• Steel and Composite Structures
• /
• 제32권1호
• /
• pp.79-90
• /
• 2019

This study introduces new connections that connect the beam to the column with slit dampers. Plastic deformations and damages concentrate on slit dampers. The slit dampers prevent plastic damages of column, beam, welds and panel zone and act as fuses. The slit dampers were prepared with IPE profiles that had some holes in the webs. In this paper, two experimental specimens were made. In first specimen (SDC1), just one slit damper connected the beam to the column and one IPE profile with no holes connected the bottom flange of the beam to the column. The second specimen (SDC2) had two similar dampers which connected the top and bottom flange of the beam to the column. Cyclic loading was applied on Specimens. The cyclic displacements conditions continued until 0.06 radian rotation of connection. The experimental observations showed that the bending moment of specimen SDC2 increased until 0.04 story drift. In specimen SDC1, the bending moment decreases after 0.03 story drift. Test results indicate the high performance of the proposed connection. Based on the results, the specimen with two slit damper (SDC2) has higher seismic performance and dissipates more energy in loading process than specimen SDC1. Theoretical formulas were extended for the proposed connections. Numerical studies have been done by ABAQUS software. The theoretical and numerical results had good agreements with the experimental data. Based on the experimental and numerical investigations, the high ductility of connection is obtained from plastic damages of slit dampers. The most flexural moment of specimen SDC1 occurred at 3% story drift and this value was 1.4 times the plastic moment of the beam section. This parameter for SDC2 was 1.73 times the plastic moment of the beam section and occurred at 4% story drift. The dissipated energy ratio of SDC2 to SDC1 is equal to 1.51.

• 한국강구조학회 논문집
• /
• 제29권1호
• /
• pp.25-36
• /
• 2017

1994년 노스리지 지진 당시 발생한 용접모멘트 접합부의 취성파괴는 주로 보 하부 플랜지에서 발생하였다. 특히 국내 기존 용접철골모멘트 접합부의 경우 과다한 전단스터드 배치에 따른 의도치 않은 합성작용로 인해 지진 내습 시 보 하부 플랜지의 취성파단이 더욱 우려되는 실정이다. 본 논문에서는 합성효과로 인한 접합부 성능저하를 개선하기 위한 목적으로 중량전단탭/수평헌치/삼각헌치로 보강된 접합부 및 RBS가 도입된 접합부에 대한 실험을 실시하였다. 통상 기존 접합부 상부 플랜지의 수정이 불가하다는 점을 고려하여, 본 연구에서는 보 하부 플랜지에만 수평/삼각헌치를 보강하거나 RBS를 도입하여 이 때의 내진성능을 평가하였다. 실물대 실험 결과 수평/삼각헌치 혹은 중량전단탭으로 보강한 실험체는 모두 합성작용으로 인한 부작용을 극복하고 특수모멘트접합부가 요구하는 수준 이상의 소성회전각 5%이상을 발현함을 확인하였다. 또한 SRC 기둥에 RBS를 도입할 경우 접합부에 소요되는 변형의 대부분을 RBS측에서 일어나도록 유도함으로써 SRC기둥에 발생하는 손상을 방지하는 효과가 있음을 규명하였다. 이 중 중량전단탭 보강에 따른 접합부의 거동을 분석하기 위하여 추가의 수치해석 연구를 실시하였으며, 제시한 각각의 보강안에 대한 권장상세를 제시하였다.

• Steel and Composite Structures
• /
• 제14권1호
• /
• pp.57-71
• /
• 2013

The prediction of the low cycle fatigue (LCF) life of beam-column connections requires an LCF model that is developed using specific geometric information. The beam-column connection has several geometric variables, and changes in these variables must be taken into account to ensure sufficient robustness of the design. Previous research has verified that the finite element model (FEM) can be used to simulate LCF behavior at the end plate moment connection (EPMC). Three critical parameters, i.e., end plate thickness, beam flange thickness, and bolt distance, have been selected for this study to determine the geometric effects on LCF behavior. Seven FEMs for different geometries have been developed using these three critical parameters. The finite element analysis results have led to the development of a modified LCF model for the critical parameter groups.

• 한국안전학회지
• /
• 제17권2호
• /
• pp.76-84
• /
• 2002

The seismic behaviors of steel moment connections with different structural characteristics are investigated. The rupture index, which represents the fracture potential, is adopted to study the effect of concrete slab and the relative strength between the coin the beam, and Panel zone on the ductility of connections. The results show that the presence of slab increases the beam strength, imposes constraint near the beam top flange, and consequently, induces concentrated deformation near the beam access hall, which reduces the ductility of the connection. The total deformation capacity of the connection depends not only on the beam but also on the column and panel zone. Therefore, the detrimental slab effects and the relative strength should be considered in the seismic design of the connection.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
• /
• pp.473-478
• /
• 2003

