon fiber laminate and steel plate were measured during the tests. The primary purpose of this research was to analyze the failure mode and structural behavior of strengthened RC beams with/without superimposed pre-load. Test results should that no significant difference was observed between with pre-loaded specimens and no-loaded specimens during rehabilitation.
Experimental Examination of Influential Variables on Unbonded Tendon Stresses
Lim, Jae-Hyung ; Moon, Jeong-Ho ; Lee, Li-Hyung ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 209~209
This paper describes an experimental study planned to examine the effects of important design variables which were used in the proposed equation by authors. Fourteen beams and slabs were designed with the variables, such as effective prestress, concrete strength, amount of tendons, amount of bonded reinforcements, loading type, and span/depth ratio. Then, deflections and tendon stresses were measured and compared according to the parametric variations of the selected variables. It was found that the tendon stress increment decreases as the level of effective prestress or the amount of unbonded tendons and bonded reinforcements increases. Also, the contributions of concrete strength, and loading type were observed to affect on the tendon stresses. However, the stress increments of unbonded tendon were minimal alt high values of span/depth in contrast with the ACI code.
An Experimental Study on the Flexural Behavior of Reinforced High-Strength Concrete Beams Using Belite Cement
Han, Sang-Hoon ; Koo, Bong-Kuen ; Kim, Gee-Soo ; Cho, Hong-Dong ; Juen, Chea-Man ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 221~221
A study was conducted to investigate the flexural behavior of reinforced high-strength concrete beams using Belite cement. In this study, fourteen reinforced Belite and control beams were tested. The major experimental variables are compressive strength(350kgf/
)of concrete and reinforcement ratios(0.0086~0.0345). They were tested by three point loading method. Comparing with flexural behavior of normal reinforced concrete beams, the investigation were to : (1) determine experimentally the load-displacement relationships and the strain distribution on the section of test beams : (2) determine experimentally the moment-curvature and the load-neutral axis relationship of Belite ; (3) investigate the flexural ductility of Belite ; (4) estimate the ratio of the capacities of nominal moment strength as a function of ACI to as a experiment. From the test results, the flexural behavior of reinforced high-strength concrete beams using Belite cement are similar to flexural behavior of normal reinforced concrete beams.
RC Flat Plate Subject to Combined In-Plane Compressive and Out-of-Plane Floor Loads
Park, Hong-Gun ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 231~231
This paper presents a numerical study on the flat plates in deep basements, subjected to out-of-plane floor load and in-plane compressive load due to soil and hydraulic lateral pressure. For nonlinear finite element analysis, a computer program addressing material and geometric nonlinearities is developed. The validity of the numerical model is established by comparison with existing experiments performed on plates simply supported on four edges. The flat plates to be studied are designed according to the Direct Design Method in Korean Building Code for Structural Concrete. Through numerical study on the effects of different load combinations and loading sequence, the load condition that governs the strength of the flat plates is determined. For the plates under the governing load condition, parametric studies are performed to investigate variations of the strength with reinforcement ratio, aspect ratio, concrete strength, and slenderness ratio. Based on the numerical results, the floor load magnification factor is proposed.
Moment Magnifier Method for RC Flat Plate Subject to Combined Axial Compressive and Floor Load
Park, Hong-Gun ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 243~243
This paper presents a numerical study for developing the moment magnifier method that is applicable to RC flat plates subject to combined axial compressive and floor load. For the nonlinear finite element analysis, a computer program addressing material and geometric nonlinearities was developed. The flat plates to be studied are designed in accordance with the Direct Design Method in Korean Building Code for Structural Concrete. This paper proposes the buckling force and the moment magnification factor for the flat plate under the governing load condition that is the combined vertical and subsequently applied uniaxial compressive load. The buckling force is defined with two ingredients: the buckling coefficient and the effective flexural rigidity. Parametric studies are performed to investigate variations of the buckling coefficient and the effective flexural rigidity. Based on the numerical results, this paper provides the design values of the buckling coefficient and the effective flexural rigidity, and the design procedure for the moment magnifier method.
Experimental Study on Nonlinear Behaviors of A 1:12 Scale 10-Story Reinforced Concrete Frame with Nonseismic Details
Lee, Han-Seon ; Kang, Kyi-Yong ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 255~255
The objective of this experiment is to observe the elastic and inelastic behaviors of high-rise reinforced concrete frames having non-seismic details. To do this, a building frame designed according to Korean seismic code and detailed in the Korean conventional practice was selected. A 1:12 scale plane frame model was manufactured according to similitude law. A reversed lateral load test and a monotonic pushover test were performed under the displacement control. To simulate the earthquake effects, the lateral force distribution was maintained to be an inverse triangle by using a whiffle tree. From the tests, base shears, crack pattern, local rotations in the ends of critical members and the relations between interstory drift versus story shear are obtained. Based on test results, conclusions are drawn on the implications of the elastic and inelastic behaviors of a high-rise reinforced concrete frame having non-seismic details.
Correlation of Experimental and Analytical Inelastic Responses of A 1:12 Scale 10-Story Reinforced Concrete Frame with Non-seismic Details
Lee, Han-Seon ; Kang, Kyi-Yong ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 267~267
The pushover analysis technique is now attracting the world-wide interest for the prediction of elastic and inelastic behavior of structures in the seismic evaluation of existing buildings. However, the reliability of this analysis technique has not been fully checked by the test results in the case of structures with nonseismic details. The objective of this study is to verify the correlation between the experimental and analytical responses of a 1:12 scale 10-story reinforced concrete frame with non-seismic details by using DRAIN-2DX program and the test results performed previously. It is concluded from this comparison that the overall responses such as the relations between story shear versus interstory drift and the local deformations such as plastic rotations can be predicted with quite high reliability.
Time-dependent Analysis of Reinforced and Prestressed Concrete Structures Incorporating Creep Recovery Function
Kim, Se-Hoon ; Oh, Byung-Hwan ;
Journal of the Korea Concrete Institute, volume 11, issue 1, 1999, Pages 279~279
The creep of concrete structures caused by variable stresses is generally calculated by step-by-step method based on the superposition of creep function. Although most practical application is carried out by this linear assumption. significant deviations between predictions and experiments have been observed when unloading takes place, that is. stress is reduced. This shows that the superposition of creep function does not describe accurately the effect of sustained compressive preload. The main purpose of this study is to propose a creep analysis model which is expressed with both creep function and creep recovery function where increase or decrease of stress is repeated. In these two function method, the creep behavior is modelled by using linear creep law for loading and creep recovery law for unloading. To apply two function method to time analysis of concrete structures, the calculation method of creep strain increment under varying stress is proposed. The calculation results based on the present method correlates very well with test data, but the conventional superposition method exhibits large deviation from test results. This paper provides a more accurate method for the time dependent analysis of concrete structures subjected to varying stress, i.e. increasing or decreasing stress. The present method may be efficiently employed in the revision of future concrete codes.