Which of the following correctly represents the ultimate tensile force (T_u ) in the tensile reinforcement (A_s ) of a singly reinforced beam at the ultimate limit state of flexure, considering the characteristic yield strength of steel (f_y )?

Explanation:

At the ultimate limit state of flexure for a singly reinforced beam, the ultimate tensile force (Tu) in the tensile reinforcement (As) is derived from the stress-strain relationship of steel in tension at its yield strength.

• f_y is the characteristic yield strength of steel.

• A_s is the area of tensile reinforcement.

At ultimate limit state:

• The stress in the tensile reinforcement is typically assumed to be 0.87 fy (the stress corresponding to the yield strength of steel).

• The tensile force in the reinforcement, Tu, is given by: Tu = 0.87 fy As​​

Additional Information

Singly Reinforced Beam:

• A singly reinforced beam is a beam where the tensile reinforcement is placed in the bottom (tensile region) of the beam, while the compression reinforcement is either absent or negligible.

• The beam is subjected to bending, and the tensile reinforcement helps resist the bending stress.