山地建筑结构地震破坏机理与抗震设计理论

The buildings in mountainous regions were usually constructed with step-back structures regardless of the basis constrained in same height or not, especially these structures have being constructed in mountainous region. According to the observation of the severe damages of buildings destroyed in Wenchuan earthquake and numerous previous studies of applicants, it is unreasonable and unadvisable to apply current codes with existing analysis methods, controlling indices and parameters as well as anti-seismic measures for guiding this type of buildings considering differences arising from geometric characteristic, force-displacement curves, dynamic response, input of ground motions and failure mechanism. Therefore revising and adapting specification aiming to conduct and guide design of step-back building. Currently, employing diverse methods with theoretical analysis, experimental study and numerical simulation can analyze slope-structure dynamic interaction considering complicate input of ground motions and summarize theoretical failure mechanism and model. Then, propose rational theory and applicable methods for design of step-back building, systematically, in the light of facts that controlling methods related to performance and conceptive design. It is important significance and value to propose controlling indices and strategy with respect to anti-seismic structural performance, thus presenting methods and measures associated with seismic design of step-back building structures, which lays foundation for code of step-back building further.

以不等高基础约束为特点的山地建筑结构在山区城镇建设中不可避免且大量存在。汶川地震中此类结构的震害以及课题组的前期研究结果揭示出，山地建筑结构有着与普通结构明显不同的结构几何特征、动力特性以及受力和变形特点，其地震作用输入、破坏机理也与普通结构不同，不能直接适用现行规范规定的结构分析方法、结构控制指标及参数以及抗震措施，专门针对山地建筑结构的设计规范正在编制中。本项目在前期研究工作的基础上，通过理论分析、试验研究和数值模拟分析等方法，系统研究边坡－结构动力相互作用及复杂地震动输入、山地结构地震破坏机理及破坏模式控制以及山地建筑结构抗震设计理论和方法，在山地建筑结构性能控制方法和概念设计理论等方面取得创新性成果，提出抗震性能控制指标和破坏模式控制策略，建立山地建筑结构概念设计理论与抗震设计方法，为山地建筑结构设计规范的修订奠定理论基础，具有重要理论意义和工程应用价值。

坡地-结构动力相互作用及复杂地震动输入、地震破坏机理和破坏模式控制、抗震概念设计理论与性能控制方法是山地建筑结构合理抗震设计亟需解决的重要问题。根据对有限基础刚度模型、坡地-结构整体模型和刚性地基结构的对比分析，明确了坡地-结构动力相互作用对结构地震响应的影响，提出了山地建筑建筑结构的合理模型化；为合理考虑输入地震动，基于台阵实测数据和数值模拟，提出了坡地场地的设计地震动调整建议，并界定需考虑局部场地效应的情况；通过数值模拟、拟静力试验和振动台试验研究了山地建筑结构动力特性、地震响应规律，以及不同抗震措施对结构抗震性能的影响；明确了掉层框架结构的“半层屈服”破坏机制，揭示了掉层RC框架结构的地震破坏机理和倒塌机制，为结构的概念设计提供依据；对各不规则程度的结构提出相应控制策略并进行验证，提出了基于失效模式的地震失效风险控制设计流程；考虑高阶振型、地震作用分布模式、复杂地震动输入对结构分析方法进行相应改进并进行验证，并为掉层框架-剪力墙的范围进行了界定；基于数值分析和规律总结，提出了山地建筑结构竖向和平面不规则性的控制指标，并提出了限值建议；引进钢支撑、消能减震、隔震等措施，为实现掉层框架结构的性能目标探索新的方向。