Influence of Diaphragm Behavior on Performance of Precast Parking Garages During Northridge Earthquake

9416274由于许多预制停车场在北岭地震中严重受损。 许多这种结构的重力荷载系统包括由倒T形梁、拱肩梁和带托臂的柱支撑的双T形楼板单元。 横向荷载体系由几个剪力墙组成，剪力墙的横隔板由带加强顶板的双T形件形成。 这两个系统通常被设计为单独的系统。 如果由于较大的面内力和弯矩而导致隔膜产生裂纹，则可能导致隔膜显著变形，并且刚性隔膜假设可能不充分。 横隔板钢筋的屈服将导致横隔板产生较大的变形。 本项目的目标是：（1）研究北岭地震期间横隔板行为对预制停车场结构重力荷载系统所经历的漂移水平的影响，（2）评估横隔板失效是否导致预制停车场结构中观察到的损坏，以及（3）提出预制横隔板的能力设计概念（如适用）。 将根据受损的停车场结构设计和详细说明一个原型停车场结构。 将使用一个线性模型和两个详细程度和复杂程度不同的非线性模型，分析研究原型结构的典型隔板的地震力-变形行为。 将考虑单向和双向地震荷载。 本文还对一典型剪力墙的地震力-变形特性进行了分析研究. 该分析的结果将用于评估隔膜变形的重要性。 如果合适，将使用原型结构的非线性动态分析结果开发基于能力的横隔板设计概念。 此次地震中受损的预制停车场结构在全国范围内广泛使用，因此可能存在重大危险。 本项目中进行的研究将评估横隔板行为的作用，并提出新的基于能力的设计概念，以避免新的预制停车场结构中横隔板行为不足。 这是一个北岭地震项目。 ***

9416274 Sause Many precast parking garages were heavily damaged in the Northridge earthquake. The gravity load system of many of these structures consisted of double tee floor units supported by inverted tee girders, spandrel girders, and columns with corbels. The lateral load system consisted of a few shearwalls with diaphragms formed by the double tees with reinforced topping slabs. These two systems are usually designed as separate systems. If the diaphragm develops cracks as a result of large in-plane forces and bending moments, significant diaphragm deformation may result and the rigid diaphragm assumption may be inadequate. Yielding of diaphragm reinforcing steel would result in much large diaphragm deformation. The objectives of this project are to: (1) study the influence of diaphragm behavior on the levels of drift experienced by the gravity load systems of precast parking structures during the Northridge earthquake, (2) evaluate whether diaphragm failure contributed to the observed damage in precast parking structures, and (3) propose capacity design concepts for precast diaphragms, if appropriate. A prototype parking structure based on the damaged parking structures will be designed and detailed. The seismic force- deformation behavior of a typical diaphragm of the prototype structure will be studied analytically, using a linear model, and two nonlinear models of different levels of detail and complexity. Unidirectional and bidirectional seismic loads will be considered. The seismic force- deformation behavior of a typical shearwall will also be studied analytically. The results of this analysis will be used to assess the significance of the diaphragm deformation. If appropriate, capacity-based design concepts for diaphragms will be developed using the results of nonlinear dynamic analysis of the prototype structure. The type of construction of precast parking structures damaged in this earthquake is widely used across the country, a nd thus a substantial hazard may exist. The research undertaken in this project will evaluate the role of diaphragm behavior and new capacity-based design concepts will be proposed to avoid inadequate diaphragm behavior in new precast parking structures. This is a Northridge Earthquake project. ***