M id A tlantic Real Estate Journal — Owners, Developers & Managers — Roofing / Waterproofing — September 2023 — 3C R oofing / W aterproofing
www.marej.com
By Alexis Herr, P.E., ECS Mid-Atlantic, LLC Know Your Davits Before You Hang
R oof-anchor testing and certification is a critical part of main-
buildings with roof ameni- ties, decorative screen walls, sunshades and other features, standard U-bar anchors, and standard testing methods, don’t always work. Many rope-decent systems use specialty anchors such as recessed roof anchors (hidden under pavers), drop-through anchors or outriggers to ac- commodate design features on a building’s roof. Some sys- tems rely on suspended scaf- folds, also called swing stages or powered platforms. When testing specialty-access sys- tems, the certifying engineer must use their understanding of the system to ensure the test replicates the required load on the anchorage points. In particular, if your goal is to avoid hanging large weights from the side of a tall building, testing davit- base systems that include
tall masts and long arms to support suspended scaffolds requires foresight and under- standing of the load path. One such system exists on Atlantic City’s MGM Tower at Borgata, formerly known as the Water Club. Built in 2008, the MGM Tower is a 38-story building with decora- tive screen walls and signage on its roof. In 2022, the build- ing was set to undergo a large glass-restoration project. To access the building façade, an elaborate davit system was used to suspend swing stages. The davits were fit - ted with tall masts and arms up to 11 feet in length. The most unique aspect of this system may be that the davit bases were not stationary but motorized and mounted on a tripod-shaped base that rolled along two tracks. Challenges for testing this
system included difficulty accessing and setting up the davits, testing equipment in limited space and providing a load test that distributed the test loads correctly between all of the system’s compo- nents and dual tracks while ensuring that the worst-case system and track locations were tested. ECS Mid-Atlantic, the firm selected for the testing, worked closely with the res- toration contractor, Clean & Polish Building Solutions, and with the building engi- neers to test and certify the davit system. Great care was taken in setting the davits at points along the track which were the most vulnerable. At- tention was paid to designing testing procedures that would replicate the in-service load on the arms, mast, base and dual-track systems.
In addition to the davits, secondary tie off points (U- bars) were not provided as frequently as needed, so the team identified, tested and certified additional anchorage points to be used to secure safety lines. With proper certification, the building is now acces- sible for future maintenance and restoration projects com- pleted by swing-stage plat- form scaffolds, rope-descent systems and industrial rope- access methods. After testing was complet- ed, the system was deemed to be safe to use for the glass-restoration project. The MGM Tower now stands as a glimmering silhouette in the Atlantic City skyline. Alexis Herr, P.E. is vice president, principal engi- neer for ECS MidAtlantic, LLC. MAREJ
taining the rope-descent system or suspended- scaffold sys- tem used to access the ex- terior façade on build- ings. Per the
Alexis Herr
Walking-Working Surfaces standard, 29 CFR Part 1910, Subpart D & I, OSHA re- quires anchors for rope de- scent be capable of maintain- ing a 5,000-pound load in any direction. The industry- standard test for common U- bar anchors is to test anchors against each other with a chain hoist, which is simple, but effective. However, as architectural- design trends push toward
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