Earthquake Resistant Design of Structures Using Cumulative Strain Energy

本研究的目的是代表适用的信息，建立基于能量概念的抗震设计。由于结构在强震作用下的动力特性处于弹塑性区，因此认为地震赋予结构的塑性能可用于评估结构的损伤和检验结构的抗震安全性。本研究的基本思路是通过比较地震输入给结构的输入能量与结构的能量吸收能力来判断结构的地震安全性。首先，采用5种典型地震动，对单自由度和多自由度结构的输入能量进行了数值分析。结果表明，结构的累积塑性能与输入能量的比值是一个较好的结构损伤评估指标。其次，通过试验研究了配筋柱和门式刚架结构的累积吸能能力。结果表明，累积吸能能力不受地震运动波形等物理特性的影响，在结构常数相同的情况下，累积吸能能力是一个常数。最后，以系统总刚度为经济性指标，以输入能量与系统能量吸收能力的关系为安全性指标，在两个指标约束下，通过处理使刚度分布与输入能量分布相等，得到了系统的最优输入能量分布。

The purpose of this study is to represent the applicable information on the establishment of earthquake resistant design based on the energy concept. Since the dynamic behaviour of structures under severe earthquake motion is exposed to elasto-plastic region, it is considered that the plastic energy of structures imparted by earthquake is applicalbe to the way of evaluating structural damage and examining the seismic safety of structures. The fundamental concept of this study is that the seismic safety of structures can be judged by the comparison between the input energy for structures imparted by seismic excitation and the energy absorption capacity of structures.Firstly, the input energy of structures having single and multiple degree of freedom systems was numerically analyzed by using 5 typical earthquake motions. It shows that the ratio of the cumulative plastic energy of structures to the input energy is good index for the estimation of structural damage. Secondally, the cumulative energy absorption capacity of reinforced columns and portal frame works was studied by experiment. It shows that the cumulative energy absorption capacity is not influenced by such physical characteristics of earthquake motions as wave forms and has constant value if the structural constants are the same. Finally, defining the total stiffness of system as an index for the economy and defining the relation between the input energy distributed to the system and the energy absorption capacity as an index for the safety, the optimum input energy distribution was obtained by handling so as to equalize the stiffness distribution with the input energy distribution under the restriction of two indices.