WR1

33% pressure increase is not allowed regardless of the soil type for example according to UBC-97 service combinations. If there is an allowance it should be clearly mentioned by the geo tech engineer/report.

Why are you still using SAFE 8. The latest is SAFE 2016. In ver 8, negative means (tension) and positive means (compression). After ver 8, it is opposite.

Dear Tufail, Please read the forum rules regarding copyrighted material. We at SEFP do not recommend, promote or give away copyrighted material. Thanks.

My point here is different. Walls are also designed as flexural members like columns. Aspect ratio is a guide line. Cols and walls however are reinforced differently but my main point is different regarding modelling. You can do an example in a 3d model try replacing a line element with shell element of same size and check how much latetal force both are resisting (compare their base reactions).

Provide L/3 that would be conservative. There is no moment in longer direction, there is no deflection, for suspended slab, it is not exposed to temperature difference, and nothing is restraining the slab opposite faces (if for example on brick walls), so nothing is required in my opinion. L/3 will be conservative. If the slab is monolithic with beams and beams are much stiffer, then that little degree of restraint (like point restraint) should also be okay by providing L/3.

Can't say. It depends on design, if it is required, it is required. Some times site people are not happy to see such numbers from a design engineer. It is a good observation but you need to consult the design engineer for further guidance.

and for long term deflection and for increasing inertia and for moment reversal and in short spans.

You guys scared the hell out of him. No one can read that many books. Dear Hassan, just pick one book and get the max out of it.

what about 200x600 column? This is just the geometrical constraint as in UBC or other codes. Usually I do it as wall; 1. if it is more than 1500mm + the above geometrical constraint. 2. if analysis is for lateral loads. If you have huge number of such elements, it will make huge difference for lateral loads (just check the % of lateral resisting load). This is because for walls, there are multiple points of support (moment from couple). If you want to model it as wall and want to act like a column then just put one point support, then the only difference between shell and line will be 4% difference of stiffness due to poisson's ratio (negligible).

That's not what I meant. Please share with us, the results from both analyses of a specific column at the same location, with design load combinations used for them.

share the snap shot of result of a specific column or wall here.

No, my point was to highlight the above statement. He is using the word 'or'. What I understood is; 1) They will use at least 3 inch scraping the surface and using new bars without hilti epoxy (kidding?) 2) Use of epoxy

1.3ld if there is tension in the column otherwise use compression ld which is equal to 20db.

Opted for 3" without using epoxy resins? Thats not possible. I assume there are no dowel bars exposed from existing column with length equal to 1.3ld. You cant just roughen 3" and put new bars if there are no existing dowel bars there. How could that be possible?

He must be kidding for one inch. In such cases you go with resins e.g. from hilti, and the drilling length is calculated from their manuals/softwares. It will be around 5 inches or more atleast, depending on conc strength, fy, thickness of materials etc.

Interesting. Yes. But what about shrinkage specially when they are not yet backfilled. And what about the uplift issues?

You will not get same results in both software. In ETABS you are assuming cracking and applying certain modifiers, where as in SAFE cracking analysis is done internally based on required or provided reinforcement iterations.

It's up to you to decide which type you intend to use (ductility) and then design accordingly.

It will be okay for earthquake. Because all american codes share same philosophy. Load factors and combinations are same. Its not okay for wind design and as from ACI 318-11 wind is changed to strength level.

This is not the right place to discuss/seek consultancy advice/design of a complete structure, in fact it is dangerous. Please hire a professional structural engineer to properly check and design it.

Yes, but my post was, how to do this in ETABS 9.7 if some one doesnt have v13.

You or someone else, need to design the form work for that load and make sure the slab sustains its self weight and construction live load.

Could you please provide a sketch to be more clear? You can do this by clicking on the button just above the 'Submit Reply', the button is 'Insert other media'.

If it is directly resting above mat foundation, then yes, all the loads (ground slab+backfill+dead+live) should be used to calculate bearing capacity.