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

在强震作用下，钢框架中的柱可以承受较高的轴向荷载和较大的侧向循环位移需求。在这种情况下，塑性铰的出现可能会导致局部屈曲，从而中断加载路径，并协同促进其他类型的失稳，如弯曲或侧向扭转屈曲。这种不稳定的不利作用降低钢柱承载能力的机理尚未得到研究，这也是本研究的重点。利用解析建模和高保真计算模拟，将进行基础性研究，以研究与柱性能不良相关的钢框架体系的脆弱性。这些研究将探讨钢宽翼缘柱和连接组件在大的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过程中和地震后促进结构竖向渐进倒塌的作用。作为这项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，这项规划拨款研究的结果将为未来的实验计划开发测试矩阵提供关键的见解，该计划将使用NEES2的能力来进一步探索问题。钢框架建筑中的柱子是防止倒塌的最后一道防线。在强烈地震事件中，这种构件承受着沉重的荷载，并受到严格的要求。清楚地了解钢框架在严重荷载作用下的承载性能如何退化，将对结构工程师如何在地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，可以实现更具弹性和坚固的设计，在严重地震事件中更好地保护生命和财产。这一发现也可能适用于可能导致柱性能不佳的其他危险。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如何发生失稳。不同层次的研究生和本科生将参与本研究的各个层次，使他们有机会在钢结构构件的行为和抗震设计方面获得重要的经验。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).