Page 176 - Forensic Structural Engineering Handbook

THE FIRST STEPS AFTER A FAILURE 5.9

FIGURE 5.6 All components from the Four Times Square scaffold collapse were labeled prior
to being dismantled.

three people for every crew that is removing items. Cooperation from the contractor who is
performing the removal will greatly facilitate the process.
There are several types of labeling systems; three of the most commonly used ones are
the following:
1. Identity piece-mark system. If the identity of a piece is known, it can be labeled with an
identity piece mark that is keyed to a drawing. If the original orientation of the element
is known from its context in the debris, but may not be otherwise readily apparent, it
should be marked on the piece. For example, “north flange” or “bottom end.”
2. Serial piece-mark system. In some cases, the identity of a piece may not be known with cer-
tainty. Such a piece should still be labeled, but in this case with an arbitrary—but unique—
piece mark. This piece mark is arbitrary in the sense that it conveys no information about
the identity of the piece; it serves solely as a label to distinguish it from other pieces. The
assigned piece mark must be unique over the entire project. If multiple persons are simul-
taneously assigning the piece marks, incorporating the person’s initials in the piece mark,
such as “JFK-23,” will help in assuring uniqueness. Obviously, any information that may
assist in later determining the identity of the piece, such as where it was found, should be
recorded either directly on the piece or in field notes. (See Fig. 5.7.)
3. Match-mark system. Match marking of mating segments can greatly facilitate later recon-
struction. It can be used on members that are severed, members that are cut, or members
that are disconnected. Match marking consists of marking both sides of mating segments
with an identical label. If necessary, a “match point” can also be indicated on the mating
ends so that they can be reconstructed with the proper relative orientation. When used in
conjunction with a piece-mark system, the match-mark pairs need only be unique to that
piece. For example, “Match #1” may suffice, if both segments are already marked with
the same piece -mark. If used as a stand-alone notation, each pair of match marks must be
unique over the entire project, so the marks will necessarily be more complex.

A combination of nomenclature systems is often used on a given project.