Design of Beams Questions and Answers

Answer: A

Side face reinforcement is required when the depth exceeds 750 mm.

IS 456:2000, clause 26.5.1.3, requires side face reinforcement where the depth of the web of a beam exceeds 750 mm. It amounts to 0.1 percent of the web area, distributed equally on both faces, at a spacing not more than 300 mm or the web thickness, whichever is less. It controls shrinkage and temperature cracking on the deep sides of the beam.

450, 500 and 600 mm are not limits in the code.

Answer: B

The effective depth is D − d_t.

Effective depth is the distance from the extreme compression face to the centroid of the tension reinforcement. The effective cover to the tension steel, d_t, is the distance from the tension face to that centroid, so subtracting it from the overall depth D gives the effective depth.

The compression steel does not enter the definition, so subtracting d_c, alone, together with d_t, or as part of an average, gives a different dimension. D − d_c is the depth of the compression steel's centroid measured from the tension face.