Evaluation of Reinforced Steel Moment Connections

1994年1月的北岭地震对钢抗矩框架的梁柱连接造成了前所未有的破坏。失效主要发生在标准焊接法兰-螺栓腹板型钢弯矩连接中。这些故障反映了非延性行为，并对当前的设计方法和标准提出了严重的问题。本项目所进行的研究将对加强型弯矩连接的性能进行实验评估。将研究两种加固方案。两者都涉及在连接处增加加强板。加强板大大增加了连接的抗弯能力，同时降低了梁翼缘焊缝的应力水平。较低的焊缝应力将显著降低连接对焊接质量的敏感性。这种增强连接细节在过去有限的测试中显示出了良好的性能。然而，需要对这些细节进行额外的大规模验证，并将由本研究项目提供。大多数试验将使用具有高屈服强度和高屈服与抗拉强度比的梁钢进行，以便对加固连接进行严格的测试。然而，一些试验也将使用屈服和抗拉强度屈服值控制较低的梁钢进行。这些试验将证明钢的强度特性在观察到的连接失效中所起的作用，并研究通过控制钢的材料特性来改善连接性能的可能性。该测试项目的结果将为结构工程师和建筑规范官员提供急需的数据，这些工程师和建筑规范官员参与设计新的钢弯矩框架，以及修复或改造现有的钢弯矩框架。这是北岭地震项目。＊＊＊

9416287 Engelhardt The January 1994 Northridge Earthquake caused unprecedented damage at beam-to-column connections in steel moment resisting frames. The failures occurred largely at the standard welded flange - bolted web type of steel moment connection. These failures reflected nonductile behavior, and has raised serious questions on current methods and standards of design. The research undertaken in this project will experimentally evaluate the performance of reinforced moment connections. Two reinforcing schemes will be investigated. Both involve the addition of reinforcing plates at the connection. The reinforcing plates substantially increase the flexural capacity of the connection, and at the same time, reduce stress levels on the beam flange welds. The lower weld stresses will significantly reduce the sensitivity of the connection to welding quality. Such reinforced connection details have shown promising performance in limited past tests. However additional large scale verification of these details is needed, and will be provided by this research project. Most tests will be conducted using beam steels with high yield strength and high yield to tensile strength ratio, in order to provide a severe test of the reinforced connections. However, some tests will also be conducted using beam steels with a controlled low value of yield and yield to tensile strengths. These tests will demonstrate the role of steel strength characteristics in the observed connection failures, and investigate the possibility of improved connection performance through control of steel material properties. The results of this testing program will provide urgently needed data for structural engineers and building code officials involved with design of new steel moment frames, as well as the repair or retrofit of existing steel moment frames. This is a Northridge Earthquake project. ***