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W/Assalam! AFAIK, there is no specific requirement of providing steel reinforcement in thick rafts, at least similar to your one, other than at top and bottom. Others might be able to help more in this regard. BTW, why the raft is so much thick? some high rise building, larger spans, or...? 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

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.

Assalam-o-alaikum! start of professional career as an engineer, in the USA, is not a simple and easy process. Although actual requirements may vary somewhat from state to state, but generally a four-step process has to be followed for obtaining license to work as an independent professional engineer. (See the thread: http://www.sepakistan.com/topic/1610-benefits-of-getting-pe- licence/#entry3958, for learning the benefits of having a PE license.) Step 1: Graduating from an accredited engineering program (e.g., B.E./B.S./M.S in Civil Engineering,...) Step 2: Passing 'Fundamentals of Engineering' (FE) exam (Details available at: http://ncees.org/exams/fe-exam/) and to become eligible for being classified as an intern, also known as Engineering Intern (EI) or Engineer-in-Training (EIT). Step 3: Obtaining required length of work experience relevant to chosen engineering discipline, after passing the FE exam. In many cases, the experience period is to be supervised by a licensed engineer, depending upon specific requirements of concerned State Licensing Board. Step 4: Passing 'Principles and Practice of Engineering' (PE) exam. Once an engineer has successfully completed the first three steps of this process, he/she may take the second exam in the licensing - the Principles and Practice of Engineering (PE) exam. The PE exam tests the ability of an engineer to practice competently in a particular engineering discipline. It is designed for engineers who have gained at least four years’ post-college work experience in their chosen engineering discipline. Each PE exam has a total duration of 8 hours, and is split into a morning and an afternoon session. PE exam specifications and design standards, applicable for the forthcoming exam are posted on NCEES web site, 6 months before the exam date. Updates for April exams are posted in November, and updates for October exams are posted in May. The specifications and details of design standards for PE Exams 2015, related to five (5) Civil Engineering disciplines, are available at following links: Civil - Construction (https://cdn.ncees.org/wp-content/uploads/2012/11/Civ-Con-April-2015_Combined.pdf) Civil - Geotechnical (https://cdn.ncees.org/wp-content/uploads/2012/11/Civ-Geo-April-2015_Combined2.pdf) Civil - Structural (https://cdn.ncees.org/wp-content/uploads/2012/11/Civ-Str-April-2015_Combined2.pdf) Civil - Transportation (https://cdn.ncees.org/wp-content/uploads/2012/11/Civ-Tran-April-2015_Combined.pdf) Civil - Water Resources and Environmental (https://cdn.ncees.org/wp-content/uploads/2012/11/Civ-WRE-April-2015_Combined.pdf) The PE exam is an open-book exam. The examinees are allowed to bring reference materials to the exam, provided they are bound and remain bound during the exam. Further details regarding PE exam can be found at: http://ncees.org/exams/pe-exam/ The design codes and manuals referred in these documents, are the ones to be followed all across the US, for the structural design of all kind of engineered structures. As such, these are the most important references, a civil or structural engineer (working in a jurisdiction, where US design codes are the basis of engineering design) will need to know, learn, and follow in his/her engineering design practice. Hopefully, this information will not only be beneficial for those, interested in taking the PE exam in near future, but would also help us improve our knowledge and understanding of code requirements regarding design and construction of various kind of civil engineering works. This, in turn, will make our structures safer as well as more code-compliant. Regards.

Waqar, What is your reinforcement ratio? Also, Uzair has raised a good point that reminds me of settlement under the raft foundation. How much settlement are you getting under the raft? Thanks.

W/assalam! You may use following steps to check deflection of a portal frame in SAP2000 (I am assuming that you are using SAP2000 version 14. Other versions might require somewhat different approach.) 1. Run SAP2000 model of your portal frame, using 'Analyze--> Run analysis' menu option. 2. Select 'Show deformed shape...' from 'Display' menu drop down option. Alternately, you may use F6 function key to display 'Deformed Shape' options window. 3. Select the Load 'case / combo' for which you want to check deflection, and press 'OK' command button. Deformed shape of structure for the selected load case will be displayed. 4. Placing the cursor on one of the member joints, will display deflections and rotations at the selected joint, in length units visible at bottom right hand corner of display window. (You will have to make the joints visible, if these are not already in view.) HTH Regards.

yes Waqas you got it right..No increase in 0.75load combinations as in ASCE/ACI

The document presented by Sir Umer clearly says that this stress increment should not be taken even in case of earth quack loads if 0.75 reduction factor has been already used in load combinations. More over, in sizing of footing, we go for ASD approach because bearing capacity given by geotechnical engineer is based on the concept that full factor of safety of 2-3 is applied on soil strength and no loads are increased. This is ASD methodology. So to be compatible, we also go for ASD while sizing of foundation. So in my opinion, if you are using load combinations which are carrying 0.75 reduction factor, you can not increase soil stress by 33% even not for earth quack loads. but if you are using the load combinations which are not having 0.75 reduction, then you can increase this stress as 33% but just for those cases where two or more than two transient loads are acting simultaneously.

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.

Sir umer i had studied this document before starting discussion. This mainly adresses the stress increase in structural materials. This was practice followed before 1990's because at that time factor of 0.75 was not introduced in load combinations. We can increase allowable bearing capacity of soil by 33% under eartquake and wind conditions.

I just came across this. Here is an article by AISC that addresses that. Its not allowed anymore and reasons are in the article. 13rd stress increase AISC.pdf