Collaborative Research: An Integrated Model for Performance-Based Assessment and Design of Secondary Systems Mounted on Building Structures

这项研究将开发，制定和验证一种创新和实用的方法，用于评估地震需求和二次系统的能力。二次系统（即，非结构部件）是容纳或连接到建筑物或工业设施的地板、屋顶和墙壁上的那些系统和元件，它们不是主承载结构系统的一部分。在地震期间和地震后，二次系统的生存对于减少人员伤亡、保持功能和减少直接损失成本（可高达建筑物总成本的85%）非常重要。目前在此类系统的地震需求评估和损坏引起的损失估计方面的知识和实践状况至少有四个方面的不足。首先，在某些情况下，现行规范规定对地震需求的估计不足，这将导致破坏和重大经济损失。第二，这些部件的简化设计方法没有明确说明过程中最重要的不确定性来源。第三，目前的损失估计方法是基于各个组成部分的损失总和，由此间接损害的概念（即，一个部件的损坏对其他部件的损坏的影响）没有明确考虑，这将导致损失的不准确估计。第四，非常有限的努力已经被放置到使用动态运动，这是更有代表性的比常用的准静态加载协议的二次系统的损害和相关的损失进行评估。本研究的目的是制定和验证一种方法，用于评估安装在弹性和非弹性主结构上的二次系统的需求和容量。这种方法将考虑到过程中存在的不确定性，并最终有助于估计地震期间由于二次系统损坏而造成的经济/伤亡/停机损失。研究结果对于以下方面至关重要：（a）了解控制安装在弹性和非弹性建筑物上的二次系统地震响应的机制和参数，（B）将结构和非结构系统的理论基础公式化为综合计算机模型，以量化此类系统的地震需求，（c）开发用于提供峰值加速度的稳健和可靠评估的综合概率模型二次系统的（强度）和变形要求，以及（d）开发一种应用和有效的方法，用于使用动态加载协议获得二次元件的能力。准确可靠地预测二次系统的地震需求将包括这一过程中最重要的不确定性来源。这对于准确估计地震事件期间二次系统损坏造成的经济损失和伤害至关重要。 更广泛的影响：这项研究的结果将是有价值的研究人员，设计工程师和建筑规范的作者谁必须作出决定和/或建立标准的抗震设计和评估的二次系统。从该项目中吸取的经验教训将纳入实验设计建议，以了解和量化二次系统的抗震能力，并减少预测中的不确定性。概率方法将促进结构工程、结构动力学、地震工程以及统计和可靠性理论概念在建筑物二次系统保护中的并行结合。这项研究将提供研究生和本科生研究助理（一名在马里兰州大学，一名在加州大学欧文分校）和一名本科生研究助理的教育。 学生将学习研究过程，并通过学习结构，动力学，地震，概率和新颖的地震工程概念受益。一名大学预科学生也将在项目期间协助研究活动。这项活动将促进代表性不足的大学预科和本科工程本科生参与与研究有关的任务。其中一名PI是代表性不足的群体的成员，因此他将成为代表性不足的学生的专业榜样。

This research will develop, formulate, and validate an innovative and practical approach for assessing seismic demands and capacities of secondary systems. Secondary systems (i.e., nonstructural components) are those systems and elements housed or attached to floors, roofs, and walls of a building or industrial facility that are not part of the main load bearing structural system. The survival of secondary systems during and after an earthquake is important for the reduction of casualties, continuing functionality, and the reduction of direct damage costs, which can reach up to 85 percent of the total cost of the building. Shortcomings in the current state of knowledge and practice in the seismic demand assessment of such systems and the estimation of damage-induced losses are at least fourfold. First, in several cases, current code provisions provide inadequate estimates of seismic demands that will lead to damage and significant economic losses. Second, simplified design methodologies for such components do not explicitly account for the most important sources of uncertainties in the process. Third, current loss estimation methodologies are based on the summation of losses from individual components by which the concept of collateral damage (i.e., the effect of damage in one component on other components' damages) is not explicitly considered, which will result in an inaccurate estimate of losses. Fourth, very limited efforts have been placed to assess damages and associated losses for secondary systems using dynamic motions, which are more representative than commonly used quasi-static loading protocols. The goal of the study is to formulate and validate a methodology for applied assessment of demand and capacity of secondary systems mounted on elastic and inelastic primary structures. This methodology will account for uncertainties present in the process and ultimately help in the estimation of economic/casualty/down-time losses due to damages in secondary systems during earthquakes.Intellectual Merit: The results of the research are essential for (a) providing an understanding of the mechanisms and parameters that control the seismic response of secondary systems mounted on elastic and inelastic buildings, (b) formulating theoretical foundations of structural and nonstructural systems into a comprehensive computer model to quantify the seismic demands for such systems, (c) developing an integrated probabilistic model useful to provide a robust and reliable assessment of the peak acceleration (strength) and deformation demands of secondary systems, and (d) developing an applied and effective methodology for obtaining capacities of secondary elements using a dynamic loading protocol. The accurate and reliable prediction of seismic demands for secondary systems will incorporate the most important sources of uncertainty in the process. This is of paramount importance for accurate estimation of economic losses and injuries caused by damage to secondary systems during earthquake events. Broader Impacts: Results from this study will be of value to researchers, design engineers, and building code writers who have to make decisions and/or establish criteria for the seismic design and evaluation of secondary systems. The lessons learned from this project will be incorporated into recommendations for the design of experiments to understand and quantify the seismic capacity of secondary systems, as well as to reduce the uncertainty in this prediction. The probabilistic methodology will promote the concurrent incorporation of structural engineering, structural dynamics, earthquake engineering, and statistical and reliability theory concepts in the protection of secondary systems in buildings. This study will provide for the education of both graduate and undergraduate research assistants (one at the University of Maryland and one at the University of California, Irvine) and an undergraduate research assistant. The students will learn the research process and benefit by learning about structures, dynamics, earthquakes, probability, and novel earthquake engineering concepts. A pre-college student will also assist with the research activities for the duration of the project. The activity will promote the participation underrepresented pre-college and undergraduate engineering undergraduate students in research related tasks. One of the PIs is a member of an underrepresented group, so he will serve as a professional role model for underrepresented students.