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These settings pertain to the interpretation and application of provisions from the National Building Code (NBC).
Importance Category
This input appears in both Beam and Column mode Load Input view and in the Concept mode toolbar.
It allows you to input the importance category for the structure and applies the appropriate ultimate limit states and serviceability states factors to live, wind, snow, and earthquake loads. The dropdown shows the Ultimate limit state factor for the load currently selected, however the category applies to all loads input, and in Concept Mode, to all members in the structure.
This selection can be saved as default for new member files and is saved for each member file. It can be applied to Concept Mode The default value is Normal.
Part 9 Snow Loads
For structures meeting the requirements of Part 9 of the NBC, many users design using Part 4 but with snow loads specified using Part 9, In this case, the importance factor is 1.0 for serviceability (deflection) rather than the 0.9 Part 4 importance factor shown in O86 Table 5.2.3.2. For this reason there is an Importance category called Normal, Part 9 snow. When this is selected, the factors are the same as for the Normal importance category, except that for snow loads are selected the serviceability limit state (SLS) factor is rather than 0.9.
Live and Snow Loads on Exterior Surface
To comply with NBC 4.1.5.5, a setting allows you to specify that a live load is on an exterior surface, so that is is not included in load combinations with snow loads. This is used to model a member supporting a surface such as a roof terrace or parking area, that can be expected to have direct live and snow loading.
To model a situation such as a member supporting a balcony with both live loads or snow loads, and an interior space with occupancy live loads, you place separate live loads on the interior space and balcony, and activate this option for the balcony load.
When the setting is checked for all live loads on a member, the program will omit those combinations that have both live (L, Ls or Lf) loads and snow (S) loads. If the program would ordinarily create combinations with L + S together but not separately, then the L-only or S-only combination is created.
Refer to the sections under Canadian Load Combinations for the precise load combinations created when this setting is checked.
In Concept Mode, those members on the roof level of the structure have this property set to “true”. For those on other levels of the building, it is “false”.
This option can be saved as default for new member files and is saved for each member file. The default value is that it is not checked.
Live Storage Loads
A dropdown box called Live Storage load due to... dropdown allows you to specify the source of loads with type Live storage: either Storage and equipment or Liquids in tanks. This input appears in both Beam and Column mode Load Input view and in the Concept mode toolbar.
If Storage and equipment is selected,Sizer will use the load factors given in NBC 4.1.3.2.(7) and NBC Table 4.1.3.4, Note 2; if Liquids in tanks is selected it will use the factors in NBC 4.1.3.2.(7) and NBC Table 4.1.3.4, Note 2 for storage and equipment. For both cases, it uses load duration factor typical of permanent loads (0.65).
This selection applies to all loads on the member, it is not possible to create storage and equipment loads and liquids in tanks loads on the same member. In Concept mode, all live storage loads on the structure are either storage and equipment loads and liquids in tanks loads, according to the setting when the Design button is pressed.
This option can be saved as default for new member files and is saved for each member file.
Refer to Live Storage Load Combinations for more information.
Total Deflection for CLT
An data group allows you to input the information needed to implement O86 A8.5.2, which applies a creep factor to long-term deflection for CLT panels. There are two inputs:
Creep Factor
You input the Kcreep factor from A8.5.2. which defaults to the 2.0 specified in the O86. It is applied to deflections due to long-term loads, that is dead loads, dead loads due to soil, live storage loads, hydrostatic loads, and the "sustained" portion of occupancy live loads.
Sustained Percentage of Live Loads
You specify a percentage of occupancy live loads that are considered to be long-term for this purpose. This is to comply with NBC 4.1.3.4.(5) , which defines a transient portion Ls and sustained portion Ls, and says that the sustained portion must be included in the calculation of any creep factor required by listed standards. These sustained live loads are due to furniture, fixtures, etc.
Please due not confuse Sizer's Ls symbol for Live storage loads with the symbol Ls in the NBC for the sustained portion of live loads. All of the Live storage load is included automatically among the loads subject to the creep factor. Live storage is included when checking the permanent deflection limits and has a long-term duration factor KD = 0.65. On the other hand, the percentage of live loads that is sustained applies only to creep, not to permanent deflection limits, and has a standard-term KD factor of 1.00.