Wind Load Generation - IS 875 (Part 3): 2015 dialog
Used to automatically generate both wind load definition and wind load cases per the IS 875 (Part 3) : 2015 code.
Opens when the Load Generation
group on the Loading ribbon tab.
- The wind profile for the loading is calculated based on Y ordinate set to 0 rather than lowest point of the building. Thus, the topographical factor (k3) may not be relevant and should be applied with caution.
- Only Y-up models may be used (that is, the SET Z UP command may not be used).
- The resulting wind load intensity vs. height values generated for IS 875 (Part 3) : 2015 are in metric, regardless of the current input units.
- The dynamic effect of wind load is not considered.
- Cl. 188.8.131.52 and Annex B for changes in terrain categories (Table 3 Fetch and Developed Height Relationships) are not considered.
- For rectangular buildings, the frictional drag per Cl. 7.4.1 is not considered.
- For free standing walls and hoarding type structures, the check for oblique wind loads per Cl. 184.108.40.206 is not considered.
- For lattice tower structures, the corner wind effect on square lattice towers with flat-sided members per Cl. 220.127.116.11(b) is not considered.
Wind Profile tab
The calculated wind intensity values (speeds and pressures) are tabulated and graphically plotted as the input parameters are updated. The calculated values are per Cl. 7.2 of IS 875 (Part 3) and the minimum pressure, pd ≥ 0.7×pz, is also considered.
Wind Load Data tab - Rectangular Clad Building
|Building Dimensions||By default, the dimensions are calculated based on the minimum and maximum global coordinates of the structure along the X, Z, and Y global axes, respectively. You may also type the Length Along X (Lx), Length Along Z (Lz), and Height (H) dimension values.|
|Coefficients||Select the option for evaluating the coefficient factor. The associated
table with the selection is made active.
External Pressure Coefficient (Cpe)
Force Coefficient (Cf)
There are four method of assignments for the generated load cases:
Wind Load Data - Unclad Frame Building
|Number of Frames||Select the number of frames in the structure along the wind direction.|
|Wind Direction||Select the wind direction for this load definition and load case.|
|Frame Information||Select the method for specifying the frame spacing:
|Force Coefficient||A separate table is listed for each frame in the structure. Select the frame
number to display that table's values.
The intermediate values along with the calculated values are displayed in the table.
You must specify the Solidity Ratio (Φ) at each height interval of the structure in each frame table. For multiple frames, you must also specify the Effective Solidity Ratio (Φe) at each height interval for frames No. 2 and higher.
If the Custom option is selected, then you must specify the Force Coefficient (Cf) values at each height interval. For multiple frames in the Custom option, you must also specify the Shielding Factor at each height interval for frames No. 2 and higher.
There are three method of assignments for the generated load cases: