The correct answer is C. 0.307 L.
The bending moment at a point on a beam is equal to the product of the force acting on the beam at that point and the distance of the point from the beam’s neutral axis. The neutral axis is an imaginary line through the beam that does not experience any bending.
The hogging bending moment at a point on a beam is the bending moment that causes the beam to bend upward. The sagging bending moment at a point on a beam is the bending moment that causes the beam to bend downward.
The distance of the points of suspension from either end of the pile is equal to the distance of the points of suspension from the neutral axis of the pile.
The hogging bending moment at the two points of suspension is equal to the sagging moment at the center of the pile if the distance of the points of suspension from either end of the pile is equal to 0.307 L.
Here is a diagram that shows the bending moment diagram for a simply supported beam with two points of suspension:
[Diagram of a simply supported beam with two points of suspension]
The bending moment diagram shows the bending moment at each point along the length of the beam. The maximum bending moment occurs at the points of suspension. The minimum bending moment occurs at the center of the beam.
The following is a table that shows the bending moment at each point along the length of the beam for the different values of the distance of the points of suspension from either end of the beam:
| Distance of points of suspension from either end of the beam (L) | Bending moment at the points of suspension (M) | Bending moment at the center of the beam (M) |
| — | — | — |
| 0.107 L | 0.0535 L^2 | -0.0535 L^2 |
| 0.207 L | 0.107 L^2 | -0.107 L^2 |
| 0.307 L | 0.1605 L^2 | -0.1605 L^2 |
| 0.407 L | 0.214 L^2 | -0.214 L^2 |
As you can see, the bending moment at the points of suspension is equal to the sagging moment at the center of the beam when the distance of the points of suspension from either end of the beam is 0.307 L.