Waqas Haider

Dear iamcivilengineer,
As you are final year student so you should make concepts regarding the field in which u r interested.If u r interested in design then u have to learn basics of structures and softwares like sap,safe ,etabs and staad etc.And if u have interest in planning then learn primeravira and MS project and fidic guide etc.For field work you will have to learn Testings like lab and field tests.For that you need to join a construction company.
But it is upto u which field u choose.
 
Thanks!

Assalam o alaikum,
I am designing a concrete frame in seismic zone 4 to which I have assigned seismic design category E. I ave insufficient data for site soil so I have assumed soil type Sd. Now I m to ask that IBC 2009 1809.13 says,footings must be interconnected. Whether this requirement only for Site Classification as E,F or it is for all site classifications? Moreover this requirement means tie beams must be at footing level or Tie beams provided at plinth level also satisfies this provision?
Thanks.

You should always do your due diligence. Most senior engineers in Pakistan have limited knowledge.
Never listen to such people as they breed ignorance.
Thanks.

W.s.
1809.13 Footing seismic ties.
Where a structure is assigned to Seismic Design Category D, E or F in accordance with Section 1613, individual spread footings founded on soil defined in Section 1613.5.2 as Site Class E or F shall be interconnected by ties. Unless it is demonstrated that equivalent restraint is provided by reinforced concrete beams within slabs on grade or reinforced concrete slabs on grade, ties shall be capable of carrying, in tension or compression, a force equal to the lesser of the product of the larger footing design gravity load times the seismic coefficient, SDS, divided by 10 and 25 percent of the smaller footing design gravity load.
Site Class is specific to E or F.
Individual Spread Footings founded on soil shall be interconnected... ; Ties shall be at foundation level.
Thanks.

Rizwan Mirza should be doing everything and anything.

Give the architect a call or talk to the client about what finishes he plans to use. You can't just assume anything. You need to have a basis to go back too.
Thanks.

The GPA You mentioned is v.good. Mine CGPA was 3.125 which is not so impressive and i don't have enough money to go abroad except scholarship etc. But my teachers (Teachers and Gold medalists of UET) have prepared some wonderful chart and sent to me. i am attaching here the same. Try to spread it umar bhai. And also guide me how to find a job abroad or at least in good Structural engineering firm where i can polish my concepts and learning. For the time being, i m working on a dam feasibility report and use to handle some independent projects where, due to unavailability of any senior, i face a lot of problems, i just want to learn in depth Structural Engineering knowledge.
Scholarship Table Final.pdf

You can draw unit width slabs with uniform thickness. Keep doing it and keep reducing your slab thickness to model tapered footings.
 
But I would not recommend that for such a problem. FEM is sensitive when thickness changes. So If you reall want to do as accurate as possible modelling (although FEM is still an approximation) you can use other softwares like STRAND7 or LUSAS or any other.
 
In SAFE I would have modelled it with average thickness (or even less than that based on engineering judgement and specific conditions). You can always develop rationality on any problem with given constraints. Thats creativity you know!

The reason why foundations are tapered is because you need a certain depth to satisfy shear and moment at locations of distance d from support for shear and face of support for moment. Beyond these points your numbers are expected to be small and you should always verify BMD and SFD diagrams.There is no point in doing a tapered analysis.
Thanks.

There are different recommendations for expansion joints in different books. I have seen no joints up to 200 feet in some text for RCC buildings. Anyways, you can do analysis for thermal differential case and see how much moment gets induced in your foundation.
Visit the link below for information about carrying out thermal analysis.
http://www.sepakistan.com/topic/1367-effect-of-temperature-changes-on-buildings/
Thanks

Assalam-o-alaikum!
 
You can get soft copies (PDF files) of the following two publications, FREE OF COST from PCA website:
 
1. PCA Notes on ACI 318-11
    (Link: http://members.cement.org/EBiz55/ProductCatalog/Product.aspx?ID=2137)
 
2. 'Simplified Design of Reinforced Concrete Buildings', based on ACI 318-11 and IBC 2009  by Kamara & Novak 2013 
   (Link: http://members.cement.org/EBiz55/ProductCatalog/Product.aspx?ID=2246)
 
You will need to go through following steps:
 
a. login at PCA website, after creating a free membership account using your valid email address.
 
b. Search and add the above publications to your 'cart'.
 
c. Both pdf files are password protected. The passwords will however be displayed in your purchase list, after you add these downloadable items to the 'cart'. Note the passwords, before 'Check out' & confirming your order.
 
d. 'Update' and 'Complete/Confirm' the order. A confirmation email, with a web link, will be sent to your email address.
 
e. Go to your email. Click on or open the link in separate window.
 
f. Login, and download the files from 'Available Downloads' list.
 
Enjoy!
 
Regards.

Some basic points regarding raft foundation are as under:
 
- It is generally provided for the building or other structures having heavy superstructure loads, low soil bearing capacity, smaller column/frame spacing or a combination thereof.
 
- General design and detailing is similar to a floor slab, except that loads and reinforcement locations are inverted.
 
- Raft foundation will be uneconomical, if the loads are smaller or bearing capacity is not too low.
 
