The Evaluation Of Code-Based Selection And Scaling Of Ground Motions

The Chinese code for seismic design of buildings(GB50011-2010) allows the use of sets of ground motions in the seismic design and analysis process. However, the prescriptions for record selection are somewhat vague compared with those specified in the other contemporary seismic codes. Through a detailed comparison between Eurocode-8 and GB50011-2010, some record selection criteria for GB50011-2010 are recommended. On the basis of those proposed criteria, selecting and scaling of recorded ground motions is mathematically formulated as an engineering-constrained optimization problem that minimizes the difference between the design response spectrum and the mean response spectrum of selected and scaled ground motions within a period range of interest. For such a constrained optimization problem, the harmony search(HS) algorithm, which conceptualizes using the musical process of searching for a perfect state of harmony, is modified in this study by incorporating the constraint-handling technique on the basis of the fitness priority-based ranking method. Using magnitude, distance, and site conditions, a total of 704 records are selected from the PEER strong ground motion database to form a search space of ground motions. The modified HS algorithm is then applied to the predefined search space to obtain the ground motions sets compatible with the target design spectrum defined in GB 50011-2010. The numerical results demonstrate that the modified HS-based solution is an efficient method for generating input ground motion sets consistent with the code-based design response spectrum.