The purpose of this study is to model the seismic behavior of Welded Unreinforced Flange and Bolted (WUF-B) connections with post-Northridge details and evaluate the system performance of the builidings with WUF-B connections. For this purpose, based on test results, mathematical model of the connections were developed and compared with test results. This connection model take into account both panel zone deformation and connection fractures. Then, SAC Phase II 3 and 9-story buildings were modeled using the connection model developed in this study. From nonlinear static pushover analysis of the buildings, maximum strength, maximum roof drift, and so forth are investigated for the buildings with post-Northridge details. Analysis results were compared with those of buildings with pre-Northridge details and ductile connections with no fractures.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
• /
• pp.29-32
• /
• 2009

Building foundations for Top-Down construction require a special setting, because the foundations have to be placed way before excavation for the substructure of main building, Usually, the foundation goes into the layer of rock and it is often called rock-pier foundation, Currently, a cage of steel reinforcing bars is inserted to the pre-excavated hole in the rock layer, hanging down from the wide flange steel column above. This paper presents a new method for connecting the prefounded column and the steel cage with a coupler for better connection between the two, The use of a circular Concrete Filled Tube (CFT) as a prefounded column makes it possible to have this type of connection. The details of the connection and application to a Top-Down construction site is also included in this paper.

• Steel and Composite Structures
• /
• 제4권4호
• /
• pp.303-315
• /
• 2004

Frame composed of concrete-filled steel tubular columns and I-shaped steel beam has been researched in order to development reasonable connection details. The present paper describes the results of an experimental program in four different connection details. The connection details considered include through-bolt between I-shaped steel beams and concrete-filled steel tubular columns and two details of welded connections. One of the welded connection details is stiffened by angles welded in the interior of the profile wall at the beam flange level. The specimens were tested in a cruciform loading arrangement with variable monotonic loading on the beams and constant compressive load on the column. For through-bolt details, the contribution of friction and bearing were investigated by embedding some of the bolts in the concrete. The results of the tests show that through-bolt connection details are very ductility and the bearing is not important to the behavior of these moment connections. The angles welded in the interior of the profile wall increase the strength and stiffness of the welded connection detail. In addition, the behavior curves of these connections are compared and some interesting conclusions are drawn. The results are summarized for the strength and stiffness of each connection.

• Steel and Composite Structures
• /
• 제6권4호
• /
• pp.303-317
• /
• 2006

The connection with combined cross diaphragm is developed for the connection of square CFT column and steel beam and proposed to be used for the frame with asymmetric span length. The structural characteristics of this connection lie in the penetration of the beam flange in the direction of major axis through the column for the smooth flow of stress. The purpose of this study is to analyze the dynamic behavior and stress flow of suggested connection and to evaluate the resistance to shock of connection. Four T-type CFT column-to-beam specimens; two with combined cross diaphragm and the others with interior and through diaphragms, the existing connection types, were made for cyclic load test guided by the load program of ANSI/AISC SSPEC 2002. The results show that the proposed connection is more efficient than existing ones in terms of strength, stress flow and energy absorption and satisfies the seismic performance required in the region of weak/moderate earthquakes.

• 한국강구조학회 논문집
• /
• 제15권2호
• /
• pp.167-174
• /
• 2003

본 연구는 보 플랜지와 스티프너의 용접부 양단, 기둥 모서리 부분 스티프너에 라운드를 두는 방법 등을 통하여 총 7개 시험체에 실물대 반복하중실험을 실시한 결과를 나타낸 것이다. 실험 결과를 통하여 다음과 같은 결론을 얻을 수 있었다. (1) 필레(fillet)를 둠으로써 응력집중을 줄여 내진성능을 크게 향상 시킬 수 있다. (2) 스티프너 폭의 증가로 접합부의 강성 및 강도는 증가하였지만 에너지 소산 능력은 감소하였다. (3) 모든 시험체는 규준에서 강진지역의 내진구조에 대해 요구하는 총 0.04 radian의 회전각을 발휘할 수 있는 것으로 나타났다.

• Steel and Composite Structures
• /
• 제22권1호
• /
• pp.141-159
• /
• 2016

Commonly in steel frames, steel beam and concrete slab are connected together by shear keys to work as a unit member which is called composite beam. When a composite beam is subjected to positive bending, flexural strength and stiffness of the beam can be increased due to "composite action". At the same time despite these advantages, composite action increases the strain at the beam bottom flange and it might affect beam plastic rotation capacity. This paper presents results of study on the rotation capacity of composite beam connected to Rectangular Hollow Section (RHS) column in the steel moment resisting frame buildings. Due to out-of-plane deformation of column flange, moment transfer efficiency of web connection is reduced and this results in reduction of beam plastic rotation capacity. In order to investigate the effects of width-to-thickness ratio (B/t) of RHS column on the rotation capacity of composite beam, cyclic loading tests were conducted on three full scale beam-to-column subassemblies. Detailed study on the different steel beam damages and concrete slab damages are presented. Experimental data showed the importance of this parameter of RHS column on the seismic behavior of composite beams. It is found that occurrence of severe concrete bearing crush at the face of RHS column of specimen with smaller width-to-thickness ratio resulted in considerable reduction on the rate of strain increase in the bottom flange. This behavior resulted in considerable improvement of rotation capacity of this specimen compared with composite and even bare steel beam connected to the RHS column with larger width-to-thickness ratio.