Royal Plaza Hotel, Thailand Presentation 27th Oct 2006

Background Collapse of Hotel Building occurred on Fri 13th August 1993 From initial failure to total collapse < 10 seconds 379 people in the Hotel buried, 137 killed and 227 badly injured This incident led to a major investigation in Thailand

Structural Background The structure originally designed to be 3 above ground (+ 1 underground) stories high Structure was modified in 1990 with the addition of 3 extra floors No record of added column or foundation strength being added during modifications Soil bearing capacity was tested This did not take into account the fact the load bearing structure within the building itself was insufficient to carry additional loading

An uncommon collapse Most building collapses occur during or just after construction In the Plaza Hotel case collapse happened 3 yrs after major modifications!! Most building collapses after a long period of use were caused by unexpected forces of nature (earthquakes floods, etc) This was not the case in this situation

Findings of the Investigation Addition of 3 floors of dead and live loads over the same set of columns reduced original F.O.S to almost zero The extent to which the original structure would have been over engineered may explain the delay between modifications and final failure Columns carried dead load of 70-80% of strength capacity, leading to development of microcracks which in turn lead to creep deformation “Progressive Failure” – failure of 1 column increased load on the other columns, causing sudden failure

Tests Conducted Tests of concrete Strength- no deficiency, compressive strength 10-15 Mpa Test of Rebars-conformed to standards Soil Test-bearing capacity sufficient for foundation even after the modification

Lessons learned The desire for profit from investors lead to poor safety standards being enforced Engineers work need to be closely scrutinised and checked by independent consultants during design and construction When a doctor makes a mistake, he kills one; when an engineer makes a mistake, he kills many (AIT Thailand)

Remedial measures taken Safety Review undertaken by Thailand universities, of more than 218 buildings Professional Engineers registration more tightly controlled Setting up of Indemnity insurance system Design of public buildings must be cross-checked and jointly reviewed by third-party engineer

End of presentation Sum up Any questions?