Page 44 - Forensic Structural Engineering Handbook

DESIGN-CONSTRUCTION PROCESS 1.25

Controlled inspections
Quality control
Photographs of partial work in place
Substantial and final completion records
Signoffs, as per jurisdictional requirements
Temporary Certificate of Occupancy and/or Certificate of Occupancy
All “as-built’ drawings, warranties, and guarantees
Punch list items
When a failure occurs, an experienced forensic investigator should be able to draw
some tentative conclusions by examining the aforementioned material. It is also essential
to investigate post-construction developments, if any, such as tenant complaints, frequent
repairs, leaks, visible cracks, settlements, or movements reported. Nothing should be
ignored when investigating a failure. Investigations should not be limited to the materials
used, or to structural analysis, but should extend on to the means and methods used by the
contractor.

ASSESSMENT OF POST-CONSTRUCTION
CONDITIONS

There are instances when a structural engineer is retained to perform a condition assess-
ment of an existing structure. In addition to visual inspections, the work may or may not
include analytical investigation, probing and testing. The engineer must be prepared to per-
form his or her investigation in a manner similar to a detective pursuing answers to ques-
tions in order to understand the behavior and facts of the case before a verdict can be
reasonably concluded. At a minimum, the following activities should be on the structural
engineer’s checklist:

Acquire the latest structural drawings and/or shop drawings.
Perform a site visit.
Confirm and/or take measurements of pertinent structural components.
For concrete structures investigate the size and location of reinforcing, initiate a pro-
gram for concrete core sampling and testing.
For steel structures check beam sizes, connections, and, if required, ascertain the type
of steel in the structure by a program of test coupons recovered from selected beams for
testing.
For masonry structures check type of block or brick, are cells grouted and/or reinforced,
check mortar type and strength, bond beams, and joint reinforcement.
For timber structures check size, type, and grade of members; check moisture content
and connections.
For foundations, probes or borings may be required to ascertain the size of footings and
in some instances the soil bearing capacity.
Observe and define the existing load path of the structure under investigation.
The engineer should be cognizant of the fact that it is always beneficial to take more
field measurements and make more sketches than may be deemed necessary at time of the