WR1

If you know its unstable then what is the question?

ur always talking abt tutorials and when im making them and sharing here in tutorials sections...your are not following ..but my tutorials are only for etabs!

i like this pic!

yes you can consider it same because soil pressure depends upon height h of the backfill! that is k0.w.h so w is denisty, ko coefficient of lateral earth pressure... In my thinking you can caluclate it the way you calcualte it for vertical face...

it depends upon column location with referene to foundation centroid..NOT THE BUILDING...because these factors are used to caluclate punching area of foundation....

happy ramadan to all of you! although im not fasting today (my 2nd of ramadan here) bcz of headache all night long....do pray for all of us mulsims and fear GOD!

no. read soil mechanics abt angle of backfill. open chap 17 of concrete design by nilson 13th edition

read any NILSON concrete design book 14th edition beam chapter.... Ofcourse there is minimum reinforcement ratio for every concrete member....you cannot put less than that..but you have to be sure that its also satisfying strength design! and serviceability too!

yes you can design it provided that you atleast have min reinf! but should be less than maximum point to note here that max reinf ratios changes for single and doubly reinf beams In addition when you take reduced moment capacity based on phi factor...note that its not always equal to 0.9 it can be 0.85, 0.87 etc..depending upon strain compatibility according to ACI....from compression cold to tension controlled section!

you cannot push a rope!

Dear sir umar, i have mentioned your name in that page for SEFP if you dont mind! ?

Dear members, This is general topic. Please visit the following link to my structural engineering blog, i have recently made some layout changes and added ABOUT ME page, I need your suggestions. Is it oK? although the words and grammer needs to be corrected but this is the draft.. I will be happy to listen from you! thanks http://www.ranawaseem.com/p/about-me.html

apart from ETABS remember that i used some softwares where they have written in manual that the limited version contains random errors so dont use it for design so if some one cracks that it will too generate errors..just dont blindly download any tool and start looking for crack and the use...pls read manual first.. but for ETABS i didnt find anything like that

thanks

very good reply...

I am confused again now..let me do somw work..thanks for the share

well im not a site guy! so was not able to comment!

but not all the things can be done manually in a fast track project...yeah should be done manually to understand the concept but to get faster results one should be familiar with computing techinques too

I have currently with me some papers, i was reading...and making notes...luckily the topic is LONG TERM DEFLECTION It is still in my pending tray...Once i find enough time to get information and absorb the topic i will write a post and share with you all. Well i was doing research on LONG TERM topic and also how to use it in SAFE and what are different options available in SAFE...well i made a comparison sheet and i found every result different than the rest...which made me more confused....

Well the same symbols are used for many different things in each discipline of science...I quickly took a look and i found some variables like n1 and Q, which are used in Gust Factor Calculation according to ASCE. but other factors i dont know. If somethings clicks my mind, I will update you!

it depends. (common sense) if you building is the building containing lot of fluids (may be in case of some industrial water buildings) then yes...but if it is just a small water tank at top then no....anyways you can conservatively include this as live load...because only upto 25% of LL is considerderd in MASS SOURCE...and Dead Loads are always much more than LL....so it will not make a huge difference.. Generally LIVE LOAD portion (25% of LL in MASS SOURCE) is less than 10% of total sesimc weight! For example if all the DEAD LOADS = 25000 kN LIVE LOADS = 10000 kN MASS SOURCE = 100%D + 25% L = 25k KN + 2.5k KN = 27.5kN Live load portion is 2.5/27.5 = 9 % approx

oh i c..i was thinking from design office point of view..!

WE ARE NOT RESPONISBLE FOR THE DIRECTION AND WC SETTING OUT...WE CONSTRUCT AND DESIGN THE BUILDING...ITS ARCHITECT RESPONSIBILITY!...I AM SURE YOU WILL NEVER FIND WC IN STRUC DRAWINGS..AND WILL NOT EVEN NOTE THAT IN ARCH DRAWINGS... BUT YEAH YOU CAN DISUCSS WITH THEM IF YOU LIKE!...I DONT THINK A GOOD ARCHITECT (EVEN THE NON MUSLIMS WORKING IN MUSLIM COUNTRIES) BUILD A DESIGN AGAINST MUSLIM NORMS..

