Page 326 - Forensic Structural Engineering Handbook

TEMPORARY STRUCTURES IN CONSTRUCTION 10.15

ensuring safe construction practices, and most of them address temporary structures. They
are, with very few exceptions, qualitative rather than quantitative requirements. The OSHA
regulations are mandatory. The ANSI and other standards are voluntary compliance stan-
dards that become mandatory when adopted by “the authority having jurisdiction.”
OSHA’s Safety and Health Standards Regulation 29CFR, Part 1926, Safety and Health
Regulations for Construction, defines mandatory requirements to protect employees from
the hazards of construction operations. Part 1926 has 24 subparts, or subdivisions, which
include Subpart L, Scaffolding; Subpart P, Excavations; Subpart Q, Concrete and Masonry
Construction; Subpart R, Steel Erection; and Subpart S, Underground Construction,
Caissons, Cofferdams, and Compressed Air. Chapter 3 of this book includes a good
overview of the OSHA regulations for the construction industry. A few of the OSHA reg-
ulations may necessitate engineering analysis and design, but most do not.
OSHA’s existing and proposed standards for the construction industry contain stated
and implied requirements for contractors to assign professional engineers to perform or
inspect jobsite activities for the assurance of safety. The role of engineers in construction
has been changing as a result of the government’s emphasis on performance rather than the
traditional prescriptive standards, and the development of new enforcement strategies. A
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good paper on these developments through the late 1990s is by Jim E. Lapping . The paper,
indeed all five articles in the proceedings, is highly recommended reading for the engineer
engaged in temporary structures work.
Although most states in the United States administer their own occupational safety
and health programs, they generally adopt the federal OSHA regulations. Because three
sets of regulations may apply to the same project at the federal, state, and local levels,
contractors are advised to follow the strictest requirement when the codes merely sup-
plement each other, and forensic investigators are advised to review all three for any
given case.
ANSI issued standards, designated as safety requirements, for scaffolding (ANSI A10.8),
concrete and masonry work (ANSI 10.9), steel erection (ANSI A10.13), and others, all of
which include the relevant temporary structures.
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The Construction Handbook for Bridge Temporary Works , is a credible and useful
guide on the subject.
State labor laws, such as the New York State Labor Law, set out rather general but
remarkably strict requirements to ensure the safety of workers and the general public.

DESIGN CRITERIA

The forensic structural engineer should be familiar with the design criteria for temporary
works. It is, however, not possible to list a set of universally accepted criteria equally
applicable for the design of all temporary structures in construction. The types, materials,
uses, and abuses of temporary structures are very wide ranging.
The concerns and interests of owners, designers, constructors, authorities having juris-
diction, and the general public are in parts different and often conflicting. Most structural
design engineers are ignorant of the intricacies of temporary works, hence are not well
qualified and not interested in the subject, and gladly use the familiar design criteria that
exist for permanent structures. Many contractors handle the temporary works to give them
the “competitive edge” in their business, hence are not interested in uniform criteria that
might limit their inventiveness and eliminate that competitive edge. Many other engineers
and contractors, however, do hold that the economy and safety of construction projects
would be improved by well-thought-out standardized design criteria, hence they are sup-
porting and, indeed, working on their development.