Evaluation of Column Cracking in Steel Moment Frames

点击翻译按钮获取中文摘要

9416112 Roeder Cracking has been noted on approximately 50 steel frame buildings as a result of the Northridge Earthquake. Considerable concerns have been expressed about the welding practice and procedures used on these structures. These welding concerns are clearly well placed, but it is unlikely that these are the sole source of the steel frame cracking. The progression of cracking into the steel column and panel zone suggest that factors in addition to the welds affect the process. At the same time, there have been changes in the professional practice and seismic design codes for steel moment frames during the past 10 years. This research project will determine if the recent changes in seismic design practice have combined with welds and contributed to the cracking problem. The research will examine the cause of cracking and possible solutions. A subcontract to the consulting firm of Brandow and Johnston will be involved in this study to provide design drawings, detailed advice, practical insight and information on the damaged buildings. Three buildings will be selected for investigation. A series of global elastic and inelastic analysis of the structures will be performed using the best available information for the shaking experienced by the buildings. Detailed elastic and nonlinear analysis of critical areas will be used to examine the weak links, the sequence of yield and cracking and the estimated resistance of the critical components. The effect of alternate design provisions to the UBC provisions would be predicted and examined. A limited series of experiments examining weld effects will be performed, and the experiments will be correlated to the analytical results. This is a Northridge Earthquake project. ***