Question

Why is it important for the sheeting ribs to be parallel to the UB?

Thats the entire question.

Answer 1

it important for the sheeting ribs to be parallel to the UB because it provide stiffness in the transverse direction. and it is used to transfer the traffic load much more efficiently in the transverse direction. and to provide much higher flexural and torsional rigidity in the longitudinal direction and shear surface become approximately horizontal and provides greater stiffness.

The tension stress is eliminated in the tension side of the slab and Long slab spans can be constructed and as a result we get Lighter and stiffer slab than an equivalent flat slab.the transverse beam stiffness increased, so bending moment of beam will be increased.