WR1

ofcourse expansion joint means 2 different buildings with 2 different behaviour...nothing connecting between 2 except foundation (raft).... model them separately....model the foundation together in SAFE...but you have to export/import properly...and renumber all the points in SAFE for one of the 2 models...(I did it for 4 buildings..just think how many points were threre ) but anyway i was asked to do this sophisticated stuff...but i would recommend you not go for the extreme modelling and keep things simple... model each part separately in ETABS and then export to SAFE separately ... foundations for columns or walls coming on expansion joints can be analyzed by other techniques...by engineering judgement or by doing only 1 set of col/wall foundation on expansion joint and replicating it...

see ubc 97 definition for column and wall

welcome dabbar!

interesting and most common... you have more reinforcement at upper columns because less axial force and more moment....so more eccentricity...more reinforcement while columns below have less moment and more axial force...as compared with the top columns meaning less eccentricity so less reinforcement from where more moment is coming on top columns? solve a portal frame 2 bay by 3 stories!

Dear members, I have recently published several topics on my structural blog. I would recommend you to read them. In order to avoid the duplication and originality of the posts, I am not copying pasting the post here. Just click on the link to read the original posts. 1) Automating the process of calculations (making pdfs) in ETABS 2) Professional Management Tools 3) Printing drawings in the order of drawing list 4) Reviewing multiple CAD drawings titles Do provide me with your suggestions and tips to improve and tell me which one of them you find most useful.

after so many associates..i think i should also open my own firm too..what about Rana Waseem associates hahaha

no waqar...you can sing the song..but at the same time can increase the stiffness of your building...to reduce drifts....it will be a good combo!

this is not exactly a thumb rule...its written in code commentary of ASCE 7-05 chapter CC3 or 2 i think... building drift should fulfill this requirement unless you are sure that the building is more ductile and can satisfy other limits for example H/200 etc... but remember this one check only for wind and the wind is service is here... you need to satisfy inter stroey drifts too for wind..and you can consider the limit to be 10mm similary you need to satisfy seismic drift of 0.025 or 0.020 and also the vertical and horizontal irregularities of the building in seismic design... close your eyes and just sing a song

first...if there is something physically present in model...so should take its self weight in DEAD with multiplier = 1.0 for example shear walls, slabs, beams, columns, braces etc... if you have non structural partition walls such as 4.5 in masonry walls...i would prefer to apply line load according to the plan by drawing a null line on slab and then apply line load lb/ft,,,also when i say null line...i does not mean NULL line as in ETABS....i would define a beam of lets say 1in by 1in and call it dummy or something...and use this line if you have other non structural partition walls, such as wooden or gypsum walls shown on architectural plans then apply uniformly distributed load on slabs for example 20psf...

waqar...thats a nice question....i would like to add that after reading what Ayesha posted...do think about the difference between an inverted and dropped beam design in ETABS....if facing difficulties post it here

thanks.... so the Smax will give the stressed area but for economical design we should use M11 and M22..noted where as M12 should be added to both M11 and M22 according to wood-armer rule...(noted) Now these out of plane moments are M11 and M22 ...both out of plane but if i want to design it as column how to convert these 2 out of plane moments to one? because in column we have major moment (in-plane) and minor moment (out of plane) From my understanding We need to analyse first by taking vertical load with M11 and then vertical laod with M22....right? For out of plane shears V13 and V23 i think we should use Vmax which is equal to SRSS of V13 and V23 and then multiplied by 1.5 for its parabolic nature... For in - plane shear...we should use F12....and for torsion we should use...in-plane shear and out of plane shear on plan section multiplied by their lever arms and taking their differences..right? Now the question arises how to calculate in-plane moment?

Hi guyz! How would you design a concrete inclined wall? in ETABS we cannot assign piers to inclined walls..So the other way i think is to use moment contours...but how to design by moment contours? A wall has 2 out of plane bending moments, 2 out of plane shear components, 1 in plane shear and moment...so if i think to solve this in PCA column as a column then how to convert 2 out of plane bending moments and shears into 1 out of plane bending moment of column? Do I have to use Mmax and Mmin in ETABS or just M11 and M22...Please suggest!

i did not receive email from you..can you send it again?

Yeah i was thinking abt it too...i will start putting tags for previous posts too...its the best way to appear in search

just look at the pictures posted by you, its evident that in ETABS you did not specify the end offsets. In ETABS (look at the moment diagram) moments are reported at the face of support. In your example moment of beam is reported at the face of column, while in sap to the centerline of column. If you want to compare then in ETABS select the lines and make their offsets = 0 Please upload the models too, so I can check it.

if its converged then no need to check anything...if not then re-ietrate by putting more number of ietrations for p delta

to calculate story stiffness without etabs...then calculate manually the stiffness and displacement of all the elments to calculate story strength use response plots of shear force in display menu

This is a secret in etabs....good question....export your story displacements and story shears in excel and use the relationship to find out story stiffness

thanks for sharing!

OUT OF PLANE stiffness reduction results in more sway because in dynamic analysis we assume that we have rigid diaphragm supported by flexible columns this rigid diaphragm is rigid "in-plane" thats why at any point we will get same sway what i was talking about was not for MEMBRANE (where out of plane stiffness is zero) i was talking about SHELL element which has significant out of plane stiffness....and this out of plane bending causes outrigger action or frame action which causes changes in stiffness and hence the lateral sway if you include shell in your model it will stiffen the building due to this effect now if you decrease the shell stiffness (out of plane) ofcouse its lateral sway will increase... on the other hand if you are talking about membrane only (classical) dynamic approach we dont take this effect...

bearing walls means ...wall carrying load in axial direction ....masonry or concrete doesnt matter....if there is a wall carrying vertical load its a bearing wall... like shear wall carries shear....bearing wall carries load too... what will you if a wall carries both shear and vertical load?

apart from strength design...how would you check your serviceability without cracking (without modifiers)?

i said for "out-of plane" modifiers for slab....not for "in-plane"

update: 19.02.2014 Read about equilibrium nd compatibility torsion. You have to determine which case you have, if it is equilibrium torsion you cannot releaee torsion so your modifier will be 1.0 like in a cantilever slab or hollow core slab supporting beams because if you will release torsion it will redistribute to slab and as in equilibrium torsion there is no redistribution possible so you cant release torsion. But in case of compatibility torsion you can release torsion and it will redistribute. Si you can make its modifier equal to 0.35 but uf you make it 0.01 make sure there is no excess cracking in slab and you design slab for increased moments...thats why code does not explicitly tells u abt torsion modifier because it depends on case to case. Value of equilibrium torsion is not affected by the modifier so always apply 0.1 or 0.35 or whatever for torsion modifier whatever the case is.

Seismic engg is based on human exp from previous damage done to buildings....they studied abt collapse and improved codes so not study the latest one. All the basics are also given in IBC but u r rite too..i my self started with ubc....