Structural redundancy of 3D RC frames under seismic excitations

Ali Massumi,Ramin Mohammadi 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.1

The components of the seismic behavior factor of RC frames are expected to change as structural redundancy increases. Most researches indicate that increasing redundancy is desirable in response to stochastic events such as earthquake loading. The present paper investigated the effect of redundancy on a fixed plan for seismic behavior factor components and the nonlinear behavior of RC frames. The 3D RC moment resistant frames with equal lateral resistance were designed to examine the role of redundancy in earthquake-resistant design and to distinguish it from total overstrength capacity. The seismic behavior factor and dynamic behavior of structures under natural strong ground motions were numerically evaluated as the judging criteria for structural seismic behavior. The results indicate that increasing redundancy alone in a fixed plan cannot be defined as a criterion for improving the structural seismic behavior.

접합부 상세에 따른 철골 커플링 보의 내진거동

이원호,윤현도,송한범 대한건축학회 2005 大韓建築學會論文集 : 構造系 Vol.21 No.3

Ductile coupled flexural wall is the primary seismic load resisting system of buildings. The coupling beams of these buildings must exhibit excellent ductility and energy dissipation capacity. To achieve better ductility and energy dissipation, steel coupling beam embedded in the reinforced concrete walls is proposed. A comprehensive experimental test involving 5 steel coupling beam specimens has been performed and results from this program are used herein to study the effect of details of steel coupling beams embedded in the reinforced concrete walls on seismic behavior. Through experimental test, the seismic behavior of typical steel coupling beams was established. These efforts have resulted in details for increasing the seismic capacity of steel coupling beam in the seismic behavior of buildings.

Seismic behavior of Q690 circular HCFTST columns under constant axial loading and reversed cyclic lateral loading

Jiantao Wang,Qing Sun 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.32 No.2

This paper presents an investigation on seismic behavior of out-of-code Q690 circular high-strength concrete-filled thin-walled steel tubular (HCFTST) columns made up of high-strength (HS) steel tubes (yield strength fy ≥ 690 MPa). Eight Q690 circular HCFTST columns with various diameter-to-thickness (D/t) ratios, concrete cylinder compressive strengths (fc) and axial compression ratios (n) were tested under the constant axial loading and reversed cyclic lateral loading. The obtained lateral load-displacement hysteretic curves, energy dissipation, skeleton curves and ductility, and stiffness degradation were analyzed in detail to reflect the influences of tested parameters. Subsequently, a simplified shear strength model was derived and validated by the test results. Finally, a finite element analysis (FEA) model incorporating a stress triaxiality dependent fracture criterion was established to simulate the seismic behavior. The systematic investigation indicates the following: compared to the D/t ratio and axial compression ratio, improving the concrete compressive strength (e.g., the HS thin-walled steel tube filled with HS concrete) had a slight influence on the ductility but an obvious enhancement of energy dissipation and peak load; the simplified shear strength model based on truss mechanism accurately predicted the shear-resisting capacity; and the established FEA model incorporating steel fracture criterion simulated well the seismic behavior (e.g., hysteretic curve, local buckling and fracture), which can be applied to the seismic analysis and design of Q690 circular HCFTST columns.

커플링 정도와 상세에 따른 병렬 전단벽의 내진거동 비교

윤현도 ( Yun Hyun-do ),박완신 ( Park Wan-shin ),이주화 ( Lee Joo-hwa ),박희연 ( Park Hee-yeon ) 한국구조물진단유지관리공학회 2003 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.7 No.2

In high multistory, reinforced concrete buildings, coupled shear walls(CSWs) can provide an efficient structural system to resist horizontal forces due to wind and seismic effects. Behavior of these structures depend on degree of coupling and details of coupling beam. This paper composed of two subjects. First subject is a verification of proposed statistical regression formula for evaluation of the degree of coupling and determination of fundamental periods of CSWS by Chaallal et al. Second subject is a comparison of elastic behavior and nonlinear seismic behavior of fully coupled shear wall and partially coupled shear wall for Details and Degree of coupling. This paper used IDARC-2D and Midas Gen 4.3.1 for the purpose of achievement these subjects. Analysis results shows that statistical regression formula by Chaallal revise a little. Elastic and nonlinear seismic analytical result shows that steel coupling beam and diagonally reinforced concrete coupling beam have good behavior. Also, fully coupled shear wall have good behavior than partially coupled shear wall.

