Wall Frame Structural System

Is there any special provision of defining shear wall  in wall frame structural system as in such a structural system 25 %  lateral load is resisted by frame and 75% of lateral load is resisted by shear wall?

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  • What you can do in RAM Frame is set the diaphragm type to Pseudo-Flexible and then attribute 25% of the story force to the moment frames and 75% of the force to the walls (loads menu - Pseudo Flexible Diaphragm Properties...). For more tips on pseudo-flexible diaphragms , see: 



  • Just a clarification: Note that the requirement is that the moment frames be designed for at least 25% of the force; it does not say that the walls only need to be designed for 75% of the force. So the appropriate approach is to the perform the analysis and look at the shear to each group of walls and frames. For each group of walls determined the % of the force that they are taking, at each level. The walls almost certainly take more than 75% of the total, and they must be designed for that. Then assign the diaphragms to be pseudo-flexible, and assign those % that you calculated to the walls. Also, assign percentages to the moment frames such that their total % is 25%. The result of this will be that the total is more than 100%, but that is the correct approach. The walls need to be designed for the shear they will attract (which will be more than 75% of the total), and the moment frames need to be designed for 25% of the total shear.

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  • Just a clarification: Note that the requirement is that the moment frames be designed for at least 25% of the force; it does not say that the walls only need to be designed for 75% of the force. So the appropriate approach is to the perform the analysis and look at the shear to each group of walls and frames. For each group of walls determined the % of the force that they are taking, at each level. The walls almost certainly take more than 75% of the total, and they must be designed for that. Then assign the diaphragms to be pseudo-flexible, and assign those % that you calculated to the walls. Also, assign percentages to the moment frames such that their total % is 25%. The result of this will be that the total is more than 100%, but that is the correct approach. The walls need to be designed for the shear they will attract (which will be more than 75% of the total), and the moment frames need to be designed for 25% of the total shear.

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