UmarMakhzumi

Share the framing plan. We can give you some alternate framing option if we know whats cooking

Salaam Everyone, Just to let you guys know that we have upgraded to the latest version of forum software. Hopefully, you will experience improved functionality. Cheers!

Thanks

Just draw beam from column center to center. I mean don't move beam in the ETABS model so that the face is flushed with the column (that will screw up the model). Draw as you would do normally for any case. Moreover, your curved beam can be drawn by two straight beam segments. Just do it and let me know if you cant. I will draw something in SAP and post here. Thanks

I thought I have beaten Mirza in judgement and harwork. lol Just kidding Sir! Respect for the guys like him. Rare to find.

Waqar, please post an image of what are you modelling? Maybe, that can help understand the situation better. Thanks.

Good firms that I have heard about while working are: Arif Associates, Lahore. (Vetted one of their projects) Rizwan Mirza Associates, Lahore. (Heard about them) Design Men, Islamabad. (Heard) AAA Associates (I dont remember the name exactly) ACES, Rawalpindi (Vetted one of their projects) SMK, Karachi (worked mutually) Mustaq & Bilal, Karachi (Heard)

This is one of the classic failure that provides some insight to what due diligence is required on engineers end. http://en.wikipedia.org/wiki/Quebec_Bridge

There are two way. The first one is to draw a beam based on small straight segments (using continuous condition). The other one is to locate a center and draw a arc like thing. http://www.sepakistan.com/topic/3-etabssap2000-dome-geometry/page__hl__dome may ring some bells.

Salaam Everyone, I would request you all to fill out the Topic Tags box when posting a new topic. See the attached file. It helps list similar thread so that a person can easily locate information on the forum. It is very important. Please uphold the request and use tags as much as you can. Just type things related to your topic and press comma to separate tags. Thanks

You're welcome. You can zip and upload them here. Cheers!

I did a quick manual check. Moment is 195 k-ft consider the 2k load at midspan is a dead load. There is something wrong with the 274kft model input. You can make another model for comparison and just apply UDL loading only to see comparison or point load only to see comparison. Both results should be same as what you manually calculate. Have a look at your reactions.

What re your moments and reactions for both ? Please post images

Thats because you are using stiffness modifiers for beams and columns too that would obviously increase sway. The discussion above is that using only slab modifiers would increase or not increase sway. I am saying it shouldnt. I don t have a frame analysis software at home so AQ check this too !!

Story Force/ Story Displacement for story stiffness and for story strength, I might have an example, I will find it and post it here.

that is a different perspective but "Outrigger action"; is in-plane too & is building mai to koi significance nahin ho ge. Anyhow, I will go through it on weekend to see what potential effects it has!

Modifiers should be used, like I said in my post. Checking serviceablity with or without is only a matter of reducing interia or not due to cracking(depending if your stress in a flexural member increase concrete modulus of rupture). I would suggest using modifiers for all flexural members. Beams, column & beam columns . Anyways, Out of plane modifiers se sway pe kaise effect pare ga Rana ? I actually didnt get it. Did you mean in a different way?

For stiffness modifiers to slabs, If your framing is such that you don't have Stiff Beams (beams normally > 3*Depth of slab), you will see a lot of difference when you apply and don't apply stiffness modifiers. Consider flat plates, where you have thick slabs on periphery beam. Now when you don't apply stiffness modifiers to such a case, you get less moment in you beam as more load is transferred by the slab to the column, and slab is considerably thick and has a reasonable stiffness relative to the beam which is supporting it. For the same case when you apply a modifier, the slab stiffness is reduced and more load in transferred to your beams which are now stiffer than your slab because of the modifier. Why should we use a stiffness modifier? for the above example, a flat plate would have some sort of cracking when subject to seismic loading and because of that the stiffness would be reduced, as a result the beams would be carrying higher load than they were actually supposed to take(considering if the original design was based on no stiffness modification for slab). Thus by using modifiers for this case, a structural engineer is able to consider the effect of heavy loaded beams and designs beams to a greater load. Therefore, using stiffness modifiers where there is a reason can help you design robust structures. What I am trying to say is that for slabs like 4", 5" the difference in moments is very small for the cases with or without modifiers if the beams are deep. Don't worry too much about using modifiers unless you have a condition that demands one. Just, plug your numbers in and do your analysis as for most of the general cases, the difference due to modifiers would be close to nothing as explained above. Every thread I go, people are confused about them. Dont worry that much, just use the default numbers and be cautious of situations like the one explained above where you really need them. @Rana, why did you say that using stiffness modifiers for slab would result in higher sway? Isnt the lateral distribution (for this case) on rigid diaphragm assumption would result into same story force no matter how thick or thin the slab is, which will determine the story sway(considering frame stiffness as constant)..

Thats correct! You can define 4 or 6 cases based on your design theme.

Just use the DL multiplier(0.2SDS) here and your auto load combos would be okay! Do a manual check.. combos should match up

To go by the book, you should consider 0.55CaI(0.2SDs) for 1.32 and 0.9D Cases. If someone is neglecting the clause for 1.32D and they can justify that it is reasonable and effect is least, than you can accept that. But considering in Pakistan, all design is done using softwares, so I don't see any point in missing that unless you are doing stuff manually and want to save calculation time. Make sure, have your loads at default eccentricity because that can effect your results a lot.

The reason that 0.55CaI or vertical component of earthquake is neglected for 1.32D is that it effects are more pronounced with 0.9D load case.This is explicitly stated in ASCE. So you should consider that in 0.9D Load case. I honestly dont remember exactly, but It was like this. Its been years since I last used UBC or ASCE.

Looks alright. Why don't you generate auto load cases for the code that you are interested?

Here are the SDS and SD1 Values for Islamabad, Karachi, Lahore & Peshaware.

What do the local building authorities follow. If you are in Pakistan, you should go with UBC. Its pretty straight up. Make combos as per the article and use EQx and EQy at 5% default eccentricity. If you have an unsymmetrical building, you will end up with 4 earthquake cases. EQx + 5%y EQx - 5%y EQy + 5%x EQy - 5%x I cant open the link in the above post by Rana, so I cant comment on his post. IBC has a supplement, for different countries where they have given the values of SDs and SD1. I will look up at my documents. If I or Baz find it, we will post it.