Concrete corbels containing neither primary nor secondary reinforcement failed in brittle manner with a noticeable difference in ultimate load.
It is clear from the results given in Table 6 that the primary and secondary reinforcement ratios increase as only the vertical load is increased.
1) The failure mode of corbels with neither secondary reinforcement nor primary reinforcement was brittle and explosive when corbel was subjected to only vertical loading;
4) The PCI equations do not specify any limits on the ratio of primary and secondary reinforcement. The study showed that some limits should be introduced in the code.
Then, the axial load and bending moment with respect to the barycentre of the section that the secondary reinforcement can bear can be calculated by the following expressions:
It must be observed that, if one sets [E.sub.sc] = [E.sub.s] in (30) and/or [E.sub.sh] = [E.sub.s] in (32), (33) expresses the contributions to the axial load and bending moment in the case in which the upper fibre and/or the lower fibre of the secondary reinforcement remain in the elastic field.
For each configuration the contributions to the equilibrium provided by the principal reinforcement ((23)and (24), under the conditions expressed by (26)), the secondary reinforcement ((28), (35), and (36), under the conditions expressed by (37)), and the compressed region of concrete ((48)and (49), considering (41)-(47)) only depend on the variables [[bar.x].sub.c] and [??], which are independent of or related to one another according to the type of analysis required (see below).
Therefore, for any loading step the upper principal reinforcement and the upper fibre of the distributed secondary reinforcement, both potentially subject to compression, cannot be in the postyielding field in tension; the lower principal reinforcement and the lower fibre of the distributed secondary reinforcement, both potentially subject to tension, cannot be in the postyielding field in compression.
Thus, the preference for the CRF-associated stimulus previously found in the single group (within-subjects) experiments, as opposed to the opposite results when a between-groups design was used, was not an artifact of the difference in the nature of the choices available to the rat during secondary reinforcement testing.
Effect of primary reinforcement schedule on secondary reinforcement strength with continuous secondary reinforcement during training.
Secondary reinforcement strength as a function of schedule of primary reinforcement.
Secondary reinforcement strength and primary reinforcement schedule: Single group technique.