ABSTRACT
The interstate highway 35W (I-35W) bridge over the Mississippi river in Minneapolis, Minnesota, collapsed within a matter of seconds at 6:05 p.m. on August 1, 2007. The 508m long bridge with the 8 traffic lane fell into the water, resulting in 13 fatalities, 145 injuries, and 111 vehicles involved in the collapse (see Fig. 8.1). In the worldwide, this type of steel truss bridge has been commonly used for middle-to-long spans that carry heavy loads (Yamamoto et al., 1988). Until the accident occurred, steel truss bridges had made the solid reputation of being reliable and economical (Astaneh-Asl, 2008; Li et al., 2008). However, many scientists were often induced to focus significant attention on reliability and safety for bridge design after I-35W bridge failure. In particular,
apparent evidence relevant to this bridge failure was pointing toward gusset plates (see U-10 panel point in Fig. 8.1(b)), which were vulnerable to buckling and fracture, as the initial event in the collapse sequence (Holt & Hartmann, 2008; NTSB, 2008; Liao et al., 2011) Therefore, adequate gusset plate design has been requested for the prevention of relapse, including safety assessment. Ordinarily, the gusset plates that connect chord members to compression diagonals and tension diagonals are designed to be stronger than the truss members, and thus shall not control the capacity of the structure.
