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Important Note – These are descriptions to changes implemented in WoodWorks Shearwalls for version 10.0 and may not reflect current behavior
The program implements the change in ASCE 7 of the ASD wind factor to 0.6 from 1.0; it retains the 1.0 wind load combination factor for deflection, which is now the strength-level factor in ASCE 7; it no longer allows input of different load combination factors than those in ASCE 7, and it shows in the output the load factors used for deflection design.
ASCE 7 and IBC now have an Allowable Stress Design (ASD) wind load factor of 0.6, rather than the previous 1.0, see ASCE 7 2.4.1. This change is in conjunction with new wind speed maps with higher wind speeds intended for strength-level design.
The new 0.6 factor is ow applied to forces used for shearwall design, hold-down selection, and drag strut forces. It is indicated in the program as follows
Loads as shown on screen and in Loads tables in output remain unfactored. The shearline forces are the forces used for shear wall design are factored by 0.6 when the loads are distributed to the lines.
The 0.6 factor has been added to the load combination shown in the plan view legend.
Beneath the Wind Shear Load table in the output, a note has been added to indicate that the loads are unfactored and the 0.6 factor is later applied to forces, similar to the note that appears for seismic loads.
The wind uplift loads you enter are considered to be unfactored. When creating hold-downs, the 0.6 factor is applied to the wind uplift component of the combined hold-down force.
The word Unfactored has been added to the description of uplift loads in the plan view legend.
Beneath the Wind Shear Load table in the output, a note has been added to indicate that the loads are unfactored and the 0.6 factor is later applied to forces, similar to the note that appears for seismic loads
The wind shear overturning component of hold-down forces is derived from the shearline force factored by 0.6. The 0.6 factor is applied to uplift wind loads when hold-down forces are made. The elevation view legend now shows the 0.6 factor for uplift component of hold-down forces instead of 1.0. The hold-down forces for deflection analysis adjust this to use strength-level factors for the hold-down displacement component.
In the hold-down design table, the legend on indicates the wind shear overturning and uplift force components are factored by 0.6
The loads that appear on the plan view and elevation view screen are unfactored; those that are used for design and appear in the Design Results output are factored. The word “unfactored” has been added to the presentation of these loads in plan view and elevation view.
The program continues to apply a 1.0 wind load combination factor for deflection. This represents a change in that previously the strength-level factor for wind design was 1.6, and now it is 1.0, so that the program previously applied ASD combinations for deflection analysis for wind loads, but now applies strength-level factors.
This change makes wind design consistent with seismic design, and with the assumption of strength-level displacements that are to be used when hold-downs are made.
This factor is indicated in the program as follows:
The 0.6 ASD shearline force factor is adjusted to the 1.0 strength level factor for deflection analysis. This force is shown only in the Deflection table of the output. The legend to the table now indicates the force v is the strength level force, and is the ASD force / 0.6.
The Uplift Force (P) shown in the Hold-down Displacement table is derived from wind shear and wind uplift forces factored by 1.0 for strength level analysis. The legend now indicates that they are strength level forces, but no longer says they are “unfactored” as there is a dead load factor of 1.2.
Upon opening files that have generated wind loads created with versions of ASCE 7 prior to 2010, and/or user input loads that were created with version 9 or before, the program prompts you with an explanation of the wind load changes, and an opportunity to adjust all your generated loads by a factor of 1.0 / 0.6 or to delete all the loads for future regeneration.
It is no longer possible to change the dead load and seismic load combination factors via the design setting. These factors are mandated by the ASCE 7 and IBC design standards are not modified by local building codes, so there is no reason for user control of these values.
Load Combinations Output
Despite the fact that they have been removed as a design setting, for informational purposes the load combination factors remain in the Design Setting table. This table now shows the strength-level load combinations used for deflection analysis alongside the ASD combinations used for shearwall design, whereas previously only the ASD combinations were shown.
Seismic Load Combinations in Hold-down Displacement Table
The legend to the Hold-down displacement table no longer says that the load combinations used are “Unfactored”, as the dead load component does have a factor of 1.2.