集中荷重にさらされたケーブル

Cables are assumed to be flexible, allowing them to change shape under applied loads, and inextensible, meaning their length does not change under tension. Additionally, the cable's weight is assumed negligible, so it does not significantly impact the cable's behavior during analysis of concentrated loads.

A free-body diagram of the entire cable often yields more unknown reaction components than available equilibrium equations. By isolating a segment at a known distance and applying the moment equilibrium equation at that point, an additional equation is obtained, allowing the system to be solved for reaction forces and tensions.

A cable subjected to concentrated loads forms several straight-line segments between load points and supports. Each segment maintains constant tensile force and connects at the load application points, creating a polygonal shape that reflects the distribution and magnitude of the applied vertical loads.

Tension in a cable segment is maximum when the segment has the largest inclination angle relative to the horizontal. Segments with steeper angles experience greater tensile forces because they must support larger vertical load components while maintaining static equilibrium across the cable system.

Once reaction forces are known from equilibrium equations, vertical distances from support A to each concentrated load are determined by recalling the equilibrium equation that states the sum of vertical forces acting on the cable must equal zero. This allows calculation of the cable's vertical geometry.

To calculate tension in each cable segment, you need the reaction forces at supports, the horizontal distances between loads, and the vertical distances from support to each load point. With these values, the tension in each segment can be computed, with maximum tension occurring in segments with the largest inclination angle.

When the number of unknown reaction components exceeds available equilibrium equations, applying the moment equilibrium equation at a point on the cable segment provides an additional independent equation. This transforms the indeterminate system into a determinate one, enabling complete solution for all reaction forces and segment tensions.