Diaphragms With End Horizontal Offsets - The Analysis of Irregular Shaped Structures - page 124

Example 3.3: Single Notched Diaphragm, Analysis in the Longitudinal Direction, Offset
Shear Walls
The diaphragm shown in Fig. 3.23 is the same layout as that in Example 3.2, except that
shear walls are placed along grid lines A, B, and C. Normally, interior shear walls act
as supports for the diaphragm, which creates a diaphragm boundary. Code requires
that drag struts/collectors, vertical lateral-force-resisting elements, or any combination
thereof must occur along the entire length of a diaphragm boundary. To comply
with this requirement for the shear wall at grid line B, a collector would have to extend
from the end of the shear wall to grid line 4. Assuming that this can be accomplished,
the loads to the individual wall lines can be distributed to each shear wall on a
tributary width basis. However, the installation of the collector is impractical because the
collector would be over 100 ft in length and would be very difficult to construct if the
joists or trusses were oriented in a direction perpendicular to the collector. A solution
to the problem is to design the shear walls along grid lines B and C to act as though
they are in the same line of lateral force resistance. Since the offset of the walls causes
F i g u r e 3.23 Single notched diaphragm, analysis in the longitudinal direction, offset shear walls.