Torsional stiffness of beam elements 1

[bkj789]

Hello, I am a junior engineer working on a fairly large and involved reinforced concrete beams and columns system. My question arises from the fact that a number of the main beams have significant torsional loads. I think that this means I will have to run my model at least twice to account for this. Once using uncracked section properties and a second time using the cracked section properties on the beams that experience torsion greater than the cracking torsion for the beam. Am I overcomplicating things or is this the proper course of action to take in this situation?

 

[Spirit]

bkj789,

in my view, if these beams are to experience torsion greater than the cracking torsion loads, they are to be resized in order to whitstand these loads without cracking, or the structure's layout has to be revised. I wouldn't be comfortable with building a structure that is expected to be working in a post-critical load environment, at least in the concrete construction field.

Just my two cents, of course.

Regards,


Spirit



'Ability is 10% inspiration and 90% perspiration.'

 

[WillisV]

Actually it is not that uncommon in concrete construction to assume that the beams framing into the girders crack at the top thus relieving the torsion placed onto the girders. The beams are of course designed as simply supported, and some smaller bars are placed at the top on the ends to keep these cracks from opening up too wide.