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Waqas Haider

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  1. Waqas Haider
    This bonding stress comes into existence when the bar experience flexural tension or compression. Now If at support, say negative moment of 50 Kip-ft is to be resisted for which i had provided 3-#6 bars, then this 50 Kip-ft moment will be resisted by these 3 bars and these 3 bars will experience corresponding tension and this tension will become cause of required development length of ldh. Now if i have provided 6 bars. This moment will be resisted by 6 bars and share of moment for each bar will be reduced and each bar now will experience less tension, 50% less than before so now 50% less ldh will also work. Is my understading correct bhai?? Kindly confirm me one thing more. We design each bar for 0.9Fy in LRFD. and for development we provide such development that the bar can experience bond stress upto yield before slippage. so each bar can go upto yielding. But after this reduction of ldh, no matter force experience by each bar not gonna increase than share of each bar, but let say, theoratically now bars can't go beyond 0.5Fy if tried to be stressed more than share on calculation basis and bars will slip just after 0.5Fy. Am i getting right?? and My building is in Quetta for which i have assigned zone 4, SDC E. And PCA Commentry says i can not apply this reduction in Zone 4 SDC E.
  2. Waqas Haider
    Umair bhai, Thanx for your guidance in this regard. I have gone for option 2 and 4 i.e. I have specified special requirements of concrete covers and have selected reduced development lengths dat fits in my 12 inch column. Regarding you 1st point, i will study it because it unaware of it and it seems very interesting way. Regarding your 3rd point, please explain it. I also cud not understand it from book/Code. Please explain in a bit detail what is it actually and how it works. Thanx.
  3. Waqas Haider
    Dear AbdurRasheed, Regarding this, i want to say you. Some go in design, some go in field, some go for higher study etc etc. But i believe no one is in loss ultimately. What thing matters is YOUR INTEREST. If you have interest in Designing, you should go for it. At start you may get less salary. But when you will become experienced, or you will get chance for abroad (Remember, Life is toooooo Long and Circumstances change a lot), u may get higher salaries. But the only thing is your interest. Otherwise you will get bore of your job one day. I am a design Engineer (Obviously you know because we are friends since last 6 years ) But i never get tired of my work because i love design job and it is a type of hobby for me. So ask your self, MAZA KIS ME ATA HE APKO? Baqi baten sham ko mil kr kren ge...
  4. Waqas Haider
    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
  5. Waqas Haider
    Baz bhai, If i make ends of beams as pinned, This member will not be able to redistribute moment and will collapse at the formation of only one plastic hinge. so How REDUCED DESIGN LATERAL FORCE will be calculated and applied to this member? And is such type of beam allowed in IMRF or SMRF which needs special requirements for integrity at joints under lateral deformation of structure?
  6. Waqas Haider
    Assalam o alaikum.. My building is in zone 4 with SMRF. Majority of its column are Over stressed in 6/5 Beam Column Capacity Ratios. Columns are pass in all other checks. Size of column is 18x18 and building has just two stories. Longitudinal Reinforcement is ranging from 1% to 1.5%. Shear reinforcement going upto Av/s =0.18........ I cant increase size of column because it is already 18x18. How can i solve this problem??
  7. Waqas Haider
    Assalam o alaikum. According to ACI 12.5.2, development length for fc' = 3000, fy=60000, for normal weight concrete and epoxy less reinforcement, The required development length comes out to be for #3 = 8.2 inch for #4 = 10.95 inch for #6 = 16.42 inch for #8 = 21.9 inch And if in my case, ACI 12.5.3 is not fulfilled, it means now i have to provide ldh as mentioned above. ldh is STRAIGHT EMBEDMENT LENGTH + RADIUS OF BEND + ONE BAR DIAMETER as shown in figure attached. Now my question is, if in my case, main reinforcement of beam is of #6 and #4, minimum column size required will be 18 inch and 12 inch respectively. Lets say by any means, i can not select #4, #3 bars and size of column where bars are to be terminated is 12 inch, how to fullfil this development length???
  8. Waqas Haider
    Oh, i was having in mind that Av is 0.045.... i was very confused dats y. Thanx Uzair.
