# Torque in an RC T-beam

1. Mar 14, 2012

### emilyy__

1. The problem statement, all variables and given/known data

For the reinforced concrete T-beam find what axial torque would cause a shear stress of vt = 0.37 N/mm2 to develop, and so make additional torsional reinforcement necessary according to BS 8110. Use the method indicated in Clause 2.4.4 of BS 8110 of distributing the torque in proportion to the hmax.hmin3 values for the component rectangles.

The T-beam is symetrical with dimensions: 850mm wide, 150mm deep flange, 250mm wide, 300mm deep web.

Ans. (5.4 kNm)

2. Relevant equations

vt = 2T / (hmin2(hmax - hmin/3))

Tn = T ((hmin3.hmax)n) / (Ʃ(((hmin3.hmax))

3. The attempt at a solution

I split the T-beam up in to 3 sections; 250 x 450 mm, 300 x 150 mm, 300 x 150 mm

However, I don't know how to find T given vt. The second equation above for Tn could be rearranged to give T in terms of Tn and then substituted into the first equation so that it can be solved for each component rectangle. However, I don't know how/if vt needs to split for the three component rectangles, or if this is even the correct way to solve this problem.

My lecturer is away for a few days so I currently can't go and ask him for advice.

Thanks for any help that can be provided.