A rectangular beam 250 mm wide, 500 mm deep is reinforced at the bottom with 4-20-mm-diameter bars and at the top with 2-16-mm bars. Concrete cover to bar centroid at the top is 80 mm and at the bottom is 70 mm. Use concrete strength f’c = 21 MPa and steel yield strength fy = 350 MPa for 20-mm bars and fy = 275 MPa for 16-mm bars. 1. Determine the maximum steel ratio if the beam is singly reinforced in negative bending with the given material strengths and the tensile strain is limited to 0.004 upon crushing of concrete. Write the answer in 5 decimal places only.
A rectangular beam 250 mm wide, 500 mm deep is reinforced at the bottom with 4-20-mm-diameter bars and at the top with 2-16-mm bars. Concrete cover to bar centroid at the top is 80 mm and at the bottom is 70 mm. Use concrete strength f’c = 21 MPa and steel yield strength fy = 350 MPa for 20-mm bars and fy = 275 MPa for 16-mm bars.
1. Determine the maximum steel ratio if the beam is singly reinforced in negative bending with the given material strengths and the tensile strain is limited to 0.004 upon crushing of concrete. Write the answer in 5 decimal places only.
2. Determine the maximum steel ratio if the beam is singly reinforced in positive bending with the given material strengths and the tensile strain is limited to 0.005 upon crushing of concrete. Write the answer in 5 decimal places only.
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