• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.6
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• pp.637-644
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• 2021

Dynamic response of structures can be evaluated experimentally by conducting cyclic loading tests. It has been known that steel materials are rate-dependent and the lateral response of a structure is significantly affected by the presence of axial force. However, the rate-dependency of steel column structures subjected to both axial and lateral loads has not been sufficiently studied yet due to the difficulty of controlling the axial force in a real-time manner during test. This study introduces an advanced way to apply the axial load in real-time to a column specimen using the adaptive time series (ATS) compensator and the flexible loading beam (FLB), where the H-shape steel columns made of SS275 are used for monotonic and cyclic loading tests with various loading rates with axial loads. The lateral strength and post-yield response of the steel columns are compared for each of monotonic and cyclic loading tests. The estimating equation of yield stress of various strain rate has proposed and finite element analysis were performed for comparison.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.287-297
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• 2022

This paper presents experimental and analytical studies on the lateral cyclic behavior of RC columns actively confined with iron-based shape memory alloy (Fe-SMA) strips. Based on the Anexperimental study, we investigated the effectiveness of active confinement through compression testings of concrete cylinders confined by Fe SMA strips and carbon fiber-reinforced polymer (CFRP) sheets. The test results showed that the specimens confined with Fe SMA strips significantly increased the deformation capacity of the concrete, even under lower confining pressures, compared to those specimensconfined with CFRP sheets. The experimental results were used to develop finite-element models of RC columns confined with Fe SMA or CFRP in their plastic-hinge region. After validating the proposed analytical model through comparison with the results from a previous RC column test, a series of lateral cyclic load analyses were carried out for the RC columns confined with Fe SMA and CFRP. The analytical results revealed that the lateral cyclic behavior of the Fe SMA-confined column was greatly enhanced in terms of deformation and energy dissipation capacities compared with tothat of the as-built and CFRP-confined columns.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.73-82
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• 2001

본 연구는 실험적 방법과 해석적 방법을 통하여 반복하중을 받는 ├형 철근콘크리트 접합부의 전단특성을 파악함을 목적으로 한다. ├형 접합부는 고강도 재료의 사용으로 인한 체적의 감소 뿐만 아니라, 지진발생 시 반복하중의 작용으로 인한 변동축력 등으로 , 구조적으로 취약한 부분이 될 가능성이 있다. 따라서 본 연구에서는 ├형 접합부의 전단특성을 파악하기 위하여 기동축력, 콘크리트 압축강도, 접합부 전단보강근비를 변수로 한 12개의 실험체를 제작하여 가력실험을 수행하였다. 또한, 유한요소 해석을 수행하여 본 실험결과와의 비교 검토를 통하여 타당성을 검토한 후, 기둥축력과 콘크리트 압축강도의 변화에 대한 변수해석을 통하여 접합부의 전단강도에 미치는 변수는 영향을 파악하였으며, 실험에 의한 실험체의 전단내력을 기존에 제안된 AIJ, ACI 규준 등과 비교 검토하였다. 본 연구의 결로부터 기둥축력과 콘크리트 압축강도가 ├형 철근콘크리트 접합부의 전단강도에 미치는 영향을 확인하였다.

• Journal of Korean Society of Steel Construction
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• v.21 no.2
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• pp.115-125
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• 2009

An experimental study was performed to investigate the cyclic behavior of the reinforced concrete frame with infilled steel plate. For this purpose, three-story compositewalls using infilled steel plates (RCSPW) were tested. The parameters for this test were the reinforcement ratio of the column and opening in the infilled steel plate. A reinforced concrete infilled wall (RCIW) and a reinforced concrete frame (RCF) were also tested for comparison. The deformation capacity of the RCSPW specimen was significantly greater than that of the RCIW specimen, although the two specimens exhibited the same load-carrying capacity. Like the steel plate walls with the steel boundary frame, RCSPW specimens showed excellent strength, deformation capacity, and energy dissipation capacity. Furthermore, by using infilled steel plates, shear cracking and failure of the column-beam joint were prevented. By using a strip model, the stiffness and strength of the RCSPW specimens were predicted. The results were compared with the test results.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.3
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• pp.19-28
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• 2018

