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EngrUzair last won the day on August 13

EngrUzair had the most liked content!

About EngrUzair

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    Lieutenant Colonel

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    MSU USA & UET Taxila
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  • Interests
    Structural loading, RC design, Steel design, Fire damaged structures, Structural evaluation & rehabilitation

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  1. 70th Independence Day of Pakistan

    Dear colleagues! Assalamo-alaikum. Congratulations to all on 70th anniversary of independence of Pakistan. May Allah bless us & make it Pakistan (i.e., the land of pure people) in the real sense. Regards.
  2. 1. AFAIK ETABS 2016 has the capabilty to design CMU (Concrete Masonry Units) Shear Walls only. The design is carried out in accordance with ACI 530-11 requirements. See the following link for the relevant Design Manual: https://www.google.com.pk/url?sa=t&source=web&rct=j&url=http://docs.csiamerica.com/manuals/etabs/Shear%20Wall%20Design/SWD-ACI-530-11.pdf&ved=0ahUKEwjfxIbNqcPVAhXGto8KHbPiAhgQFggtMAE&usg=AFQjCNHg0YZpIutlVDDoPos320qUvD_90g 2. Several masonry design software, other than Prokon ( https://www.prokon.com/design/masonry-design ) mentioned in previous post, are available on the internet. Here are the links of a few of thesr masonry design software:- a. MasterKey - BS & Eurocodes based ( http://www.masterseries.com/product-specific/masonry-design) b. NCMA Structural Masonry Design software; IBC, TMS402 & ASCE 7 based ( http://www.ncma-cpu.org/ProductSubCats.aspx?SubCatID=42) c. MASS - Canadian code based ( www.masonryanalysisstructuralsystems.com ) d. GEO5 Masonry Wall; Euro code & Australian code etc ( http://www.finesoftware.eu/geotechnical-software/masonry-wall/) e. DigitalCanal Masonry Wall - ACI 318-11 & IBC 2012 ( http://digitalcanalstructural.com/masonry-wall/ 3. A simple internet search will yield names & links for many more masonry design programs, if needed. Regards.
  3. Sag rod is basically a structural steel member, carrying tensile load only. For knowing detailed methodology for modelling a tension-only member in ETABS, see the following link:- https://wiki.csiamerica.com/m/view-rendered-page.action?spaceKey=etabs&title=Tension-only+elements+in+ETABS Regards.
  4. R/f at top in isolated footing

    Top reinforcement might be required in isolated column footings in following circumstances: a. When the foundation is in tension b. To counter shrinkage cracks Regards.
  5. Lower compressive strength of concrete

    In general, this issue is controlled by relevant clause of contract agreement. Following are the possible options that may be or might have been specified in the contract:- a. Demolition & recasting, in case actual strength falls MORE than a certain percent below the required concrete strength b. Strength evaluation of actual structure, according to applicable design code & acceptability or rejection of structure accordingly. c. Rarely, there might also be an option to strengthen the structure (using conventional or advanced strengthening techniques & materials) to the required level (where possible). Regards.
  6. Solid slab

    If you are asking about possibility of designing a single slab of given dimensions, theoretically it can be. Practically however such a large slab will have undesirably high self-weight and deflection, if designed without beams. Self-weight as well as deflection can be controlled by providing beams along outer edges & at suitable intervals parallel to short span of the slab for reducing required thickness of slab from deflection point of view. Regards.
  7. Here are my two cents:- 1. General guidance regarding placement of construction joints in RC work has been provided in Section 6.4 of ACI 318-08 and its commentary. Some clarity is given in section 6.4.3, where it is stated that "Construction joints shall be so made and located as not to impair the strength of the structure. Provision shall be made for transfer of shear and other forces through construction joints." For transfer of shear etc through construction joints, reference is made to the ACI Section 11.6.9 that deals with the calculation of shear-friction, at the interface between two concretes cast at different times (beside other situations described in section 11.6.1 of the code). Moreover, Section 6.4.4 suggests that "Construction joints in floors shall be located within the middle third of spans of slabs, beams, and girders. 2. Regarding construction joints in columns, however, Section 6.4 does not provide guidance clearer than that in Section 6.4.6 stating that the "Beams, girders, or slabs supported by columns or walls shall not be cast or erected until concrete in the vertical support members is no longer plastic." And, the commentary section R6.4.6 explains that "Delay in placing concrete in members supported by columns and walls is necessary to prevent cracking at the interface of the slab and supporting member caused by bleeding and settlement of plastic concrete in the supporting member." 3. The support member (referred in previous paragraph) will generally be a column or a wall. And, in a simplified form, Section 6.4.4 & its commentary are advising us NOT to cast beams & slab monolithically with the wall or column, BUT only after the supporting column (or wall) concrete has hardened, in order to avoid plastic cracking at the beam-column (or beam-wall) joint. 4. In our normal field practice (within Pakistan as well as abroad), beams & slabs are cast at least one day after casting of columns or supporting walls. This gap of one day (between casting of column & beam concretes) ensures that the column (or wall) concrete poured one day earlier has hardened (is no longer plastic), thereby avoiding any possibility of plastic cracking (discussed in paragraph 2 above). 5. Now coming to your queries; In general terms, it is preferable to cast the column in one pour.. However, in compelling circumstances it may be done in more than one pour too, subject to certain conditions. Already described in initial paragraphs. This is the normal & IMHO desirable practice, according to ACI code Section 6.4.6. IMO, leaving 9" or 12" column depth below the beam soffit is excessive & undesirable. It should not be more than 1" or 2" in any case. IMO, this practice is based on the requirements of ACI 318-08 (also ACI 318-11) Section 6.4.6. The same requirement is available in ACI 318-14 Section (a) as well. HTH Regards.
  8. Strap Footing

