The purpose of this study was to investigate the performance of hollow reinforced concrete bridge column systems with reinforcement details for material quantity reduction. The proposed reinforcement details have economic feasibility and rationality and make construction periods shorter. A model of hollow reinforced concrete bridge columns was tested under a constant axial load and a quasi-static cyclically reversed horizontal load. As a result, proposed reinforcement details for material quantity reduction were equal to existing reinforcement details in terms of required performance. The companion paper presents the experimental and analytical study for the performance assessment of hollow reinforced concrete bridge column systems with reinforcement details for material quantity reduction.

The Age-adjusted effective Modulus Method(AEMM) is one of the methods adopted for the construction stage analysis of concrete structures. The AEMM uses the aging factor to consider the effects of the varying concrete stress. In the aspects of computation time and the accuracy of the results, the AEMM is considered as one of most appropriate methods for construction stage analysis of tall building structures. Previous researches proposed appropriate values of the aging factor in the forms of graphs or using very simple equations. In this paper, an equation for estimating the aging factor as a function of rebar ratio in the section, compressive strength of concrete, notional member dimension, and age of concrete at the load application. The validity of aging factor proposed in this paper were examined by the comparison with the results of step-by step method.

최근 환경오염 문제에 대한 심각성이 대두되며 전 세계적으로 환경부하 저감을 위해 다양한 노력을 쏟고 있다. 특히 환경 저해 산업의 하나인 건설분야에서는 CO2배출량과 에너지 소비량을 줄이기 위해 활발한 연구를 진행해 왔다. 그러나 건설분야의 기존 연구들은 대부분 CO2배출량이 가장 큰 사용 및 유지관리 단계에만 집중하고 있으며, 설계단계에 대한 연구는 2D의 철근콘크리트 부재 및 구조물에 대해서만 실행되었을 정도로 초기단계이다. 사실, LCA적 관점에서 친환경적 건설산업을 이루기 위해서는 건물의 초기설계 단계에서부터 CO2배출량을 저감시키기 위한 방향으로 설계를 유도할 수 있어야 하며, 구조 엔지니어로서 환경성을 고려한 설계안을 제시할 수 있어야 한다. 그러므로 본 연구에서는 매입형 합성기둥(SRC)을 대상으로 CO2최적화 기법을 제시하였으며, 이를 통해 얻은 여러 설계단면을 이용하여 SRC기둥의 CO2배출량에 영향을 미치는 3가지 요소(① 강재 크기, ② 콘크리트 압축강도, ③ 작용 하중 크기)에 대한 영향관계를 분석하였다.

Ultra high performance concrete which has recently been studied was developed to complement the brittle behaviour and dynamic uppermost limit of high strength concrete. Fiber reinforced concrete which mixed steel fiber is receiving attention as an alternative about this and is being developed to complement the disadvantages of high strength concrete including lower toughness coefficients and crack resistance and spalling in fires. Review about fiber reinforced ultra high strength concrete that this study tries to treat includes reduction of self shrinkage generated by high cement content per unit volume of concrete, evaluation of compression and tension strength to lower internal and external spalling resistance and fragility factors of member of framework, and flow characteristics of concrete which doesn't harden according to steel fiber amounts and used materials. As the result, the more fiber reinforcement increases, the more compression and tensile strength increase and deformation control of cement matrix and improvement of energy absorption ability showed the great effect in shrinkage reduction.

철근 및 FRP Bar를 보강재로 사용한 콘크리트 보의 전단 거동을 실험적으로 평가하였다. 실험 변수는 특성이 다른 보강근을 휨 및 전단 보강한 것과 전단보강근비이다. 콘크리트 보의 전단강도 산정에 일반적으로 널리 이용되는 수정트러스 이론의 타당성을 실험 결과의 분석을 통하여 평가하였다. CFRP 및 GFRP를 휨 및 전단 보강한 콘크리트 보에 그대로 적용하는 것은 적절하지 않음을 알 수 있었다. 실험결과는 FRP Bar를 보강근으로 사용한 콘크리트 보의 전단 문제에 수정트러스 이론을 그대로 적용하는 것은 타당하지 않다는 것을 알 수 있었다.

본 논문에서는 유전알고리즘을 사용하여 철근콘크리트 구조물의 최적 지진설계를 효율적으로 수행하기 위해 클러스터를 사용하는 경우 확장성을 확인하였다. 클러스터를 구성하는 코어프로세서의 개수를 증가시키면서 유전알고리즘의 각 세대에 소요되는 시간의 감소를 관찰하였다. 단일 퍼스널 컴퓨터의 구성을 분류한 후, wall-clock time과 암달의 법칙으로 예상된 값을 비교하여 예상되었던 병목현상을 확인하였다. 이에 클러스터의 확장성에서 복합적인 요인에 의한 경향을 확인할 수 있었다. 병목현상의 물리적인 요인과 알고리즘 측면에서의 요인을 구분하기 위해 유전알고리즘의 개채수를 나누어 실험을 수행하여 결과를 확인하였다.

