What condition is indicated by the statement "the structure is statically determinate"?

A structure being described as "statically determinate" means that the internal forces and reactions can be determined solely from the equations of static equilibrium. This can be expressed mathematically through a specific relationship between the number of members, joints, and the overall stability of the structure.

In the context of planar structures, a statically determinate structure adheres to the formula: the number of members equals two times the number of joints minus three. This accounts for the fact that each joint can provide two reactions (typically in the x and y directions), and three equations of equilibrium apply to the whole structure: summing forces in the x-direction, summing forces in the y-direction, and summing moments.

Choosing the other answer options may reflect common misconceptions. While the relationship of members and joints in the first option suggests a static equilibrium, it does not capture the necessary conditions for a statically determinate structure. The statement that a structure can only support static loads directly focuses on load types rather than the determinate nature of structural forces. Lastly, while stating that members equal joints may hold for some trivial structures, it does not encompass the more complex considerations of structural relationships necessary for determining static determinacy.

Thus, the correct choice directly aligns with the