This set of Repair and Rehabilitation of Structures Multiple Choice Questions & Answers (MCQs) focuses on “Common Crack Patterns in Buildings”.
1. In masonry structures shear cracks occurs in ceiling level in __________
a) Main walls
b) Cross walls
c) Partition walls
d) RCC walls
View Answer
Explanation: The roof slab undergoes alternate contraction and expansion in load bearing structures due to thermal variations and as a result of this shear cracks occurs in cross walls due to inadequate thermal insulation or cover for the roof slab.
2. A layer of material with good insulating property and also with less reflectivity coefficient is coated over the flat roof stabs.
a) True
b) False
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Explanation: Usually good insulating material with high reflectivity coefficient is used as a coat over the flat roof stabs because only those materials have a good heat reducing capacity and also at the same time they give good wearing and draining surface on the terrace.
3. Thermal coefficient of concrete is __________ that of brickwork.
a) thrice
b) four times
c) twice
d) half
View Answer
Explanation: Thermal coefficient of concrete is twice as that of brickwork and this causes differential expansion and contraction which lead to the formation of horizontal cracks at the base of parapet wall.
4. The plastering for masonry and RCC works should be made discontinuous by providing V-groove in plaster.
a) True
b) False
View Answer
Explanation: When a V-groove is provided in-between the plastering works for masonry and RCC works so that cracks will be made to conceal behind the groove thereby preventing the extension of cracks to the other work.
5. Horizontal cracks are mostly confined to the lower most storey below slab level.
a) True
b) False
View Answer
Explanation: Horizontal cracks are mostly occurs in the top most storey below slab level because of the light vertical load encountered on the wall due to which the slab lifts up without any restraint whereas the lifting of corners in lower most storey is prevented by the vertical load on upper stories.
6. When large span of the slabs cannot be avoided the deflection of the slabs can be reduced by increasing the _________ of the slab.
a) length
b) depth
c) breadth
d) area
View Answer
Explanation: When the span of the slabs cannot be restricted due to various reason then the deflection of the slabs can reduced by increasing the depth of the slab thereby increasing their stiffness which in turn reduces the formation of cracks.
7. Diagonal cracks are formed in the cross walls of _____________ building of load bearing structure.
a) high rise
b) double storey
c) single storey
d) multi storey
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Explanation: These diagonal cracks that are formed in the cross walls of multi storey building of load bearing structure due to the differential strain developed in the internal and external load bearing walls into which the cross walls are bonded. And also when the walls are built with variation in stress at different parts, then excessive shear stress is developed leading to the crack formation.
8. Vertical cracks occurs in the topmost storey of the building at the __________
a) corner
b) edge
c) centre
d) bottom
View Answer
Explanation: The vertical cracks occurs at the corner in the top most storey of the building due to thermal contraction and also due to shrinkage of RCC roof slab on initial drying thereby exerting an inward pull on the walls in both the direction.
9. Vertical cracks are most common around stair case and balcony openings.
a) True
b) False
View Answer
Explanation: These vertical cracks that more common in the area around the staircase and balcony openings are due to drying shrinkage and also due to thermal movement that takes place in the building. These cracks can be prevented by delaying the time taken to plaster so that they undergo initial shrinkage.
10. Vertical cracks in the side walls at the corner of long building are more common if the building is constructed in cold weather.
a) True
b) False
View Answer
Explanation: When the buildings are constructed during cold weather, the chances of moisture penetration are greater leading to the formation of vertical cracks in the corner of a long building.
Sanfoundry Global Education & Learning Series – Repair and Rehabilitation of Structures.
To practice all areas of Repair and Rehabilitation of Structures, here is complete set of Multiple Choice Questions and Answers.
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