Under which condition is a structure most likely to fail?

A structure is most likely to fail under maximum allowable load because this condition represents the highest level of stress that the materials and design are intended to withstand. At maximum capacity, the structural integrity is pushed to its limits. If any additional stress or unexpected load occurs beyond this threshold, the likelihood of structural failure increases significantly due to material fatigue or exceeding the material’s strength limits.

In normal operational conditions, structures are typically designed to perform effectively and safely, without approaching failure points. With no applied loads, there is no stress on the structure, thereby eliminating the risk of failure. Design safety factors incorporate a buffer by which structures can support loads beyond the expected maximum; thus, they are engineered to prevent failure well below the maximum allowable load. This indicates that to ensure structural safety, a considerable margin exists below those maximum limits.