UmarMakhzumi

@baz has explained this well and quiet lucidly (like always). I will just add that for truss, since all your forces would be axial (compression or tension), the governing limit state would be failure of individual members for max axial load + moment due to eccentricity of gusset plate (unless its a section where gusset goes in between like 2L - double angles). Overall moment capacity of a truss isn't considered as all forces are axial but you can consider the couple to estimate equivalent moment resistance like he said. Thanks.

Raft design is no different from that of a slab! Its infact an inverted slab. Thanks.

Read my signature!

Its given in ACI 351.3R, Figure 3.13. Please see the following forum topics. The lower one (Pile Design For Machine Foundation) has a full blown tutorial attached too. Thanks.

I do them manually. Generally, the geotech report outlines how to do it and then you need to do a structural check considering piles as a beam column. To determine lateral capacity of pile, LPile is generally used. Thanks.

What you have stated is provisionally correct. All, I am asking you is to compare your Staad Pro results with a ETABS results. The reason being that E is used in a lot of places, and we might not be fully aware of the implications of this method. Once you have done the comparison (let it be a very high level), you have done due diligence on your end. You will at-least have a basis to compare your results too. Thanks.

That is not correct. Your span is not big. You can do a simple waffle or one way. For one way slab just add more beams and divide your length into smaller panels. You can also do a post-tensioned flat slab as long as you can design it and there is an experienced contractor who can execute the job. Thanks.

Ahmed, So you will have to enter modifier shear modulus manually. For the above mode, you need to define at least 3 materiel properties. One for Beams (0.5*E), one for slabs(0.25*E) and one for columns and shear walls (0.7*E). I totally agree with Rana that tweaking modulus of elasticity is not a wise thing to do, but you can at least give it a shot and do a quick comparison with ETABS to see how off your results are. Your understanding is not correct. When you change E, everything for that material would be based on modified E, not original E. Thanks.

Make sure you also change your shear modulus (when you change your E) to have consistency. Thanks.

You are welcome

W.Salaam, I think the number of locations might be as per meshing for CSI Safe. I might be wrong here but when I use RISA3D, it allows me to select number of locations along where length where I want results to be reported. Normally, I choose 100 locations along beam length. Irrespective of that, the softwares report results along the length of the beam. The question is that how does SAFE define "end", "middle" and "start" regions? Like if you have 100 reporting points along a beam length, would 100/3 in the middle be reported as "middle", and other 2/3rd as "end" and "start". You will need to look up SAFE software manual for that. Let me know if the above makes sense to you or not. I will be happy to answer any follow up questions. Thanks.

More information: http://www.bbc.com/news/world-asia-36059487

Here is an updated infographic that I came across today. Looks like failure occurred due to lateral torsional buckling. The girders compression flange lacked support. Interestingly, this is the second failure I have seen within an year caused by lack of compression flange support. You can read about the other one below: This photograph from March shows the three twisted girders that caused all the problems. (Supplied) Thanks.

Hi Samiullah, I will try to answer your question but I don't have access to SAFE. So I might ask you some questions to get a better understanding of the problem. How many locations along the beam does SAFE report the results? Thanks.

Sohaib, You can do a RAFT foundation supported on piles that can support your building columns. In order to design the piles you need to ask geotechnical consultant to provide you with skin friction values that can be used to do the geotechnical design of pile. Once that is done, you need to do structural design of pile. Pile design is fairly simple. You can do driven steel or concrete piles based on geotech recommendation. For the slab, 44' by 66' is not a big span. You can design it using Safe. You provide beams to reduce the slab thickness. Thanks.

Read more: http://www.bbc.com/news/world-asia-36009407 Thanks.

All, I am thinking about changing the member rank system. The current system is show below. Please have a look and provide your suggestions. Thanks.

AQ, Can't just have a cantilevered truss from the end of two columns. You need to make a space frame(or huge piers) and connect your truss members like shown in the attachments. Concept.pdf ; Truss Connection.pdf Hope it helps. Thanks.

Wind loads are applied slightly differently. I would advise you to see a text book to see an example. Thanks.

All, I have updated the settings to allow Linkedin, Microsoft Live and Google emails to be used to register to the forum. Thanks.

Normally in Canada, it would have initiated an Request for Information asking the design office to look into it. Construction would have been on hold. The construction practice in South Asia is horrible.

Normally sensitivity analysis is done till you hit convergence; that is any further mesh refinement doesn't increases the result by an acceptable margin. That margin is again dependent on firm practice, local experience and judgement. It is true that stress would go higher as you refine your mesh but also the circle would become smaller and smaller. If your stresses are within 5-10% of allowable, you should be good. If the max stress is higher than that, you should change your design to have it in that range. Let me know how it goes. Thanks.

You should get significant reduction but it depends how many shear walls you add and what is the length of each shear wall. If you just add one shear wall, it might not help, if you add two small shear walls the affect might be small, if you add reasonable sized shear walls, then the reduction would be significant. Thanks.

It depends upon kind of framing. Assuming that floor height is 3m, the total height of the building would be 3m * 20 = 60 m. Based on H/200 limit, the max deflection limit, I get 60,000 mm / 200 = 300 mm, so the deflection probably makes sense although its a big number. The deflection should reduce drastically after adding shear walls. I can't comment on that. You should do a manual check (basic load development) to see what the software is giving you is correct. Perhaps you can ask that expert to tell where you were wrong as I don't know what you modeled. Thanks.

It depends what is the source of the load. For example if the concentrated load is due to an equipment, the realistic basis would be to see the footprint of the equipment and divide the load over that area. The question about strip width is always tricky. Certain firms have their own design preferences too and its varies a lot from firm to firm. I normally discuss this with my checker of If I am the checker I discuss it with the engineer and we both agree to some common interpretation. Ask you checker/ engineer and agree upon something. I wouldn't get stresses over size of mesh. Reasonable size mesh (that doesn't hurt your analysis time) would provide conservative results. The finer your mesh gets, the finer the stress contours become (because of better stress averaging). You can do some sensitivity runs to be more confident on what to use. Thanks.