Building Drift in ETABS Drift is a very complex topic in structural engineering. It involves too many factors to arrive at a suitable decision. It involves engineering judgment, the phenomenon fresh engineers might not feel. In this article, I have tried to explain what is building drift, allowable limits, ways and means to check in ETABS models and to control the excessive drift. Please keep in mind, this article is not about the building drift as far as structural science is concerned, rather this topic of drift is related to ETABS software. First of all you must be familiar with the term story drift. For convenience, I am quoting here the definitions from UBC-97 code:- STORY DRIFT is the lateral displacement of one level relative to the level above or below. STORY DRIFT RATIO is the story drift divided by the story height. 1) Maximum Limits Now what for story drift limits? What is the maximum permissible value? Well it depends upon the type of drift. Is it seismic or wind? For seismic, I will refer to UBC-97 code which in section 1630.10.2 talks about drift limits for earthquake. Now in simple words, the maximum limit for seismic drift is:- delta M shall not exceed 0.025 x story ht (if building seismic period is less than 0.7) delta M shall not exceed 0.020 x story ht (if building seismic period is equal or greater than 0.7) Important to note here is that it talks about SEISMIC drift so SEISMIC building period not the WIND period. Now delta M = Max inelastic response displacement = 0.7R delta S where R = from Table 16-N delta S = displacement from static, elastic analysis this value is read from ETABS. you multiply this value by 0.7R to get delta M This was all about seismic drift, but for wind drift code is mute. I will refer you to ASCE 2005 commentary CC.1.2 So we can understand that the limit for wind drift is "on the order of l/600 to l/400" for "common usage". This is common thing, however, in reality this figure can be up or down depending upon the ductility of cladding material and finishes. However for common usage value of l/400 is thought to be well satisfactory. Here l means story ht. The concept of drift limits is same throughout all the governing codes, and the typical limits of story height by some number is same, but obviously you have to take care of the process of calculating the wind force or seismic forces. You should not calculate wind force from one code and apply limits of another code. 2) Load Combinations Once the drift limit has been determined separately for seismic and wind forces, now is the need to check the actual drift vs the limit. Determination of actual drift depends on the load combination and the period of recurrence. If not properly calculated, this may dramatically increase or decrease the accepted drift values in model. Seismic force E is always already factored so that's the reason its factor is always 1.0 in load combinations of ACI/ASCE code. The recurrence period for seismic force is 50 years. In seismic drift we do not convert it into service seismic force. Seismic drift is checked against the direct load case of EQx, EQy etc in ETABS. For wind drift, we need to convert 50 year wind to service wind force. It has been recommended by ASCE commentary CC.1.2 To convert 50 year service wind force to 10 year service wind force it is multiplied by 0.7, as the equation says, and other gravity loads; D and 0.5L are also added. So in a nutshell we create following load combinations in ETABS to check our drift:- DRIFTWx1 = D+0.5L+0.7Wx DRIFTWx2 = D+0.5L-0.7Wx DRIFTWy1 = D+0.5L+0.7Wy DRIFTWy2 = D+0.5L-0.7Wy For seismic drift, as discussed earlier, we do not need any combination, drift will be checked just on EQx and EQy load cases only. 3) How to check in ETABS Now we have obtained both the actual drift and the drift limit, but how can we do this in ETABS easily? Well, after creating the drift combinations as discussed in step 2, we need to do as below:- For seismic drift goto File>Print Tables>Summary Report Select the file name Scroll down to the end of the page, you will find out a section about drifts, similar to this one:- It displays the max drift for each lateral load case for each story. As we want the drift for wind to be on drift load combinations and not on wind load cases, so we will not compare this wind drift without limits. In this table we are going to check just the drift values of our ETABS model for individual seismic load cases; EQx and EQy. As you noticed, this table shows us values in fraction format. For example 1/105 that becomes 0.009523809524. This 1/105 value is story drift divided by story ht. It means delta S / story ht. Now this value is delta S. First we need to convert it to delta M by multiplying it with 0.7R. Assume R here is 3.5 so delta M = 0.7 x 3.5 x 1/105 = 7/300 = 0.023333 which is less than 0.025 so safe ( if T<0.7). So instead of calculating every time by 0.7R we can check these limits in other way. If our limit is 0.025 then the limit we get is 0.025/R/0.7. Assume R=3.5. Now the values in ETABS are inverse so our limit is 0.7x3.5/0.025 = 98. In ETABS the drift is reported as 1/x where x is some number. Now as long as x (some number) is greater than 98 our limit of 0.025 x story ht is being satisfied. This way you can quickly check and compare seismic drifts. Now for the wind drifts, goto Display>Show tables, select Point displacements>Story drifts and then select only drift combinations for results. Click on and then copy the table to EXCEL. To save time you can right click on EXCEL taskbar and select maximum and minimum. Then just select the column H or I and see the maximum value that should be less than H/400 to H600 limit (0.0025 t0 0.00167). Again the values reported in ETABS are divided by story ht. http://4.bp.blogspot.com/-9qv8XKHgL8Q/UALNKflmVsI/AAAAAAAAAEQ/AwKBYWt2iys/s320/image022-773193.jpg 4) Controlling Excessive Drift Values sometimes you may face problem of excessively large values in drift tables in ETABS. Well we are not going to talk about different measures and modeling techniques to control the drift values. We are going to talk about large numbers in drift tables. Sometimes it happens that a point or node is free in the model or is connected to a NULL line or very flexible section. Drift tables for example the story drift table in wind captures the maximum displaced points. Obviously the displacement of several meters in tables is not what we are looking for. Drift values (relative) may be still okay for these points, but it requires you to check the displacement values too before checking directly the drift. Unlock the model and remove all free points, check for any discontinuity and modify your models to remove all the errors.

i dont think anyone can change the results by ETABS even by cracking!