A COMPARISON BETWEEN THE REQUIREMENTS OF PRESENT AND FORMER ROMANIAN SEISMIC DESIGN CODES, BASED ON THE REQUIRED STRUCTURAL OVERSTRENGTH

摘要

Due to several factors, the lateral resistance of a structure is, usually, greater than lateral force used in seismic design. As a result, a structure has a "reserve" strength (overstrength) that can be mobilized in variable amounts when the structure is subjected to lateral seismic loads. The available structural overstrength is difficult to evaluate analytically; a more promising quantity for research is the required overstrength, i.e. the overstrength necessary to a structure in order to withstand specified seismic forces. In the paper, the required overstrength was expressed through the ratio between the actual spectral ordinates and the corresponding values of the code-specified design spectra. The actual spectral ordinates were calculated for two selected sets of representative Romanian seismic records. Calculations were performed, separately, for both versions, old and new, of the Romanian seismic code. Based on the results, the severity of the requirements of the two codes was assessed comparatively.