Key factors that ensure competitiveness of modular unit include consistent high quality and connection condition that ensures high structural performance while minimizing the overall scale of the on-site process. However, it is difficult to evaluate the structural performance of the connection of modular unit, and its structural analysis and design method can be different depending on the connection to its development, which affects the seismic performance of its final design. In particular, securing the seismic performance is the key to designing modular systems of mid-to-high-rise structure. In this paper, therefore, the seismic performance of the modular system with bracket-typed fully restrained moment connections according to stiffness and the shapes of various connection members was evaluated through experimental and analytical methods. To verify the seismic performance, a cyclic loading test of the connection joint of the proposed modular system was conducted. As a result of this study, theoretical values and experimental results were compared with the initial stiffness, hysteresis behavior and maximum bending moment of the modular system. Also, the connection joint was modeled, using the commercial program ANSYS, which was then followed by finite element analysis of the system. According to the results of the experiment, the maximum resisting force of the proposed connection exceeded the theoretical parameters, which indicated that a rigid joint structural performance could be secured. These results almost satisfied the criteria for connection bending strength of special moment frame listed on KBC2016.

• Journal of Korean Society of Steel Construction
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• v.10 no.3 s.36
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• pp.339-353
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• 1998

In this paper, the previous damage models for structures and their components under seismic repeated loading were reviewed systematically. A failure criterion for steel members under severe cyclic excitations as in strong earthquakes was described. A new approach to seismic damage assessment for steel members was proposed. This method was based on a series of the experimental and numerical investigations for steel members under very low cyclic loading. In this study, very low cyclic loading means repetitive loading, 5 to 20 loading cycles, within the large plastic range. The proposed damage assessment method was focused on the local strain history at the cross-section of the most severe concentration of deformation.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.59-71
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• 2012

Results of the analysis of the structural behavior of axially loaded nodes in freeform structure were not fully understood due to certain difficulties, including the application of various welding and bolting types. In this study, a node of single layered freeform structure was tested to determine its structural behavior when subjected to axial loads. The tests were classified into node ball tests to evaluate the center of the node subjected to cyclic and monotonic loading. The node part tests were also conducted to evaluate the whole node subjected to monotonic loading. The test showed that the node ball is safe with the tensile force, but the node ball needs to increase its strength with the node loaded compressive force due to the additional bending moment of the node ball's asymmetric form.

• Journal of Korean Society of Steel Construction
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• v.11 no.2 s.39
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• pp.241-241
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• 1999

The analysis and design of steel frames are usually carried out under the assumption that the connections of beam-to-column are either fully rigid or ideally pinned. However the connections actually show semi-rigid behavior in many cases. The authors investigated the structural behavior of simi-rigid connection with reformed T-stub by using of SM490 steel. The objective of the study is to investigate the structural behavior of the beam-to-column semi-rigid connection with reformed T-stub, which is made of SS400 steel. The beam-to-column connections by using reformed T-stubs were tested under monotonic loading and cyclic loading condition. The possibility of application of semi-rigid connections with reformed T-stubs was ascertained from test results.

• Journal of Korean Society of Steel Construction
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• v.12 no.4 s.47
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• pp.339-350
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• 2000

The objective of this study is to investigate the structural behavior of the beam to column connection with reformed T-stubs and to ascertain the application of semi-rigid connection with reformed T-stubs to middle high rise buildings. The tests of steel frame using semi-rigid connections with reformed T-stub and existing T-stub were performed under cyclic loading condition. Finite element analysis was also carried out and the results of FEM were compared with results of tests. The thickness of reformed T-stub and the distance of bolt were used for parameters in the analysis. The structural behaviors of reformed T-stub were understood qualitatively and the possibility of application of semi-rigid connections with reformed T-stubs was ascertained.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.627-634
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• 2004

The purpose of this study is to investigate seismic performance of a bearing wall system for apartment buildings. An 1/3 scale three-story specimen was constructed and tested under cyclic lateral loads. The specimen was consisted of pierced walls and coupling elements as well as floor slabs. The bearing wall system is considered to have a adequate deformation capacity up to $2.0\%$ of roof drift ratio, and the experimental results showed the ductile load-deformation characteristics even though some walls were failed in shear Nonlinear analysis was peformed to compare the load-deformation curve obtained from the experimental program. The result of nonlinear analysis could be useful to predict the actual behavior characteristics of the bearing wall system subjected to lateral loads.