• 한국지진공학회논문집
• /
• 제21권6호
• /
• pp.303-310
• /
• 2017

The coupled shear wall system with coupling beams is an efficient structural system for high-rise buildings because it can provide excellent ductility and energy dissipation to the buildings. The objective of this study is to simulate the hysteretic behavior of diagonally reinforced concrete coupling beams including pinching and cyclic deteriorations in strength and stiffness using a numerical model. For this purpose, coupling beams are modeled with an elastic beam element and plastic spring element placed at the beam ends. Parameters for the analytical model was calibrated based on the test results of 6 specimens for diagonally reinforced concrete coupling beams. The analytical model with calibrated model parameters is verified by comparing the hysteretic curves obtained from analysis and experimental tests.

• Structural Engineering and Mechanics
• /
• 제7권1호
• /
• pp.69-80
• /
• 1999

The purpose of this study is to propose an analytical model for the simulation of the hysteretic behavior of RC (reinforced concrete) beam-column subassemblages under various loading histories. The discrete line element with inelastic rotational springs is adopted to model the different locations of the plastic hinging zone. The hysteresis model can be adopted for a dynamic two-dimensional inelastic analysis of RC frame structures. From the analysis of test results it is found that the stiffness deterioration caused by inelastic loading can be simulated with a function of basic pinching coefficients, ductility ratio and yield strength ratio of members. A new strength degradation coefficient is proposed to simulate the inelastic behavior of members as a function of the transverse steel spacing and section aspect ratio. The energy dissipation capacities calculated using the proposed model show a good agreement with test results within errors of 27%.

• 한국지진공학회논문집
• /
• 제22권2호
• /
• pp.95-101
• /
• 2018

Diagonally reinforced concrete coupling beams (DRCB) play an important role in coupled shear wall systems since these elements dissipate most of seismic input energy under earthquake loading. For reliable seismic performance evaluation using nonlinear response history analysis, it is important to use an accurate analytical model for DRCBs. In this study, the Pinching4 model is used as a base model to simulate the cyclic behavior of DRCBs. For simulating the cyclic behavior of DRCBs using the Pinching4 model, the analytical parameters for backbone curve, pinching and cyclic deterioration in strength and stiffness should be computed. To determine the proper values of the constituent analytical parameters efficiently and accurately, this study proposes the empirical equations for the analytical parameters using regression analyses. It is shown that the hysteretic behavior of coupling beams can be simulated efficiently and accurately using the proposed numerical model with the proposed empirical equations of model parameters.

• Structural Engineering and Mechanics
• /
• 제38권1호
• /
• pp.39-63
• /
• 2011

Referring to the formulation of physical stochastic optimal control of structures and the scheme of optimal polynomial control, a nonlinear stochastic optimal control strategy is developed for a class of structural systems with hysteretic behaviors in the present paper. This control strategy provides an amenable approach to the classical stochastic optimal control strategies, bypasses the dilemma involved in It$\hat{o}$-type stochastic differential equations and is applicable to the dynamical systems driven by practical non-stationary and non-white random excitations, such as earthquake ground motions, strong winds and sea waves. The newly developed generalized optimal control policy is integrated in the nonlinear stochastic optimal control scheme so as to logically distribute the controllers and design their parameters associated with control gains. For illustrative purposes, the stochastic optimal controls of two base-excited multi-degree-of-freedom structural systems with hysteretic behavior in Clough bilinear model and Bouc-Wen differential model, respectively, are investigated. Numerical results reveal that a linear control with the 1st-order controller suffices even for the hysteretic structural systems when a control criterion in exceedance probability performance function for designing the weighting matrices is employed. This is practically meaningful due to the nonlinear controllers which may be associated with dynamical instabilities being saved. It is also noted that using the generalized optimal control policy, the maximum control effectiveness with the few number of control devices can be achieved, allowing for a desirable structural performance. It is remarked, meanwhile, that the response process and energy-dissipation behavior of the hysteretic structures are controlled to a certain extent.

• 한국공간구조학회논문집
• /
• 제20권1호
• /
• pp.79-86
• /
• 2020

The performance enhancement of various damping systems from natural hazards has become an highly important issue in engineering field. In this paper, ENTA hysteretic dampers were tested under cyclic loadings to evaluate their performance in terms of ductility and energy dissipation. The test results showed that the hysteretic dampers are effective damping systems to enhance the buildings performance for remodeling and retrofit of buildings. Also, the hysteretic dampers were modeled in FEM(Finite Element Method) structural analysis program. As comparing the computer modeling and the experiment, this study model reflects the nonlinear behavior of steel and derives the hysteresis loop.

