Failure of Welded Steel Connections and Members: A Forensic Engineering Case Study

The connections of structural steel framing members are a critical component of building safety and stability. Connection failures occur when the connection is no longer able to perform its intended design function of transferring the reactions from one element of the structure to another. In some circumstances the failure of a connection in structural systems which have no redundancy may result in an overall catastrophic collapse of the structure itself. In the event of a weld failure, it is imperative to follow proper forensic engineering procedures. The implementation of repair procedures, without investigating and determining the actual cause, simply masks the problem and will not reduce the risk of repeated failures in the future. This could be detrimental to the safety and stability of the whole structure. In a recent construction project of a thirty story high rise building, weld cracks were observed on both shop and field welded connections and members. Some cracks appeared months after the testing and inspection agency had certified these welds as acceptable. In addition, the failures occurred in connections and elements that were significantly dissimilar from one another. This paper examines the forensic engineering analysis procedures used in determining the causes of the various weld failures, the procedures to repair them, and how to avoid the recurrence of additional failures.