【摘要】 寻求合理高效的方法求得不同材料阻尼特性混合结构的地震作用及其效应是工程抗震界较为关注的问题之一。目前,用于计算不同材料阻尼特性混合结构地震作用效应的复模态叠加法和直接积分法都是基于黏性阻尼假定推导而来。黏性阻尼假定存在能量耗散与激振频率有关的缺陷,导致结构高频模态地震作用效应偏小,且阻尼矩阵与复模态分析结果相互影响,计算结果不唯一,合理性不易被判定。复阻尼假定避免了黏性阻尼假定的不足,但通常求得的地震作用效应为复数,不便于工程应用。为此提出一种基于复阻尼假定的复模态叠加法,直接在物理空间中求解,计算结果唯一,比基于黏性阻尼假定的复模态叠加法计算效率更高。与运用本文方法计算的地震作用效应结果相比,广为采用的折算阻尼比方法计算结果是不合理的。此外,给出了基于复阻尼假定的计算模态有效质量系数的方法,可用于确定合理的叠加模态个数。更多还原

【Abstract】 One of the much concerned problems in seismic engineering is to seek reasonable and efficient method to obtain earthquake action and its effects on structures of various material damping characteristics in components.Currently,the most often used complex mode superposition method and direct integration method to calculate transient earthquake responses are developed based on viscous damping assumption.Viscous damping assumption has disadvantages.For example,the earthquake effects of high frequencies may be underestimated since the energy dissipation is related to excitation frequencies according to the viscous damping assumption.Furthermore,since the damping matrix interacts with results of complex mode analysis,results of above mentioned methods are not unique and the rationality of the results is difficult to be determined.Complex damping assumption can avoid disadvantages of viscous damping assumption,though usually it brings out complex form results which may be inconvenient to use.A complex mode superposition method based on the complex damping assumption which resolves directly in physics space and obtains unique results was put forward.It is proved that the new method is more efficient than that based on the viscous damping assumption.Compared with results of the new method,results of widely used equivalent damping ratio method are unreasonable.In addition,method for calculating modal effective mass factor which can be used to determine reasonable number of superimposed modes based on the complex damping assumption was also put forward.更多还原