|
|
|
|
|
Deflection Load Combinations from IBC 1604.3
Use L + 0.5D for deflection (Note d)
When this check box is checked then, for dry service conditions, the deflections for the load combinations D + L, D + Lr, and D + L + Lr are calculated with the dead load component multiplied by 1.0 for CLT and 0.5 for all other materials. This load combination is the short-term live load plus the creep component of dead load.
The live roof Lr load type is mentioned in the note, but not in the table heading.
All other load combinations, such as D + 0.75 (L + S), remain unchanged; the full dead load is used for deflections in those combinations. The reaction, shear, and bending are not affected for any load combination.
Note d also says that for wet service conditions, 1.0 D is used, however, sizer does not implement this note for wet service conditions and the check box is disabled in this case.
The program renames the setting to Use L+ 1.0 D when CLT is selected.
Note d says that this provision is not to be used in conjunction with long term loading from NDS 3.5.2, so if this box is checked, the creep factor option is disabled for long term loading (see below). Note that the dead load, including creep, for long term deflection is 1.5 D for dry service conditions and 2.0 D for wet service and CLT, so this checkbox offers you a choice of designing for long-term deflection or designing for short term deflection + dead load creep.
This setting can be saved as default for new member files, and is saved for each member file. The original default value is that it is checked.
- .42W for C&C loads
This implements IBC Table 1604.3 Note f, which says that C&C wind loads can be factored by 0.42, rather than the usual 0.6. This entails an additional factor of 0.7. Essentially by checking this you are saying that the wind loads on the member are component and cladding loads. When the setting is checked, the deflections for all load combinations containing a wind component are calculated with a 0.7 factor multiplied by the factor(s) that are currently applied to the wind component (0.6 wind factor multiplied by either 0.75 or 1 factor for combination with other non-dead loads).
This setting does not apply to Concept mode, because Concept Mode’s structural members are assumed to be part of the main wind force resisting system with respect to any vertical wind loads that are placed on the building, and Concept does not handle horizontal wind loads
This setting cannot be saved as default for new member files, but is saved for each member file. The factory default value is that it is unchecked.
Construction Loads
All live Loads are Construction Loads
To allow for construction loads (duration factor 1.25) which are a variety of live loads (duration factor 1.0) in terms of load combinations in ASCE 7-05 2.4. a checkbox indicates all live loads are construction loads. It is it impossible to model construction loads and occupancy live loads simultaneously, except for roof live loads.
This setting can be saved as default for new member files and saved for each member file. The default value is that it is not checked.
All Roof live Loads are Construction Loads
NDS Commentary C2.3.2 indicates that it is conventional practice to consider a roof live load as a construction load for which the 1.25 load duration factor applies, so it is in fact necessary to allow both construction roof live loads and occupancy live loads on the structure at the same time.
Sizer therefore has a check box "All roof live loads are construction loads" which allows roof live loads to be treated as construction loads even when live loads on other parts of the structure are not.
This setting can be saved as default for new member files and saved for each member file. The default value is that it is not checked.
Long Term Factor from NDS 3.5.2
This setting allows you to apply a creep factor according to NDS 3.5.2 to the dead load component of total deflection. It applies to all load combinations except the counteracting uplift combination .6D + W.
This setting can be saved as default for new member files, and is saved for each member file. The default value depends on the service conditions set in Beam view -the user default for dry conditions, 2.0 for wet conditions. The factory default is to apply a 1.5 factor for dry conditions.
Load Duration factors
Set the load factors for each type that apply to your jurisdiction. The default values are those recommended in NDS Table 2.3.2.
This setting can be saved as default for new member files, and is saved for each member file.
Restore Original Options
For those items that can be saved as default for new files, to restore the original default values that came with Sizer, press Reset original options,