Page 411 - Forensic Structural Engineering Handbook

12.2 MATERIAL-SPECIFIC FORENSIC ANALYSES

CASE STUDIES OF NONPERFORMANCE AND FAILURES 12.33
Case Study of Deficient Parking Structure 12.33
Case Study of Shear Failure in Waffle Slab 12.35
ACKNOWLEDGMENT 12.38
REFERENCES 12.38

INTRODUCTION

Reinforced concrete is an excellent morphological building material. In its fluid state, concrete
can be placed in forms to make virtually any shape. Continuity is easily obtained by continu-
ing reinforcement through beam-to-column connections. Once concrete is in place, creep and
shrinkage assist in redistributing loads to locations where reinforcing bars provide resistance.
When defects and failures occur in a reinforced-concrete structure, careful analysis can
determine the causes and point to appropriate remedial measures. Documented forensic
investigations are required to demonstrate the cause of poor performance.

ENGINEERING PROPERTIES

Any textbook may be consulted for detailed discussions of the engineering properties of con-
crete. This section highlights only those properties that most commonly create problems and
failures.

Deformation Properties
Concrete consists of three basic materials: portland cement and other cementitious materi-
als, aggregate, and water, as shown in Fig. 12.1. When they are mixed together, the Portland

FIGURE 12.1 Three basic materials of concrete, aggregate, portland cement,
and water. (Courtesy of Portland Cement Association.)