  9. Waqas Haider
    Assalam o alaikum. I have just designed a frame structure with SMRF. The out put of shear seams weird to me. Column reports design shear Av/s as 0.045. (Images are attached). but when i right click the member, it must show me the most critical case HIGHLIGHTED AUTOMATICALLY. But it highlights load combo 38 (auto-generated combos have been used) which reports Av/s as 0.038. And 0.045 value is at combo 32. Is their any logic behind it?? More over how to interpret this Av/s?? means 0.045 in kip-in units means what? How can i convert this into spacing??
  10. Waqas Haider
    Assalam o alaikum, ACI 21.11.1 tells about diaphragms in seismic zones. My building is in zone 4 and it is frame structure. i have provided SMRF. Is my slab going to act as Diaphragm? Since diaphragm means elements that transfer horizontal forces to vertical elements. and slab becomes cause of major horizontal inertial force and it transfer lateral forces to beams which transfer to columns. Is my slab diaphragm??
  11. Waqas Haider
    Assalam o alaikum. ACI 21.1.4.2 says, Specified compressive strength of concrete should not be less than 3000psi. I am confused whether is it just for FRAME MEMBERS and members resisting lateral forces or this is for all members i.e. slabs etc?
  12. Waqas Haider
    This is a critical analysis about approach of codes to reduce seismic forces in terms of over strength factor. overstrength theory.PDF
  13. Waqas Haider
    Assalam o alaikum all, How to decide what type of support should i provide at base of my building in ETABS?? If I provide pin support then sway of my building is 1.5 in and if i provide fix support then sway reduces to 0.9 in. Some one in this forum replied to a thread (I am unable to find the same thread) that if soil is stiff then we can provide fix support other wise pin support for loose soil. But I think it is upto our will then whether we provide fixed or hinged, sizes of our footings will become accordingly. In my case, building is in Quetta with BC 0.75 tsf. Suggest me please.
  14. Waqas Haider
    Really thanx a lot brother. You have presented wonderful explanation. Last day i have searched a lot over it and found a very useful document which challenges practice of reduction of forces due to this over strength. i m unable to attach the document at the moment. i am unable to find option of attaching. i will attach later. After reading your explanation, now i m clear completely. Jazak Allah.
  15. Waqas Haider
    Thanx. i have also taken Soure type A because quetta has suffered many erathquacks of more than 6.0 intensity. But i have chosen distance 10Km just to be conservative. I wil confirm what to take. i will search on references u gave.
  16. Waqas Haider
    Assalam o alaikum, What are near source factors for quetta?
  17. Waqas Haider
    Umar bhai, I want to model beam footing in SAFE. How to introduce beam along with footing pad?? I form a slab and draw a beam there. then i match bottom of beam with bottob of pad by adjusting insertion points. Is it correct modelling?
  18. Waqas Haider
    Assalam o alaikum Dear friends, I have two questions. I am to detail SMRF for zone 3. I was reading ACI 318-11 chapter 21. Now i have some confusion. 1) 21.1.1 says, ........................................For which, design forces , related to earth quack forces, have been determined on the bases of ENERGY DISSIPATION IN NONLINEAR RANGE OF RESPONSE. My question is What is meant by energy dissipation in non linear range of response?? What i have get through my research and understanding is, When Earth quack comes, due to inertia of building, it produces lateral forces in building. Due to these forces, structure deflect. If members of structure have big amount of reinforcement and cross sections, the force (or in other words energy) exerted by earth quack to the building will not yield the members and structure and members will restore to initial positions. In this case, members will not yield, and will remain in ELASTIC RANGE. But this makes structure too costly. On the other hand, if members have ability to yield but not fail, this energy will be used to yield the members and hence much of this energy will be dissipated in non linear range of members response. And we design structures for this because this is does not make structures too costly. So we design structure in the 2nd way. But due to this energy dissipation , structure is no longer in use at service stage and needs some or much requirement. We compromise over serviceability stage upto some extent and does not compromise over limit stage.. Is my concept right???? Is this the mean of energy dissipation in non linear range of response?? 2) Commentary of R 21.1.1 says, The integrity of the structure in the inelastic range of response should be maintained because the design earth quack forces, defined in documents such as ASCE/SEI 7, the IBC, the UBC and NEHRP provisions are considered less than those corresponding to linear response at the anticipated earthquack intensity. What does it mean?? Jazak Allah...