The purpose of this study is to evaluate the effectiveness of the seismic retrofit performance for a reinforced concrete structure with steel damper. The nonlinear static analysis of the RC frame specimens with and without retrofit using the steel damper was conducted and the reliability of the analysis was verified by comparing the analysis and test results. Using this analysis model and method, additional nonlinear analysis was conducted considering varying stiffness and strength ratios between RC frame and steel damper and the failure mode of RC frame. As the result of the study, the total absorbed energy increased and the damage of RC frame was reduced as stiffness and strength ratios increased. The seismic retrofit performance, evaluated by means of the yield strength, increasing ratio of the absorbed energy and damage of the frame, increased linear proportionally with the increase of the strength ratio. In addition, the seismic retrofit performance was stable for stiffness ratios larger than 4~5. The energy absorption capacity of the frame governed by shear failure was better than that of the frame governed by flexure failure.

The purpose of this study is to investigate the inelastic behavior of hollow reinforced concrete bridge column sections with reinforcement details for material quantity reduction and to provide the details and reference data. Among the numerous parameters, this study concentrates on the shape of the section, the reinforcement details, the diameter of the transverse reinforcement and loading types. Eighteen column section specimens were tested under quasi-static monotonic loading. In this study, the computer program RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used. A modified lateral confining effect model was adopted for the hollow bridge column sections. This study documents the testing of hollow reinforced concrete bridge column sections with reinforcement details for material quantity reduction and presents conclusions based on the experimental and analytical findings.:

This study proposed proposes a retrofitting method using an H‐beam frame to improve the seismic performance of non‐seismic designed reinforced concrete frames. To evaluate the seismic performance with the H‐beam frames, a cyclic lateral load test was performed and the experimental result was compared with the bared frame, and a masonry infilled RC frame. The results was were analyzed regarding aspects of the load‐displacement hysteresis behavior, effective stiffness, displacement ductility, and cumulative energy dissipation. AlsoIn addition, it was possible to prove both an increase of in the maximum load capacity, effective stiffness, and energy dissipation capacity using the H‐beam frame.

The purpose of this study was to investigate the performance of hollow reinforced concrete bridge column sections with reinforcement details for material quantity reduction. The proposed reinforcement details has have economic feasibility and rationality and makes construction periods shorter. A model of column sections with reinforcement details for material quantity reduction was tested under quasistatic monotonic loading. As a result, the proposed reinforcement details for material quantity reduction was were equal to existing reinforcement details in terms of the required performance. In the a subsequent paper, the an experimental and analytical study will be performed for the performance assessment of hollow reinforced concrete bridge column sections with reinforcement details for material quantity reduction will be performed.

In this paper, the a static experiment of on two reinforced concrete (RC) frame sub‐assemblages was conducted to evaluate the seismic behaviors of existing RC frames that were not designed to support a seismic load. The specimens were a one span and actual‐sized. One of them had two columns with the same stiffness, but the other had two columns with different stiffness values. As Regarding the test results, lots of many cracks occurred on the surfaces of the columns and beam‐column joints for the two specimens, but the cover concrete splitting hardly occurred was minimal until the test ends. In the case of the specimen with the same stiffness offor the two columns, the flexural collapse of the left‐side column occurred. However, in the case of the specimen with different stiffness values for of the two columns, the beam‐column joint finally collapsed, even though the shear strength of the joint was designed to be strong enough to support the lateral collapse load. The nonlinear Nonlinear static analysis of the two specimens was also conducted using the uniaxial spring model, and the analytical results successfully simulated the nonlinear behaviour of the specimens in accordance with the test results.

This study investigates the stress-strain relations of internally confined hollow concrete filled tube pier reinforced with GFRP tube by uniaxial compression test. The confined concrete subjected multi-axial stresses have been known as the strength of concrete increases significantly. Many researchers have studied in confining effects of CFT which have only outer GFRP tube. In this study, specimens reinforced with outer and inner GFRP tube were tested by uniaxial compression test. To investigate the influence of concrete strength increase by confining conditions in GFRP tube, 13 specimens with different thickness of tube, hollowness ratio and nominal concrete strength were tested and compared with Steel tube.

Carbon fiber reinforced polymeric plastic (CFRP) can be used for the deteriorated reinforced concrete members. CFRP reinforcement method, which is one of the reinforcement methods, can improve the strength and durability of reinforced concrete member. CFRP reinforcement method has been proved that it has sufficient effect on the flexural strengthening of reinforced concrete flexural member through numerous previous researches. In this paper, we present the analytical result of investigation pertaining to the CFRP reinforcing effect on the singly reinforced and doubly reinforced rectangular flexural members and T-shape singly reinforced flexural member. The analytical study is performed according to the code by ACI Committee 440 and previous research results.

