What Modifier Should We Take For Servicibility Check (Deflection And Drift)
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 tak
Many engineers are confused with stiffness modifiers stuff in ETABS including me. Let me add my cent here.
1. Any reasonable set of stiffness can be used as explained in ACI 318.
2. You have to determine what type of frame you are analyzing; braced or un-braced
3. Whats the analysis type? Strength, service?
4. Code allows use of 0.35,0.7 factors on inertia in chapter 10 of ACI 318 for slenderness effects.
5. Also according to code, you can use the above same model in step 4 f
