Reliability of Strongly Nonlinear Structures and Systems under Seismic Excitations

地震激励下强非线性结构和系统的可靠性

• 批准号: 9312640
• 负责人: Y.K. Lin
• 金额: $ 15万
• 依托单位: Florida Atlantic University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-15 至 1996-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9312640&HistoricalAwards=false
• 关键词: Reliability; Strongly; Nonlinear; Structures; Systems

9312640 Lin The research is directed at evaluating the reliability (1 probability of failure) of strongly nonlinear dynamical systems under severe earthquake excitations. Two types of nonlinear systems are considered: (l) highly hysteretic structures, exhibiting large deformations, and (2) non structural systems, which respond to seismic excitations in the form of rocking, sliding, or combined rocking and sliding, essentially as rigid bodies. Failure of hysteretic structures is conceived to be an accumulation of damage to a critical magnitude, which is measured by both the largest deformation and the total dissipated hysteresis energy. Failure of rigid body type systems occurs due to topping, colliding, or pounding against each other. When a failure state is reachable, it provides an absorbing boundary for the sample space in which the sample functions are distributed. A sample function is removed from the population, once it reaches the absorbing boundary. Therefore, the total probability cannot be conserved within the sample space. Such an absorbing boundary must be taken into account; otherwise, the reliability estimate is unconservative. Moreover, while failure of a hysteretic structure is manifested primarily in a predominant failure mode, a random excitation consisting of a wide band of frequencies has the tendency to push the system slightly from the dominant mode from time to time, thereby permitting some energy to be consumed by other non dominant modes. These facts will be considered in this research to obtain an accurate probabilistic characterization of the response of these highly nonlinear systems. ***

本研究旨在评估强非线性动力系统在强烈地震作用下的可靠度（失效概率）。考虑两种类型的非线性系统：(1)高度滞后结构，表现出大的变形；(2)非结构系统，以摇晃、滑动或摇晃和滑动组合的形式响应地震激励，本质上是刚体。迟滞结构的破坏被认为是损伤累积到临界量级，这是由最大变形和总耗散的迟滞能量来衡量的。刚体型系统的失效是由于顶部、碰撞或相互撞击造成的。当失效状态可达时，它为样本函数分布的样本空间提供了一个吸收边界。一旦到达吸收边界，样本函数就从总体中移除。因此，总概率在样本空间内不能守恒。必须考虑到这种吸收边界；否则，可靠性估计是非保守的。此外，虽然迟滞结构的失效主要表现在主导失效模式中，但由宽频带组成的随机激励有可能不时地将系统稍微推离主导模态，从而允许一些能量被其他非主导模态消耗。本研究将考虑这些事实，以获得这些高度非线性系统响应的准确概率表征。* * *