An experimental evaluation of the crack propaga
tion and post-cracking response of macro
fiber reinforced concrete in flexure is c
onducted. Two types of structur
al fibers, hooked end
steel fibers and continuousl
y embossed macro-synthetic fibers are used in this study. A fiber
blend of the two fibers is evaluated for spec
ific improvements in the post peak residual load
carrying response. At 0.5% volume fraction, both
steel and macrosynthetic fiber reinforced
concrete exhibits load recovery at large
crack opening. The blend of 0.2% macrosynthetic
fibers and 0.3% steel fibers shows a significa
nt improvement in the immediate post peak load
response with a significantly smaller load drop and a
constant residual load carrying capacity
equal to 80% of the peak load. An analytical
formulation to predict fle
xure load-displacement
behaviour considering a multi-linear stress-
crack separation (σ
-w) relationship is developed.
An inverse analysis is developed for obtaining the multi-
linear σ
-w relation, from the
experimental response. The
�
-w curves of the steel and
macrosynthetic fiber reinforced
concrete exhibit a stress recovery after
a significant drop with increa
sing crack opening.
Significant residual load carrying capacity is attained
only at large crack separation. The fiber
blend exhibits a constant residual
stress with increasing crack sepa
ration following an initial
decrease. The constant residual stress is
attained at a small crack separation
