A reinforced concrete beam of rectangular section has a width of 300 mm and effective depth of 450 mm to the centroid of the tension reinforcements. The beam is reinforced for tension with 6 – 32 mm diameter bars placed in two layers with the outer bar layer having a depth of 478 mm to the centroid of the bar. The section is provided with 2 – 28 mm diameter compression reinforcements having a total bar covering of 65 mm. Use f’c = 34.5 MPa and fy = 415 MPa. Neglect the concrete displaced by the compression reinforcements and assume that the compression steel yields. Use the 2010 NSCP. a) Calculate the balanced steel ratio if the beam is singly reinforced. b) Calculate the steel ratio of a singly-reinforced section in order that the extreme tension steel will reach a strain of 0.005. c) Find the number of pieces of 32 mm diameter tension reinforcements for a doubly-reinforced section if reinforced with maximum tension steel for tension control.
A reinforced concrete beam of rectangular section has a width of 300 mm and effective depth of 450 mm to the centroid of the tension reinforcements. The beam is reinforced for tension with 6 – 32 mm diameter bars placed in two layers with the outer bar layer having a depth of 478 mm to the centroid of the bar. The section is provided with 2 – 28 mm diameter compression reinforcements having a total bar covering of 65 mm. Use f’c = 34.5 MPa and fy = 415 MPa. Neglect the concrete displaced by the compression reinforcements and assume that the compression steel yields. Use the 2010 NSCP.
a) Calculate the balanced steel ratio if the beam is singly reinforced.
b) Calculate the steel ratio of a singly-reinforced section in order that the extreme tension steel will reach a strain of 0.005. c) Find the number of pieces of 32 mm diameter tension reinforcements for a doubly-reinforced section if reinforced with maximum tension steel for tension control.
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