Question

An ____________ is in a pure compression form.

(a) arch

(b) hinge

(c) rigid

(d) truss

The question was asked in quiz.

The origin of the question is Roof Covering, Sloping Roof & Flat Terraced Roof topic in division Rules and Methods of Measurement of Civil Engineering Drawing

Answer 1

Correct option is (a) arch

To elaborate: 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.