Half-Baked: How ASME A120 and IWCA I-14.1 Have Attempted to Undermine the Value and Validity of Structural Load Testing

摘要

Subcommittees of the American Society of Mechanical Engineers (ASME) and the International Window Cleaning Association (IWCA) - namely ASME A120, which writes and maintains the standard ASME A 120.1 Safety Requirements for Powered Platforms and Traveling Ladders and Gantries for Building Maintenance, and IWCA I-14.1, which writes and maintains the standard IWCA I-14.1 Window Cleaning Safety -- have in recent years adopted a concept of "half-load" testing. Half-load testing refers to the limits imposed by these voluntary standards on load testing of existing facade access structural support equipment for the purpose of verifying required capacity. In each case, the voluntary standard prohibits testing beyond 50 percent of the minimum OSHA required strength. This paper highlights the folly of the half-load testing concept adopted and promulgated by A120 and I-14.1, and is intended to educate engineers involved in the certification of facade access equipment about the dangers of such an approach. A number of case studies are provided that demonstrate how half-load testing can fail to identify critical problems in structural elements.