• 한국강구조학회 논문집
• /
• 제29권4호
• /
• pp.261-268
• /
• 2017

본 논문에서는 강관철탑의 3차원 비선형해석 및 비교 검증 실험을 통하여 보조재의 역할 및 결구 거동 특성을 파악하였다. 특히 기존 철탑의 삼각결구를 단순화한 사각결구의 거동특성을 살펴보기 위하여 외측결구와 내측결구의 형상을 달리하고 각 결구의 다양한 조합을 통하여 보조재가 철탑의 내력에 미치는 영향을 살펴보았다.

• Structural Engineering and Mechanics
• /
• 제59권2호
• /
• pp.327-341
• /
• 2016

This study addresses the effect of pre-stressed cables on a pre-stressed mega-braced steel frame through employing static analysis and pushover analysis. The performances of a pre-stressed mega-braced steel frame and a pure steel frame without mega-braces are compared in terms of base shear, ductility, and failure mode. The influence of the cable parameters is also analyzed. Numerical results show that cable braces can effectively improve the lateral stiffness of a pure frame. However, it reduces structural ductility and degenerates structural pre-failure lateral stiffness greatly. Furthermore, it is found that 20% fluctuation in the cable pretension has little effect on structural ultimate bearing capacity and lateral stiffness. As comparison, 20% fluctuation in the cable diameter has much greater impact.

• Earthquakes and Structures
• /
• 제13권2호
• /
• pp.137-150
• /
• 2017

This paper focuses on the post-earthquake serviceability of steel arch bridges installed with three types of seismic dampers suffered mainshock-aftershock sequences. Two post-earthquake serviceability verification methods for the steel arch bridges are compared. The energy-absorbing properties of three types of seismic dampers, including the buckling restrained brace, the shear panel damper and the shape memory alloy damper, are investigated under major earthquakes. Repeated earthquakes are applied to the steel arch bridges to examine the influence of the aftershocks to the structures with and without dampers. The relative displacement is proposed for the horizontal transverse components in such complicated structures. Results indicate that the strain-based verification method is more conservative than the displacement-base verification method in evaluating the post-earthquake serviceability of structures and the seismic performance of the retrofitted structure is significantly improved.

• 한국강구조학회 논문집
• /
• 제27권2호
• /
• pp.169-180
• /
• 2015

최근 구조물의 내진설계 기준이 2009년도 개정되면서 내진설계기준이 점차 구체화 되고 있다. 이에 따라 내진설계기준이 반영되지 않았거나 현재의 기준을 만족시키지 못하는 국내 구조물에 대해 재 검토 될 필요가 있다. 특히 중 저층 구조물의 경우 횡력 저항 요소는 대부분 가새에 의해 설계되어 있다. 즉 현재 사용 중인 가새가 반복적인 지진하중에도 전체 구조물의 안정성을 확보할 수 있도록 합리적인 보강방안이 구체화 될 필요가 있다. 본 연구에서는 무용접 냉간성형 강재로 조립된 압축가새의 구조적 성능과 거동을 분석하고자 한다. 실험변수는 보강길이 그리고 보강단면 비를 중점으로 구조실험을 수행하였다. 따라서 본 연구에서는 세장한 H형강 가새의 휨좌 굴을 억제하여 압축내력을 발휘토록 보강방안을 제안하였고, 보강안의 압축거동을 검증하기 위해 세장비와 보강량을 변수로 구조 성능 실험을 수행하여 강도, 강성, 변형성능과 파괴거동의 분석을 수행하였다.

• 한국강구조학회 논문집
• /
• 제23권2호
• /
• pp.169-177
• /
• 2011

본 논문은 반복하중을 받는 고강도강 원형강관의 T형 접합부의 면내 휨모멘트 내력에 대해 체계적으로 수행된 유한요소 해석으로부터 얻은 결과를 제시하고 있다. 용접된 원형강관의 T형 접합부의 회전강성 및 이에 따른 파괴모드를 분석하기 위하여 T형 접합부의 3차원 비선형 유한요소모델을 이용하였다. 주관과 지관의 세장비, 주관과 지관의 지름비와 같은 기하학적 파라미터 및 항복비 등에 따른 T형 접합부의 다양한 구조적 거동을 제시하였으며, 또한 주관의 압축응력의 크기에 따른 T형 접합부의 극한 면내 휨모멘트 내력의 변화를 분석하였다.

• 국제강구조저널
• /
• 제18권5호
• /
• pp.1525-1540
• /
• 2018

A test rig with multi-functional purposes was specifically designed and manufactured to study the behavior of multi-planar welded tubular joints subjected to multi-planar concurrent axial loading. An experimental investigation was conducted on full-scale welded tubular joints with each consisting of one chord and eight braces under monotonic loading conditions. Two pairs or four representative specimens (two specimens for each joint type) were tested, in which each pair was reinforced with two kinds of different internal stiffeners at the intersections between the chords using welded rectangular hollow steel sections (RHSSs) and the braces using rolled circular hollow steel sections (CHSSs) and welded RHSSs. The effects of different internal stiffeners at the chord-brace intersection on the load capacity of joints under concurrent multi-planar axial compression/tension are discussed. The test results of joint strengths, failure modes, and load-stress curves are presented. Finite element analyses were performed to verify the experimental results. The study results show that the two different joint types with the internal stiffeners at the chord-brace intersection under axial compression/tension significantly increase the corresponding ultimate strength to far exceed the usual design strength. The load carrying capacity of welded tubular joints decreases with a higher degree of the manufacturing imperfection in individual braces at the tubular joints. Furthermore, the interaction effect of the concurrent axial loading applied at the welded tubular joint on member stress is apparent.

