Interstate Bank Building Fire;
BUILDING DESCRIPTION
The First Interstate Bank building,
the tallest in the city (and the state of California),
is located at the intersection of Wilshire Boulevard
and Hope Street in downtown Los Angeles. It was built
in 1973, one year before a high-rise sprinkler ordinance
went into effect, and had sprinkler protection only
in the basement, garage, and underground pedestrian
tunnel. The 62-story tower measures 124 feet by 184
feet (22,816 sq. ft.). It contains approximately 17,500
net square feet of office space per floor, built around
a central core. It is occupied primarily by the headquarters
of the bank corporation with several floors occupied
by other tenants. Approximately 4,000 people work
in the building.
The tower contains four main stairways (numbered
5, 5-A, 6, and 6-A in the 12th-floor plan in Appendix
A). Stairs 6 and 6-A are enclosed within a common
shaft, and stairway 5-A has a pressurized vestibule
separating each floor with the stair shaft. Each stairway
contains a combination standpipe with a pressure reducing
valve at each landing. The building is topped with
a helicopter landing pad.
The building has a structural steel frame, protected
by a sprayed-on protective coating, with steel floor
pans and lightweight concrete The exterior curtain
walls are glass and aluminum. |
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A complete automatic sprinkler system costing $3.5 million
was being installed in the building at the time of the fire.
The installation was not required by codes at the time the
owners decided to provide increased fire protection for
the building. The project was approximately 90 percent complete,
with work in progress at the time of the incident. The piping
and sprinkler heads had been installed throughout the five
fire floors and connected to the standpipe supply. However,
a decision had been made to activate the system only on
completion of the entire project, when connections would
be made to the fire alarm systems, so the valves controlling
the sprinklers on completed floors were closed.
Interstatebank Sschematic Floor Plan
The 262 m high, 62-story office tower was the tallest building
built in Los Angeles, USA, in 1973. The tower was known
as the UCB building until 1981, when United California Bank
changed its name to First Interstate Bank. The tower was
renamed 707 Wilshire Tower in 1996 and became Aon Center
in 2003.
The tower has a structural steel frame with lightweight
concrete slab on profiled steel deck. A typical floor measures
37.8 m by 56.1 m, providing about 1,626 m2 of
tenant area per floor around a central service core which
contains the lift and staircase shafts. The external cladding
system was made of glass and aluminium
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