Diaphragm Basics - The Analysis of Irregular Shaped Structures - page 65

F i g u r e 2.32 Vertical transfer of chord and strut forces at C.
F i g u r e 2.33 Horizontal offsets.
The photograph in Fig. 2.34 shows an example of the architectural features of a
modern home. The section above the garage door opening has a high sloped cantile-
vered roof with a cantilever length equal to the back span length. The roof back span is
supported off of the end of a second-floor cantilever diaphragm which forms the
ground-level covered entry. The shear wall at the gable end above the garage door is
triangular and has a window opening at the left edge. The two vertical shear wall chords
fall at the end of the second-floor cantilever and near midspan of the portal frame
(garage door opening) wall below. The shear wall is vertically discontinuous to the
foundation. The portal frame was not tested for this type of load. The entire section is
supported by a portal frame, which creates a soft story. The structure is located on the
edge of an escarpment. It also has a steep roof slope that will produce a high wind force