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Tip1: Being ambitious is good and appreciated. But dont go so deeper and end up having an unyielding tough topic making your life harder. Think big, start small. Okay? For topics in bachelors, let me direct to some; have you thought about these? My suggestion is to think of yourself as the 'future leader' of structural engineering...not just a technical number cruncher.... 1. Highlighting the ordinary house construction mistakes and tackling them? like putting more steel always isnt good in a beam, like snap-failure of concrete floors killing people in factories, mosques and homes in pakistan? A sort of guide for public? Could go on publishing in media as well afterwards. 2. Environment? Value engineering/whole life cost, structural engineering solutions in pakistan to protect environment from construction effects??? What are the shortcoming. 3. Rehab of ordinary public homes to protect for future earthquakes? 4. Study of moderately mid to high rise or complex shape buildings that are dynamically sensitive. For example you could consider an important national building (faisal mosque ?) whose shape is very sensitive to dynamic loading (wind/seismic) and how the design was done and what are the your suggestions to improve? or the lessons learnt for future buildings of same kind. 5. 3d printing, what are the effects and how and at what scale it could be implemented in pak and what type of sector can use it? can we make better and cheap and environmentally friendly homes from it? if not now then may be in future? 6. structural health monitoring? 7. Preparing tables for beams, slabs that shows economy vs span for ordinary construction in pk? Could be distributed as served as a guide in design offices. For example google 'concrete center' span tables. 8. Structures and Terrorists! How would you protect important buildings in Pakistan from terrorist threat? Evacuation plans and structural engineering, blast resistant, progressive collapse, what material is better? Implementation plan? What are more sensitive national buildings?

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.

All, The following posts are available with a Structural Design and Consulting firm in Islamabad. Details are: 1) Junior Structural Engineer - Fresh Grad to 3 years of experience in structural design. 2) Intermediate Structural Engineer - 4 to 7 years of experience in structural design. Firm is Arif Consulting Engineers. Website is http://www.aceconsults.com Salaries shall be based on experience. For job application, please send your resumes to epcarif@gmail.com. For further details you can also contact 03005108587. Thanks.

Hi, Share your experiences on the best structural design firms that you have found while working in Pakistan. It can provide insight to members on the board to: join, not to join, or look for opportunities in different firms. Listing pros and cons will help others. Thanks

I heard about Bilal & Mushtaq in Karachi. They do lot of highrises. In the end and based on my exp, work never ends in any firm. experiences vary. But its all routine, its all typical. Self study and hard work is everywhere. But I am more interested in "work culture" and employees care. All firms are doing business, earning money, and you work for them. I have never seen/heard about a good company in Pakistan or abroad that has a nice relaxed work culture and relations for structural engineer :p. So good luck for choosing structural engineering practice. An no one to blame, even if you open your own consulting firm, you would follow the same old boring routine...it all depends on money coming in.

It will be EMAS Khan associates after some years Insha Allah

1) Rizwam mirza is famous for design of poultry structure (Feed Mill,hatchery,& poultry farm) in pakistan I think 80% poultry structure in Pakistan is design by Rizwan mirza 2) AA associate.(karachi) is best firm of structure design for industrial project (textile, steel mill,warehouse etc) in private industrial sector many project is design by AA associate .there drawing are very easy for field engineer with more detail.i think AA is top firm of structure design in pakistan after nespak 3) Akbar associate , Iqbal uzair Associate, Abdul Razaq associate is well known for structure design.

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)