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Load combinations used for column design are the same, as used for concrete frame design. For the designs conforming to ACI 318-08 or ACI 318-11, relevant load combinations are available in chapter 9 of the relevant code. However, for the concrete column designs compliant to ACI 318-14, the applicable load combinations have been provided in chapter 5 of the code. Regards.

I agree with Umar. Normally, we provide a uniform minimum thickness of mat everywhere, except under columns carrying heavier loads, and requiring larger mat thickness due to punching shear requirements. Moreover, You may model you mat in SAFE (and possibly in other foundation design software as well), providing different mat thicknesses at desired locations. Regards.

Mhdhamood, The situation is quiet common. You can thicken up portions of mat where required. Detailing that I have seen provided a 45 degree angle where the transition is happening, but nothing is stopping you to provide what you drew. Make sure your analytical model represents what you plan to provide and all possible limit states are checked. Thanks.

You got the appropriate advise.

There is also an option to design composite sections in ETABS 2013 and 15. You can read ETABS composite design manual from help menu for more information. Or you can use CSi column to design composite sections.

batoul, In case you follow American Design codes for your designs, you may use following references, among others: 1. Specifications regarding design of composite members are given in Section I of Part 16 in AISC Steel Construction Manual, 14e, 2011. 2. Several examples of design of composite members (including composite columns), have been provided in Chapter I of AISC Design Examples version 14.1, that can be downloaded FREE OF COST from the AISC website, using following link: http://www.aisc.org/WorkArea/showcontent.aspx?id=33520 3. 'Structural steel design' book (5e) by McCormac has a complete chapter on composite columns, besides a chapter on composite beams. Regards.

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.

Dear members, does the footings are effected by wind and earthquake loadings?it is said that the wind and earthquake doesn't effect the footings but the superstructure.

in my experience with normal gravity loads..here in saudi arabia! even zone 2A (UBC Seismic Zone) makes footing size approx more than double of the original (gravity loads). This is because you need self weight to resist uplift for wind pressure and earthquake. Reinforcement is also changed and often you have to do non linear uplift analysis for these cases. Footings are ofcouse desgined for earthquake and wind reactions to support structures. Otherwise the building may overturn due to uplift, soil liquefaction and other things.

Every load experienced by superstructure has to be transferred to foundation, where else it can go? One of the important factor in earthquake cases is the soiltype : you cannot put isolated foundation on the soil susceptible to liquefaction. Having said that, Earthquake/wind loads may not have same influence on every structure, depends on type of structure and also construction material. Footing dimensions under the structure with huge gravity loads have lesser effect due to earthquake or wind loads: if soil is not susceptible to liquefaction.