Double Tee Connections with Larry Keenan

Presentation Abstract

Flange connections of precast concrete double-tee parking structures are poorly configured to withstand high-cycle vehicular loading and fail to meet Code requirements for fatigue resistant design. Connection failures typically spread along the joint until the joint is completely severed. While commonly considered a maintenance item or nuisance, these connections are an essential part of the lateral load resisting system; loss of connections along a joint severs the deck diaphragm and threatens the general stability of the structure. Testing and analysis recently performed by the precast industry purport to allay concerns regarding these connections; however, careful review of these studies reveals the common, modern connection exacerbates the fatigue failure mechanism by concentrating stress at the ends of the welded connection. This presentation explores the fatigue failure mechanism as it applies to double-tee connections and explains how fatigue failures are easily identified in the field. Code requirements for high-cycle fatigue…