Load Distribution

Important Note – These are descriptions to changes implemented in WoodWorks Shearwalls for version 9.1 and may not reflect current behavior.

1. Rigid Diaphragm Distribution using Deflection for Low-rise Wind Loads (Bug 2294)

   For ASCE low rise wind loads, rigid diaphragm distribution to shearlines with stiffnesses based on deflection analysis was unreliable, and any design based on it should be re-evaluated.

   For example, because there are no torsional effects for low-rise wind loading, the program should distribute loads equally to two identical lines on a symmetric building; however there is a sharp difference in shearline forces when distributed using deflection.

   When distributed using capacity, the shearline forces were equal as they should be.

   This problem has been corrected.

2. Bi-Directional Seismic Rigid Diaphragm Analysis (Bug 2282)

   The program did not do seismic rigid diaphragm analysis in both force directions, it only analysed east-to-west and south-to-north directions. This became problematic when deflection analysis was added to the program; due to hold-down configuration, stiffness can be different in opposing directions, so that rigid analysis is required in opposing directions.

   Note that direction of force was being considered when distributing shear within the line, based on the stiffness of individual segments, as it should be.

   In Plan view, the seismic shear force was displayed as a bi-directional force, now it is displayed as a directional force (similar to how wind forces are displayed). When you select to display critical forces, the worst-case seismic force on each shearline is now displayed.

3. Wind Uplift Loads over Openings (Bug 2132)

   When a wind uplift load is applied to an entire wall line, the uplift load did not appear over openings in elevation view, and the load over the openings was not distributed to the hold-down forces at the sides of the opening.

4. Restraint force t in Combined Hold-down Forces for Wind vs. Seismic. (Bug 2318)

   For multi-storey structures with a perforated wall on an upper floor containing openings, and offset walls or openings on the floor below, the combined wind hold-down force mistakenly contained the seismic restraint force t from SDPWS 4.3.6.4.3.1 if one existed.

   This effect is usually small and conservatively increases the hold-down force.