Collaborative Research: Transforming Building Structural Resilience through Innovation in Steel Diaphragms

美国依靠坚固和有弹性的建筑来最大限度地减少地震和飓风等极端自然灾害对公民和经济的伤害。在过去，结构工程师们把注意力集中在创造更强、更韧性、更可靠的横向阻力系统上，这些系统可以在建筑物的墙壁内使用，以抵御与这些自然灾害相关的极端要求。相对而言，很少有人注意到建筑物的地板系统在抵抗这些要求方面的作用。地板隔膜作为一个关键的元素，在极端事件中，将建筑中产生的需求分配给横向阻力系统，并最终分配给建筑基础。钢甲板，即薄的波纹钢板，通常用混凝土填充，是多层钢结构建筑中最常用的隔膜元件之一。该项目的目标是：发展对钢桥面横膈膜作为整体建筑性能的结构系统的基本理解，在三维建筑模型中制定准确建模地板系统的改进策略，并为钢桥面横膈膜开发新的解决方案，以增强建筑物的整体结构弹性。目前缺乏关于楼板隔膜系统的知识，阻碍了建筑设计方法从关注二维框架设计到在三维建筑设计中实现创造性解决方案的必要演变。隔膜作为一种能量耗散系统的利用尚未在建筑物中得到利用或优化。该项目将开发一系列适合钢甲板隔板的建筑原型。将在连接和隔膜尺度上进行综合实验计划，包括在测试过程中揭示损伤和变形的新型非接触式测量方案，以弥合目前阻碍三维建模和建筑设计的关键知识差距。为了探索耗能隔膜的新解决方案，该项目将对结构保险丝进行测试，并开发将这些保险丝集成到钢隔膜系统中的原型。该项目还将完成高保真材料和几何非线性有限元模型，以便对膜片内部以及膜片与所有连接部件之间的力流进行详细研究。将开发一系列较低保真度、降阶模型，适用于选定建筑原型的整体建筑分析。将对隔膜在建筑响应中的作用进行正式优化，包括一种新的两级优化方案。综上所述，这些活动将在最先进的建筑隔板设计方面取得重大进展。通过与工业界的全面合作，研究结果将转交给工程师，并用于提高国家建筑的结构弹性。

America relies on a robust and resilient building stock to minimize harm to its citizens and damage to its economy due to extreme natural hazards such as earthquakes and hurricanes. In the past, structural engineers have focused their attention on creating stronger, more ductile, more reliable lateral-resistance systems that can be used within the walls of buildings to resist the extreme demands associated with these natural hazards. Comparatively little attention has been paid to the role of the floor systems of buildings in resisting these demands. The floor diaphragm acts as a critical element that distributes the demands developed in a building during an extreme event to the lateral-resistance systems and eventually to the building foundation. Steel deck, i.e., thin corrugated steel panels typically with concrete fill, forms one of the most commonly used diaphragm elements in multi-story steel buildings. This project has as its objectives: to develop fundamental understanding of steel deck diaphragms as structural systems integrated within the overall building performance, to develop improved strategies for accurate modeling of floor systems within three-dimensional building models, and to develop new solutions for steel deck diaphragms that enhance the overall structural resilience of buildings.Current lack of knowledge about floor diaphragm systems impedes a needed evolution for building design approaches from focusing on two-dimensional frame design to enabling creative solutions within three-dimensional building design. The utilization of the diaphragm as an energy dissipating system has not been harnessed nor optimized in buildings. This project will develop a series of building archetypes appropriate to steel deck diaphragms. An integrated experimental program will be conducted at the connection and diaphragm scale, including novel non-contact measurement schemes for revealing damage and deformations during testing, to bridge critical knowledge gaps that currently impede three-dimensional modeling and design of buildings. To explore new solutions for energy-dissipating diaphragms, this project will perform testing of structural fuses and develop prototypes for integrating these fuses into steel diaphragm systems. This project will also complete high fidelity material and geometric nonlinear finite element models to enable detailed investigations of the flow of forces in diaphragms and between the diaphragm and all connected components. A series of lower fidelity, reduced order models will be developed, appropriate for whole building analysis of selected building archetypes. Formal optimization of the role of the diaphragm in building response, including a novel two-level optimization scheme, will be performed. Taken together, these activities will provide a significant advancement in the state-of-the-art for design of building diaphragms. Through a comprehensive outreach effort with industry, the findings will be transferred to engineers and utilized to improve the structural resilience of the nation's buildings.