Page 208 - Forensic Structural Engineering Handbook

6.10 ENGINEERING RESPONSE TO FAILURES

TABLE 6.4 Records of Field Activities
Sketches of overall failed configuration
Observation of behavior of adjacent construction during and subsequent to failure
Detailed sketches of critical members and connections
Inventory of construction materials to establish dead loads
Observation of deterioration
Records of detailed as-built conditions, including plan and detail dimensions
Description of fracture surfaces
Records of samples removed
Procedures and results of field tests
Indications of environmental conditions acting on facility at time of failure
Log of photographs
Records of conversations with others

FIGURE 6.8 Accurate documentation can be challenging under changing site conditions as
collapse debris is removed.

The purpose of the field investigation is to determine the actual as-built condition of the
structure and realistic loads in place at the time of failure. This is the first step in answer-
ing the critical question: why did the actual demand exceed the in-place capacity at this
time, or vice versa, why did the in-place capacity not meet the demand at this time?

Eyewitness Accounts
It has been the authors’ experience that eyewitness accounts are rarely fully reliable. This
is not because people are intentionally dishonest, but because most lay observers are not
trained in structural engineering and the experience of witnessing a traumatic collapse can
leave memories distorted. Nevertheless, eyewitness accounts can be useful for obtaining