An Approach for Quantifying Dynamic Properties and Simulated Deployment Loading of Fire Service Escape Rope Systems

Rope systems are simple mechanical structures that provide life-critical protection from dynamic loading in a variety of applications where falls from height are possible. Recently, the Fire Service has realized the importance of using fall protection systems while endeavoring to gain a better understanding of how these systems will respond during fire ground deployments. A new extensometer, utilizing a linear variable differential transformer, was designed to advance the ability to characterize the dynamic and static properties of these ropes. A series of experiments were conducted to replicate various deployment scenarios, quantifying the effect of fall height, payout length, and ledge geometry on the dynamic loads a firefighter and his/her equipment may expect in realistic escape scenarios utilizing common rope systems. These loads are compared to occupational health-safety-based maximum load recommendations and the quasistatic strength of the rope. While the ropes constructed from all aramid fibers were the strongest in standard quasistatic tests; during dynamic loading they generated the largest maximum arrest loads that were consistently above the occupational health-safety recommended load of 8 kN. Finally, using the experimentally determined rope properties measured with the new extensometer, positive agreement was found between the experimental drop tests and numerical simulations.