Advancing the seismic performance of cold-formed steel framed building structures

易于制造，高强度重量比，尺寸精度，无限的可回收性和可重复使用性，以及其他属性，导致冷弯型钢（CFS）框架多层住宅和商业建筑的建设增加。CFS框架结构是一种复杂的结构体系，在地震作用下对其生命周期的要求最为苛刻。改进的设计程序将直接提高建筑物居住者和业主的生命安全。目前正在制定新的北美设计标准，以解决CFS结构的横向荷载要求。然而，许多现有的研究可以作为新的横向荷载设计标准的基础，这些研究仅限于在静力或反向循环位移荷载作用下的单层剪力支撑墙的试验。剪力墙和支撑墙的动力试验20次，以及少量CFS框架隔膜试验。虽然提供了信息，但现有的研究并没有纳入建筑物对地面运动的整体反应的影响，这取决于；横膈膜，屋顶和地板横膈膜与垂直墙的相互连接以及非结构部件的存在。为了达到创新、高效和有弹性的建筑的下一个阶段，工程师们经常发现自己要对完整的3D结构系统进行建模。鉴于CFS建筑工程师目前的知识水平，他们必须对地板和屋顶隔板、隔板和墙壁之间的连接以及其他结构和非结构部件的建筑模型进行总体简化。简化导致i)效率低下，因为忽略了隔膜和隔膜-壁面界面的影响；Ii)不准确性，因为隔膜传递给墙壁的力是近似和简化的，并且隔膜本身产生的力没有得到很好的理解；iii)不正确的振动周期估计，因为忽略的非结构构件（石膏护套内墙和覆层外墙）通常具有与结构CFS墙等效的刚度；iv)过度设计，因为忽略的非结构构件与结构CFS墙具有相似的抗剪能力。综上所述，这些导致v)对完整的三维CFS抗震力系统的不完整理解。该研究计划的长期目标是为CFS框架系统开发可靠的抗震设计方法。具体的5年短期目标是：i)提供典型的楼板、隔膜和墙壁力与变形迟滞反应的特征，包括和不包括非结构部件；Ii)设计一个适合于动态地震荷载下建筑物响应评估的数值模型，以研究建筑物中主要结构部件的影响，包括墙壁、隔板（地板和屋顶）、墙壁之间的连接、隔板和非结构部件；Iii)使用此数值模型进行评估，以识别和量化建筑物（隔膜/墙壁）对地面运动的响应；iv)就如何在CFS框架结构的实际工程设计中准确处理隔板和非结构部件的影响提出指导意见；及v)将建议的CFS抗震设计程序纳入相关设计标准；AISI S400， CSA S136和国家建筑规范。考虑到CFS的设计标准适用于整个北美地区，因此必须将与加拿大工程师有关的问题纳入设计文件；这就要求加拿大大学参与设计标准的制定。

Ease of fabrication, high strength-to-weight ratio, dimensional accuracy, infinite recyclability & reusability, among other attributes, have led to the increase in construction of cold-formed steel (CFS) framed multi-storey residential and commercial buildings. CFS framed buildings are complex systems that under earthquake excitations experience the most severe demands of their life cycle. Improved design procedures will lead to a direct enhancement of life safety for building occupants & owners. New North American design standards to address the lateral loading demands on CFS structures are being developed. However, much of the existing research on which one can base the new lateral loading design standards is limited to tests of single-storey shear & braced walls under static or reversed cyclic displacement-based loading, approx. 20 dynamic tests of shear & braced walls, and a handful of CFS framed diaphragm tests. While informative, this existing research has not incorporated the influence of a building's overall response to ground motions, which is dependent on; the diaphragms, the interconnectivity of the roof & floor diaphragms with the vertical walls and the presence of non-structural components. To reach the next phase of innovative, efficient and resilient buildings engineers often find themselves modeling the full 3D structural system. Given the current state of knowledge of CFS buildings engineers are left in the situation where they must make gross simplifications in the building models for the floor & roof diaphragms, connections between the diaphragms & walls, along with other structural & non-structural components. Simplifications that lead to i) inefficiencies, because the influence of the diaphragm & diaphragm-to-wall interface is ignored; ii) inaccuracies because the forces transmitted by the diaphragm to the walls are approximated & simplified, and the forces that develop in the diaphragms themselves are not well understood; iii) incorrect period of vibration estimates because the ignored non-structural components (gypsum sheathed interior walls & clad exterior walls) often have equivalent stiffness to the structural CFS walls; and iv) over-design because the ignored non-structural components have similar shear resistance to the structural CFS walls. Taken together these lead to v) an incomplete understanding of the full 3D CFS seismic force resisting system. The long term objective of the research program is to develop proven seismic design methods for CFS framing systems The specific 5 year short term objectives of the proposed research are: i) provide characterization of typical floor diaphragm & wall force vs. deformation hysteretic response with & without non-structural components; ii) devise a numerical model, appropriate for building response evaluation under dynamic seismic loading, to investigate the influence of the main structural components in a building including the walls, the diaphragms (floors and roofs), the connections between walls, diaphragms & non-structural components; iii) carry out evaluations using this numerical model to identify & quantify building (diaphragm/wall) response to ground motions; iv) recommend guidelines as how to accurately address the influence of diaphragms & non-structural components in the practical engineering design of CFS framed structures; and v) include the recommended CFS seismic design procedures in the relevant design standards; AISI S400, CSA S136 & the National Building Code. Given that the design standards for CFS are intended for use throughout North America it is imperative that issues relevant to Canadian engineers be incorporated within the design documents; this requires the participation of Canadian universities in design standards development.