Design of gravity force-resisting systems accounting for seismic displacement demands

建筑中的结构系统必须设计成既能抵抗重力的垂直荷载，也能抵抗风或地震作用施加的横向荷载。在结构设计中，结构框架通常由两个独立的体系组成：重力抗力体系和侧向力抗力体系。虽然抗震规范传统上侧重于抗侧向力体系的设计要求，但地震事件引起的地面震动会导致整个结构发生变形，即在重力和抗侧向力体系中都会产生变形要求。在这方面，加拿大最新版本的混凝土设计标准承认，重力式框架的破坏是地震期间建筑物倒塌最常见的原因之一。因此，规范引入了新的要求，旨在确保不属于抗震系统的构件具有足够的强度和延性，但会受到地震引起的变形。传统的结构设计依赖于等效线弹性分析模型来复制建筑物的预期非线性响应。然而，加拿大混凝土设计标准的这一新要求并没有解决如何准确地发展这种等效线弹性分析模型来进行重力式框架的抗震设计。为了应对这一挑战，Glotman Simpson正在与不列颠哥伦比亚大学合作开发一种程序，提供一致和可信的结果，以促进根据最新规范要求对重力式车架进行新的设计检查。这项工作将有助于继续交付安全和经济的设计。

The structural system in a building must be designed to resist both vertical loads from gravity, as well as lateral loads imposed by wind or seismic action. It is common in structural design for the structural frame to consist of two separate systems: a gravity force-resisting system and a lateral force-resisting system. While seismic codes have traditionally focused on the design requirements of lateral force-resisting systems, ground shaking due a seismic event will cause the entire structure to deform, i.e. it will impose deformation demands both in the gravity and the lateral force-resisting systems. In this regard, the latest edition of the concrete design standard in Canada recognizes that failure of gravity frames is one of the most common causes of building collapse during an earthquake. Thus, the code introduced a new requirements intended to ensure adequate levels of strength and ductility in elements that are not part of the seismic force-resisting system, but are subjected to seismically induced deformations. Conventional structural design relies on equivalent linear elastic analysis models to replicate anticipated nonlinear response in buildings. However, this new requirement of the concrete design standard in Canada does not address how to accurately develop this equivalent linear elastic analysis model for the seismic design of gravity frames. To address this challenge, Glotman Simpson is partnering with the University of British Columbia to develop a procedure that provides consistent and trustworthy results to facilitate these new design checks of gravity frames per the latest code requirements. This work will facilitate the continued delivery of safe and economical designs.