In orbit, centrifugal acceleration upwards from your orbit velocity and gravity acceleration downwards vary. The net acceleration is what creates loads on the cable, so it must be calculated at each point. You must also add the loads from any equipment, cargo pods, etc. to the loads of the cable on itself. Our example of a steel column had the same area at all heights. This is not required. Instead, you find the loads at each point of the elevator cable, and give it enough area to support that load. Typically, for a hanging cable, the load is greatest at orbit height, since the whole cable and all the attached items are hanging from that point. As you go down, there is less cable and attachments below a given point, and so the cable area can be lower. This results in a tapered cable.

Structures can theoretically be rigid (break before bending) or flexible (bend before breaking). Real objects like a piece of lumber are somewhere between. They can bend a little before breaking. For a real structure, the question is what forces create bending and breaking loads, and how much movement is allowed from these loads. Generally the lower the ratio of length to width, the more rigid and less flexible a structure is. Thus tall buildings must have a certain width in relation to height. If they are too thin, wind loads would bend them like a tree, and make people sick or interfere with the elevator shafts.

Loads can be constant (static) or variable (dynamic). In a space elevator, a static load would be the Earth's gravity acting on the structural mass. Variable loads would be the Moon and Sun's gravity, since their distance and direction varies with time, and acceleration or deceleration of cargo pods. Obviously the structure must be designed for peak loads combined, plus a multiplier above that, called a "Factor of Safety". Dynamic loads which are sideways to the structure can cause vibration (rhythmic bending). If the timing of the loads matches the vibration period, the bending can become larger each time, unless damping is designed into the structure.

In modern design, all the loads are analyzed using structural analysis software or a custom simulation. If an initial design gives an unsatisfactory result, it can be modified and analyzed multiple times until a good result is obtained. During the early concept exploration phase of a project, simpler analytical formulas and approximations can be used.



