While the 2000 IBC, Section 1621.3.10.1 essentially indicates
that if the design force and displacement per NFPA 13, when multiplied by a
factor of 1.4, exceeds that determined by the IBC, then the NFPA criteria shall
override that required by the IBC, the more fundamental question in Georgia is
whether the Building Code even requires fire sprinkler piping to be seismically
protected. Once it is established that it would be required, then the applicable
NFPA or IBC seismic design considerations are needed.
2000 IBC, Section
1621.1.1.1 concerns applicability for seismic restraints, and has provisions
that would exempt fire sprinkler components from the architectural, mechanical
& electrical seismic design requirements if the Component Importance Factor
(Ip) is 1.0. Section 1621.1.6 lists these factors, and Life Safety components
that are required to function after an earthquake receive a factor of 1.5.
Life Safety components expected to function after an earthquake in
Georgia would be Fire Walls/Barriers/Doors, Elevator shutdown, Hazardous
Materials containment systems, systems that are part of a Life Safety Evaluation
required by 2000 LSC, Section 12.1.7.3 (i.e. Assembly Occupancies with an
Occupant Load over 6000) in accordance with Section 12.4.1.2, and similar Life
Safety features not dependent on factors outside the control of the Building and
Fire Codes.
Fire sprinkler systems dependent on a water supply, in which
utilities in Georgia have not had to specifically design to withstand seismic
forces, can not be readily expected to function after an earthquake. This would
place fire sprinkler systems in the ‘All other components’ category since they
could not be fully expected, nor thereby required, to function after an
earthquake, and thus the applicable Ip would be 1.0. Since the 2000 IBC, Section
1621.1.1.1 would exempt this component in most cases, plus the fact that due to
the very low probability and low occurrence of earthquakes in Georgia (and the
cost vs. the benefit is not worth it), it basically determines that seismic
bracing on fire sprinkler piping is not required. The 2000 IBC does not
specifically indicate anywhere that a fire sprinkler system is one of the life
safety systems that shall be designed to operate after an earthquake (fire
barriers, haz-mat containment, etc. could and should be). O.C.G.A. indicates
'Fire protection sprinkler system' means an integrated system of overhead and
underground piping designed in accordance with fire protection
engineering standards. The installation includes one or more automatic water
supplies. And if the entire fire protection sprinkler system
is not designed for seismic resistance (i.e. the underground utility water
supply is not seismically designed), nowhere is it said seismically restraining
only a portion is adequate.
Life Safety components that could reasonably
be expected to function after an earthquake, should be and are required to do
so. Fire Barriers and similar Life Safety components could reasonably be
expected to function after an earthquake, for their design is not dependent on
influences outside of the control of the AHJ, owner, designer, etc. Life Safety
systems that depend on an extremely critical influence such as the very water
supply providing the life blood of the sprinkler system, which is not designed
to the same seismic conditions as the system, nor under the control of AHJ,
owner, designer, etc., is a folly at best as the likelihood of this ‘weakest
link’ breaking during the event is similar to that of the system breaking,
making the effort to only seismically restrain the sprinkler piping ‘portion’ of
the system almost worthless, possibly deceptive, with the benefit clearly
outweighing the cost at least as far as Georgia is concerned.
Reductions
in Building construction requirements due to the building being fully
sprinklered are indeed often used. The sprinkler protection provides an
equivalency to the code requirements based upon the potential for a fire, not
for the potential of earthquakes, meteors, riots, plane crashes, etc., and
although these may be the cause of the fire, statistics indicate construction
designed to withstand all possible scenarios is more costly than the derived
benefit. If it is a mild earthquake, small meteor, ineffective riot, or a small
plane that crashes, and then a fire ensues, then the probability is that the
system will survive and perform – larger catastrophes will turn all preparations
into an effort in futility.
States where statistics have indicated the
likelihood, and severity, of an earthquake to be so great, and the loss of life
so insurmountable, have determined the derived benefit outweighs the cost by
many factors. Therefore not only the construction, but the infrastructure, has
been designed to withstand the earthquake influences to the degree of protection
that probability, and cost, have established. Georgia just does not appear to be
one of those states that typically considers earthquake protection to be this
cost effective. However, the 2000 LSC, Section 12.1.7.3 earthquake factor
consideration is an example where the potential for loss of life could be so
great (6000 + people in one area), that Georgia would normally require the
effects of an earthquake be considered in the Life Safety Evaluation, which
could feasibly influence some of the sprinkler trade-offs since the water supply
could not be relied on as readily.
Requiring the sprinkler piping portion
of the system to be seismically restrained does not provide any additional life
safety benefit if the entire ‘system’ (e.g. sprinkler and utility piping) is not
designed likewise, and doing so throughout Georgia is impractical. In the
individual case of seismic restraint of sprinkler piping, per the 2003 IFC,
Section 104.8, the requirement for seismically restraining sprinkler piping due
to earthquakes as required by NFPA 13 (2002), Section 9.3.1.1 is not required.
An exception to this statement would be certain critical occupancies (hospitals,
911 centers, etc.) located in the very small far northern portion of the State
(see seismic maps and the IBC seismic section for more), and of course the 6000+
occupant load large assemblies per the LSC...