Moment Frame Connections Revisited: A Fundamental Fracture Mechanics Approach

重新审视力矩框架连接：基本断裂力学方法

• 批准号: 9703864
• 负责人: Wai-Fah Chen
• 金额: $ 19.68万
• 依托单位: Purdue Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9703864&HistoricalAwards=false
• 关键词: Moment; Frame; Connections; Revisited; Fundamental

9703864 Chen The 6.8 magnitude earthquake that shook California's San Fernando Valley on January 17th in 1994, did not cause the collapse of any steel structures but connections, confidently designed and constructed in the past with traditional code simplifications and common site-welding techniques, were discovered no to meet our expectations. This project will study the performance of structures depends on the performance of connections. This will be accomplished by analyzing the fracture strength and toughness of the moment connection. The load effect as determined by a structure's global response, and its performance as controlled by local material properties and geometric configuration will be considered. The interaction and relative importance of horizontal and vertical seismic forces will be evaluated. The effect of composite action (concrete floor-slab on steel girder) and panel zone deformation will be included. Locally, a detailed nonlinear finite element model will provide the stress state information needed to perform a fracture analysis. The fracture strength of the moment connection will consider the effect of reduced toughness in the heat treated region; line and semi-elliptic cracks will be used to simulate weld flaws; stress intensity factors at these locations will quantify the effect these weaknesses have on the ultimate strength of the joint. It has been recognized that the best means to describe the strength performance of structural members, must now be followed by a similar "back to the basics" approach to connection design. Fracture mechanics is proposed to provide that foundation: empirical relationships based upon theoretical analyses will be presented to estimate the ultimate strength resistance of moment connections to seismic loads and brittle fracture ***

9703864 Chen 1994 年 1 月 17 日震撼加利福尼亚州圣费尔南多谷的 6.8 级地震，并未导致任何钢结构倒塌，但过去使用传统规范简化和常见现场焊接技术自信地设计和建造的连接，被发现不符合我们的预期。 该项目将研究结构性能取决于连接性能。 这将通过分析力矩连接的断裂强度和韧性来实现。 将考虑由结构的全局响应确定的载荷效应以及由局部材料属性和几何配置控制的性能。 将评估水平和垂直地震力的相互作用和相对重要性。 将包括复合作用（钢梁上的混凝土楼板）和面板区域变形的影响。 在局部，详细的非线性有限元模型将提供执行断裂分析所需的应力状态信息。 弯矩连接的断裂强度将考虑热处理区域韧性降低的影响；将使用线和半椭圆裂纹来模拟焊接缺陷；这些位置的应力强度因子将量化这些弱点对接头最终强度的影响。 人们已经认识到，描述结构构件强度性能的最佳方法现在必须遵循类似的“回到基础”的连接设计方法。 断裂力学旨在提供这一基础：将提出基于理论分析的经验关系，以估计地震载荷和脆性断裂的力矩连接的极限强度抵抗力***