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

基于性能抗震设计的退化多自由度结构的倒塌分析和位移估计

• 批准号: 0324442
• 负责人: Ashraf Ayoub
• 金额: $ 7.5万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-11-15 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0324442&HistoricalAwards=false
• 关键词: Collapse; Analysis; Displacement; Estimates; Degrading

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.

用于基于性能的抗震设计的退化多自由度结构的倒塌分析和位移估计，CMS建议0324442PI：美国阿尤布，美国地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。已经开发了新的分析程序来估计性能评估的地震需求。这些程序大多基于简单的模型，没有考虑退化效应，退化效应是影响结构在地震激励下行为的主要因素。更重要的是，这些模型中的大多数都不能预测结构在地震荷载下的倒塌。本研究项目的主要目标是开发一种将退化效应纳入多自由度系统地震需求评估的程序。P.I.已经开发了一个能够分析退化结构系统的新的数值平台。基于能量的方法被用来定义几种类型的退化效应。新开发的模型被添加到广泛使用的多自由度结构体系抗震分析商业软件的材料库中。该模型还允许多自由度结构在地震激励下的倒塌预测。拟议的工作包括几项任务。首先，对退化单自由度体系的倒塌预测和位移估计进行数值研究。其次，为了研究缩尺地震记录在退化系统多自由度分析中的有效性，进行了统计参数研究。第三，对退化的多自由度体系进行了广泛的数值研究，以估计基于性能的抗震规范规定中使用的最大弹塑性位移，并确定使结构出于防止倒塌极限状态设计的目的而使结构倒塌的强度水平。最后，将进行地震易损性分析，其中将生成针对大范围结构体系的倒塌准则的易损性曲线。该研究项目的智能优点是在基于性能的抗震设计方法中包括退化效应。为了完成这项任务，必须建立准确的可降解材料的本构模型。目前，通用的三维框架分析程序中几乎没有劣化模型。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影响是提供一个机会，让坦帕湾地区的学生和结构工程师接触到新的设计技术。这将通过开发关于结构非弹性分析的新课程和基于绩效的程序来实现，这些课程将在互动式网络教学工具Blackboard5上提供。该项目还提供了一个机会，让USF的学生，特别是代表人数不足的群体的学生，参与一项涉及国家利益的减轻地震灾害的研究工作，因为目前已经有一名这样的少数族裔学生参与了类似的工作。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，这将向整个结构界提供重要信息。