휨 거동 및 전단부의 전단거동으로 인한 철근상세 및 사용되어지는 철근의 과다로 인하여 취성파괴의 양상이 발생 하고 있다. 이에 본 실험에서는 유리섬유망을 이용하여 철근과의 휨 및 변위 거동을 통하여 무보강철근과 유리섬유망의 ply 수에 따른 휨거동 실험을 통하여 균열을 살펴보고서 향후 휨 거동에 적정한 유리섬유망의 철근의 배치겹수에 대한 사용량을 검토하고자 한다.

This study is the research appling the representative Displacement-Based Design which is the basic concept of Direct Displacement Based Design proposed by Chopra and Goel to original Reinforced Concrete moment frame and determining the thickness of retrofit Steel Jacket about the Maximum design ground acceleration, and developing the more improved Algorithm as well as program by the Retrofit Design method and Nonlinear analysis by the Performance design method before and after reinforcement appling the determined retrofit thickness. It also shows the result of the seismic performance improvement which is the ratio of seismic performance appreciation result yield displacement 19%, yield strength ratio 24%, displace ductility ratio the maximum 27% comparing Multi degree of freedom, column member of Reinforced Concrete with the performance improvement column member considering the thickness of the determined Steel Jacket. The developed Algorithm and program are easy to apply seismic design and application to the original Reinforced Concrete building, at the same time, it applicate to display well the design result of Target displacement performance level about nonlinear behavior.

In this paper, analytical models for reinforced concrete shear wall systems designed based on Korean Building Code (KBC2009) are proposed, which have special and semi-special seismic details and are compared with experimental results for a verification of analytical models. In addition, semi-special seismic details aimed to improve constructability and enhance economic efficiency were proposed and evaluated. The analytical models were performed based on nonlinear static and dynamic analysis. Through the nonlinear analyses, two seismic details showed the similar seismic behavior from the cyclic test and the analytical models for the two different seismic details represented the behavior in terms of the initial stiffness, maximum strength and strength degradation. And newly proposed seismic details(semi-special) provided with similar hysterestic behavior as well as the maximum drift.

PURPOSES: As pavement generally provides service shorter than an expected life cycle, maintenance cost increases gradually. In order to help extending the service life and reduce maintenance cost, a new multi-functional composite pavement system is being developed in Korea. METHODS: This study is a part to develop the multi-functional composite pavement and is to investigate the mechanical performances of fiber-reinforced lean concrete for pavement subbase. The inherent problem of fiber reinforced concrete is dispersion of fibers in concrete mix. This study additionally evaluated fiber dispersion characteristics with respect to different fiber types. RESULTS: From the test results, the compressive strengths of the concretes satisfied the required limit of 5MPa at 7days. The standard deviation of the measured number of fibers were lower in the order of nylon, steel fiber and polypropylene. CONCLUSIONS: Reject ash was shown to be satisfactory as a replacement material to Portland cement in lean concrete base. The fiber volume fraction is suggested to be 0.4% even though the fracture toughness did not vary significantly with respect to fiber types. However, fracture energy absorbed up to complete failure increased with the increased fiber volume fraction increment.

In this study, 5-story structures were designed in accordance with KBC2009 for inelastic time history analysis of RC IMRF. Bending moment-curvature relationship for beam and column was identified with fiber model and bending moment-rotation relationship for beam-column joint was calculated with simple and unified joint shear behavior model and moment equilibrium relationship for the joint. The hysteretic behavior was simulated with three-parameter model suggested in IDARC program. The analytical results showed that the inelastic shear behavior of the joint could be neglected in the structural design for seismic design category C but the structure of category D did not satisfy the criteria of FEMA 356 for collapse prevention performance level.

PURPOSES : Hollows are easily made, and bearing capacity can be lowered near underground structures because sublayers of pavement settle for a long time due to difficult compaction at the position. If loadings are applied in this condition, distresses may occur in pavement and, as the result, its lifespan can decrease due to the stress larger than that expected in design phase. Although reinforced slab is installed on side of box culvert to minimize the distresses, length of the reinforced slab is fixed as 6m in Korea without any theoretical consideration. The purpose of this paper is investigating the behavior of concrete pavement according to the cover depth of the box culvert ad the length of the reinforced slab. METHODS : The distresses of concrete pavement slabs were investigated and cover depth was surveyed at position where the box culverts were located in expressways. The concrete pavements including the box culverts were modeled by finite element method and their behaviors according to the soil cover depth were analyzed. Wheel loading was applied after considering self weight of the pavement and temperature gradient of the concrete pavement slab at Yeojoo, Gyeonggi where a test road was located. After installing pavement joint at various positions, behavior of the pavement was analyzed by changing the soil cover depth and length of the reinforced slab. RESULTS : As the result, the tensile stress developed in the pavement slab according to the joint position, cover depth, and reinforced slab length was figured out. CONCLUSIONS : More reasonable and economic design of the concrete pavement including the box culvert is expected by the research results.