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

钢抗弯矩框架中的柱在强地震事件中可以承受高轴向载荷和大横向循环位移需求。在这种情况下，塑性铰的发生会引入局部屈曲，从而中断荷载路径，并协同促进其他类型的失稳，如弯曲或侧向扭转屈曲。这种不稳定性相互作用降低钢柱承载能力的机制尚未得到研究，这是本研究的重点。使用分析建模和高保真计算模拟，将进行基础研究，以调查与柱性能差相关的钢弯矩框架系统的脆弱性。这些研究将解决钢宽法兰柱和连接组件在大轴向载荷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垂直递进式倒塌中的作用。作为本研究的一部分，开发的模型将在将基于性能的设计推向下一个水平方面发挥重要作用。此外，这项计划拨款研究的结果将为未来实验项目的测试矩阵的开发提供关键的见解，该实验项目将使用NEES2的能力来进一步探索这个问题。钢框架建筑中的柱是防止倒塌的最后一道防线。这些构件载荷很大，在强烈的地震事件中承受着苛刻的要求。清晰地了解它们的承载性能在严重荷载下是如何退化的，将对结构工程师如何在震区设计钢框架产生重大影响。通过了解钢柱和承载系统的潜在脆弱性，可以实现更有弹性和更坚固的设计，在严重的地震事件中更好地保护生命和财产。研究结果也可应用于其他危害，其中存在潜在的不良柱性能。作为本研究的一部分，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的不稳定性是如何发生的。研究生和本科生将参与本研究的各个阶段，使他们有机会获得钢构件行为和抗震设计方面的重要经验。该项目的模拟和元数据将通过NEES数据存储库提供。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).