m.
Design and Analysis Procedures. Step-by-
buildings. Seismic joint coverage will be flexible
and architecturally acceptable.
step design and analysis procedures are provided for
buildings conforming to Performance Objective 1A
i.
Elements that Connect Buildings. Certain
in Table 4-5, and illustrated in a flow chart in Figure
types of structures commonly found in industrial
4-1. Similar procedures for buildings with enhanced
installations are tied together at or near their tops by
performance objectives, using linear elastic analysis
with the m modification factors, are provided in
connecting parts such as piping, conveyors, and
ducts. The support of these elements will allow for
Table 4-6, and in a flow chart in Figures 4-2 and 4-
the relative movement between buildings.
3.
The nonlinear elastic static procedures for
Performance Objective 3B are described in Table 4-
j.
Bridges Between Buildings. Clusters of
7, and in a flow chart in Figure 4-4.
buildings are often connected by bridges. In most
n.
Nonstructural Participation.
cases it would not be economically feasible to make
For both
bridges sufficiently rigid to force both buildings to
analysis and detailing, the participation effects of
vibrate together. A sliding joint at one or both ends
nonstructural filler walls and stairs must be
of the bridge can usually be installed.
considered.
The nonstructural elements that are
rigidly tied to the structural system can have a
k.
Stairways. Concrete stairways often suffer
substantial
influence
on
the
and
seismic damage because they act like struts between
distribution of earthquake forces. Such elements act
the connected floors. This damage can be avoided
somewhat like shear walls, stiffening the building
by anchoring the stair structure at the upper end and
and causing a reduction in the natural period, and an
providing a slip joint at the lower end of each
increase in the lateral forces and overturning
stairway, or by tying stairways to stairway shear
moments. Any element that is not strong enough to
walls.
resist the forces it attracts will be damaged, and
should be isolated from the lateral-force-resisting
l.
"Short Column" Effects. Whenever the
system. Following are some design considerations to
lateral deflection of any column is restrained, when
minimize damage to nonstructural components, and
full height deflections were assumed in the analysis,
to preclude life safety hazards to the occupancy of
it will carry a larger portion of the lateral forces than
the building.
assumed. In past earthquakes, column failures have
frequently
been
inadvertently
caused
by
the
(1)
Details that allow structural movement
stiffening (shortening) effect of deep spandrels,
without damage to nonstructural elements can be
stairways, partial-height filler walls, or intermediate
provided. Damage to items such as piping, glass,
bracing members. Unless considered in the analysis,
plaster, veneer, and partitions may constitute a major
such stiffening effects will be eliminated by proper
financial loss. To minimize this type of damage,
detailing for adequate isolation at the junction of the
special care in detailing, either to isolate these
column and the resisting elements.
elements or to accommodate the movement, is
required.
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