O/S #45 "Shear Stress due to Shear Force and Torsion Exceeds Maximum Allowed". 5

[Ganesh Persaud]

Hello everyone,

I’m working on a concrete frame model in Etabs and came across this failure error.

O/S #45 "Shear Stress due to Shear Force and Torsion Exceeds Maximum Allowed".

How can I deal with this if the depth of the section is limited.

Thank you.

 

[BridgeSmith]

I don't know anything about the program, but if the loading and analysis are accurate, then you need to provide more shear capacity. The ways I can think of to accomplish this would be (in no particular order): 1) Use higher strength concrete. 2) Increase the cross section size - if you can't go deeper, go wider. 3) Increase the shear reinforcement.

 

[Ganesh Persaud]

Thanks @hotrod10
This was very helpful.

 

[rapt]

If it is exceeding Vumax, adding shear reinforcement is not an option. It is an absolute maximum shear stress.

Increase concrete strength will work up to a point. Many codes limit the maximum concrete strength.

 

[hokie66]

The first thing you need to do is to understand what the program is doing and telling you. Some hand calculations would help to shed light on the issues.

 

[Agent666]

Also review your code provisions regarding whether or not you require torsion reinforcement for compatibility or equilibrium purposes.

If its only required for compatibility purposes, often codes will let you set the torsional stiffness to zero for the analysis, provided (typically) that some minimum level of torsion reinforcement is provided, and that all longitudinal reinforcement is appropriately developed/anchored.

What this recognises is that the member can crack under torsion and this release/redistribution of the torsional forces does not impact on the stability of the system.

You didn't say what code you are working to so I can't give you any specifics, but I believe ACI318 adopts this type of approach.