• Structural Engineering and Mechanics
• /
• 제84권1호
• /
• pp.113-127
• /
• 2022

Steel plate shear walls (SPSWs) are commonly utilized to provide lateral stiffness in high-rise structures. The simplified model is frequently used instead of the fine-scale model in the design of buildings with SPSWs. To predict the lateral strength of steel plate shear walls with diagonal stiffeners (DS-SPSWs), a simplified model is presented, namely the cross brace-strip model (CBSM). The bearing capacity and internal forces of columns for DS-SPSWs are calculated. In addition, a modification coefficient is introduced to account for the shear action of the thin plate. The feasibility of the CBSM is validated by comparing the numerical results with theoretical and experimental results. The numerical results from the CBSM and fine-scale model, which represent the bearing capacity of the DS-SPSW with varied stiffened plate dimensions, are in good accord with the theoretical values. The difference in bearing capacity between the CBSM and the fine-scale model is less than 1.35%. The errors of the bearing capacity from the CBSM are less than 5.67% when compared to the test results of the DS-SPSW. Furthermore, the shear and axial forces of CBSM agree with the results of the fine-scale model and theoretical analysis. As a result, the CBSM, which reflects the contribution of diagonal stiffeners to the lateral resistance of the SPSW as well as the effects on the shear and axial forces of the columns, can significantly improve the design accuracy and efficiency of buildings with DS-SPSWs.

• Steel and Composite Structures
• /
• 제14권6호
• /
• pp.621-636
• /
• 2013

Response modification factor is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake, in conformity with the point that many seismic design codes led to reduce the loads. In the present paper it's tried to evaluate the response modification factors of dual moment resistant frame with buckling restrained braced (BRB). Since, the response modification factor depends on ductility and overstrength; the nonlinear static analysis, nonlinear dynamic analysis and linear dynamic analysis have been done on building models including multi-floors and different brace configurations (chevron V, invert V, diagonal and X bracing). The response modification factor for each of the BRBF dual systems has been determined separately, and the tentative value of 10.47 has been suggested for allowable stress design method. It is also included that the ductility, overstrength and response modification factors for all of the models were decreased when the height of the building was increased.

• Earthquakes and Structures
• /
• 제10권3호
• /
• pp.589-611
• /
• 2016

This paper presents an analytical study aimed at evaluating the seismic performance of steel moment resisting frames (MRFs) retrofitted with different approaches. For this, 3, 6 and 12 storey MRFs having four equal bays of 5 m were selected as the case study models. The models were designed with lateral stiffness insufficient to satisfy code drift and hinge limitations in zones with high seismic hazard. Three different retrofit strategies including traditional diagonal bracing system and energy dissipation devices such as buckling restrained braces and viscoelastic dampers were used for seismic upgrading of the existing structures. In the nonlinear time history analysis, a set of ground motions representative of the design earthquake with 10% exceedance probability in fifty years was taken into consideration. Considering the local and global deformations, the results in terms of inter-storey drift index, global damage index, plastic hinge formations, base shear demand and roof drift time history were compared. It was observed that both buckling-restrained braces and viscoelastic dampers allowed for an efficient reduction in the demands of the upgraded frames as compared to traditional braces.

• Steel and Composite Structures
• /
• 제3권5호
• /
• pp.321-331
• /
• 2003

The paper presents the results of an experimental investigation conducted on welded tubular joints, that are employed in offshore platforms, to study the behaviour and strength of these joints under axial brace compression loading. The geometrical configuration of the joints tested were T and Y. The nominal diameter of the chord and brace members of the joint were 324 and 219 mm respectively. The chord thickness was 12 mm and the brace 8 mm. The tested joints are approximately quarter size when compared to the largest joints in the platforms built in a shallow water depth of 80 m in the Bombay High field. Some of the joints were actually fabricated by a leading offshore agency which firm is directly involved in the fabrication of prototype structures. Strength of the internally ring-stiffened joints was found to be almost twice that of the unstiffened joints of the same configuration and dimensions. Bending of the chord as a whole was observed to be the predominant mode of deformation of the internally ring-stiffened joints in contrast to ovaling and punching shear of the unstiffened joints. It was observed in this investigation that unstiffened joint was stiffer in ovaling mode than in bending and that midspan deflection of unstiffened joint was insignificant when compared to that of the internally ring stiffened joint. The measured midspan deflection of the unstiffened joint in this investigation and its relation with the applied axial load compares very well with that predicted for the brace axial displacement by energy method published in the literature. A comparison of the measured deflection and ovaling of the unstiffened joint was made with that published by the author elsewhere in which numerical prediction of both quantities have been made using ANSYS software package. The agreement was found to be quite good.