Earticle

While the method of construction for modular school building is systemically studied and widely disseminated, The purpose of this study is to improve the structural shortcomings of modular school building including low structure efficiency as mediated with twofold use of structural members and defects in the joint component design of column-beam connection, thereby enabling to develop both economical and eco-friendly technique which might be attributed to the construction of modular house. Furthermore, this study aims to establish and disseminate the fundamental data for the standardization design of modular units, container house, by accumulating technical data.

As structures are high-rise and bigger, the demands of high strength steels have enabled it to be produced which have excellent properties such as strength, ductility, weldability and toughness than conventional steels do. Computer models of WUF-B connection were formed and analyzed using the finite-element analysis computer program of ABAQUS. The analysis model is based on the test program using high and normal strength steel. In general, the failure mode and maximum deformation obtained by test could not be simulated from the finite element analysis specially for the cyclic loading. The maximum equivalent strain and accumulated plastic strain obtained by FEA were found based on the cyclic test result at the failure. The applied load history of FEA model was traced as same as the cyclic test until it failed. And, the accumulated equivalent plastic strain was selected to find the global deformation capacity of connection at failure. Analysis results show that the selected maximum accumulated equivalent plastic strain at failure for different strength, normal and high strength steel, are different. The suggested plastic strain could be used to find numerically the limit of deformation capacity of beam-to-column connection, which results in the reduction of expensive test.

For steel structures of building, the connect which connects column and beam must have structural rigidity of the movement and the transmission of stress, with showing the resistance force and the ability of deformation by design considered performance for construction work enough. Generally, all of the analysis and design of connect is assumed the rigid style that does not make a rotation occur but delivers the moment at the panel point and the pinned style which breaks out a rotation only. However, actually, the safety of frame and economical design is not applied in movement of realistic buildings, because the movement of column-beam connect slightly have binding force for delivering moment and rotation. Accordingly, this research will give the basic materials of connect design by reformed T-stub which closes to semi-rigid connection improved turning force. In cases of four models, I had loaded the specimens with giving variables the length of overhang. Through the research, I got some conclusions as follows. 1) The leverage effect of the tension connect did not happen. 2) TL4 specimen which was the longest overhang length had the biggest ultimate strength. 3) The semi-rigid connection of unified T-stub connect showed good restoring force situation for repeated load. 4) It is necessary that we should find a proper measure to take care of slip phenomenon of the connect caused by repeated load.

Interest in modular buildings has surged recently, leading to their construction at increasing heights. However, seismic performance evaluations for modular connections remain insufficient. Based on Jang's (2019) experimental research, this study validates an analytical model and conducts parametric analyses on the shear strength ratio between the panel zone and beam, and the width-to-thickness ratio of the bracket. When the panel zone-to-beam shear strength ratio was 1.5 or higher, plastic hinge formation shifted from the panel zone to the beam. Consequently, a shear strength ratio between 1.5 and 2.0 is recommended. Analysis of the bracket’s width-to-thickness ratio revealed local buckling in models with non-compact sections, suggesting that brackets in modular connections be designed with compact sections or greater to enhance structural performance.

The PCS system, which consists of precast concrete column and steel beam, is a kind of composite structural systems. In this paper, experimental study and Nonlinear finite element analysis is conducted to predict the structural behavior of precast concrete column and steel beam connected by using bolted connections. Based on experimental results from the seismic testing of eight interior PCS specimens, it shows that the PCS system is satisfied with seismic performance criteria of ACI such as strength deterioration, stiffness degradation and energy dissipation capacity except initial stiffness. In order to investigate cause of initial stiffness loss, we experiment one specimen applied symmetry monotonic loading and perform 3-D finite element analysis using the nonlinear FE program, ABAQUS. Analysis is stiffer than testing result, but we estimate testing results using the GAP element.

