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

制造的简易性、高的强度重量比、尺寸的精确度、无限的可回收性和可重复使用性等特性导致了冷弯薄壁型钢(CFS)框架多层住宅和商业建筑的建造增加。CFS框架建筑是一种复杂体系，在地震作用下经历了其生命周期中最苛刻的要求。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。北美正在制定新的设计标准，以满足CFS结构的横向荷载需求。然而，现有的许多可以作为新的水平荷载设计标准基础的研究仅限于单层剪力支撑墙在静力或基于反复位移的荷载作用下的试验。20个剪力墙和支撑墙的动力试验，以及少量的CFS框架横隔墙试验。虽然这项现有的研究提供了丰富的资料，但没有纳入建筑物对地面运动的整体反应的影响，这取决于横隔板、屋顶和楼板横隔板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阶段，工程师们经常发现他们要对完整的3D结构系统进行建模。鉴于目前对CFS建筑的了解状况，工程师们不得不对楼板和屋顶横隔板、横隔板和墙之间的连接以及其他结构和非结构部件的建筑模型进行全面简化。这些简化导致：i)效率低下，因为忽略了横隔板和横隔板-墙之间界面的影响；ii)不准确，因为横隔板传递到墙的力被近似和简化，并且横隔板本身产生的力没有被很好地理解；iii)不正确的振动周期估计，因为被忽略的非结构部件(石膏夹层内墙和外墙)通常具有与CFS结构墙相同的刚度；以及iv)过度设计，因为被忽略的非结构部件具有与结构CFS墙相似的抗剪能力。综上所述，这导致了对全三维CFS抗震体系认识的不完整。该研究计划的长期目标是为CFS框架体系开发经过验证的抗震设计方法。拟议研究的具体5年短期目标是：i)提供典型的楼板横隔板和墙力与非结构构件的变形滞回反应的特征；ii)设计一个适用于建筑物在动力地震荷载下的反应评估的数值模型，以研究建筑中主要结构构件的影响，包括墙、横隔板(楼板和屋顶)、墙、横隔板和非结构构件之间的连接；Iii)使用此数值模型进行评估，以识别和量化建筑物(横隔板/墙)对地面运动的反应；iv)就如何在CFS框架结构的实际工程设计中准确处理横隔板和非结构构件的影响提出建议指南；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。鉴于CFS的设计标准打算在整个北美使用，因此必须将与加拿大工程师有关的问题纳入设计文件；这需要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.