Concrete Technology (321-340)

Updated: Apr 30, 2020

321. For a prestressed concrete bridge beam, a minimum clear spacing of the cable or group of cables should be 40 mm

322. Drops are provided in flat slab to resist shear

323.Assertion A : The behaviour of an over reinforced beam is more ductile than that of an under reinforced beam.

Reason R : Over reinforced beam contains more steel and steel is more

ductile than concrete

A is false but R is true

324. Flexural collapse in over reinforced beams is due to primary compression failure


In the P.S.C. beam shown in Fig. 14.6, fck = 45 Mpa and it supports a u.d.l. of 15

kN/m including self weight. It is prestressed by a parabolic cable carrying

an effective prestress of 200 kN. The shear resistance of uncracked section at

the support will be 94.5 kN

326.In the case of a P.S.C. beam, to satisfy the Limit State of Serviceability in cracking, match List I with List II and select the correct answer using the codes given below the Lists

327. A reinforced cantilever beam of span 4 m, has a cross-section of 150x500 mm. If checked for lateral stability and deflection, the beam will

fail in both deflection and lateral stability

328. In an RCC beam, side face reinforcement is provided if its depth exceeds

750 mm

329. The maximum spacing of vertical reinforcement in RCC wall should not

exceed 3 times the thickness of wall

330. In a reinforced concrete retaining wall, a shear key is provided, if the retaining wall is not safe against sliding.

331. The magnitude of loss of prestress due to relaxation of steel is in the range of

2 to 8%

332. IRC prescribes Coulomb's theory of earth pressure for the design of abutments and wing walls. The ratio of height of centre of pressure above the bottom to the height of the wall is equal to 0.33

333. In the limit state method of design, the failure criterion for reinforced concrete beams and columns is Maximum principal strain theory

334. Combination of partial safety factors for loads under limit state of collapse and limit state of serviceability will be 1.5 (D.L. + L.L) or 1.5 (D.L + W.L)

or 1.2 (D.L. + L.L + W.L) and 1.0 (D.L + L.L) or 1.0 (D.L + W.L) or D.L + 0.8 (L.L + W.L)

335. The bending moment coefficients for continuous RC slabs in IS 456-1978 code is based on Yield-line theory

336. The sum of nodal forces at any yield line intersection in a slab is zero

337. The assumption that the plane sections normal before bending remain normal after bending is used in both working stress and limit-state

methods of design

338. The ratio of the lateral pressure of the bulk storage material at the time of emptying to that at the time of filling is greater than one

339. In the design of prestressed concrete structures, which of the following limit

states will come under the limit states of serviceability?


2. Cracking

340. Given that Φ is the angle of internal friction, 'p' is' the safe bearing capacity

and γ is the unit weight of soil, the minimum depth of foundation of a

masonry footing is given by

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