A concrete box girder bridge has the rectangular x-section. The box is prismatic and considered thin-walled. It span is L=48m and simply supported at points A,B,C and D. The supports are assume to be able to transfer tensile forces. Diaphragms(x-beams) have been constructed at AB and CD to transfer the support reactions into the hollow x-section. Support A undergoes a settlement as a result of which a torsional moment is induced in the beam. The maximum shear stress due to this torsional moment is 1N/sq. mm. Use G=13.5GPa for shear modulus.
1.Determine the torsional moment in the hollow x-section
2.Determine the settlement of support A.
3.Determine the support reactions due to the settlement of support A.