kHURRAM ALI

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About kHURRAM ALI

  • Rank
    Lieutenant

Profile Information

  • Gender
    Male
  • Location
    karachi pakistan
  • University
    NED universisty
  • Employer
    structure engineer in BEG associates
  • Interests
    civil engineering

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  1. HOW CAN I GET THESE VALUES IN ETABS
  2. aslamwalekum to all, when we need semi rigid diaphragm , i normaly take rigid diaphram for beam slab system , i got a vetting project (model made on ETABS 2016) , in which flat slab are used and semi rigid diaphram is assign , A/c to IBC 2006 , concrete slab with thickness more than 1.5 in , not consider as flexible diaphram , here is the code refrence. ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 1613.6.1 Assumption of flexible diaphragm. Add the following text at the end of Section 12.3.1.1 of ASCE 7: Diaphragms constructed of wood structural panels or untopped steel decking shall also be permitted to be idealized as flexible, provided all of the following conditions are met: 1. Toppings of concrete or similar materials are not placed over wood structural panel diaphragms except for nonstructural toppings no greater than 11/2 inches (38 mm) thick. 2. Each line of vertical elements of the lateral- force-resisting system complies with the allowable story drift of Table 12.12-1. 3. Vertical elements of the lateral-force-resisting system are light-framed walls sheathed with wood structural panels rated for shear resistance or steel sheets. 4. Portions of wood structural panel diaphragms that cantilever beyond the vertical elements of the lateral- force-resisting system are designed in accordance with Section 2305.2.5 of the International Building Code ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' here in my case slab is 8 in thick , so can it be act as flexible diaphragm. i belive for metal decking , i can use semi rigid diaphram , but not for 8 in thick flat slab
  3. ASLAMWALEKUM IN ETAB MODEL THE SECONDARY BEAM BREAK ON PRIMARY BEAM ,SO THAT POINT LOAD OF SECONDARY BEAM CAN APPLY ON PRIMARY BEAM , BUT IF TWO BEAMS OF SAME STIFFNESS , SPAN AND LOADING ARE INTERSECTING AT THEIR MID POINTS , HOW TO DECIDE WHICH ONE WILL BE PRIMARY AND SECONDARY BEAM , I AM ATTACHING THE ETABS PALN
  4. i have posted a few lines mention in the ACI 318 code refrence R10.10.4.1 below ,please review and confirm for 43% increase in service modifires , i belive drift is also a kind of deflection and deflection always calculate at service level , thats why i think for drift modifiers will not be same as they use for ultimate design the code lines are Section 10.10 provides requirements for strength and assumes frame analyses will be carried out using factored loads. Analyses of deflections, vibrations, and building periods are needed at various service (unfactored) load levels10.37,10.38 to determine the serviceability of the structure and to estimate the wind forces in wind tunnel laboratories. The moments of inertia of the structural members in the service load analyses should be representative of the degree of cracking at the various service load levels investigated. Unless a more accurate estimate of the degree of cracking at service load level is available, it is satisfactory to use 1.0/0.70 = 1.43 times the moments of inertia given here for service load analyses.
  5. aslamwalekum we normally use special seismic option for zone 3 or 4 , but then why we donts use for zoe 2B , when we use special seismic option then load combination of 1.2 D AND 1.2 E , IS THIS IS TRUE OR WRONG
  6. you can find manual calculation in taranath book
  7. aslamwalekum , when we design reinforced concrete elements , for beam we take 0.35 , for column and wall we take 0.7 and for slabs we take 0.25 as modifiers , but i read in aci that for servicibilty analysis these modifiers has to increase by 43% which means for beam it become 0.5 , for column and shear walls it become 1.0 and for slab it become 0.35 , by doing this model drift and deflection both reduce to almost half of its original value. one thing more when we do manual check we dont take crack sections , for e.g for simply supported beam the deflection is 5\384 WL^4\EI , here the I (inertia ) is not the for the crack section ,its for the uncracked section , so what modifiers should be use 0.35 or 0.5 or 1.0
  8. thanks for the refrence, but i still dont know how to calculate boundary element steel , as etabs give just length for boundary element , can you show me the formula to caclculate steel for boundary element ,if wall is 8in thick ,5ft long ,10ft height and 1ft boundary element length given by etabs and ratio is 0.25% for the wall.
  9. aslamwalekum to all etabs gives only boundary element length not steel , can anybody told me how to calculate boundary element steel for shear walls
  10. many engineers in pakistan use this practice when modeling a beam in etabs , that if beam is fail in shear and torsion than they just change the torsion modifier from 0.35 to 0.001 , and then redesign that beam , after designing that beam appear to be pass in shear and torsion , also showing zero r/f required for this particular beam. i want to know that is this the right way to model beam, does code provide such kind of solution ,or it has no meaning.
  11. yes i have that book of 2008 ,remind me on my email engkhurramali@gmai.com , i will send you
  12. use alignment charts to compare stiffness of beam and column with the help of K value if K value is near to 0.5 it is consider to be fix or if it is 1 then it is near to pin
  13. thanks to all, is there is any concept of using shear plate in these beams.