마찰 슬라이딩 거동을 보이는 건물 내 중량 설비의 내진성능 향상을 위한 감쇠기 연결 방안

옥승용,박관순,이지호 한국안전학회 2020 한국안전학회지 Vol.35 No.1

This study proposes a new damper configuration for seismic performance improvement of heavy sliding facilities inside a building. For this purpose, we deal with two connection types of control system, and the parametric study has been performed to investigate their comparative seismic performances according to the variations of the control capacity. In order to simulate the seismic responses of the proposed system, we employed a recently-developed seismic response analysis method that can deal with the two-mass system with nonlinear frictional sliding behavior. The numerical results demonstrate that the typical method of diagonal bracing damper connection can exhibit effective control performance both on structure and the heavy sliding facilities, whereas the structure-facilities connection method does not show any control effect on both responses. On the other hand, the typical method has some limitations that it can adversely cause excessive sliding of the facilities, depending upon the frequency characteristics of structure and earthquake. On the contrary, the structure-facilities connection method is very effective in reducing the sliding displacement of the heavy facilities, even with small amount of control capacity. Thus, the following potential expectations can be inferred from these results: The typical diagonal bracing damper connection method will have some promising benefits in controlling the sliding facilities inside the building as well as the building itself, and the structure-facilities connection method can be a cost-effective way of protecting the internal heavy important facilities inside the structure already designed with sufficient seismic performance.

Predictions of Seismic Behavior of Reinforced Concrete Bridge Columns

김태훈,김운학,이광명,신현목 한국콘크리트학회 2004 콘크리트학회논문집 Vol.16 No.3

The objectives of this study are to investigate the seismic behavior of reinforced concrete bridge columns and to provide the data for developing improved seismic design criteria. The accuracy and objectivity of the assessment process can be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The low-cycle fatigue damage of both concrete and reinforcing bars has been also considered in order to predict a reliable seismic behavior. The proposed numerical method for the prediction of seismic behavior of reinforced concrete bridge columns is verified by comparison with the reliable experimental results.

형상기억합금의 휨거동 및 교량변위제어장치적용 연구

최은수,박주남,김학수,이도형 한국지진공학회 2007 한국지진공학회논문집 Vol.11 No.5

본 논문은 형상기억합금 바의 휨 거동 특성 파악하기 위하여 여러 가지의 휨 거동 실험을 수행하였으며, 형상기억합금 바의 휨 거동분석을 통하여 지진 시에 적용 가능성을 규명하는데 목적이 있다. 이를 위해 단순 휨 및 이중 휨 실험을 재하속도 및 최대변위를 변수로 수행하였다. 힘-변위 곡선에서 추정한 재하 및 제하 시의 강성이 추정되었으며, 등가의 감쇠비도 각 실험결과에서 추정되었다. 단순 휨에서 형상기억합금 바는 32 mm 변위 이후에 강성증가현상을 나타냈으며, 이것은 SIM(Stress-Induced-Martensite) 현상에 의해서 발생하는 것으로 추정된다. 재하속도의 증가는 형상기억합금 휨 강성 증가에 영향을 주지 않는 것으로 나타났다. 이중 휨 거동에서 형상기억합금 바는 단순 휨에 비해 강성이 약 5배정도 크게 나타났으며, 감쇠비는 유사하게 나타났다. 휨 거동의 형상기억합금 바를 지진 변위 제어장치로 사용하여 3경간 단순지지 교량에 적용하여 지진해석을 수행하였다. 이러한 지진변위 제어장치는 매우 효과적인 것으로 나타났으며, 실용적인 것으로 판단된다. 본 논문의 의미는 형상기억합금 바의 휨 거동에 대한 기초 지식을 제공하는데 있다. The goal of this study is to perform several bending tests on a shape memory alloy bar and to analyze the characteristics of the bending behavior. The other goal is to verify the seismic performance of an SMA bar bending application. Single and double bending tests were conducted with varying loading speeds and maximum displacement. The loading and the unloading stiffness were estimated from the force-displacement curves and the equivalent damping ratio of each test was also assessed. In single bending, the SMA bar showed the stiffness hardening after the displacement of 32 mm. It is assumed that this phenomenon is due to the stress-induced-martensite hardening. The increasing loading speed did not influence on the stiffness of the single bending SMA bar. The stiffness of the double bending bar is about 5 times of that of the single bending. This study introduced a seismic application of SMA bending bars as seismic restrainers for bridges and showed its practicality. SMA bars in bending are used for seismic restrainers in a three-span-simply-supported bridge. They showed the effectiveness to reduce the responses of the bridge and the applicability for a seismic restrainer. The significance of this study is to provide basic knowledge of SMA bending and its seismic applications.

