Earthquake Resistant Engineering Structures VIII

Abstract

The evaluation of the seismic action which the structures must withstand is the most critical item of the full process of analysis, monitoring and mitigation of seismic risk. Seismic action has been recorded worldwide for moderate to severe earthquakes. In the last 30 years the recorded accelerations have significantly increased. One reason could be due to the increasing number of recorded stations and to the location of a considerable amount of recorded stations on soft soil, where significant site amplification can occur. By the way the recorded accelerations have exceeded the designed acceleration given by seismic codes. That particularly occurs in the case of strong earthquakes, where the evaluation of seismic action given by source mechanism gives, in some cases, a seismic design earthquake greater than that given by the probabilistic evaluation reported by the codes.