It is noticed that when ductile design is done (even only near supports), that there is a big jump in shears in the “Mid” span. Let me know if this is unexpected
Reply: For Non ductile and Ductile beam, Shear force at end is depend on the following settings,
As per above settings, for ductile beam the end shear would be considered as per 2xDepth of beam. For Non ductile it would be L/3. It is purely depend on the depth of the beam and length of the Beam. If the Beam L/3 is more than the 2xD then it is possible that at mid zones shear would be less as compared to ductile beam.
RCDC provides following two options for Sway shear check in Beam design.
For Ductile Shear at Support : Sway shear would be calculated only at ends.
For At All Station : Sway shear would be calculated at all 13 stations for which beam is designed. Maximum of Shear due to sway at mid zones would be considered as critical in design.
It is not clearly mentioned in the IS code up to which location the sway shear is to be considered. The Option is added as per our discussion with the IIT professors. Professors is in opinion that, Earthquake loads are impact loads and shear due to Lateral loads might extend up to the mid span of beam. To avoid this kind on un-foreseen condition he has suggested us to add the option of checking sway shear at all stations. Thus, these two options are available in RCDC. But It would be user’s choice.