By Gregory Havel
Scaffolds are temporary structures that are used by construction andmaintenanceworkers for access to elevated work areas and to support workers, tools, and materials. They are present in buildings and on construction job sites in a variety of types, ranging from small and simple to complex multistory scaffolds.
Photo 1 shows a simple wheeled scaffold of a type commonly used in building maintenance and in the final stages ofconstructionand remodeling.
(1) Photos by author unless otherwise noted.
这种类型的支架通常被称为一个“贝克”;我t is manufactured in sizes measuring from 24 to 36 inches (61 to 91.5 cm) wide and from 48 to 72 (122 to 183 cm) inches long. It is usually made ofsteelsections that connect to each other with cam locks or spring-loaded lock pins. The caster brakes must also be locked at any time the scaffold is occupied because of the possibility of serious injury to workers on it if it were to move under them.
Photos 2 and 3 show the complex scaffoldsystempresently in use for the restoration of the dome on the United States Capitol Building in Washington, D.C. A scaffold system this complex must be designed and inspected by a structural engineer after installation.
(2, 3) Photos courtesy of the Architect of the U.S. Capitol Web site(http://www.aoc.gov/dome/project-updates.)
Photo 4 shows a welded steel frame scaffold that has been built for the construction of a four-storymasonryelevator hoistway at the site of a hotel that is under construction.
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Photo 5 shows a welded steel frame scaffold with a heated winter enclosure that protects the masonry from freezing. These enclosures are usually built of flame-retardant sheetplasticand tarps stretched over a steel framework that is supported by the scaffold. Sometimes, sheet plastic and tarps without flame retardant treatment are used because of lower cost despite the increased risk to the workers on the scaffold.
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Photo 6 shows a tube-and-coupler scaffold in use during the renovation of a multistory building. This scaffold supports two rubbish chutes at the left, arope-and-pulley system for raising tools and equipment to the upper levels of the scaffold, and an access stairway from ground level to the roof and all levels in between. These features can be installed on scaffolding of any type, if it is designed for these purposes. The scaffold in Photo 6 is the same type of scaffold system in use in Photos 2 and 3.
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As in any type of structure, the connections between the scaffold components are theweakpoints. The failure of any single connection may cause the collapse of the scaffold and the death of—or serious injury to—the workers using it.
No type of scaffold is permitted to be higher than four times the narrow dimension of its base because of its tendency to tip if it is higher unless it has outriggers, guy lines, or ties to a wall or other substantial structuralelement.
On construction job sites, scaffolds can be the location of the same types of fire-related and medical emergencies as any permanent structure, with added hazards such as the following:
- The temporary nature of the structure.
- The lack of fire resistance.
- The lack of automatic fire sprinkler systems.
- Rapid spread of fire after ignition.
- Limited access because of ground conditions and temporary construction roads.
- Access to upper levels often only by ladder or a narrow, steep stairway.
- The tendency for the scaffold to collapse if overloaded, out of plumb, or if ground conditions change from wet to dry or frozen to thawed ground.
If you have a large construction project in your response area that involves large or complex scaffolds, contact the construction manager or general contractor to discuss job site tours for your personnel; and the possibility of performing ladder evolutions with hose lines, and patient removal drills using weighted mannequins, from an upper level of the scaffold.
For a description of the many types of scaffolds, a discussion of their hazards, and requirements for their proper use, visit the Occupational Safety and Health Administration (OSHA) Website atwww.osha.govandhttps://www.osha.gov/SLTC/scaffolding/index.html. These Web sites have links to resource documents as well as to the regulations that apply to the erection, use, and dismantling of many types of scaffolds and to the workers who use them.
You can also do a Web search for “scaffold manufacturers” for links to detailed descriptions and specifications for scaffold equipment and accessories.
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Gregory Havel我s a member of the Town of Burlington (WI) Fire Department; retired deputy chief and training officer; and a 35-year veteran of the fire service. He is a Wisconsin-certified fire instructor II, fire officer II, and fire inspector; an adjunct instructor in fire service programs at Gateway Technical College; and safety director for Scherrer Construction Co., Inc. Havel has a bachelor’s degree from St. Norbert College; has more than 35 years of experience in facilities management and building construction; and has presented classes at FDIC.
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