NEESR-CR: Multi-Scale, Mechanistic Fracture Prediction and Optimal Panel Zone Participation in Steel Moment Frame Buildings

NEESR-CR：钢框架建筑中的多尺度机械断裂预测和最佳面板区域参与

• 批准号: 0936599
• 负责人: Gary Fry
• 金额: $ 122.6万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0936599&HistoricalAwards=false
• 关键词: NEESR; CR; Multi; Scale; Mechanistic

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This award is an outcome of the NSF 09-524 program solicitation "George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)" competition and includes Texas A&M University in College Station, Texas (lead institution), The University of Texas in Austin, Texas (subaward), Lafayette College in Easton, Pennsylvania (subaward), and Texas A&M University in Galveston, Texas (subaward). This project will utilize the NEES equipment site at the University of Minnesota.Steel moment frames are widely used for seismic-resistant building construction throughout the United States and in many other parts of the world. Although steel moment frames were studied extensively following the 1994 Northridge, California, earthquake, one critical technical issue remains unsolved: the role of the panel zone in steel moment frame joints (beam to column connections). Recent U.S. building codes have significantly increased the required strength of panel zones in steel moment frames. To satisfy these requirements, column sizes must be increased or doubler plates must be welded to the column, resulting in increased cost, sometimes substantially so. However, there is significant experimental evidence that moment frame joints with weak panel zones show highly ductile performance, and consistently achieve large interstory drift angles under cyclic loading without strength degradation. There is also analytical evidence suggesting excellent overall seismic performance can be achieved by moment frames with weak panel zones. This strongly suggests that current building codes have adopted an incorrect approach to panel zone design, needlessly increasing the cost of construction while potentially degrading seismic performance. The overall goal of this research is to resolve the question: how much panel zone participation should be permitted in evaluating the inelastic seismic response of a steel moment frame? Despite a number of past studies on this issue, there are sharply conflicting views of how panel zones should be treated in design, both within the research community as well as within the building regulatory community. At the crux of the disagreements are concerns regarding fracture induced by panel zone yielding. There appears to be broad agreement that panel zone yielding is a highly ductile process. However, there is broad disagreement on the role that panel zone yielding plays in joint fracture. To address these concerns will require the fundamental capability to predict fracture at joints with weak panel zones subject to seismic loading. Thus, the intellectual merit and a key objective of this research is to advance the state of the art in predicting cyclic rupture within critical ductile components of steel building structures, and to apply this knowledge to the problem of the panel zone in steel moment frames. To meet these goals, this research project will integrate (1) fundamental studies on cyclic rupture of steel components combined with high resolution finite element simulations of beam-column joints,(2) advanced frame simulation studies, (3) large-scale experimental studies conducted at the NEES equipment at the University of Minnesota, and (4) parametric computational studies on joint performance. With respect to broader impacts, the knowledge gained from this research is expected to impact design practice and building codes for seismic-resistant steel moment frames. The project team will conduct a professional development program for high school science and mathematics teachers to create and deliver web-based instructional materials to bring concepts of earthquake engineering-related problems into the classroom. Data from this project will be archived and made available to the public through the NEES data repository.

该奖项由2009年美国复苏和再投资法案(公法111-5)资助。该奖项是NSF 09-524项目征集“小乔治·E·布朗地震工程模拟网络(NEES)研究(NEESR)”竞赛的结果，包括德克萨斯州A&A&M大学(主要机构)、德克萨斯州奥斯汀的德克萨斯大学(分奖项)、宾夕法尼亚州伊斯顿的拉斐特学院(分奖项)和德克萨斯州加尔维斯顿的德克萨斯A&M大学(分奖项)。该项目将利用明尼苏达大学的NEES设备现场。钢结构弯矩框架广泛用于美国和世界许多其他地区的抗震建筑建设。尽管1994年加州北岭地震后，钢框架得到了广泛的研究，但有一个关键的技术问题仍然没有得到解决：板区在钢框架节点(梁柱连接)中的作用。美国最近的建筑规范大幅提高了钢框架中板区的强度要求。为了满足这些要求，柱尺寸必须增加，或者必须在柱上焊接双倍板，从而导致成本增加，有时甚至是相当大的增加。然而，有重要的试验证据表明，带有薄弱板区的弯矩框架节点具有很高的延性性能，在反复荷载作用下，在不降低强度的情况下，可以一致地获得较大的层间倾角。也有分析证据表明，带有薄弱板区的弯矩框架可以获得良好的整体抗震性能。这强烈表明，目前的建筑规范采用了不正确的板区设计方法，不必要地增加了建筑成本，同时可能会降低抗震性能。这项研究的总体目标是解决这样一个问题：在评估钢框架的非弹性地震反应时，应允许多少节点区域参与？尽管过去对这一问题进行了多项研究，但无论是在研究界还是在建筑监管机构内部，对于如何在设计中处理嵌板区域，都存在着严重的分歧。分歧的症结在于对板区屈服引起的断裂的担忧。人们似乎普遍认为，板区屈服是一个高度延展性的过程。然而，对于板区屈服在关节骨折中所起的作用，存在着广泛的分歧。要解决这些问题，将需要基本的能力来预测在地震荷载作用下具有薄弱板区的接缝处的断裂。因此，这项研究的学术价值和一个关键目标是提高预测钢建筑结构关键延性构件内循环断裂的技术水平，并将这一知识应用于钢框架中的板区问题。为了实现这些目标，本研究项目将结合(1)钢构件循环断裂的基础研究和梁柱节点的高分辨率有限元模拟，(2)高级框架模拟研究，(3)在明尼苏达大学NEES设备上进行的大规模试验研究，以及(4)节点性能的参数计算研究。在更广泛的影响方面，从这项研究中获得的知识预计将对抗震钢框架的设计实践和建筑规范产生影响。该项目团队将为高中科学和数学教师开展一项专业发展计划，以创建和提供基于网络的教学材料，将与地震工程相关的问题的概念带入课堂。该项目的数据将被存档，并通过NEES数据库向公众提供。