L'Ambiance Plaza Collapse Bridgeport, Connecticut April 23, 1987 Group 15 David Conneely Jonathan Heney David Misstear Roisin Smith Background 16-storey residential project in Bridgeport, Connecticut ‘Lift slab’ system used for floors Hydraulic lifting apparatus used to put slabs into position At time of collapse, the building was a little over half complete Collapse of one slab triggered collapse of whole building 28 workmen killed Building Layout Possible Technical Factors Contributing to the Disaster Overloading of lifting jacks Floor slabs placed incorrectly Post-tensioned tendons arranged incorrectly Substandard welding Inadequate shear walls Hydraulic Lifting Assembly (L'Ambiance Plaza Collapse, Martin R., 1994) Human and Managerial Factors Contributing to the Disaster Gross negligence on part of management Sloppy practices (e.g. placing concrete in sub-zero temperatures) Corners cut to save money (e.g. crushed rock used instead of hard surfaces for temporary structures) Building regulations not sufficient for innovative ‘lift slab’ method Lessons to be Learnt Responsibility for each aspect of a project as well as overall venture should be clearly allocated Construction should be constantly monitored by qualified engineers - frequent and adequate testing The lateral stability of a structure under construction using the “Lift Slab Method” should be ensured: temporary bracing, cribbing, sway bracing The Building Authorities should set aside adequate resources to approve building designs and to send independent engineers to check progress.