Leaderboard

from the pic, your area of allowable bearing capacity violation is large , better not to do average. Though the method of averaging is by importing nodal soil pressure table in excel and take joints avg.

Hi Sir, I am using Sap 18 for analysis. I had a look at assembled joint masses, where I see and located the joints showing -ve masses, but its program calculated and I don't want to alter that. I have not applied any loads to Slab mesh point. What I have done is, I have assigned my equipment pulling load in new Load pattern “L.L-Pull” and didn't added that Load Pattern in my Mass Source. That way I am not having warning for "-ve Mass source". And added that new Load Pattern in my Old Case “L.L” to counter it in member Design.

Here is an example to explain what I mean by general values: If you have a shear wall located on a raft foundation and the only area where you have high stresses is under the shear wall, and the rest of raft has values within the acceptable range, then ignore the high values right under shear wall and focus on more general values or focus on the rest of the foundation. For your case, @Hafsa Azmat has correctly pointed out that averaging wouldn't work or it would be very limited. For example you can average 11 and 10 E3 zones (The purple colored stresses) as that is more of a concentrated zone. Not all of the raft. Hope that helps.

@Ayesha what do you mean by more general values? Please elaborate? actually i need help in this context.

I had an idea i was thinking to share it with any student or teacher. Idea is to compare design, economy and durability (pros and corns) of the steel structure based shelter house, load bearing masonry house and concrete frame structure. Actually these systems are sequential in terms of cost(i think). But a detailed study will really help to introduce economical housing in region. Thanks

no reference it is based on judgement and experience.

performance based seismic design of concrete building

Hello Israr, As madam Ayesha said there are areas of high stress concentration in raft. Could you specify the location where you are getting 10 Kip/ft2. As specified if this pressure is at corners in small concentrations then you can ignore, however if the area is large then need to apply changes to raft design. Thanks.

As far as high-rise design goes, there is always areas of high concentration in a raft. General practice is to ignore them and focus on more general values and see if they are within the allowable limit or not. There is no guideline for stress average. People do it by using their engineering judgement.

@sameersaleem Any reference for this combination...................?