WR1

Put the ratio of main mesh as compression/tension. And for fr it is 0.62(f'c)^0.5 as per ACI. It will be half of this value for restrained slabs.

I followed and developed similar approaches but it all varies so much from one project to another.

But the damping is for response spectrum or time history. And converting wind load cases to time history is complex. Better to send for wind tunnel test.

Yes, you need to do stress averaging which is not very straight forward. I do not rely on software stress averaging as it will average the stresses based on the given length. Imagine if stress at localized area is too high (peak), even after the stress averaging you will get higher stress and the extent will also be too much. You need to develop your own rational approach for stress averaging, or need to adjust meshing some times.

You should read the beam design process in ETABS documentation for the desired code. Vp is the shear based on max probable moments at each joint. Vp will be added to gravity shear as ETABS is doing.

What is this related to? Is it the answer to your own question or this what CSI people replied to you? And yes, the clause you are referring to applies to intermediate moment resisting frames, and that is why you define such beams as spandrels when designing for overstrength factors and for this clause so as not to duplicate

By default, design utilization is 95% irrespective of which version you are using. Someone might have changed this to 100% in your older model. Following link should be in your bookmarks; https://www.csiamerica.com/products/etabs/releases I have gone through release notes history and could not find any difference/update to shear wall design for ACI codes in ETABS. If any thing has changed it might be related to code updates and not the version itself.

Do you really think any reputable software would start giving that much difference in results between different versions? I'd like you to go back and try to understand the shear wall design procedures in help menu and update us what did you find in any case. If still you have doubts, we are ready to investigate it further.

I would first check the distribution of shear forces between columns and walls. If columns carry less than 25% and you intend to make it a dual system, increasing the forces through load combinations is inherently a wrong practice. You need to re run the analysis with different stiffness so the analysis yields at least 25% shear in columns. For this thing, never increase load combination factors. Then, I'd use the special seismic combinations with omega factor for discontinuous elements (and with stiffness modification of 1.0) regardless of the system used and percentage of base shear resisted.

Could you be more clear about your question? I could not make any sense to what are you actually asking. Could you rewrite it more clearly for us? And I feel like you don't have any idea about slab design. You can use slab thickness less than the minimum suggested by code provided that you check deflections yourself and they are within limits. Another point, using minimum slab thicknesses by code is no guarantee against deflection as they are independent of load. These L/36 etc. empirical formulas are only good for a starting point in analysis. You have to verify deflections in all cases.

You can easily use an Excel sheet based on above formulas where you can change any variable and see its effect.

Yes, as i said above. But semi-rigid is a must requirement at least here in Dubai. Beside that there are several good reasons for modelling slabs in a model (extensively used and required here); e.g. checking lateral punching for slabs in newer ETABS etc and their design. I agree for simple models with slabs on beams to just transfer the load manually. Doesnt work for complex big models; flat slab systems etc.

Assuming a factor of safety of 1.0 (although in reality, you need to decide what FOS you need to achieve...1.5? 2.0?), the weight needed to hold on to the applied load of 100kg is also 100kg. But there is a moment too at the base which is equal to 100kgx1m = 100kg.m. To stabilize this you need to counter this acting moment with 100kg.m stabilizing moment in the opposite direction. In the figure; acting moment is anti-clock wise: 100kg.m You need 100kg.m in clock wise direction (assuming FOS=1.0) which can only be provided by the weight of support block on the right half x length to the middle of right half of support block. So you need to decide either horizontal or vertical dimension of the block too (not just the weight). Note: although the base is just a free standing weight (not fixed) but the pipe in reality is considered fixed into the block. The way you fix the pipe into block will also effect these calculations; either it is firmly fixed or just inserted into an over sized hole for example. There could be many shortcut formulas but you need to fixed some variables first; for example, let's say that for the support block; a) 75% of x dimension is towards right from the center of the pipe 0.75L b) let's assume that height of the block is twice the length so h = 2L c) let's say the dimension into the paper of block is also L (square block on plan); so now the weight of right side of the block = W = density x 0.75L x 2L x L = density x 1.5L³ Now the stabilizing moment will be; 100xFOS = W x 0.75L/2 i.e. W = 2x100xFOS/0.75L if say FOS = 1.5, density of uniformly solid concrete block = 2500 kg/m³ then formula becomes; L = (4M/3750)^0.25 where M = Load x arm (100x1m = 100kg.m in this example).

I agree for gravity only models. What are your thoughts for lateral load models for omitting slabs? excessive sway, absence of out-of-plane stiffness, absence of in-plane stiffness (specially when rigid diaphragm cannot be applied due to legal/municipality requirements) etc.

Difference of 0.2 in² is nothing. You will not get 100% same results. If error is large, check again for dissimilarities.

You are comparing apples to oranges. Your statement that you are not performing cracked analysis is actually NOT TRUE. 1. There are stiffness modifiers in ETABS for beams, slabs and columns (in other words, you applied cracking in ETABS). However, in your SAFE model, there is no cracking analysis performed or stiffness modifiers applied. 2. The self weight of beams or columns (check which one, I don't remember now) is zero in SAFE (again a mismatch). Create a new load case in both let's say "A" and apply 50psf to compare results. Adjust this and you will get minor but uniform difference between results (in other words, results will be same in ETABS & SAFE).

Design moment is always different than the analysis moment for several reasons e.g. in p-delta effects you magnify the analysis moment. The additional moment in your question above is due to 'Sway Special' (look at the top right corner of image above). Refer to code why this additional moment is required, however, if the frame is not special sway, then change it to ordinary/intermediate in over-writes and this will be solved. Similar are the cases with (where design moment is different than analysis) pattern live load, p-delta etc.

L/36 where L = 58' is a good approximation for choosing two way slab thickness i.e. 20". 6"/8" looks very ambitious and DANGEROUS specially with someone who is asking basic structural questions here. But also not impossible, your can always innovate something.

Not practical in all cases due to legal, design or other issues.

It looks like you have defined them as 'columns'.

Please share the bending moment figure also with values shown. Maybe there is difference in material properties between both models?

What I know and found in few examples of modelling two buildings together is the mode shapes, dynamic properties etc. are misleading. I am not sure about the 'Tower' option (haven't explored in detail), but this is what I observed. The only benefit I see people modelling two towers together is for the ease of 1 joined foundation model (at the expense of wrong analysis results???) Having a joined one foundation of multi-buildings in SAFE is not that difficult from different ETABS models. You just need to play with import-export or macro stuff.

Not able to watch YouTube right now but will check. Are you talking about non-linear EATBS or other software? Because gaps and pounding etc. cannot be visualized atleast in linear version of ETABS. And I fail to understand why to have all this hassle just for seismic pounding? It is very easy to calculate seismic pounding manually that is SRSS of inelastic displacements of both towers. If the heights are different, you calculate at that particular level. Been doing this all the time. Or is there something crucial I am not able to grasp here?

Completely different models. There's no point modelling them in same model.

What reference anyone could ask for? This is common sense. Tell it to your senior (assuming you understood him as you said here).