An Analytical Research on Determination of Beam and Column Contribution to Plastic Energy Dissipation of RC Frames

Abstract

Determination of capacities of structural members, both in terms of strength and deformation, and estimation of seismic demand are essential issues in earthquake-resistant design. In energy-based design and evaluation, both the structural capacity and the demand imposed by earthquake are considered in terms of energy and accordingly energy dissipation capacity of the structure is associated with seismic energy demand. Plastic energy dissipation of structures under monotonic lateral loading may be obtained by using the resultant pushover curves of nonlinear static analyses. However, the time variation of individual contribution of structural members to the dissipated plastic energy cannot be determined. In this study, the contribution of beam and column deformations to the plastic energy dissipated in multistory reinforced concrete (RC) frames is determined by using nonlinear time history (NLTH) analysis. It is found that rotational deformations of beams are dominant in plastic energy dissipation. Accordingly, some linear relations considering the contribution of dissipated plastic energy in beam plastic hinges to the total plastic energy dissipation of RC frames are derived. Pushover analysis of frames in conducted and the area under the resultant pushover curve is determined to satisfy the mean value of the maximum plastic energy dissipated in frames during the selected earthquakes. The interstory drift ratios are calculated and compared with the interstory drift ratios directly obtained from NLTH analyses. The results are evaluated and presented by graphs and tables.