Thrust, Shear Force, and Bending Moment

An arch is a curved structure that is designed to bear loads and distribute them along its curved shape. It is commonly used in bridges, buildings, and other architectural structures. When a load is applied to an arch, it undergoes various internal forces and moments. The correct answer to the given question is option 'B', which states that an arch may be subjected to thrust, shear force, and bending moment. Let's understand each of these forces and moments in detail:

1. Thrust:
Thrust is a horizontal force that is exerted by an arch on its supports. It is caused by the weight of the arch and any additional loads applied to it. The thrust force is directed outward from the center of the arch and is resisted by the supports. It is essential to consider the thrust force while designing an arch to ensure its stability and prevent it from collapsing.

2. Shear Force:
Shear force is a force that acts parallel to the cross-sectional area of the arch. It occurs due to the vertical loads applied to the arch. Shear forces can cause the arch to deform or fail if they exceed the structural capacity of the arch. It is important to analyze and design the arch to withstand the shear forces and ensure its structural integrity.

3. Bending Moment:
Bending moment is a measure of the internal forces that cause an arch to bend or deform. It occurs when there is a moment applied to the arch, causing it to rotate. Bending moments can result in tension and compression forces within the arch, which need to be considered in its design. By analyzing the bending moments, the structural engineer can determine the required strength and dimensions of the arch to ensure its stability.

In summary, an arch is subjected to thrust, shear force, and bending moment when subjected to external loads. These forces and moments need to be carefully considered and analyzed during the design process to ensure the structural integrity and stability of the arch.