Diaphragm Basics - The Analysis of Irregular Shaped Structures - page 72

disrupted member force to the outer supports by simple beam action. The supports for
the simple span transfer diaphragm occur at grid lines A and C. The propped cantile-
ver transfer diaphragm has the disrupted chord or strut force applied at the end of the
cantilever at grid line C, which causes the transfer diaphragm to act as a propped can-
tilever beam. The supports for this transfer diaphragm occur at grid lines A and B.
Transfer diaphragms are thoroughly covered in Chap. 3.
Figure 2.39 shows the condition where a discontinuous interior shear wall is sup-
ported by the floor diaphragm below. The main diaphragm in this case is the transfer
diaphragm which prevents the upper shear wall from sliding off of the diaphragm and
transfers the lateral force of the discontinuous wall into the shear walls below. A beam
is required to support the discontinuous shear wall and must be designed for overturn-
ing forces applied from the shear wall in addition to the gravity loads. The beam is also
used as the collector and must extend across the full depth of the diaphragm in order to
uniformly distribute the force into the diaphragm.
It is important to call out and fully detail all struts, collectors, and their nailing
requirements on the drawings; otherwise, the system may not be installed in accordance
with the intent of the design. An example of why this is important can be seen in Fig. 2.40.
F i g u r e 2.40 Special collector nailing issues.