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Hello. I just came to know about this new foundation method known as post tensioned waffle mat slab foundation. Does anyone know how it is designed? If I can get any reference document it be helpful.

I have two questions related to mat footing design in SAFE v16. 1) How to calculate the width of the design strips of mat footing? 2) I imported the model base reactions to Safe but punching shear design is not checked. What can be the possible solutions of the problem?

How to model mat on pile cap on SAFE ? Does anyone have similar experience ?

Dear All, I have recently designed Raft foundation for 6 story building in SAFE. I have 4 feet offset area on site and have already spread the raft upto 4 feet offset edges. The SBC is 17000 lb per sq.ft. I created uplift load cases according ACI-318-08 as shown in the attached picture. After analysis I observe that the uplift pressure is negative but the magnitude exceeds SBC. I watch many tutorials where negative results are considerd safe but I am still confuse whether is it Ok or I should reduce the result. Please match the SAFE results with the mentioned SBC and answer this topic. Thanks in advance.

Assalamu Aalikum, Hi, I am a new member. I have a plot measuring 30*70 feet. Most of houses being built here (in Rawalpindi) have masonry foundations (a pyramid of bricks on PCC or sometimes the PCC layer has three to four iron rods of size 3/8 or 4/8 in this "PCC" layer. I want to make a raft foundation instead of masonry foundation but the cost seems to be high. I want to ask if I make a raft 1 feet thick and put a single mesh of center to center distance 12 inch. Even this will cost more but if it gives more strength then I want to go for this. Would such foundation more durable and strong?

I need help regarding MAT footing design in safe. Please read questions mentioned below and comment if any extra step or correction need to be done. This MAT footing is for 4 storey building in zone 2A and bearing capacity would be more than 1.25 ton/sft. 1) Does we need to increase the bearing capacity by 33% as mentioned in NILSON book for soil pressure calculation or not if we are taking basic load combinations of UBC including earthquake loads not the alternative load combinations. 2) If we want to take reduced live load for footing then is there any way to export in form of reactions from Etabs to safe. In my opinion Etabs does not give Reduced live load reaction, Correct me if I am wrong. 3) When we use the basic load combinations which include earthquake load then there is very localized uplift (due to earthquake combo) when we check soil pressure. is it normal or something wrong with my reactions. If it is normal then we always used non-linear basic combinations to check soil pressure and non-linear design combinations for design of raft? 4) Does it required to check crack width and settlement in case of raft or not. If required then explain in few words. 5) At boundary of raft where there are shear walls/lift core, soil pressure is more than the bearing capacity in these localized regions. what we need to overcome this situation if we cannot increase the area of raft at that side. any additional check which you think important for design then write in comment your help would be appreciated Regards

Dears; The minimum steel ratio =0.0018 is for one face or for the 2 faces of the section (top & bottom)?? As far as I know that 0.0018 is for the face exposed to tension (not the 2 faces). Since the Mat suffers tension at top and bottom of the section at the same section so we provide 0.0018 for 2 faces . Am I right??? Regards

Dear Respected Engineers; I want to make local thickening in a MAT foundation due to failure in Punching . Is there any limitation on the dimensions of this "drop Panel" because in my thought I will make it somewhat longer than the d/2 (after critical path) . For example in my case I have a 1000 mm Mat with cover 100mm then the d/2 = 450 mm, if the column was 15000*300 mm then the minimum width of the local thickening =1200 mm and minimum length=2400 mm . Am I right ? Regards

Dears seniors; I have an urgent issue I need your help all. The issue is that I want to make a MAT like in the picture please see the problem interpretation in the picture.

assalam o alaikum, Dear Seniors, Kindly clarify what is the difference between MAT and FOOTING option in SAFE while defining slab property. Thanks.

when we have raft foundation, is it necessary to draw it as we draw slab or just select all the joints at base level and turning them to fixed support will generate the effect of raft in analysis?