71. The weight of reinforced concrete, is generally taken as

A. 2200 kg/m3

B. 2300 kg/m3

C. 2400 kg/m3

D. 2500 kg/m3

72. If the permissible compressive stress for a concrete in bending i C kg/m2, the modular ratio is

A. 2800/C

B. 2300/2C

C. 2800/3C

D. 2800/C2.

73. For a continuous slab supported at ends and carried over intermediate beams,

A. w/2 Max. sagging B.M. for the end spans =0

B. Max. hogging B.M. over penultimate supports w12

C.w12Max. sagging B.M. for the interior spans + --12

D. All the above.

74. For a continuous floor slab supported on beams, the ratio of end span Length and intermediate span length, is

A.0.6

B.0.7

C.0.8

D. 0:9.

75. If the length of an intermediate span of a continuous slab is 5m, the length of the end span is kept

A. 4.5 m

B. 4.0 m

C. 3.5 m

D. 3.0 m

76. If the ratio of long and short spans of a two way slab with corners held down is r, the actual reduction of B.M. is given by

A. 1r7-2 M

B. 1 +r2r2 M

C. r21 r3

D. -5 r2 M

77. According to I.S. : 456, slabs which span in two directions with corners held down, are assumed to be divided in each direction into middle strips and edge strips such that the width of the middle strip, is

A. half of the width of the slab

B. two-third of the width of the slab

C. three-fourth of the width of the slab

D. four-fifth of the width of the slab

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