This document serves as tutorial to show the RAM Elements tool for wind loads generation on members (open structure).
Open the “45.00m-height electrical tower.retx” model. The structure is formed by A36 steel equal leg angles for all segments and elements in the tower. The configuration is typical for electrical transmission towers.
3D model Lateral view
All support bases are assumed to be pinned for the four-legged tower.
Gravitational loads are assumed as follows:
Imposed load considered as dead loads:
The referenced model has been created with the previous loads. This example is focused on assigning the wind loads using the wind loads generation tool for members.
Lateral loads to apply:
The model already has several design and service load combinations based upon ASCE 7-16 code.
Note. The tower dimensions are used to fill the geometry of the building. These field are defined in ASCE/SEI 7-16, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, chapter 26 and chapter 27, Directional Procedure, Part 1.
Note. The previous data is defined in ASCE/SEI 7-16, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, chapter 26 and chapter 27, Directional Procedure, Part 1.
Note. The data used in this group is defined in the Australian Standard AS/NZS 1170.2-2011, Structural design actions, Part 2: Wind actions, section 5 and Appendix E for exposed structural members.
The wind load is calculated using the following expression:
Load = qz * G * Cfig * Width
qz is the velocity pressure evaluated using ASCE/SEI 7-16, Chapter 26.
G is the gust-effect factor determined from ASCE/SEI 7-16.
Cfig is the aerodynamic shape factor evaluated using the AS/NZS 1170.2-2011 criteria.
Width is the member face width against the wind.
2. Select the desired members to assign wind loads using the tool. For this example, select all the members in the tower model since the tool can assign wind loads at once for the whole selection for one wind direction.
3. Select the Members > Loads on members spreadsheet.
4. On the Spreadsheet ribbon tab, select the Assign wind loads tool in the Active spreadsheet tools group.
The dialog to assign Wind load on members opens.
Wind loads on horizontal members
Wind loads on vertical members
Wind loads on diagonal members
Wind loads on all tower loads
Then select the Wind loads option for a desired load condition: