An existing

$1$

$2$

$"$

$$wide x

$2$

$8$

$"$

$$deep rectangular reinforced concrete beam is reinforced with

$3$

$,$

$$#

$9$

$$bottom rebars at the midspan

$($

in a single layer

$)$

$.$

$$Assume an effective depth, d

$=$

$2$

$4$

$.$

$5$

$$inches; fc

$\text{'}$

$=$

$6$

$0$

$0$

$0$

$$psi and fy

$=$

$6$

$0$

$.$

$0$

$0$

$0$

$$psi$.$

Using the flexural rebar specified in this existing reinforced concrete beam,

A

$)$

$$Calculate the design moment capacity in

$($

ft

$-$

kips

$)$

$$of the beam.

B

$)$

$$Show$,$ with aid of calculations, that the strength refuction factor is

$.$

$9$

$0$

$.$

$$

DO NOT check As

$,$

min.