Notes on Design Of Steel Parking Structures Including Seismic Effects 2001

The need for multi-story parking structures has grown considerably over the years and will
continue to grow as metropolitan densities increase. There are several key issues, which need to
be addressed in the design of multi-story parking structures. They are:
1. Site considerations, environmental and neighborhood impacts and traffic access
2. Number of parking spaces, car circulations, ramps and other architectural aspects
3. Security and safety
4. Structural aspects (particularly in highly seismic areas, seismic design aspects)
5. Cost and speed of construction
6. Life cycle cost of maintenance
7. Fire resistance and/or need for fireproofing.
The first three items in the above list, to great extent, are impacted by the decisions of
architects. Items 4 to 6 in above list, also are impacted by architectural aspects, however, these
three items are primarily impacted by the structural design and decisions made by the structural
engineers. Today, structural steel provides viable systems that address the above key issues. In
the past, a large percentage of parking structures throughout the country were designed and built
using reinforced concrete structures. However, since 1980’s in many regions of the US including
seismic areas such as California, more and more steel parking structures have been designed and
built. According to Emile Troup (1989), nearly three out of every five car parks for which
contracts were awarded in 1987 in New England were steel. He attributes this increase in use of
steel structures in open parking structures to the fact that as a result of research and testing done
in 1970’s the issue of fire-proofing of steel structures in car parks was put to rest and the use of
“unprotected steel“ in parking structures was accepted (Troup, 1989). Because of extensive
research and testing of bare steel structures subjected to fire, the fire codes no longer have very
stringent requirement for fire protection of steel car parking structures. This development, along
with education and dissemination of information on viability and economy of using steel structures
in car parking, may have been instrumental in visible increase in design and construction of steel
parking structures.
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