In this study, Beam-column joint specimens of building structural steels(SN490) and welding structural steels (SM490) were conducted lateral cycle test. The experimental method was conducted Certification testing methods presented in KBC2009. Through experiments, Hysteretic behavior of Load-displacement, Moment-Rotation angle ductility, stiffness and energy dissipation capacity was analyzed. Specimens type is all welded type(WA-1, WA-2) and welded flange, double angle spliced web(WB-1, WB-2) total 4 types. Instead, fracture occurred at heat-affected zones or the stress- concentrated point near the weld access hole of the beam flanges.

RCS construction method is to take an advantage by applying reinforced concrete column and steel beam. RCS construction method has a complex structural analysis, compared with single structural system, due to interaction of different material, behavior of load distribution, diversity of joint detail and failure behavior. Therefore, this study aims to describe behavior of RCS joint as a simplified analysis model. The first, for understand behavior of RCS joint through test literatures related to RCS from the inside and outside of country and presented an analysis model, which to reflect each characteristic. So first of all, the researcher divided RCS specimen into four groups, according to its form and stress distribution element. The 'C' group, which is a flexural failure model, was explained properly using a factor in not order to generate stiffness reduction, strength reduction and pinching with polygonal model. The 'A', 'B' and 'D' groups, which are origin oriented models, were explained properly using smooth model and they had little bigger values in stiffness and strength reduction than general RC joint and a factor of pinching was explained through a combination among slip length, slip sharpness and moment level of slip in each group.

This study aims to evaluate the ultimate shear strength of the connections of composite steel beam(CSB) composed of reinforced concrete (RC) column and steel beam. Total number of specimens of CSB were 66 carried out by researchers in domestic and foreign countries. The specimens were considered with various types of shear reinforcement such as shear reinforcement of vertical and end concentration, band plate and stud bolt and welding of main bar, etc. Ultimate shear strength of the connections with various reinforcement types was evaluated through experiments and code equations. In this study, experimental result were compared with code formula(KBC-RC, JIS-RC, JIS-SRC) and Zsutty`s Equation. The average test-to-code ratio of ultimate shear strength for all specimens was 1.05(KBC-RC), 1.59(JIS-RC), 1.16(JIS-SRC), and 0.96(Zsutty). Categorized by shear reinforcement type of specimen, ultimate shear strength by code formula and Zsutty’s equation deviated from 6% to 41% from experimental results and the average of deviated percentage was 25%(KBC-RC), 29%(JIS-RC), 29%(JIS-SRC), and 21%(Zsutty). Specimen reinforced at end with fixed plate showed the best correlation with code formula and Zsutty’s equation.

Beam-to-column connections are very important in steel structure buildings, and have direct effect on safety and economic efficiencies of the buildings. Especially, they have rigidity and ductility that are necessary for behavior and stress transmission of buildings. Furthermore, they are also needed carry strength and strain with easy construction. The design and analysis of steel structure connections are generally considered to consist of rigid, semi-rigid or pin joint. Deformation characteristic of H-shaped beams with newly T-stub connections is investigated for the effect of these joints on inelastic behavior of the beams in this paper. This research applies the model of exponential function based on the equations of equilibrium and compatibility equations at the location of bolts. The prying action reducing both the ultimate load capacity and the fatigue of the bolts are not considered in this study. The elasto-plastic behavior has been studied through various models with parameters of the length of T-flange, distance of bolts and the diameter of bolts. The results indicated that the distance of bolts has a great effect on the ultimate strength and deformation capacity of T-stub connections. The presented method may be a useful tool for the design of T-stub connections.

본 연구는 국내에서 주로 사용되는 강구조 보-기둥 접합상세와 논스캘럽접합상세의 내진성능을 비교하기 위해 실대형 정적반복실험과 실험과 동일한 모델링 통한 FEM해석을 진행하였다. 정량적인 수치비교를 위해 이전연구에서 사용된 변형률집중지수와 모멘트전달효율을을 인용하였다. 보 웨브의 용접면적 감소에 따라 플랜지 부분의 변형률이 증가되어 회전각에 따른 소성변형능력이 감소되거나 취성파단이 일어나는 현상을 보였다. 해석결과와 실험결과 비교시 H형 전체단면적에 대한 웨브 용접비가 60%이하로 떨어질 경우 취성파단이 일어날 가능성이 높아지는 경향이 나타났다.

