ANCHORAGE ZONE REINFORCEMENT

The design of the anchorage zone reinforcement is computed using the force in the strands just before release.

Force in the strands before release is:

F_{p i} = 36 \times 98.7 \times 0.75 \times 1861.58 = 4961392 N = 4961.39 k N

The bursting resistance, P_r, should not be less than 4.0% of F_pi. [LRFD Art. 5.10.10.1 and Art. C3.4.3].

P_{r} = f_{s} A_{s} \geq 0.04 F_{p i} = 0.04 \times 4961.39 = 198.46 k N

Where:

where:

A_s = total area of transverse reinforcement located within the distance h/4 (as per 2002 Interim) from the end of the beam, mm²

f_s = stress in steel but not greater than 137.90 MPa,

Therefore, the required area of steel is:

A_{s} = \frac{198.46 \times 10^{3}}{137.90} = 1439.18 {m m}^{2}

So, at least 1439 mm² of vertical reinforcement should be provided at the end of the beam for a distance equal to one-fourth of the depth of the beam, h/4 = 1600/4 = 400 mm.

A_ps^* = Area of prestressing steel on the flexural tension side of the member modified to include the effect of the gradual buildup of the strand force in the development length.

= 4(98.71)=394.84 mm² reduced for development length

= 213.43 mm²