Innovative Steel Braced Frame Systems for Enhanced Seismic Performance

钢支撑框架是最受欢迎的结构体系之一，用于抵抗风和地震强加给建筑结构的横向荷载。当系统在弹性范围内响应时，如在风和小地震情况下，系统是非常有效的。然而，该系统已被证明在强震下表现出较差的性能，如大塑性变形和显著的永久变形。更高的抗震设计载荷，严格的高度限制和其他要求已经在规范中实施，以实现对公众的最低安全。这些都增加了建筑成本，限制了系统的应用范围，建筑业主可能面临长时间的停机时间以及重大地震事件后的重大维修/重建成本，这将给加拿大经济造成重大损失。*******本研究旨在开发新型钢支撑框架系统，在极端地震后表现出卓越的性能，没有或有限的损坏，从而可以迅速恢复运营，并将修复成本降至最低。将研究三种系统：用于低层应用的带有基础剪切保险丝的摇摆框架；用于中高层建筑的模块化脊柱系统和用于高层单层应用的多层支撑框架。这三种应用几乎涵盖了在加拿大建造的所有钢建筑结构。将开发摇摆框架，以适应地震施加的位移，通过摇摆和自定心剪切熔断器串联作用，使每个机构的需求受到限制，结构承受结构损坏。模块化的脊柱概念消除了软层的反应，允许钢支撑框架用于超过加拿大规范规定高度限制2倍的建筑物中。该系统的设计使非弹性地震变形只发生在专用元件中，这些元件在地震后很容易被替换。因此，即使在非常强烈的地震中，该结构也不会受到破坏。多层支撑框架现在必须用更重的柱来构造，以抵抗地震引起的弯曲需求并防止屈曲破坏。提出了替代支撑配置，要求更小的柱，同时减少结构位移。*******申请人最初提出了这三个系统，拟议的研究旨在完成正在进行的开发工作。对于这三个系统，研究包括开发有效的结构安排，使用先进的非线性地震分析来检查它们在强地面运动下的反应，开发设计策略以优化它们的反应，并进行大规模的物理测试来证明它们的性能。******

Steel braced frames are among the most popular structural systems used to resist wind and earthquake lateral loads imposed to building structures. The system is very effective when responding in the elastic range as is the case under wind and small earthquakes. However, the system has been shown to exhibit poor performance under strong earthquakes such as large plastic deformations and significant permanent deformations. Higher seismic design loads, stringent height limits and other requirements have been implemented in codes to achieve minimum safety to the public. These have increased construction costs and limited the range of application of the system and building owners are likely to face long downtime periods as well as major repair/reconstruction costs after a major seismic event, which will result in major losses for the Canadian economy.*******This research aims at developing new steel braced frame systems exhibiting superior performance with no or limited damage after an extreme earthquakes such that operations can be resumed rapidly and repair costs are minimized. Three systems will be studied: rocking frames with base shear fuses for low-rise applications; modular spine systems for medium-rise buildings and multi-tiered braced frames for tall single-storey applications. These three applications cover nearly the entire range of steel building structures that are built in Canada. The rocking frame will be developed to accommodate seismic imposed displacements through rocking and self-centering shear fuse acting in series such that the demand on each mechanism is limited and the structure sustain no structural damage. The modular spine concept eliminates soft-storey response, allowing steel braced frames to be used in buildings more than 2 times the height limit currently specified in the Canadian code. The system is designed such that inelastic seismic deformations only develop in dedicated elements that can be easily replaced after an earthquake. Hence, the structure sustain no damage, even in very severe earthquakes. Multi-tiered braced frames must now be constructed with much heavier columns to resist the seismic induced flexural demand and prevent buckling failure. Alternative bracing configurations are proposed that require smaller columns while reducing the structure displacements.*******The applicant has originally proposed the three systems and the proposed research aims at completing ongoing development work. For all three systems, the research consists in developing effective structural arrangements, examining their response under strong ground motions using advanced nonlinear seismic analysis, developing design strategies to optimise their response and performing large scale physical testing to demonstrate their performance.******