In this study, in order to compare the seismic performance of steel structure beam-column connection details and non-scallop connection details mainly used in Korea, a full-scale static cyclic loading test and FEM analysis were conducted through the same modeling as the experiment. For quantitative numerical comparison, the strain concentration ratio and moment transfer efficiency used in previous studies were cited. As the welding area of the beam web decreased, the deformation rate of the beam flange increased, and the plastic deformation capacity according to the rotation angle decreased or brittle fracture occurred. Comparing the analysis results with the experimental results, the possibility of brittle fracture tended to increase when the web welding ratio for the total cross-sectional area of H-shaped fell below 60%.

There are many Beam-Column connections in general structures and ship structures. For simplicity and convenience of analysis, the connections are mostly considered hinged when not reinforced or rigidly fixed when reinforced. This paper has intended to analyze the Beam-Column connection which is assumed two dimensional flat plate. The analysis has been preformed by Finite Element Method following the change of moment of inertia at connection. The conclusion of this investigation is as follows: By reinforcing or increasing the moment of inertia at connection part, the stress distribution of whole structure and the stress concentration at that part are relieved. Displacements of beam(when column is fixed) are almost linearly decreasing by the change of moment of inertia at connection.

The first thing in developing precast post-tensioned concrete frame system verify the shear resistance capacity of the beam-column connection at which the transfer of member forces become discontinuous. Complying with the necessity of such experimental research, shear tests have been performed for six test specimens which were cast and cured at Dong-Ah Concrete Manufacturing Company and post-tensioning at Concrete Laboratory of Inha University. Shear key and magnitude of post-tensioned force are taken test variables. From the test results, it has been observed that the shear resistance of the specimens attained to higher values than those of theoritical calculations based on the shear friction with shear friction coefficient being 0.6.

취성파괴는 구조물의 파괴거동 중 하나로서 구조재료의 내진성능에 큰 영향을 미친다. 하중속도는 취성파괴의 주요 발생원인 중 하나로 작용하며, 특히 지진과 같은 상황에서 건축물에 높은 하중속도가 작용하게 된다. 하지만 현재 국내·외 강구조 보-기둥 접합부의 내진성능평가는 대부분 정적실험을 통해 수행되고 있다. 따라서 기존 내진성능평가에서는 지진 시의 높은 하중속도에 의한 재료 인성 저하 및 최대변형률 감소 등의 요소에 따른 취성파괴가 충분히 고려되지 않았을 가능성이 존재한다. 본 연구에서는 기존 실험방법에 따른 낮은 하중속도에서의 정적실험과 진동대를 이용한 높은 하중속도에서의 동적실험을 각각 실시한다. 각 실험결과에 따른 파괴형상 및 구조성능 등을 비교·분석하고 최종적으로 하중속도의 크기가 접합부의 내진성능에 미치는 영향을 분석한다.

Brittle feature is one of the fracture behaviors of structure s and has a great influence on the seismic performance of structure materials. The load velocity acts as one of the main causes of brittle fracture, and in particular, in situations such as earthquakes, a high load velocity acts on buildings. However, most of the seismic performance evaluation of the domestic and external steel connections is conducted through static experiments. Therefore, there is a possibility that brittle fracture due to factors such as degradation of material toughness and reduction of maximum deformation rate due to high load velocity during an earthquake was not sufficiently considered in the existing seismic performance evaluation. This study conducts a static test at a low load velocity according to the existing experimental method and a dynamic test at a high load velocity using a shaking table, respectively. It compares and analyzes the fracture shape and structural performance according to the results of each experiment, and finally analyzes the effect of the load velocity size on the seismic performance of the connection.

