Rcc Structures Design - Study Mode
[#56] According to I.S.: 456, 1978 the thickness of reinforced concrete footing on piles at its edges, is kept less than
Correct Answer
(B) 30 cm
(G) 15 cm
[#57] For M 150 grade concrete (1 : 2 : 4) the moment of resistance factor is
Correct Answer
(B) 8.50
Explanation
Solution: M150 grade concrete refers to a mix ratio of 1:2:4 (Cement : Sand : Aggregate), where the characteristic compressive strength (fck) is 15 N/mm² . The moment of resistance factor (R) , also known as the limiting moment of resistance per unit width and square of effective depth, is a design parameter used in the limit state method for RCC beam design. According to standard design aids and tables based on IS 456:2000, for M15 grade concrete , the commonly referred value of the moment of resistance factor is approximately 8.50 . Option A: 0.87 is incorrect, as it usually refers to the partial safety factor or percentage of steel yield stress, not the moment of resistance. Option C: 7.50 and Option D: 5.80 are not the correct standard values for M150/M15 grade concrete. Therefore, the correct answer is Option B: 8.50 .
[#58] To have pressure wholly compressive under the base of a retaining wall of width b, the resultant of the weight of the wall and the pressure exerted by the retained, earth should have eccentricity not more than
Correct Answer
(D) $$frac{{ ext{b}}}{6}$$
[#59] For M 150 mix concrete, according to I.S. specifications, local bond stress, is
Correct Answer
(B) 10 kg/cm 2
[#60] A reinforced concrete cantilever beam is 3.6 m long, 25 cm wide and has its lever arm 40 cm. It carries a load of 1200 kg at its free end and vertical stirrups can carry 1800 kg. Assuming concrete to carry one-third of the diagonal tension and ignoring the weight of the beam, the number of shear stirrups required, is
Correct Answer
(C) 40