Simulating Loads on a Roof Structure Caused by a Worker Falling from a Roof Edge

Abstract

Changes in the Occupational Safety and Health Administration (OSHA) fall-protection guidelines for residential construction since late 2011 have required the use of fall-protection and fall-arrest systems for workers past a certain height. Evaluation of fall-arrest anchor capacity depends on placement within a structure and includes strength of connections, truss/rafter elements, and bracing. The purpose of this study was to explore the use of a displacement-rate test for evaluating the strength and stability of fall-arrest anchors connected to truss assemblies as a supplement to currently used drop-test methods. A two-truss assembly with bracing was used for comparison. A range of displacement rates from 254 mm/min (10 in./min) to 381 mm/min (15 in./min) was recommended for evaluating the capacity of truss assemblies. A comparison of truss-assembly failures found similar results for the displacement-rate test and the drop test. The addition of the displacement-rate test can provide valuable information about truss performance, including an estimation of maximum load on structures, the ability to identify individual truss/bracing element failures, and the measurement of individual member deflection.