Select the most appropriate answer for the following questions.

1.

In a reinforced concrete section the compressive strength of concrete is 3500 psi. The value of β₁ for the calculations will be taken as

(i)   0.6              

(ii) 0.85              

(iii) 0.9                

(iv) none of these

2.

The total depth of a beam is 10 in. It has one layer of steel (3 bars of #4) in the tension zone. If the clear cover is 1.5 in. the effective depth will be equal to

(i)   8.25 in.         

(ii) 8.5 in.            

(iii) 9.5 in.           

(iv) none of these

3.

A singly reinforced section has one layer of reinforcing bars. The effective depth is 12 in. and the depth of neutral axis is 4 in. from the top edge. The strain developed in steel will be  equal to

(i)   0.005           

(ii) 0.006             

(iii) 0.003             

(iv) none of these

4

A singly reinforced section of width 8 in. is to be provided with bars of #10. The minimum clear distance between two steel bars should be

(i)   0.75 in.           

(ii) 1.27 in.          

(iii) 1 in.            

(iv) 0.5 in.

5.

As per ACI 318, the value of strength reduction factor for flexural members is taken as

(i) 0.6                 

(ii) 0.9                

(iii) 0.65             

(iv) 1.4

6.

The value of average stress adopted for equivalent stress block is

(i) 0.55 f^'_c                  

(ii) 0.85 f^'_c            

(iii) 0.95 f^'_c                  

(iv) 0.45 f^'_c