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谱分析法是从频率结构方面计算结构系统在随机激励下的响应值上界,要求输入结构系统的激励谱(动力环境),用谱分析程序计算结构系统随机振动响应的可能出现的最大值。各种不同的谱分析计算程序,由于所用的计算方法不同,要求不同的激励谱曲线,也就是β—T曲线。对于各种车辆讲,激励谱就是路面谱,对于地震就是地震谱,对于海洋结构就是海浪谱等。下面针对SAP5程序的谱分析功能块的输入要求,来介绍激励谱β—T曲线的编制方法。 SAP5程序的谱分析功能块是用于求结构的地震响应和车辆的路面响应等基础运动类型问题的.若系统的质量矩阵[M]正定,刚度矩阵[K]非负定,基础运动{U_0}按x、y、z三个方向平动输入,则其物理坐标的微分方程:
The spectral analysis method is to calculate the upper bound of the response value of the structural system under random excitation from the frequency structure. It is required to input the excitation spectrum (dynamic environment) of the structural system and to calculate the maximum possible value of the random vibration response of the structural system by the spectral analysis program. Different spectrum analysis and calculation procedures, due to the different calculation methods used, require different excitation spectrum curves, that is, β-T curves. For a variety of vehicles, the excitation spectrum is the road spectrum, for the earthquake is the seismic spectrum, the ocean structure is the wave spectrum. The following for SAP5 program spectral analysis function block input requirements, to introduce excitation spectrum β-T curve preparation method. The spectrum analysis function block of SAP5 program is used to solve the basic motion type problems such as the seismic response of the structure and the road response of the vehicle.If the system’s mass matrix [M] is positive and the stiffness matrix [K] is negative, the basic motion {U_0 } By x, y, z translation of the three directions input, then the physical coordinates of the differential equation: