Diaphragms With End Horizontal Offsets - The Analysis of Irregular Shaped Structures - page 142

F i g u r e 3.35 Diaphragm notched at both ends.
as that of a single notched diaphragm, with the exception that two transfer diaphragms
are required to transfer the disrupted chord forces. A good example of this condition
can be seen in Fig. 3.35. This configuration is not an ideal lateral-force-resisting system
layout due to a minimal number of vertical lateral-force-resisting elements. Creating a
system with the least number of shear walls possible is generally not good practice.
Adding shear walls in locations similar to the optional layouts shown in Fig. 3.41 adds
redundancy to the system and reduces the shears and forces within the diaphragm to
acceptable limits. Keeping the system simple yet redundant can reduce the demand on
the lateral-force-resisting elements and in many cases reduce construction costs. These
layouts are typically better-performing systems.
Example 3.5: Notch at Both Ends, Analysis in the Transverse Direction, Multiple Chord
Discontinuities (See Fig. 3.35)
The diaphragm in this example is 120 ft long by 50 ft deep. There is a 14 ft horizontal
offset between grid lines 1 and 2 and a 30 ft horizontal offset between grid lines 5 and 6.
Both of these offsets produce a notching effect and a discontinuity in the diaphragm
chords at grid lines 2C and 3B, as shown in Figs. 3.35 and 3.36. A collector at both of
these locations extends into the transfer diaphragms marked TD1 and TD2, where the