Estimation of Lateral Drifts of RC Wall Structural System by Monitored Coupling Beams

Abstract

This study aims to enhance understanding of seismic damage patterns of RC wall structural system (RCW) by monitoring the mechanical behavior of coupling beams. The coupling beam, configured with elastic steel truss and friction dampers, is able to consume massive energy during earthquakes, and continuously get the complete histories of sustained forces and deformations by measuring strains of truss diagonal web members and the sliding of friction dampers, respectively. The histories of sliding and force are useful to comprehensively understand the status of dampers and the lateral deformation of coupled wall systems, which further determine the seismic damage state of the overall structure and whether the dampers shall be replaced after an earthquake. In this paper, a series of quasi-static tests were first performed on the proposed coupling beams. The results from the tests indicated that the force contribution of truss chord members gradually increased in a nonlinear pattern with respect to the deformation of coupling beam. This was attributed to the axial force sustained by the coupling beam. Then a theoretical model was proposed to build up the relationship between the strain of diagonal web members and the sustained shear force. The coefficient was given by the equation derived from the simplified model, which provides a prediction with the largest error of 10%. Subsequently, the measured sliding displacements of friction dampers were correlated to the lateral deformation of RC walls considering the bending, shearing, and axial compression of coupled walls. This relationship was examined by a quasi-static test on a three-story coupled wall substructure, and acceptable prediction results can be obtained. These correlations make it possible to assess the damage state of the overall building. The findings of this study not only contribute to the development of a more accurate theoretical model for coupling beams but also offer a practical monitoring technique.