海洋平台确定多维地震动最不利输入方向的一种有效方法  

APPLICATION OF WAVELET TRANSFORM IN MULTI-COMPONENTS SEISMIC RESPONSE OF OFFSHORE PLATFORM——SEARCHING THE CRITICAL ANGLE OF SEISMIC WAVE

作　　者：何晓宇[1] 李宏男[1] 

机构地区：[1]大连理工大学海岸与近海工程国家重点实验室,大连116024

出　　处：《振动与冲击》2007年第12期49-54,共6页Journal of Vibration and Shock

基　　金：教育部长江学者创新团队发展计划资助项目基金(IRT0518)资助

摘　　要：提出一种快捷、高效且可靠的方法来确定海洋平台结构多维地震反应分析中地震动的最不利输入方向。该方法利用MATLAB中的小波分析工具箱可以方便且形象地显示地震动的局部时频特性,并根据平台结构的模态信息提取所关心响应的重要小波系数曲线从而获得地震动的有效输入能量时间过程,并判别地震动的最不利输入方向。以某一实际海洋平台为例,采用所提出的方法对四类场地的十组实际地震动不同角度输入情况进行了计算,同时利用ANSYS软件对平台的各种工况进行了时程反应分析以校核该方法的有效性;同时采用相同的方案对一组单自由度系统在某一地震动作用下进行了计算与校核。计算结果均表明:当结构对地震动方向较敏感时,在地震动以不同角度输入情况下,地震动有效输入能量最大的方向正是结构响应最大的方向,小波变换系数法在多维地震反应分析中具有很好的应用前景。An efficient, convenient and reliable method is presented to search the critical angle of seismic wave in multi-components seismic response of offshore platform. Wavelet analysis toolbox in MATLAB is used to reveal the time-frequency information of the earthquake wave visually. Based on both the mode information of the platform and the time-frequency characteristics of the earthquake, the key wavelet coefficient curve can be drawn to obtain the effective energy time-history curve, through which the critical angle of seismic wave can be determined. As an example, the critical angle of seismic wave is determined towards an actual platform under ten groups of seismic loads, which represent loads on four types of grounds with a group of single degree of freedom systems. Different cases are verified through time-history analysis with ANSYS program. The results show that when the structure is sensitive to the input direction of earthquake, the effective energy and the structure's response reach their peak value at the same input angle of seismic wave, and this angle is just the critical angle of seismic wave.

关 键 词：小波变换 海洋平台 多维地震反应 

分 类 号：TB123[理学—工程力学]