This study was intended to investigate the cyclic behavior of high strength concrete beam-column connection. Four assemblies were designed 2/3 scale beam-column-slab joint and tested. The obtained results are follows. 1) The transverse beams increase the shear resistance and ductility of joint, 2) The slab was contributed to increase of the flexural capacity of the beam, but was not contributed to increase the joint ductility under lateral loads.

In this study, a simple moment-resisting precast concrete beam-column connection is proposed for highly seismic zone using dywidag ductile rod [DDC]. DDC is superior system for ductility, energy dissipation capacity, connection strength, and drift capacity. A study was carried out to investigate the connection behavior subjected to cyclic inelastic loading. Four Precast beam-column interior connections and one monolithic connection will be tested. The variables will be examined were the strength relationship between joint's ductile rod and beam reinforcement for gain energy dissipation capacity. The specimens will be tested only reverse cyclic loading in accordance with a prescribed displacement history. Connection performance is evaluated on the basis of ductility, energy dissipation capacity, connection strength, and drift capacity. the precast connection using DDC is capable of matching of exceeding the performance of the monolithic connection and thereby provides moment-resisting behavior.

The composite systems, consisting of R/C Columns-Steel Beams, are reasonable structures because of their constructional and economical advantages, workability and so on. But, it is difficult to apply the composite systems to actual design due to material dissimilarity and complicate stress flow in the connection. This study aims to propose the hybrid beam-column connection system with structural tee and through experimental research make clear the shear and moment resistance capacity and stress transfer mechanism.

The purpose of this study is to compare the response of the high-strength concrete beam-column-slab subassembly with the response of a normal-strength concrete specimens. Four assemblies were designed 2/3 scale beam-column-slab joint(fc'=240kg/cm2 fc'=700kg/cm2) and tested to investigate seismic behaviour. From the test results 1) flexral cracks emerge to inside of bean deeply for high strength concrete member 2) the high-strength specimens represented stable hysteretic behaviour for the displacement ductility 5.5 but degradation in stiffness and strength and unstable hysteretic behaviors were observed owing to the brittleness of high-strength concrete beyond its range.

이 연구에서는 볼트접합 및 프리스트레스를 적용한 프리캐스트 콘크리트 보-기둥 외부접합부의 내진 및 구조적 성능을 평가하였다. 총 5개의 보-기둥 외부접합부 실험체를 제작하고 보 단부에 변위제어 방식으로 반복하중을 가하며 실험을 수행하였다. 이 연구의 결과를 근거로 다음과 같은 결론을 얻을 수 있었다. 완전 건식공법이 적용된 PC 접합부는 완전 습식공법이 적용된 RC 접합부보다 에너지소산이나 핀칭현상에 있어서 불리한 거동을 보였지만 이는 설계과정에서 의도된 현상이며, 횡변형 능력에 있어서는 우수한 결과를 보였다. 또한 층간변위비 4%까지 횡하중 저항성능의 손실이 발생하지 않았고 매설용너트에 항복이 집중되는 메커니즘을 보이는 점으로 미루어 볼 때 개발된 접합부는 외부접합부 횡저항시스템으로서 적합한 것으로 사료된다. 추가적인 프리스트레스는 PC 접합부의 과도한 핀칭현상 방지 및 접합부 균열제어에 효과적이었으며 PC 접합부의 전체적인 내진성능을 향상시켰다.

In this study, experimental research was carried out to investigate the seismic and structural performance of precast concrete exterior beam-column joints using bolt type connection and prestressing method. A total of five full-scale exterior beam-column joints were constructed and tested under reversed cyclic loading, controlled by displacement. Results of the test are as follows: Energy dissipation capacity and pinching phenomenon of PC beam-column joints showed disadvantageous behavior compared to RC beam-column joints. However, drift capacity of the PC joint was excellent. Also, yield mechanism concentrated on embedded nuts was suitable as an exterior beam-column joint of lateral load resistance frame. Additional application of prestressing method was also very effective to control excessive pinching and cracking in the joint region, and thus improved an overall seismic performance of the PC joint.