The Analysis of Irregular Shaped Structures: Wood Diaphragms and Shear Walls, Second Edition by R. Terry Malone Scott E. Breneman and Robert W. Rice

Author:R. Terry Malone, Scott E. Breneman and Robert W. Rice
Language: eng
Format: epub
Publisher: McGraw Hill
Published: 2022-08-15T00:00:00+00:00

FIGURE 7.4 Shear transfer options at vertical offset.

One of the reasons an open-front/simple-span diaphragm configuration should not be used is that section 2 would be supported at grid line 3 and assumed to act as a simple support. As such, theoretically, there would be no moment or chord force at grid line 3. The diaphragm chords of each section would then be assumed to act independently. As a minimum, ASCE 7-16 Section 12.1.3 requires that both sections of the diaphragm must be interconnected to prevent separation or tearing at the offset. Because chord continuity is required at the offset, there is no reason to use a cantilever diaphragm approach. Continuity in the diaphragm chords can be accomplished by installing full height vertical transfer walls between grid lines 2 and 3, at both grid lines A and B that extend from the foundation to the upper roof diaphragm with transfer areas located between the offset chords as shown in Figs. 7.5 and 7.6. The walls can be sheathed full height to act as shear walls for longitudinal loading or only in the transfer area to accomplish the chord splice.

The method of distributing the forces into the transfer wall and across the vertical offset shows that the wall area between the upper and lower roof acts more like a transfer area than a transfer diaphragm, where the eccentric chord forces causing rotation of that area are resisted by the columns placed at each end of the wall. Since the columns transfer their forces directly into the foundation, there is no shear in the wall section below the collector. The force at the top of that transfer wall is equal to the accumulated transfer shears into the diaphragm chord from grid lines 1 to 3. The direction of the diaphragm shears being transferred into the chord show that the member is in tension. The chord force applied at the top of the wall is equal to the chord force at the low roof at the vertical offset.

Figure 7.5 shows an elevation of the wall and transfer area under transverse loading (chord action).

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.