WR1

L/360 etc are for which load cases? Read that table again carefully!

if it is shell you will apply 0.25 for slabs....as long as you have drifts less than allowable its ok..but what do you mean by deflections slighly more than allowable? where did you find in code which tells about seismic allowable DEFLECTIONS? instead of drifts!

im still waiting for some to ask about over-strength factor..omega in seismic combinations..lets see when our curious young minds...raise this question...(as i said..im waiting for you )

1) goto File>Print Summary and ETABS will report you V = 0.05W something like this....means base shear V = 5% of W where W = effective seismic weight which is equal to the weight you put in mass source in etabs to check W ...after analysis...goto Display>Show Tables...Select all load cases you put in mass source and show Story Shears in tables> goto last story of model....you will see top and bottom of each story just add all load cases P (axial load) at the bottom most story (bottom)...this is equal to your effective seismic weight you put in mass source dialogue box note it down..lets say 1000 kip now similarly show tables and see EQx and EQy in tables at the bottom most story..both values should be equal if your time period and R are same in both load cases..this is your total base shear in x and y...you can see this value from the graph by Display>Show Story Response Plots.. lets say 100 kip So it means your V = 100 kips, W = 1000 kip which means your base shear = 10% of your effective building seismic weight 2) study UBC chapter on seismic design or IBC or ASCE ...you will find what is R...R is response modficication factor of building system...... values of displacements or drifts in ETABS are elastic....but earthquake design goes into in-elastic range...so to convert your elastic displacement value you should first convert it into in-elastic values before checking drifts...(this applies only for seismic design...as wind displacements remain in elastic region) in ASCE or IBC this 0.7R is equal to Cd/I where Cd is amplification factor for drifts in these codes..and I is the importance category... UBC is obselete now....start studying IBC 2006 or 2010...or if possible 2012...you are young generation...follow the latest codes..with background of old codes..I will upload here the 2012 code soon

for all dead cases...selfweight, partitions finishes etc...all

it is based on allowable stress design method 2001 steel code.......still you need to make sure that your auto generated combos are ok

no need to draw the raft in ETABS unless you are doing analysis of a very heavy building where soil interaction effects are critical....even for that its done by springs....

just goto HELP menu and open documentation for lateral analysis manual, there select your desire code...steps are given for each code in ETABS...and how ETABS handles code parameters...

sorry for drifts i replied in your other thread regarding p delta..please check that

Please refere to CSI wikki and search for p-delta they recommend you 1.2D+0.5L reasons is that it covers all the load combinations in ACI chapter 9...(conservatively) for lateral analaysis.. for P (big P) delta..you need to include all gravity loads that are with lateral load combinations.. as lateral loads will sway your frame...and will create some displacement lets say in column...then the column will experience magnified moments because of the P (axial dead loads on colum) so this P multiplied by delta ...create moment M = P.e start with 2 or 3 ietration then aftera analsyis...goto last analysis run log and check if p delta converged or not...if not then increase the number of iterations... please have a look at this manual in this thread...it will clear some of your doubts http://www.sepakistan.com/topic/28-etabs-model-checking-tips-tricks/ for drifts...see this topic on my website or search in this forum: http://www.ranawaseem.com/

you need to make them fixed or pinned...and then export to SAFE and draw there the raft and do analysis in SAFE

there are many reasons for these errors..you should not let it happen for example extrude your model and check if your geometry is okay...some times...1000m is put instead of 1000mm in section properties making very stiff elements with flexible check if out of plane modifiers are applied to membrane check if base is properly restrained...some times like in springs..vertical restraint is provided but not horizontal if your struc is 2d make sure to analyze it in 2d not in 3d in analyze>analysis options menu check if vertical elements are not accidently deleted in mid stories distrubing the load path check if very thin shells are modelled... and so on

if you are designing a concrete structure only..the trick is to use steel or vice versa.. go to option>steel frame design preferences>and select ASD in design code..then goto define>add auto load combos and tick on convert to editable this way you can make auto generated service load combinations you need service combos not only for foundations but also to check wind drift and other serviceability criteria you need these service combos usually in SAFE not in ETABS but its preferrable to add service combos in ETABS too if you are used to check deflections and drifts in ETABS...its upto u use just 4 load cases for earthquake not 6 if you are designing for lahore (seismic) vertical component will be less than 0.2 depending upon the value of Sds...you can ignore it then in ETABS this factor is 0.2 by default in special seismic load combinations dialogue box...this is called DL multiplier in ETABS..by default its 0.2...you have to change it manually..remmeber it for wind...remember this that for drift you need to multiply W by 0.7 to convert it into service level wind for drift (10 year return period..) if you are not using UBC... please search in the forum for these topics..some of these things are already covered..before... good luck

