Group 15 Simon Phelan Phillip Barry Simon White Fabien Raoux

 Residential project under construction in Bridgeport Connecticut in  16 storey structure with 3 parking levels and 13 apartment levels.  There were two offset rectangular towers, separated by a construction joint at the central elevator lobby.  The building used the lift-slab method of construction.  Lateral restraint in the structure was provided by shear walls in each of the towers.  On April 27, the incomplete structure was overloaded and collapsed, killing the 28 workers.

 Improper arrangement of post-tensioning tendons in concrete slabs, columns around openings.  Over stressed concrete sections due to open slots left in the slabs to accommodate later casting of shear walls.  The lifting collar design was deemed inadequate as well as the lift slab construction technique  Frame stability and lateral strength was poor due to incomplete and inadequate temporary connections.

Schematic of L’Ambiance Plaza Aftermath

 A two-judge panel mediated a universal settlement between 100 parties closing the L’Ambiance Plaza case. Twenty or more separate parties were found guilty of "widespread negligence, carelessness, sloppy practices, and complacency."  Those injured and the families of those killed in the collapse received $30 million.  Another $7.6 million was set aside to pay for all of the claims and counter claims between the designers and contractors of L’Ambiance Plaza.  This also ended all investigations prematurely, leaving the exact cause of collapse undetermined.

 Responsibility for design was fragmented among so many subcontractors that several design deficiencies went undetected.  Adequate safety factor not implemented for design.  Assumptions that the design engineer made about sequencing were not clearly communicated to those responsible for field operations.

 Appointment of a Construction Manager whose sole purpose is to oversee the various parts of the construction sequence.  A high factor of safety should be provided during construction also, not just once completed.  During all stages of construction, temporary lateral bracing should be provided.  Cribbing (temporary posts which support the concrete slab until it is completely attached to the column) should be used.  Sway bracing (cables which keep the stack of floors from shifting sideways) should be used. This was required, but not used in L’Ambiance Plaza.