1. Royal Plaza Hotel, Thailand
Presentation 27th Oct 2006

2. 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

3. 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

4. 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

5. 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

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

7. 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)

8. 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

9. End of presentation
Sum up
Any questions?