Presentation 28th Oct 2011 BLANC DALTON HALLIGAN Korat 1983: Massage parlour 1985: Hotel building 13th August 1993 < 10 seconds 379 people buried Major investigation in Thailand 3 above ground stories high 1990 : addition of 3 extra floors No record of added column or foundation Soil bearing capacity was tested But bearing structure was not calculate The Building collapsed in a fashion commonly seen in professional demolition Reduced to a ‘neat stack’ - Suggests building fell under it’s own weight Happened so quickly building had no time to fall sideways All columns were effectively at their limit of load carrying capacity In the 3 years after addition of extra storeys micro-cracks developed in the lower columns This lead to creep deformation whereby some columns became shorter than neighbouring columns As a result there was an uneven distribution of loads between ground floor columns Judging from the mode of failure it can only be concluded that all ground floor columns failed at practically the same time The failure of one column caused a sudden redistribution of loads leading to ‘Progressive Failure’ of all other columns Had the effect of dropping the entire 7000ton mass of the building from 5m The huge impact caused a compressive wave through the upper columns causing all of them to collapse shortly after Assessment of the debris showed the upper columns had buckled due to this compressive wave Ground floor columns had shattered into pieces (inadequate factor of safety) The impact also caused the columns to effectively 'punch through’ other levels Legal action Establishment of Engineering Council Assessment of work practices Improvements/renovation of existing buildings Routine inspections Tighter regulation and enforcement