Collapse Behavior of Building Frames under Severe Earthquakes and Performance-based Seismic Design Method

本课题的目的是揭示建筑框架在强震作用下的倒塌行为，并提出一种新的基于性能的抗震设计方法。在本项目中取得了以下成果。研究表明，当框架结构受到强烈地震作用时，框架下部的几块石块会发生变形集中。推导出了抑制下部几层变形集中和抑制巷道的条件。通过数值响应分析，验证了这些条件的有效性。进行了三层单跨钢框架模型在恒定竖向荷载和反复水平荷载作用下的静力和动力试验。建立了一种新的弓形变形起始和振动中心漂移起始预报方法。已经证实，这些预测与实验…吻合得很好。结果更多的是L。提出了一种新的反应分析方法，可以模拟梁端破坏和滞回阻尼器的破坏。通过新开发的数值分析程序，揭示了这些破坏对框架结构地震反应的影响。本文提出了一种在由弹性脆性构件组成的结构中发生断裂时，在荷载-位移关系中寻找失稳平衡路径的新方法。提出了框架结构断裂发展的分析方法，推导了框架结构的稳定性判据。提出了一种新的基于性能的抗震设计方法。剪切式建筑模型的楼层刚度设计使得剪切式建筑模型在设计中等地震作用下将显示特定的层间位移分布。然后通过简化的模型-框架逆变换确定相应框架模型的构件尺寸。利用新发展的等效线性化方法，提出了设计大震作用下的另一种设计方法。较少

The purpose of this project is to disclose collapse behaviors of building frames under severe earthquakes and to develop a new performance-based seismic-resistant design method. The following results have been obtained in this project.1. It has been revealed that, when a building frame is subjected to severe earthquakes, deformation concentration could happen on lower few stones of a building frame. The conditions have been derived for suppression of such deformation concentration on lower few stories and for suppression of drifts. The validity of these conditions has been demonstrated through numerical response analysis.2. Static and dynamic experiments on three-story one-span steel frame models have been conducted under constant vertical loads and repeated horizontal loads. A new prediction method of initiation of bow-shaped deformation and initiation of drift of the vibration center has been constructed. It has been confirmed that these predictions coincide well with the experimenta … More l results.3. A new response analysis method has been developed which can simulate failure at beam ends and failure of hysteretic dampers. The effects of these failures on the seismic response of building frames have been disclosed via the newly developed numerical analysis program.4. A new method has been developed for finding an unstable equilibrium path in the load-displacement relation in the case where a fracture develops in a structure consisting of elastic brittle members. An analysis method of fracture development in a building frame has been presented and its stability criterion has been derived.5. A new performance-based seismic-resistant design method has been developed. The story stiffnesses of a shear building model have been designed so that the shear building model would exhibit a specified distribution of interstory drifts under design moderate earthquakes. The member size of the corresponding frame model has then been determined via reduced model-frame inverse transformation. Another design method under design major earthquakes has been proposed utilizing a newly developed equivalent linearization method. Less