    References given in the following link might be useful in this connection: http://www.sepakistan.com/topic/1978-strap-footing-design/ Regards.
  9. ACI 318 clause for beam and column definition

    Yes. ILYAS is right. Definitions of beam & column are also given in Section 2.3 of ACI 318-14. In earlier versions of the ACI 318 (2005, 2008, 2011 etc ) definition of column was also given in Chapter 2. However, definition of beam was not included till then. Rather it was referred as a flexural member. AFAIK definition of "beam" was most probably included for the first time in 2014 version of ACI 318, after it was included in ACI Concrete Terminology 2013. Regards.
  10. ACI 318 clause for beam and column definition

    According to ACI Concrete Terminology 2013, a "beam" is defined as " a structural member subjected primarily to flexure but may also be subjected to axial load." Whereas, a "column" is a "member with a ratio of height-to-least-lateral-dimension exceeding 3 used primarily to support axial compressive load." Design of a structural member (as a beam or column) in ACI 318 code is based on above-mentioned definitions. Regards.
  11. fresh engineer but dont know about the field

    Dear Shafqat, AA. Field work of a civil engineer generally consists of following activities: a. Surveying / levelling of the project area b. Supervision of construction work for buildings, roads, culverts, bridges etc., in accordance with detailed working drawings, applicable material specifications and quality standards. c. Preparation of material estimates, by calculating quantities of different items of work (e.g., excavation, concrete, brickwork, plaster, reinforcing steel etc-in case of buildings, and subbase, base, wearing course etc, in case of roadwork) included in working drawings of the project. 2. To perform all these tasks in better & efficient way, you will need to review your class notes & text books of relevant subjects (Surveying, Civil Engineering Practice, Estimating & Costing, Highways & Roads, Engineering Materials) taught during your civil engineering studies, in order to understand theoretical & practical aspects of these subjects. 3. As regards, which subject you should review first, would depend upon the work you are asked /assigned to do by your senior engineer. As a Trainee Engineer, you will certainly be attached with a senior engineer, who will assign you different engineering tasks & check your work. You may & must obtain his advice in all the work matters, where you are in doubt, or unclear about how to perform a given task. 4. In case you have futher querries, please do ask, by narrating your problem in detail. I will be happy to help you, as far as I can. By the way, what kind of civil works are carried out by your company mostly? Building work, roadwork or both? Regards.
  12. High Strength Rebar With Low Strength Concrete

    Following are a few disadvantages of using higher strength rebars with a lower strength concrete: 1. Larger tension (as well as compression) development & lap-splice lengths will be required. 2. Overall load carrying capacity of a compression member will be lesser, compared with when higher strength concrete is used. 3. Maximum amount of steel reinforcement, that can be used in a flexural member, will also be lesser, thereby reducing its overall load carrying capacity. 4. Member size & self-weight will be somewhat larger, when steel yield strength is more than 60,000 psi. Regards.
  13. Screen Time

    I agree with waqar. IMO, childern must be motivated towards & provided opportunities to play different health improving outdoor games (football, cricket, badminton, etc) , instead of watching TV or playing games on computer. My chidren are school going, and whenever they have done their homework, and it is pleasant outside (especially after Asr prayer), I send them out in a nearby park area. There they can play football or cricket, and can do exercise as well. On weekends, during vacations and on other days when they are unable to go outside, they generally watch tv for 1-2 hours.
  14. R value for Minaret structure..

    IMO, if the lift core consists of RC walls and columns are part of a frame system, it may possibly be considered a Dual System consisting of RC shear walls with IMRF (R=6.5) or simply IMRF ( R=5.5). Otherwise, the minaret might be considered to correspond to "Distributed mass cantilever structures such as stacks, chimneys, silos and skirt-supported vertical vessels" (S/No. 3 in UBC-97 Table 16-P), for which R=2.9. HTH Regards.
  15. Washigton Accord !!!

    Dear Waqar, AFAIK, main benefit will be in the form of opportunity to practice engineering (work as an engineering professional) within other Signatory i.e full member countries of the Accord, as the engineering qualifications of Pakistani Engineers will be acceptable to them now. Other requirements of Licensing Authorities of these countries, as and where applicable, would also need to be fulfilled. Further details about Washington Accord, including list of Signatories & FAQs, may be checked at the following link: http://www.abet.org/global-presence/mutual-recognition-agreements/engineering-washington-accord/ Regards.

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