What is the measure of deformation produced in a member by a load?

The measure of deformation produced in a member by a load is known as strain. Strain quantifies how much a material has deformed in relation to its original length due to an applied force or load. It is typically expressed as a ratio or a percentage, indicating the change in length divided by the original length of the material.

When a force is applied to a structural member, it experiences deformation, leading to strain. This concept is crucial in engineering and material science, as understanding how materials respond under different loads helps in the design of safe and effective structures.

Stress, on the other hand, is the force applied per unit area within materials, and while it is related to strain, it does not measure the deformation itself. Allowable stress refers to the maximum stress that a material can sustain without failure, while ultimate stress indicates the maximum stress it can withstand before failure occurs. These concepts are important for assessing the performance of materials under load, but they do not directly measure the deformation produced by the load itself.