Collapse Analysis and Displacement Estimates of Degrading MDOF Structures for Performance-Based Seismic Design

基于性能的抗震设计的多自由度结构的倒塌分析和位移估计，CMS提案0324442 PI：Ayoub，USF抗震设计方法最近采用了基于性能的程序的新的一般概念。这一新概念已反映在若干业务守则中。新的分析程序已经开发出来，以估计性能评估的抗震需求。 大多数这些程序是基于简单的模型，并没有考虑退化效应，一个主要因素，影响结构的行为在地震激励下。更重要的是，大多数这些模型不预测地震荷载下的结构倒塌。本研究项目的主要目标是开发一个程序，将退化效应的多自由度系统的抗震需求评估。 P.I.已经开发了一个新的数值平台，可以分析退化的结构系统。基于能量的方法被用来界定几种类型的退化效应。新开发的模型被添加到一个广泛使用的商业软件的多自由度结构体系的抗震分析的材料库。 该模型还允许倒塌预测的多自由度结构在地震激励下。拟议的工作包括几项任务。首先，将进行退化单自由度体系的倒塌预测和位移估计的数值研究。其次，统计参数的研究进行，以研究的有效性缩放地震记录的多自由度分析的退化系统。第三，一个广泛的数值研究进行退化多自由度系统，以估计最大非弹性位移用于基于性能的抗震规范的规定，并确定强度水平，受倒塌的结构，以防止破坏极限状态设计的目的。最后，将进行地震易损性分析，其中将以数值方式生成大量结构系统的倒塌标准的易损性曲线。 该研究项目的智力价值在于将退化效应纳入基于性能的抗震设计方法中。为了完成这一任务，降解材料的精确本构模型必须开发。 目前，很少有退化模型存在于一般的三维框架分析程序。 该研究项目采用了新定义的基于能量的退化模型，该模型已被纳入商业非线性地震分析程序。 拟议的研究项目的更广泛的影响是提供一个机会，让学生和结构工程师在坦帕湾地区的新设计技术。这将通过开发关于结构非弹性分析和基于性能的程序的新课程来进行，这些课程将在基于网络的交互式教学工具Blackboard 5上提供。该项目还提供了一个机会，让南佛罗里达大学的学生，特别是代表性不足的群体的学生，参与国家感兴趣的减轻地震灾害的研究工作，因为目前有一名这样的少数民族学生已经参与了类似的工作。最后，拟议研究的统计结果将以数据库格式记录在互联网上，这将为整个结构社区提供重要信息。

Collapse Analysis and Displacement Estimates of Degrading MDOF Structures for Performance-Based Seismic Design, CMS proposal 0324442PI: Ayoub, USFSeismic design methodologies have recently adopted the new general concept of performance-based procedures. The new concept has been reflected in several codes of practice. New analysis procedures have been developed to estimate seismic demands for performance evaluation. Most of these procedures are based on simple models, and do not take into account degradation effects, a major factor influencing structural behavior under earthquake excitations. More importantly, most of these models do not predict collapse of structures under seismic loads. The main objective of this research project is to develop a procedure for incorporating degradation effects for seismic demand evaluation of MDOF systems. A new numerical platform that permits analysis of degrading structural systems was already developed by the P.I. Energy-based approaches were used to define several types of degradation effects. The newly developed models were added to the material library of a widely used commercial software for seismic analysis of MDOF structural systems. The models also permit collapse prediction of MDOF structures under seismic excitations. The proposed work consists of several tasks. First, a numerical study on collapse prediction and displacement estimates of degrading SDOF systems will be conducted. Second, a statistical parameter study is performed in order to study the effectiveness of scaling earthquake records for MDOF analysis of degrading systems. Third, an extensive numerical study is conducted on degrading MDOF systems to estimate maximum inelastic displacements for use in performance-based seismic code provisions, and to determine strength levels that subject the structures to collapse for collapse-prevention limit state design purposes. Finally, seismic fragility analysis will be performed, where fragility curves for a collapse criterion for a large spectrum of structural systems will be generated numerically. The intellectual merit of the research project is to include degradation effects in performance based seismic design methodologies. To perform this task, accurate constitutive models of degrading materials have to be developed. Currently, few if any deterioration models exist in a general three-dimensional frame analysis program. The research project employs newly defined energy-based degrading models that have been incorporated into a commercial nonlinear seismic analysis program. The broader impact of the proposed research project is to provide an opportunity to expose students and structural engineers in the Tampa Bay area to new design techniques. This will be performed through the development of new courses on inelastic analysis of structures, and performance-based procedures, that will be available on the interactive web-based teaching tool Blackboard5. The project also represents an opportunity to involve students at USF, especially of underrepresented groups, in a research work of national interest on seismic hazard mitigation, as currently one such minority student is already involved in a similar work. Finally, the statistical outcomes of the proposed research will be documented in a database format to be available on the internet, which will provide important information to the whole structural community.