 
You may get more detailed and to the point advice, by providing some specific details of the the house, like
 
- common & maximum room sizes,
 
- number of stories
 
- Whether framed structure (with maximum column spacing), or load-bearing wall structure,
 
- material of construction
 
- type of loads to be considered
 
- allowable soil bearing pressure, etc.
 
 
Following threads may also give you some insight regarding the design of raft foundation for building structures:
 
1. http://www.sepakistan.com/topic/1440-raft-design-for-a-2-basementg24-story-building/?hl=raft
 
2. http://www.sepakistan.com/topic/160-minimum-thickness-of-footing/?hl=raft
 
 
Hope this helps to some extent.
 
 
Regards

Providing lap splices at mid height is a pain in neck from a constructability point of view, probably thats why code recommends it for the case of SMRF only where ductility demand is the highest. Regarding omitting splices, I am not sure what the complete sentence is and its context. I have to look it up and let you know.
Thanks.

There are situations where this provision is helpful. To quote a real example, Saudi Embassy building X amount of schools in Northern Regions of Pakistan. Majority of buildings shall fall to SMRF and probably two or three would go under IMRF. In such situations, you can use the higher SDC and keep things simple for construction and your field team in-terms of drawings and rebar detailing.
Thanks.

Assalam o alaikum... Can we model beam footing in safe? Please guide about procedure.

That is a great book!

oho bhai reinforcement type has nothing to do with the type of FEM element you select. You can provide the reinforcement in center part as you have shown in image. But for analysis I would recommend you to model it as slab. Then provide reinforcement details as done in beams but take results from this slab element in SAFE

Assalam-o-alaikum!
 
In the USA, no one can start working as an engineer, just by graduating from an accredited engineering university in civil (or some other) engineering discipline.  Rather, each engineer has to pass a comprehensive examination, called Fundamentals of Engineering (FE) Exam, before he/she is eligible for joining some government or private consulting organizations as Engineering Intern (EI) or Engineer-in-Training (EIT), for gaining relevant professional experience to work as independent engineer later on.  

This exam covers and reviews all the basic subjects, a freshly graduated engineer is expected to have studied in the university during the engineering education. The FE exam is a closed book exam, except that 'FE Reference handbook' (a standard booklet, developed by NCEES_ the exam developing and conducting organization), is the only source material the examinees may consult during the exam.

FE reference handbook gives a very good overview of the type and extent of basic technical knowledge (subjects, tables, formulas, equations etc) and concepts, a fresh graduate engineer (whether civil/structural, or any other) must have, to enter into practical engineering field in a technologically advanced country, like USA.

The study of 'Civil engineering' portion of this handbook and relevant 'exam specification' at the end, may help us understand level of engineering knowledge we should have, as well as the subject areas requiring improvement of knowledge and strengthening of concepts, in order to make us better engineers.     

FE Reference Handbook may be downloaded from NCEES website,using following link, free of cost. :
 
http://ncees.org/exams/study-materials/download-fe-supplied-reference-handbook/

Note: You will have to enter your email address in the space provided on the above webpage, and to press 'Submit email' button. The site will send you a password on your given email address. You need to provide this password (on the above webpage) in order to obtain/unlock download link of the FE handbook.
 
Regards.

Thank You Very Much Sir.
Could you give a name or link of FEM book you preferred?
Guide me if you have time to teach us, thank you Sir.

yes Mu is +2.61 and -5.1 kip-ft, but you have to make sure + sign represents inner or outer face of wall. It will depend upon the direction of local 3-3 axis.
 
Furthermore, you dont need to design (Mu) for peak/max values shown in status bar of ETABS/SAP/SAFE. 
 
This should be enough for longhorns but to be a veteran you need to look at other things too. Read a good book about FEM. It will really be an eye opening and advantageous for you.
 
Read how to take design values from contours, what are stress concentrations, what Guass points and how meshing affects stress concentrations.
 
In short for a simple problem, yes, use M22 moments for vertical steel design and M11 for horizontal steel of a wall (if default orientation of local axis is used)

I also would like to know the answer for this topic.
Please explain shell stresses/forces of etabs after analysis.

Assalam o alaikum,
In Etabs, How to interperate Shell stresses/Forces. I highlighted M22 Force and i got max value as 2.61 in kip-ft units and minimum as -5.112 in Kip-ft units. What i found from the link 
http://docs.csiamerica.com/help-files/etabs/Menus/Display/Show_Member_Force_and_Stress_Diagrams/Shell_Forces_Stresses_Form.htm
that
M22: Direct moment per unit length acting at the mid-surface of the element on the positive and negative 2 faces about the 1-axis.
Does it mean -5.112 Kip-ft/ft and is M22 the moment for which i am to calculate vertical steel. Kindly suggest me the value of Mu for which i am to design reinforcement. I have also attached Picture.

Do not provide the reinforcement that can resist the moment at slab/wall joint. In other words, provide no reinforcement  on the earth side, in the basement wall, at the that joint.

Assalam-o-alaikum!
 
Check out Figures 1 & 2, pertaining to recommended one-way slabs and beam reinforcing details,  in Part C 'Figures and Tables' of ACI 315-99 on pages 20 & 21 respectively. These figures are also available in .ACI Detailing Manual -2004 (SP66) on same page numbers.
 
Regards.

Thank you very much bhai for you response.