철근콘크리트 커플링 보의 해석기법과 병렬 전단벽의 거동 비교

이주화,박완신,윤현도 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2(구조계)

Ductile coupled flexural walls are the primary seismic load resisting systems of many structures. The coupling beams of these structures must exhibit excellent ductility and energy absorption ability. But the present analytical method about nonlinear behavior of reinforced concrete coupling beam scarcely anything. This paper composed of two subjects. First subject is a suggestion of analytical method of diagonally reinforced concrete coupling beam and longitudinally reinforced concrete coupling beam and rhombic coupling beam, and selected 5 specimens for that. Second subject is a comparison of seismic behavior of fully coupled shear wall and partially coupled shear wall. This paper used lDAHC-2D and Midas Gen 4.3.1 for the purpose of achievement these subjects. Suggested analytical method expected that it showed good agreement with reinforced concrete coupling beam inelastic behavior. Also, comparison of seismic behavior result showed that fully coupled shear wall have good behavior than partially coupled shear wall.

Interaction of internal forces of exterior beam-column joints of reinforced concrete frames under seismic action

Hua Zhou,Zhisheng Zhang 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.2

Detailed analysis of internal forces of exterior beam-column joints of RC frames under seismic action is reported in this paper. A formula is derived for calculating the average joint shear from the column shears, and a formula is proposed to estimate torque in eccentric joints induced by seismic action. Average joint shear stress and strain are defined consistently for exterior joints, which can be used to establish joint shear constitutive relationship. Numerical results of shear, bending moment and torque in joints induced by seismic action are presented for a pair of concentric and eccentric exterior connections extracted from a seismically designed RC frame, and two sections located at the levels of beam bottom and top reinforcement, respectively, are identified as the critical joint sections for evaluating seismic joint behavior. A simplified analysis of the effects of joint shear and torque on the flexural strengths of the critical joint sections is made for the two connections extracted from the frame, and the results indicate that joint shear and torque induced by a strong earthquake may lead to “joint-hinging” mechanism of seismically designed RC frames.

Interaction of internal forces of exterior beam-column joints of reinforced concrete frames under seismic action

Zhou, Hua,Zhang, Zhisheng Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.2

Detailed analysis of internal forces of exterior beam-column joints of RC frames under seismic action is reported in this paper. A formula is derived for calculating the average joint shear from the column shears, and a formula is proposed to estimate torque in eccentric joints induced by seismic action. Average joint shear stress and strain are defined consistently for exterior joints, which can be used to establish joint shear constitutive relationship. Numerical results of shear, bending moment and torque in joints induced by seismic action are presented for a pair of concentric and eccentric exterior connections extracted from a seismically designed RC frame, and two sections located at the levels of beam bottom and top reinforcement, respectively, are identified as the critical joint sections for evaluating seismic joint behavior. A simplified analysis of the effects of joint shear and torque on the flexural strengths of the critical joint sections is made for the two connections extracted from the frame, and the results indicate that joint shear and torque induced by a strong earthquake may lead to "joint-hinging" mechanism of seismically designed RC frames.