your model looks okay, but following are some of my concerns apply torsion modifier for beams = 0.35 slab modifier are not applied...make them m11=m12=m22=0.25, this will increase your sawy too story8 slab load above grid 6 is not applied story2 and story 8 diaphgram extent misses some external points...look at that make sure your load combination are okay ​wall meshing is missing in your model....mesh them your base-shear is equal to about 5% of seismic weight which seems okay with R=5.5 and UBC 2B seismic zone You dont have to worry about the magnitude as far as you satisify the seismic drift limits of UBC which are 0.025 and 0.020 times story height...based on time period of your building....remember to convert your elastic displacement values to inelastic displacement by mulitplying it to 0.7xR also check the building separation gap, if necessary again, make sure your load combinations are okay! one last thing: incease the column cross section, for 8 storey building in 2B zone, they look smaller...increase the size...to reduce your reinforcement from 3%...make them to 2 or 1.5%.... rest your model is okay apart from above points of concern good luck..keep us updated

For spectral acceleration values you have to consult values from local code in your country If you dont have a local code, you can get values from this site (USGS). ASCE values are based on USGS. https://geohazards.usgs.gov/secure/designmaps/ww/signup.php Just enter your email address and click on SIGN UP button, you must have java in ur pc to run online application. If the page does not load and you have chrome, then just click on SHIELD button in address bar just left to the "STAR" button to bookmark a page. After clicking click on "LOAD ANYWAY" button just enter the long and lat values of the place, To see the long and lat values you can use maps.google.com Alternatively, you can use UBC-97 as baz has mentioned, both are american codes. I would recommend you to read this interesting book about relationship between UBC and other american codes for seismic design. ICBO_UBC-UBC.pdf First the site classification in UBC are same as in IBC For Fa and Fv values see this image For Sds and Sd1 see this and for UBC seismic zones outside, see appendix of UBC code where some of the world cities are mentioned. For example, for Pakistan see the image below

yar...displacement at support (roller) is zero...but displacement at support for spring is not zero....that displacement is inversely proportional to the force applied....for example as sir baz has mentioned in case of foundations... Like if you hang a bar , one end fixed , and some weight on other end..it will elongate under this weight...displacement at fixed support is zero..but displacement or elongation in the the bar it self depends upon stiffness (in axial direction)...now consider that bar is a spring....so the elongation in spring is a function of its stiffness springs are used in foundations, they are used to check displacement in one direction...A fixed support has infinite stiffness so thats why displacement is zero....

well thats not very simple Sir Umar! What I mean is applying automatically wind pressure on shell areas from excel. Well Sajid add me on skype (check my user id from my profile) and lets talk about this.

Just to correct you here (and my self too) that mass source command is used for calculating Center of Mass of the diaphgram. So this option is used even for wind load or any other load where we need these two centers. Pardon for my old post which was a mistake

for your reference i have uploaded my concrete DDM assignment...please look at it..it might help

Please download my assignment in last semester... http://www.4shared.com/office/cJteuxje/DDM_Assignment.html

i did not understand any thing

no we dont take it as uniform load...we take actual load...its triangular or trapezoidal or whatever shape...we take actual load...how can we take it uniform? I am sorry if i did not get your point... but yeah we take this loading (in whatever shape) as distributed over the entire length of beam...(again this is not called uniformly distributed...this called distributed over the entire length)

yeah i checked so whats wrong in that? this is trapezoidal loading from trapezoidal distributary area from slab...solve it by the last figure i attached for you in last post...(but that fig was for one span beam) you can find similar formulas for continuous beams online...or in Reynolds book....in continuous beams chapter....or simply convert the loading to equivalent udl by multiplying it by 1.30 and use moment coefficient method of ACI 8.3....is there any other confusion? tell me

waqar i did not understand your question....yes it is the tributary area of slab which in turn makes loading on beam also triangular or trapezoidal...if the area is triangular (and the load on slab is uniform) then the loading on beam will also will be triangular...sure...and your are mentioning figures 14.1 and fig 14.2 of which edition? 13,14,10??? Please upload those pictures here....

well said waqar