Collapse Simulation of Shear-Dominated Reinforced Masonry Wall Systems

配筋砌体墙结构在地震作用下会产生复杂的非线性行为，涉及到钢筋与砌体之间的相互作用，而钢筋与砌体的力学性能有着明显的差异。此外，在建筑系统中，结构墙与其他构件（如不同方向的墙、承载重力荷载的柱、梁和楼板）的相互作用可能导致设计中未预期的非线性行为和倒塌机制。分析模型捕捉这些机制和相互作用的能力对于准确评估建筑物的倒塌潜力至关重要。虽然先进的分析模型已被开发来模拟RM结构的损伤机制和非线性行为，但由于缺乏实验数据，它们捕获濒临崩溃的结构系统中的材料和组件相互作用的能力尚未得到验证。这项研究将获得必要的实验数据，以了解RM墙结构的行为，直到崩溃点，然后将使用这些数据来推进和验证分析建模能力。在该项目中获得的数据和开发的分析工具将有助于推进抗震性能评估方法，从而实现更安全和更具成本效益的RM建筑，并且还将有利于具有类似行为的钢筋混凝土墙系统的设计。该项目团队由首席研究员、一名博士生和本科生研究助理组成，将开展模型开发、数值模拟、大规模实验测试和数据分析，以实现上述目标，并传播研究成果和分析工具，用于未来的研究、教育和工程实践。 该项目的实验数据将在NSF支持的NHERI数据库（http：//www.example.com）中存档和提供。www.designsafe-ci.org该项目的有限元模型将与NSF支持的NHERI计算建模和仿真中心共享，以便使用其软件实施。该项目团队还将与NSF支持的NHERI DesignSafe网络基础设施团队合作，为一些原型建筑开发的计算模型开发一个简单的用户界面，供初中和高中学生使用，以研究不同设计变量的影响，例如垂直和水平钢筋的数量，以及材料的强度，对RM结构的抗震性能和倒塌风险的影响。本研究的主要目的是提出基于物理的计算模型，以捕捉RM墙系统的非线性行为，直到倒塌点，考虑材料和组件相互作用对系统水平行为的影响，并开发大规模的模拟，以评估RM墙系统的倒塌裕度比。为此，将进行大规模的实验室测试，以更好地了解处于崩溃边缘的RM墙系统的行为，并校准和验证分析模型。试验和数值研究将量化：（1）墙翼板对RM墙的剪切强度和延性的影响，（2）结构系统中水平横隔梁引入的耦合力对系统强度和变形能力的影响，以及（3）非地震荷载承载墙和柱对抗倒塌性的影响。在实验计划中，两到三个单层，全尺寸，RM墙系统将进行测试，崩溃使用NSF支持的自然灾害工程研究基础设施（NHERI）室外振动台在加州大学，圣地亚哥。这些墙系统将有不同程度的复杂性，以确定非地震荷载承载元件对墙系统抗倒塌性的影响。一旦通过实验数据验证，将在参数研究中使用基于物理的精细模型，以了解不同设计变量和结构配置对双向地震地面运动下RM建筑物倒塌潜力的影响。这些变量将包括墙间距和配置、水平横隔的强度和刚度、水平横隔与墙的连接以及是否存在重力柱。此外，简化的分析模型的能力，以评估RM建筑物的倒塌裕度比与增量动态分析将进行评估。

Reinforced masonry (RM) wall structures subjected to severe seismic forces can develop complicated nonlinear behavior involving interaction between steel and masonry, which have distinctly different mechanical properties. Furthermore, in a building system, the interaction of structural walls with other elements, such as walls that are oriented in a different direction, columns carrying gravity loads, beams, and floor slabs, could lead to nonlinear behavior and collapse mechanisms that were not anticipated in design. The ability of analytical models to capture these mechanisms and interactions is essential to have an accurate assessment of a building's collapse potential. While advanced analytical models have been developed to simulate the damage mechanisms and nonlinear behavior of RM structures, their ability to capture the material and component interactions in a structural system on the verge of collapse has not been validated due to the lack of experimental data. This research will obtain necessary experimental data to understand the behavior of RM wall structures up to the point of collapse, and then will use the data to advance and validate analytical modeling capabilities. The data acquired and analytical tools developed in this project will help advance seismic performance assessment methods, resulting in safer and more cost-efficient RM buildings, and will also benefit the design of reinforced concrete wall systems, which have similar behavior. The project team, consisting of the Principal Investigator, one doctoral student, and undergraduate research assistants, will carry out model development, numerical simulation, large-scale experimental testing, and data analysis to achieve the aforementioned goals, as well as disseminate the research results and analytical tools for use in future research, education, and engineering practice. Experimental data from this project will be archived and made available in the NSF-supported NHERI Data Depot (http://www.designsafe-ci.org). Finite element models from this project will be shared with the NSF-supported NHERI Computational Modeling and Simulation Center for implementation with their software. The project team will also collaborate with the NSF-supported NHERI DesignSafe cyberinfrastructure team to develop a simple user interface for the computational models developed for a few archetype buildings that can be used by middle and high-school students to study the influence of different design variables, such as the amount of vertical and horizontal reinforcement, and the strengths of the materials, on the seismic performance and the risk of collapse of RM structures.The main aim of this research is to advance physics-based computational models to capture the nonlinear behavior of RM wall systems up to the point of collapse, accounting for the influence of material and component interactions on the system-level behavior, and to develop large-scale simulations to assess the collapse margin ratios of RM wall systems. To this end, large-scale laboratory testing will be conducted to acquire a better understanding of the behavior of RM wall systems on the verge of collapse, and to calibrate and validate analytical models. The experimental and numerical studies will quantify: (1) the influence of wall flanges on the shear strength and ductility of RM walls, (2) the influence of the coupling forces introduced by horizontal diaphragms in a structural system on the strength and deformation capability of the system, and (3) the influence of non-seismic load carrying walls and columns on collapse resistance. In the experimental program, two to three one-story, full-scale, RM wall systems will be tested to collapse using the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) outdoor shake table at the University of California, San Diego. These wall systems will have different levels of complexity to identify the influence of non-seismic load carrying elements on the collapse resistance of a wall system. Once validated by experimental data, refined physics-based models will be used in a parametric study to understand the influence of different design variables and structural configurations on the collapse potential of RM buildings under bi-directional earthquake ground motions. The variables will include wall spacing and configurations, the strength and stiffness of horizontal diaphragms, horizontal diaphragm-to-wall connections, and the presence or absence of gravity columns. Moreover, the ability of simplified analytical models to assess the collapse margin ratios of RM buildings with incremental dynamic analysis will be assessed.