# Civil Engineering Drawing Questions and Answers – Jack Arched and Flat Terraced Roof

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This set of Civil Engineering Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Jack Arched and Flat Terraced Roof”.

1. Unlike regular arches, jack arches are not semicircular in form.
a) False
b) True

Explanation: Figure showing jack arch

2. An apartment (or flat in Britain and most other Common wealth countries) is a self-contained housing unit that occupies only part of a building.
a) True
b) False

Explanation: Such a building may be called an apartment building, apartment complex, flat complex, block of flats, tower block, high-rise or, occasionally, mansion block (in British English), especially if it consists of many apartments for rent. In Scotland, it is called a block of flats or, if it is a traditional sandstone building, a tenement, a term which has a pejorative connotation in the United States. Apartments may be owned by an owner/occupier, by leasehold tenure or rented by tenants (two types of housing tenure).

3. The most reliable estimate is Cube rate estimate.
a) True
b) False

Explanation: The most reliable estimate is detailed estimate. Detailed estimating, sometimes referred to as “Prime Cost”, “Bottoms Up” or “Grass Roots” estimating requires a thorough and detailed analysis of all the tasks required to deliver a project or product. The estimate can be developed using a combination of estimating methods.
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4. The damp proof course (D.P.C.) is measured in Sq m.
a) True
b) False

Explanation: General principles to be observed while laying damp proof course are:
i. The DPC should cover full thickness of walls excluding rendering.
ii. The mortar bed upon which the DPC is to be laid should be made level, even and free from projections. Uneven base is likely to cause damage to DPC.
iii. When a horizontal DPC is to be continued up a vertical face a cement concrete fillet 75mm in radius should be provided at the junction prior to the treatment.
iv. Each DPC should be placed in correct relation to other DPC so as to ensure complete and continuous barrier to the passage of water from floors, walls or roof.

5. The fixed arch is most often used in reinforced concrete bridge and tunnel construction, where the spans are short.
a) False
b) True

Explanation: Because it is subject to additional internal stress caused by thermal expansion and contraction, this type of arch is considered to be statically indeterminate.

6. An arch is a pure compression form.
a) True
b) False

Explanation: It can span a large area by resolving forces into compressive stresses and, in turn eliminating tensile stresses. This is sometimes referred to as arch action. As the forces in the arch are carried to the ground, the arch will push outward at the base, called thrust. As the rise, or height of the arch decreases, the outward thrust increases. In order to maintain arch action and prevent the arch from collapsing, the thrust needs to be restrained, either with internal ties or external bracing, such as abutments.

7. A ____________ is a structural element in masonry construction that provides support at openings in the masonry. Alternate names are “flat arch” and “straight arch”.
a) round arch
b) equilateral arch
c) flamboyant arch
d) jack arch

Explanation: Unlike regular arches, jack arches are not semicircular in form. Instead, they are flat in profile and are used under the same circumstances as lintels. Unlike lintels, which are subject to bending stress, jack arches are composed of individual masonry elements cut or formed into a wedge shape that efficiently uses the compressive strength of the masonry in the same manner as a regular arch.

8. Which type of arch is shown below?

a) Round arch, or semi-circular arch
b) Lancet arch
c) Equilateral pointed arch
d) Reverse ogee arch

Explanation: The simplest shape is the long opening with a pointed arch known in England as the lancet. Lancet openings are often grouped, usually as a cluster of three or five. Lancet openings may be very narrow and steeply pointed. Lancet arches are typically defined as two-centered arches whose radii are larger than the arch’s span.

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