摘要

In this paper, a framework for generating multi-point earthquake motion of target filed in China, basing on focal mechanism and taking account of the spatial variability of soil properties, is given and proposed. The main contents include: (1) the transfer function of site including multiple soil layers is es-tablished based on random vibration theory, (2) based on the improved bedrock spectrum applicable to the target site in China, the variability among different site condition is reflected by establishing the transfer function of local site, (3) non-flat factor of site surface is considered on the basis of previous literature, (4) explicit expression phase-angle change by the filtration of multiple soil layers is also given for the convenience of the subsequent program code. Then, according to the theory framework, the visual program MEMS V2011.6 (Multi-support Earthquake Motions Simulation Version 2011.6) is developed and run successfully. The specific functions of the program involves the focal parameters assignment, inputting soil parameters, calculating and displaying transfer function of site soil with multi-layer, adjusting non-stationary parameters and frequency, generating multi-point earthquake motion histories, verifying the coherence of spatial seismic motions, fitting code-specified spectrum for bridge, building and electronic facility. In addition, based on a bridge example, the multi-point seismic motions of the target field are generated using the program MEMS V2011.6, and the sensibility analysis of the generated ground motions to local site effect and epicentral distance is analyzed as well. The content in this paper involve theory and practicability, and can provide directly reference for engineering.

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