• 대한토목학회논문집
• /
• 제26권6A호
• /
• pp.935-941
• /
• 2006

지진과 같은 동적반복하중을 받은 강구조물은 정적하중시와 다른 이력거동을 보인다. 이는 동적변형중인 구조용 강재는 정적상태와 다른 역학적 특성 및 응력-변형률 관계를 보이기 때문이다. 즉, 지진하중을 받는 원형 강기둥과 같은 강구조물의 이력거동을 정확히 예측하기 위해서는 정동적 변형 상태를 가정한 재하속도에 따른 대상구조물 내하력 및 변형의 차이점을 명확히 파악해야 한다. 이에 본 연구에서는 저자에 의해 제안된 SM490강재의 동적 반복소성모델과 이를 적용한 3차원 탄소성 유한요소해석을 이용하여 재하속도와 지름-두께(D/t)비를 변수로한 SM490 원형강기동의 동적해석을 수행하였다. 해석 결과를 통하여 정적에서 동적변형상태로 재하속도 변화에 따른 SM490 원형강기둥의 이력거동 특성 즉, 내하력 및 에너지소산효율의 변화를 명확히 파악하였다.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2001년도 춘계학술대회 논문집
• /
• pp.287-295
• /
• 2001

The purpose of this paper to describe an analytical model that is capable of reproducing the hysteretic behavior of beam-column joints under cyclic loading and to suggest the variable of hysteretic model for the inelastic analysis of R/C frame structures to do this quasi-static analysis using IDARC program was performed for the beam-column joints. The effort to obtain the result of analysis similar to those of experiment was made by determining the value for hysteretic parameters representing stiffness degradation, strength deterioration and pinching effect. The accuracy and reliability of the proposed analytical model was demonstrated by comparison of load-displacement relation, maximum strength, stiffness degradation and energy dissipation.

• Structural Engineering and Mechanics
• /
• 제59권5호
• /
• pp.885-899
• /
• 2016

The energy-based approach to predict the fatigue crack growth behavior under constant and variable amplitude loading (VAL) of the aluminum alloy 2024 T351 has been investigated and detailed analyses discussed. Firstly, the plastic strain energy was determined per cycle for different block load tests. The relationship between the crack advance and hysteretic energy dissipated per block can be represented by a power law. Then, an analytical model to estimate the lifetime for each spectrum is proposed. The results obtained are compared with the experimentally measured results and the models proposed by Klingbeil's model and Tracey's model. The evolution of the hysteretic energy dissipated per block is shown similar with that observed under constant amplitude loading.

• Earthquakes and Structures
• /
• 제16권1호
• /
• pp.41-54
• /
• 2019

Reinforced Concrete (RC) shear walls are widely used in Nuclear power plants as effective lateral force resisting elements of the structure and these may experience nonlinear behavior for higher earthquake demand. Short shear walls of aspect ratio less than 1.5 generally experience combined shear flexure interaction. This paper presents the results of the displacement-controlled experiments performed on six RC short shear walls with varying aspect ratios (1, 1.25 and 1.5) for monotonic and reversed quasi-static cyclic loading. Simulation of the shear walls is then carried out by Finite element modeling and also by macro modeling considering the coupled shear and flexure behaviour. The shear response is estimated by softened truss theory using the concrete model given by Vecchio and Collins (1994) with a modification in softening part of the model and flexure response is estimated using moment curvature relationship. The accuracy of modeling is validated by comparing the simulated response with experimental one. Moreover, based on the experimental work a multi-linear hysteretic model is proposed for short shear walls. Finally ultimate load, drift, ductility, stiffness reduction and failure pattern of the shear walls are studied in details and hysteretic energy dissipation along with damage index are evaluated.

• Computers and Concrete
• /
• 제1권1호
• /
• pp.77-98
• /
• 2004

This paper presents a numerical model for simulating the nonlinear response of reinforced concrete (RC) shear walls subject to cyclic loadings. The material behavior of cracked concrete is described by an orthotropic constitutive relation with tension-stiffening and compression softening effects defining equivalent uniaxial stress-strain relation in the axes of orthotropy. Especially in making analytical predictions for inelastic behaviors of RC walls under reversed cyclic loading, some influencing factors inducing the material nonlinearities have been considered. A simple hysteretic stress-strain relation of concrete, which crosses the tension-compression region, is defined. Modification of the hysteretic stress-strain relation of steel is also introduced to reflect a pinching effect depending on the shear span ratio and to represent an average stress distribution in a cracked RC element, respectively. To assess the applicability of the constitutive model for RC element, analytical results are compared with idealized shear panel and shear wall test results under monotonic and cyclic shear loadings.