美国地震区划图的发展——地震危险性图与抗震设计图

在过去的数十年里,美国地震区划图随着建筑抗震设计需求而不断发展变化,从最初的一张图发展成现今抗震设计图和地震危险性图两图共生的形式。地震危险性图主要反映依据地震科学认识与基础观测资料评估得到的国土地震危险性分布,抗震设计图则继承了传统地震区划图的主要功能,反映国土范围内建筑抗震设计所需地震动设计参数的分布,服务于建筑设计。依据抗震设计需求,美国地震区划图的演化过程可划分为地震系数分区区划、设计地震地震动区划和最大考虑地震地震动区划3个阶段,各阶段均始于地震危险性图的改进,并以抗震设计理念与方法的更新换代以及与之相适应的抗震设计图的编制为标志。本文总结了美国地震区划图的演化历程,对地震危险性图与抗震设计图发生变革的技术原因、主要特征、应用意义及其影响进行了重点的分析与论述。

Review of Seismic Zonation in United States, Seismic Hazard Maps and Seismic Design Maps

During the past few decades, seismic zonation maps in the United States keep developing and improving with change of requirements of building seismic design, from early single-map mode to nowadays two-maps mode consisting of Seismic Design Maps and Seismic Hazard Maps. The SHM is used for presenting the distribution of seismic hazard in territory which is evaluated based on science understanding about earthquakes and observational data. The SDM inherits the main function of the seismic zonation map, and is used for presenting the distribution of buildings seismic design coefficients. The history of the US Seismic Zonation Maps can be divided into three stages which using different parameters of seismic design ground motion, the coefficients of seismic zones, the design earthquake ground motion and the maximum considered earthquake ground motion. Each stage begins with improving of SHM and marked by a significant advance in seismic design procedures and SDM. In this paper, the history of US seismic zonation map is reviewed, and the technical reasons caused SDM updating, main features of SDM, significance and influence of SDM application and so on are focused to discussion.