Following Volumes III and IV that dealt with the fracture mechanics of
concrete emphasizing both material testing and structural application in
general, it was felt that specimen size and loading rate effects for
concrete require further attention. The only criterion that has thus far
successfully linearized the highly nonlinear crack growth data of
concrete is the strain energy density theory. In particular, the crack
growth resistance curves plotting the strain energy density factor
versus crack growth known as the SR-curves are straight lines as
specimen size and loading steps or rates are altered. This allows the
extrapolation of data and provides a useful design methodology. This
book is unique in that it is devoted specifically to the application of
the strain energy density theory to civil engineering structural members
made of concrete. Analyzed in detail is the strain softening behavior of
concrete for a variety of different components including the influence
of steel reinforcement. Permanent damage of the material is accounted
for each increment of loading by invoking the mechanism of elastic
unloading. This assumption is justified in concrete structures where the
effective stiffness depends primarily on the crack growth rate and load
history. Crack growth data are presented in terms of SR-curves with
emphases placed on scaling specimen size which alone can change the mode
of failure from plastic collapse to brittle fracture. Loading rate
effects can also be scaled to control failure by yielding and fracture.