kHURRAM ALI

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.

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

you can find manual calculation in taranath book

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

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.

aslamwalekum to all etabs gives only boundary element length not steel , can anybody told me how to calculate boundary element steel for shear walls

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.

thanks

yes i have that book of 2008 ,remind me on my email engkhurramali@gmai.com , i will send you

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

thanks

thanks to all, is there is any concept of using shear plate in these beams.

Can somebody help me to design load bearing strucutre, BS code is only code writen for massonary strucuture , i am also looking for a book in which load bearing design example are provided, so if somebody have any information than inform me.

also try PDISP software

can somebody explain how to design load bearing strucuter , what software i should use?

aslamwalekum to all, many time it happens that beam that joining two shear wall failed in shear, if i increase its depth or width it takes more shear force than bofore and again fail and due to door opening i cant further increase its depth and shear wall thickness thickness is limited to 18 in so i cant increase its width also, can somebody guide me is there any method by which i can design this beam

kindly donot write text in blue color ,its really hard for me to read, may be its beacause of color blindness, so please its a request donot use blue color font

i think the data coming out from wind tunnel test can be incorporated in etabs by using eccentricity overrides for wind load cases, correct me if i wrong.

L\ 400 limit use for wind drift

you have to consider yield line theory for non rectangular slab

i think base shear depends on response resistance factor R that is taken in static load case for earthquake ,greater the R the base shear will be multiple of it.

is there any way of finding torsion constant in ETABS

for distribution of steel in beam of etabs PLEASE DOWNLOADTHIS IMAGE