EP 1110-2-12
30 Sep 95
Figure 3-6. Tensile strength range, RCC, MSA > 1.5 inches, consistency > 30 seconds vibration, no mortar
bedding
3-9.
Allowable Tensile Stresses
establishing an allowable tensile stress which is
greater than the actual peak tensile stress as shown in
Figure 3-7. In this figure, the dashed line represents
When the response to ground motion increases
the tensile stress/strain relationship assuming linear-
beyond the elastic limit, energy is dissipated through
elastic behavior as opposed to the actual nonlinear
crack development and crack propagation in accor-
stress/strain relationship which is shown as a heavy
dance with the stress/strain relationship shown in
solid line. The amount the peak tensile stress is
Figure 3-7. To account for all nonlinear response
increased in establishing the allowable stress depends
including that in the tensile softening zone of the
on the extent of tensile cracking that can be tolerated,
stress/strain curve requires a complex nonlinear anal-
which in turn is based on the performance require-
ysis. The simpler linear-elastic analysis may be uti-
ments for the design earthquake under consideration.
lized in a manner which accounts for response in the
The economics of the design also becomes a factor in
linear region, and the nonlinear pre-peak region.
the higher seismic zones. In these zones, a somewhat
greater amount of cracking can be justified economi-
a. Comparing linear and nonlinear curves.
cally because there is a point where the cost of pro-
Since a linear-elastic analysis converts strains to
ducing RCC mixes with high tensile strengths to
stress using a constant modulus of elasticity, the
resist cracking will exceed the cost of repairing the
stresses from the analysis will be higher than actual
cracks as long as the cracking is not too extensive.
stresses when in the nonlinear pre-peak and post-peak
strain regions. This may be compensated for by
3-7
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