  19. Waqas Haider
    I will reply u in the evening.. But for the time being, i want to say Engr Uzair's a thousands of Likes because i strongly believe in what ever he has said about MANUAL CALCULATIONS. I also meant the same when i mean learn softwares. Learn the calculations manually so dat u may trace ur errors in modeling, reading results, and correcting design etc. Every software has its manual of background calculations. What i believe, to be a good designer, u must not only know DESIGN OF STRUCTURES. You must also know ANALYSIS OF STRUCTURES which is first part of design. What i suggest and try to do myself, Design a building in ETABS/SAP/Staad. and Then design each thing manually. I m doing these now a days. To your other questions, i will comment later as i am in office at the moment. The other thing i would like to say, this forum is really very very informative and helpful. Keep surfing it.
  20. Waqas Haider
    Assalam o alaikum... Can we model beam footing in safe? Please guide about procedure.
  21. Waqas Haider
    Assalam o alaikum. Kindly tell me whether SAFE has capability to do stability checks especially Sliding check and Overturning Check? Is yes then How? I model footing in safe and when i provide horizontal forces, my footing gets slide. Jazak Allah.
  22. Waqas Haider
    I am also a relatively fresh graduate. I completed my civil Engineering in 2013. The first and foremost thing u MUST know is ur interest. In what field you have Interest, learn about ur field the most u can. Because in student life, you have plenty of time to study and these BOOKISH KNOWLEDGE is going to benefit you ultimately. In field you see things practically but in student life, you must focus on your concepts etc so that they an benifi you when you are in field. The second thing is that, Try to learn maximum softwares. I am a structural design engineer so softwares for this field you MUST LEARN are, AUTOCAD, ETABS, SAP, STAAD, SAFE, MS OFFICE etc. MS Project and Primavera must also be learnt. There is one also software called TEKLA that you must learn. There are 2 years still left so you can learn these softwares well.. And the most important thing,,,,, GO AND JOIN PART TIME JOB/INTERNSHIP Paid/Unpaid with any of professional you get chance. Big names are not necessary. At start attach with any of professional you get chance.. but this will benefit you because when you will complete your degree, you will be already having professional experience. by the way what is ur university?
  23. Waqas Haider
    I have once Done this SRSS in previous office when our new building was to built near an existing building. So we did this under the title SEPERATION OF ADJACENT BUILDINGS from UBC97. Now in my case, my maximum inelastic displacement is 5.3 inch at roof. so SSRS gives me required separation 7.5 inches. Now i m worried it will seem weird to Provide 8" expansion joint because between corridors of upper stories etc, how will i cover it. More over, should i also provide expansion joint in footing?
  24. Waqas Haider
    Assalam o alaikum.. My building is in zone 3 and it has a 2 inch expansion joint in it... So my building is divided into two blocks. Now I m worried when my structure will go under seismic excitation, Whether both blocks of structure will behave exactly same and will have same frequency of vibrations or will both of them can move towards each other causing collision.. Maximum story displacement for my structure is 0.81 inch. and I have assigned it value of R as 8.5. So maximum inelastic response displacement will be 0.7 x 8.5 x 0.81 = 4.82 inch. which is more than expansion joint. Both of blocks are NOT SYMMETRICAL. So both may not be having same stiffness.
  25. Waqas Haider
    Now i m confused about some more things. UBC section 1612.3.1 provides with ASD load combinations i.e. D D+L D + W D + E/1.4 0.9D + E/1.4 D + 0.75L + 0.75 W D + 0.75L + 0.75 E/1.4 and for zone 3 and zone 4, two more special load combinations are given. 1.2D + f1 +1.0Em 0.9D + 1.0Em Now Section 1630.1.1 tells the following earth quack loads shall be used in load combinations... E = p.Eh + Ev Em = omega.Eh Here Em will be calculated to be used in special load combinations... And E = p.Eh + Ev will be used in normal ASD lod combinations in place of E. Am i right?? And if i select option INCLUDE SPECIAL SEISMIC LOAD EFFECTS in ETABS,, will it automatically include this E = p.Eh + Ev?? how can i define 1.2D + f1 +1.0Em, 0.9D + 1.0Em in etabs??
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