Inelastic Response of Reinforced Concrete Frames to Seismic Ground Motions Having Different Characteristics

Abstract

<p>Observations of structural damage following recent major earthquakes have indicated that ground motion characteristics have a significant effect on the damage of building structures. An analytical study is undertaken to investigate the effect of ground motion characteristics on the inelastic response of multistorey reinforced concrete frame structures and to evaluate the seismic performance of reinforced concrete frame structures designed in conformance with current Canadian seismic provisions. In addition, the possibility of using simplified analysis procedures to estimate inelastic response is studied for regular building frames subjected to different types of earthquake ground motions.</p> <p>An earthquake data set consisting of 45 horizontal components of strong motion records is selected and subdivided into three groups representative of seismic ground motions having low, intermediate, and high peak acceleration-to-velocity (A/V) ratios. This data set is analyzed to investigate the significance of the A/V ratio as a parameter to indicate the dynamic characteristics of earthquake ground motions resulting from different seismic environments. Four regular moment resisting reinforced concrete building frames having different fundamental periods are designed for combined gravity and seismic effects determined in accordance with the 1985 edition of the National Building Code of Canada (NBCC 1985). The structural members are proportioned and detailed to satisfy the requirements of the 1984 edition of the Canadian Concrete Code (CAN3-A23.3-H84). These four frames are used as structural models having very short, short, moderate, and long fundamental periods.</p> <p>To gain insight into the inelastic behaviour of the designed frames, the inelastic static responses of the frames to monotonically increased lateral loading are examined first. Following this inelastic static analysis, the inelastic dynamic responses of the frames to the three A/V groups of earthquake accelerograms are analyzed statistically. In addition, the elastic dynamic responses of the frames to the three A/V groups of earthquake records are obtained to provide a reference for the evaluation of the inelastic dynamic responses. In the course of the dynamic analyses, overall energy indices are defined for multistorey building frames and their numerical computation is implemented in a computer program.</p> <p>A simplified analysis procedure is proposed to estimate both overall and localized inelastic deformations for regular building frames. This simplified analysis procedure is evaluated based on a comparison of the inelastic deformational demands estimated from the procedure with the statistical results obtained from the inelastic dynamic analysis of the frames.</p>