NEESR Planning: Influence of Local-Global Synergistic Instabilities on the Seismic Collapse Resistance of Steel Columns

钢抗弯框架中的柱在强地震事件期间可经受高轴向荷载以及大的侧向循环位移要求。在这种情况下，塑性铰的发生可以引入局部屈曲，其中断载荷路径并且可以协同地促进其他类型的不稳定性，例如弯曲或侧向扭转屈曲。这种不稳定性的机制，不利地相互作用，以减少钢柱的承载能力尚未被调查，是本研究的重点。利用分析建模和高保真度计算模拟，将进行基础研究，以调查与柱性能差相关的钢框架系统的脆弱性。这些研究将解决钢宽翼缘柱和连接柱在大轴向荷载和侧向位移下的非弹性行为，并确定柱的局部和整体屈曲在地震事件期间和之后促进结构的垂直连续倒塌中所起的作用。作为本研究的一部分开发的模型将在将基于性能的设计提升到下一个水平方面发挥重要作用。此外，这项规划补助金研究的结果将为未来的实验计划开发测试矩阵提供关键见解，该计划将使用NEES2功能进一步探索问题。钢框架建筑中的柱是防止倒塌的最后一道防线。这种构件在强烈地震事件期间承受重载荷并受到严格的要求。发展一个清晰的理解，他们的承载性能如何在严重的负载制度下退化将有显着的影响，结构工程师如何在地震区设计钢框架。通过了解钢柱和承载系统的潜在脆弱性，可以实现更具弹性和鲁棒性的设计，从而在严重的地震事件中更好地保护生命和财产。这些发现也可能适用于色谱柱性能可能较差的其他危害。作为本研究的一部分开发的可视化模型有可能改善钢结构设计教育，并帮助学生更好地想象钢结构构件中的不稳定性是如何发生的。研究生和本科生水平的学生将参与本研究的各个层面，使他们有机会获得钢构件和抗震设计行为的重要经验。该项目的模拟和元数据将通过NEES数据库提供。 该奖项是国家减少地震灾害计划（NEHRP）的一部分。

Columns in steel moment resisting frames can be subjected to high axial loads coupled with large lateral cyclic displacement demands during strong seismic events. Under such conditions, the occurrence of plastic hinging can introduce local buckling, which interrupts the load path and can synergistically promote other types of instabilities, such as flexural or lateral torsional bucking. The mechanisms by which such instabilities adversely interact to reduce the load carrying capacity of steel columns have not yet been investigated and are the focus of this research. Using analytical modeling and high fidelity computational simulation, fundamental studies will be conducted to investigate the vulnerability of steel moment frame systems associated with poor column performance. The studies will address the inelastic behavior of steel wide flange columns and connection subassemblies under large axial loads and lateral displacements and determine the role that local and global buckling of columns plays in promoting vertical progressive collapse of a structure during and after a seismic event. The models developed as part of this study will play a major role in moving performance-based design to the next level. Moreover, the findings of this planning grant research will provide key insight toward the development of test matrices for a future experimental program that will use NEES2 capabilities to further explore the problem. Columns in steel frame buildings are the last line of defense against collapse. Such members are heavily loaded and subjected to severe demands during strong seismic events. Developing a clear understanding of how their load-carrying performance degrades under severe loading regimes will have a significant impact on how structural engineers design steel frames in seismic regions. By understanding the potential vulnerabilities of steel columns and the load carrying system, more resilient and robust designs can be achieved that better protect lives and property during severe seismic events. The findings may also be applied to other hazards where there is potential for poor column performance. Visualization models developed as part of this research have the potential to improve steel structural design education and help students better envision how instabilities occur in steel structural members. A diverse pool of students at both the graduate and undergraduate level will be involved at all levels of this study, allowing them the opportunity to gain important experience in the behavior of steel members and seismic design. Simulation and metadata from this project will be made available through the NEES data repository. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).