Page 294 - Forensic Structural Engineering Handbook
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DEFECTS, DETERIORATION, AND DURABILITY 9.5
leading cause of masonry distress—including cracking, spalling, and collapse—is the lack
of coordination between the structural steel and the supported masonry. A lack of expan-
sion joints below shelf angles may lead to masonry crushing (see Fig. 9.3), or a systemic
failure such as bowing of the entire wall. These failures can be prevented by the engineer
providing not only the traditional structural details, but also the details pertaining to the
interface between the structural and the architectural elements.
FIGURE 9.3 Masonry crushing due to lack of soft joint below shelf angle.
It is also the responsibility of the designer to research and specify appropriate products
for a given application. Manufacturers’ representatives often work closely with designers
to assist in the selection of products for construction applications. Reputable manufactur-
ers have vast experience with the performance of their products in different applications,
and can help prevent design errors based on inappropriate product selection.
Product Defects. Defects may be introduced at the factory by poor quality control, such
as the introduction of contaminants in manufacturing. Improper storage can also impair the
performance of materials. The best products are only as good as the information that is pro-
vided with them; errors and omissions in product data sheets have contributed to countless
failures.
Errors in manufacturing may also introduce product defects. For example, if a steel col-
umn is fabricated with an out-of-straightness that exceeds the AISC-specified fabrication
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tolerances, stresses may be introduced in the member under loading that were not
accounted for in the initial design process.
Construction Defects. Many defects are attributable to errors that occur during construc-
tion. For example, defects that arise in concrete construction may be due to improper place-
ment, consolidation, curing, or finishing. Improper location of reinforcing steel and
