What determines the number of cycles during testing of dynamic construction joints?

The correct answer focuses on the rate of movement, which directly influences how a dynamic construction joint is tested. In the context of firestop systems, dynamic joints are designed to accommodate movement resulting from building expansion and contraction, seismic activity, or differential settling. The number of cycles during testing is determined by simulating the actual conditions under which these joints will function in service.

The rate of movement takes into account how frequently the joint will open and close during its operational life. For example, if a joint is expected to experience rapid or significant movement, the testing may require a higher number of cycles to ensure that the firestop system will maintain its integrity and effectiveness throughout that range of movement.

Other factors, while relevant to the overall design and performance of the joint, do not directly dictate the number of cycles for testing as precisely as the rate of movement. Design specifications provide guidelines, material types influence performance characteristics, and theoretical limits might set boundaries, but the actual testing cycles are predominantly based on the anticipated movement scenarios. This relationship ensures that the firestop systems installed will effectively perform under expected dynamic conditions.