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Wa-alaiku-assalam! Here are a few start points: 1. ACI 318-08 sections 11.11.6 and 13.4 deal with openings in slabs. Openings in structural diaphragms are discussed in section 21.11. 2. Effect of openings in slabs on shear strength, has been elaborated in chapter 16 (Page 16-11) of PCA Notes on ACI 318. Whereas, effect of openings on flexural strength has been explained in chapter 18 (pages 18-6 to 18-8) of PCA Notes. 3. Have a look at the following documents: a. https://www.structurepoint.org/publication/pdf/PCA-Concrete-Floor-Slab-Openings.pdf b. http://cement.org/buildings/tech_note_floor_openings.pdf c. http://mak.ac.ug/documents/Makfiles/aet2011/Tayebwa.pdf d. https://pure.ltu.se/ws/files/30966569/LTU-EX-05200-SE.pdf 4. You may model a slab in SAFE software and experiment by providing openings of different size, and at different locations (with respect to slab edges), to see effect on variation of stresses around the openings, in order to decide the amount and placement of required reinforcement. Regards.

Mhdhamood, For both cases, the factor with E is 1.0. It wouldn't make any difference. Thanks.

From the figure that you have provided, you can check if torsional irregularity exist at certain level. The torsional irregularity exists when the maximum story drift at a corner including accidental torsion, is more than 1.2 times the average of the drifts at the corresponding corners. Accidental torsion is related to the minimum eccentricity between center of mass and center rigidity that must be considered at each level.

Strength design load combinations should be used to calculate the drift. Analysis should take into the account the reduction of stiffness of structural members, as well as, the effect the effect of gravity load acting on deformed shape ( second order analysis). You can check the drift only against against E. The difference is negligible for most of the structural configurations.

Salam Alaikom fellow Engineers! I have found the "The Seismic Performance of RC Frame Buildings with Masonry Infill Walls" article very useful. So I would like to share it with you, especially for junior structure design engineers. Regards The Seismic Performance of RC Frame Buildings with Masonry Infill Walls.pdf