WR1

look! first you need to study code for proper load combinations. This is very very critical. All the design results and serviceability criteria is based on it. You need to understand which load combination to use and when to use. Read chapter 9 of ACI and PCA Notes..Read its commentary..Read UBC...Try to know what is the difference between 1.3W of UBC and 1.6W of ACI. Get to know why the factor in E is 1.0 in strength load combinations. Know why omega factor is used. 2nd...Research what are the options in softwares which affect automatic load combination creation. For example in ETABS what is the impact of code you select for concrete or steel design and the seismic design category? Why there is SPECIAL SEISMIC LOADS option in ETABS under define menu? I would recommend you to print the page of ACI where load combinations are defined and also for UBC and keep it in front of you!..Take a paper and write all the appplicable load combinations based on your load cases. Then compare ACI vs UBC I would say you dont use automatic load combinations rather make your own combinations. Once you are done and confident about your understanding of load combinations then use the AUTOMATIC load combinations. You should know which combination is appropriate for Seismic drift limit or wind drift limit. What is the meaning of probability or exceedence of seismic or wind forces? If still this all stuff seem boring to you! do this Goto options in ETABS> define design code to be ACI 2008..Select appropriate seismic design category. If you are not familiar with SDC open chapter 1 of ACI and see what is the equivalent SDC of UBC in Table 1.1 of ACI Then goto define menu>Special seismic forces. If your SDC is C or less it will not have an impact. So you select it or not...doesnt matter then create automatic load combinations and verify them one by one..Do this atleast in your first few models. There is a trick to make service load combinations automatic too...if you are interested i will tell you later!

lolx this is what i do...you have any questions ?

this is really a controversial question! based on what i have been doing uptill now here is the summary! if you have very hard rock support use fixed if the soil is weak and fear of liquification use pinned remember its always conservative to use pin support for column design as all the moment will be redistributed to column but for foundation design if you make the support fixed you have to design it for moment just a rough rule:- for isolated foundations use pin for mat or combined footings use fixed

to asadishfaq! Well i think you better post this in software issues section where i have already started a thread called SAFE/ETABS/CSI Problems/issues!

for both of you above! if you want to start a topic which is not relevant to this category you can start a new thread so that its not confused with the original discussion!

lean is not part of concrete foundation modelling...unless you are doing a high fi phd scientific research...( i think)...and in ETABS we provide modifiers to account for cracking in concrete members as told in ACI chapter 10..

in which semester you are? do you know how to use FEM tools? ETABS etc? i quite often have private structural tasks...and im willing to teach you if you can work for me! but first let me know by sending me an email or PM that what is your level?

yes my friend you are right!...dome is very complex geometry and FEM takes months to complete...(if its not a 2 storey building )

pm the admin of the forum about your problem...additionally i will convey your problem to him!

as a working engineer its really not easy to upload an official document complete or part...from office systems but i think you can google the phrase and i hope you will find it.. plus these parameters are difficult to find in a geotechnical report..they have sections and index explaining each and every thing..just start with a simple geo tech report....more often the report consists of not more than 50 pages...unless its quite complex project!

actually its not always boring and long...what you have to see is bearing capacity of soil (for foundation areas) coefficient of lateral earth pressure (for basement or retaining walls) soil spring stiffness or modulus of subgrade reaction (for modelling foundations) soil spring stiffness or for piles depth of foundations etc

@waqar...then ur my buddy cz ur a mathematician too.. i would ask for your help in solving equations

i was very busy on last weekend...hope to upload material this weekend...give me details what type of material exactly you need...plus about internships..i dont have any idea about companies in pakistan...as i never did a job in pakistan...except a training (internship)

the idea is like a pin support..slabs supported on masonry walls has max moment at mid span wl²/8 no moment (ideal) at the wall support...so in that case for gravity loads..yes no moments at joitns but if you talk about lateral loads...they do take somehow out of plane moments but they are very weak in tension as concrete. So in that case reinforcement is added and moment can also be transffered to base (footing) and by inbuilt concrete cols or beams... remember masonry system can be used as lateral resistant system

i agree with Admin, plus you will get to know other codes than the traditional ACI taught in undergrad

structural engineers!

if you mean to say that we use different concrete section that is i) rectangular & ii) circular but keep the reinforcement and layout of reinforcement same what would be the effect rite? it will not matter much at normal scale in a normal building unless you have huge dimensions but anyway, ofcourse circular shape is more desireable due to archtectural reasons and also due to structural issues like circular cols will not have corner stress concentration less material as compared to square/rect cols but at the same time same moment of inertia equal capacity at every rotation of axis no matter from where the loading is coming

spiral reinforcement is better it has less capacity reduction factor hence more strength...but if you use circular ties it is same like rectangular ties..so in that case ties (rect or circular both are same)

what is height of this tower and also tell me if you can the seismic zone !

believe me guyz! i have personal experience in this...but God saved me...cz the design which i had done by selecting SI units was conservative...it will always be! so it was not under designed...i found this mistake after spending continous 4 full nights on the issue! If any one interested i can provide him with full conversation to his personal email! but the summary is here --------------------- 1) If you use SI units it will report tension capacity of bolts in Mpa but the value will be still in ksi units! its the biggest confusion! although the shear value will be ok 2) If you use SI units it will not calculate the pull out and other concrete anchorage capacities correctly!

i think thats a very good idea...keep it up admin..we want to c new trends here unlike other forums!

Welcome ABBAS! we hope you will learn a lot here!

i have experience in making load combinations in etabs at quite complex level...believe it or not for some buildings i have made 200 ultimate and 200 service combinations...i really hate the etabs combination dialogue box which cannot be resized...unlike SAFE! where you can export it into excel! anyway this sheets i just designed for my own custom application...thought to share with you guyz if you find it helping..

Dear guyz, here is a tip for you based on my experience with RISABASE, the only software (reliable) i was able to find to analyse biaxial moments and concrete anchorage design for baseplates. I found a very strange problem in it! while working in Metric units...so please always work in imperial units other wise you will be mislead here is the summary of my long conversation with risabase guyz...at last they accepted their mistake and promised to remove it next version..unfortunately they are releasing next version at the end of this year! -------------- From: Support [mailto:support@risatech.com] Sent: Tuesday, May 15, 2012 8:41 PM To: Waseem Sarwar Subject: RE: Inquiry about Risabase calculations Waseem, I am seeing a problem with this. I have written this up as an issue and we will make sure this is fixed for version 3 of RISABase, due out later this year. Thanks for your persistence on this. Sincerely Michael Olson RISA Technologies Ph: 949-951-5815 Fax: 949-951-5848 Have any comments on the quality of our service? Please email Bruce Bates, president of RISA Technologies, at bruceb@risatech.com and let him know about it. (for privacy reasons i cannot share all the conversation) if you are interested contact me

i didnt get it! what do you mean by the capability? ofcourse if you are going to build SMRF you have to build it in proper way by any means..other wise if you say you dont have the capability or resources to build it then obviously dont build it!