Implications of structural overstrength on the calibration of seismic codes

A computer program is developed to test the influence of the structural overstrength to calibrate seismic codes. The program automatically performs an iterative design-evaluation process to calibrate the seismic code. A numerical example is performed in order to test the different approaches. The virtual simulation shows that the force reduction factor cannot be directly deduced from building performance in past earthquakes. This custom of deducing the force reduction factor from the building performance under past earthquakes artificially increases the ratios elastic spectrum to design spectrum due to the design structural overstrength. The similitude of the simulation with the historical calibration of the design spectrum in the seismic codes in the United States of America (USA) is evident.