![]() Revise your Plans Preparation Manual to require that the qualified independent peer review for category 2 bridge structures include checking and verifying the design calculations used for all nodal forces.To the Florida Department of Transportation: Assist the American Association of State Highway and Transportation Officials with developing a requirement that concrete bridge structures be designed with reasonable estimates for interface shear demand, the cohesion and friction contributions to interface shear capacity, and the clamping force across the interface shear surface.It only analysed the design for the completed structure and not for its various construction phases. Post-collapse, Louis Berger confirmed to NTSB investigators that it analysed the design as one structure in its completed state. Louis Berger performed the independent peer review of Figg’s design using Adina, a finite element analysis software program, in accordance with FDOT standards. Investigators also found that Louis Berger failed to meet FDOT requirements for a peer reviewer to employ at least three registered professional engineers, each with a minimum of five years’ experience in designing complex concrete bridges. In a post-collapse interview, the Louis Berger engineer who conducted the peer review told the NTSB that the agreed budget did not stretch to this level of analysis. The NTSB has also been unequivocal in stating that Louis Berger, as design checker, should have noticed this error. ![]() Post-collapse calculations showed that the load demand on the node was twice that designed. The NTSB has been unequivocal in stating that Figg’s load and capacity calculation errors at this key node probably led to the failure. Investigators have overwhelmingly concluded that the trigger for the collapse was punching shear failure at the node where the end vertical and diagonal truss members met. This triggered the significant cracking which should have given warning that collapse was imminent. This induced unexpected stresses and strains in the structure which were exacerbated when the end diagonal truss member was de-stressed after it was positioned. In the casting yard there was full contact support across the deck and its two ends, yet while resting on the pier the shims were placed either side of the central truss – meaning there was no direct support under the truss location. The FIU bridge in Miami-Dade County was being constructed by Magnum Construction Management (MCM) under a design and build contract when it collapsed.Ī National Transportation Safety Board report into the collapse concluded that design calculation errors made by MCM’s consultant Figg Bridge Engineers were ultimately to blame. But failures by the independent design checker, client, contractor and on-site construction supervisor also contributed to the disaster. The cables were to support a 862t deck post tensioned prestressed concrete deck structure with a bottom flange serving as the walkway and a top flange providing cover from bad weather.Īt time of collapse, the 53m long deck structure had been installed over the main highway, but the back span, spanning over a river, the pylon and the cables were yet to be installed. The bridge was to be cable stayed with one central pylon. ![]() The cable stayed bridge was being built in the city of Sweetwater as a safety measure so that students did not have to cross the busy highway to get to and from its Modesto A. ![]() Three years ago today, the under construction Florida International University (FIU) pedestrian bridge collapsed onto a Florida highway, crushing cars and killing six people and injuring 10 others.
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