Royal Plaza Hotel Collapse
Thailand
Group 24
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Summary on Collapse
Collapsed on Fri 13th August 1993 in
less than 10 seconds
 379 people in the Hotel were buried,
137 killed and 227 badly injured
 Collapse was compare to that of a
demolition with the use of explosives

Structural History

Original building, constructed in 1983, was
3 stories high with 1 underground level
 Original use was as a massage parlour,
changed to a hotel in 1985
 Building was modified in 1990, adding 3
extra stories
 Soil bearing strength was measured, but
no foundation or column strengthening
carried out
Unusual Collapse
Most buildings collapse during or
just after construction
 Royal Plaza collapse 3 years after
modifications
 There were no extreme
environmental factors, e.g.,
earthquakes or floods
 No misuse of the building

Investigation Tests

Concrete Stress Test - Concrete
compressive strength was between 1015MPa, within reliability limits
 Rebar Tests - Rebar samples found to
conform to standards
 Soil Bearing Capacity - Soil able to carry
loads even after modification
 Process of elimination - creep deformation
in columns cause of collapse
Investigation Findings




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Original structure adequately overdesigned
with a large Factor Of Safety, explaining
delay in collapse
Additional floors added to dead and live
loads, reducing original margins for safety
to zero
Columns carrying dead loads at 70-80%
capacity, causing micro-cracks
When one column close to failure, its loads
would be redistributed to the others
Called “Progressive Failure” as a collapse
of one column leads to the rest failing
Lessons learned

Outlooks changed: Buildings that
withstood construction without collapse
were not only in danger in events of
misuse or environmental disaster

Change in practices: Buildings could not
be constructed with saving money over
people’s safety as a priority any more
Procedures Implemented
All buildings that were under
suspicion of lacking safety in the
country were reviewed. 218 were
renovated as a result.
 All engineers were required to
register with a newly established
Council of Engineers and their work
was more closely monitored

Thank you!

Questions…