Concrete Technology (61-80)

Updated: Apr 9, 2020

61. Minimum pitch of transverse reinforcement in a column is lesser of the above three values

62. Maximum distance between expansion joints in structures as per IS : 456 - 1978

45 m

63. A continuous beam is deemed to be a deep beam when the ratio of effective span to overall depth (1/D) is less than 2.5

64. Critical section for shear in case of flat slabs is at a distance of d/2 from periphery of column/capital/ drop panel

65. Minimum thickness of load bearing RCC wall should be 100 mm

66. If the storey height is equal to length of RCC wall, the percentage increase in

strength is 10

67. In reinforced concrete footing on soil, the minimum thickness at edge should not be less than 150 mm

68. The slab is designed as one way if the ratio of long span to short span is greater than 2

69. Ratio of permissible stress in direct compression and bending compression is

less than 1

70. A higher modular ratio shows lower compressive strength of concrete

71. The average permissible stress in bond for plain bars in tension is increased by 25% for bars in compression

72. The modular ratio m in terms of permissible compressive stress due to bending in concrete σcbc (in N/mm2) is given by

73. The expression for modular ratio

where σcbc is the permissible compressive stress due to bending in concrete in N/mm2

partially takes into account the long term effect such as creep

74. In working stress design, permissible bond stress in the case of deformed bars is more than that in plain bars by 40%

75. The main reason for providing number of reinforcing bars at a support in a simply supported beam is to resist in that zone bond stress

76. Half of the main steel in a simply supported slab is bent up near the support at a distance of x from the centre of slab bearing where x is equal to 1/7

77. When shear stress exceeds the permissible limit in a slab, then it is reduced by

increasing the depth

78. If the size of panel in a flat slab is 6m x 6m, then as per Indian Standard Code, the widths of column strip and middle strip are 3.0 m and 3.0 m

79. For a slab supported on its four edges with corners held down and loaded uniformly,the Marcus correction factor to the moments obtained by Grashoff Rankine's theory is always less than 1

80. The permissible diagonal tensile stress in reinforced brick work is about 0.1 N/mm2

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