مهندسی عمران شریف (Feb 2019)
A PROPOSED NUMERICAL MODEL FOR NONLINEAR CYCLIC ANALYSIS OF STEEL AND CONCRETE COUPLING BEAMS IN RC COUPLED SHEAR WALLS SYSTEM
Abstract
Concrete coupled shear walls consist of two reinforced concrete (RC) shear walls that are connected by coupling beams over the height of the wall. Coupling beams provide a transfer of vertical forces between adjacent walls, which creates a coupling action resisting a portion of the total overturning moment induced by the base shear. This element has been usually made of deep reinforced concrete (RC) beam. In addition, Steel coupling beam in RC coupled shear wall system is a proper substitute for deep RC coupling beam. Coupling beam must behave in a ductile manner, yield before the wall piers, and exhibit significant energy dissipation characteristics. Therefore, coupling beams should be designed to avoid over coupling, which causes the system to act as a single wall. In addition, light coupling should be avoided as it causes the system to behave like two isolated walls. Therefore, it is obvious that for a precise understanding of the seismic behavior of tall buildings with coupled shear walls, their accurate nonlinear modeling is necessary. Most of the numerical modeling methods for coupling beams employ the FEM with fine meshes that are costly and time-consuming. In this paper, by introducing a new technique, accurate nonlinear dynamic modeling of the concrete shear wall with steel or concrete coupling beam is performed by employing bar elements. In this technique, coupling beams are modeled using an elastic beam, shear-flexural hinges, and shear and sliding hinge. In addition, shear walls are modeled by employing multi-layer shell finite elements with fiber sections where they can consider the confinement effect in wall's edges. In order to verify the proposed model of coupled shear walls, the results of numerical analyses are compared with those of experimental model. The results indicate that the technique proposed in this paper to model the dynamic behavior of these walls can adequate simulate their behavior.
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