When loading in compression, the failure appears first in the weak concrete zone induced by the random distribution of voids.
The compressive strain variation of the concrete zone is linear from the neutral axis to the outer fiber, and the strains and stresses follow Hooke's law.
These calculations are based on the theoretical shear mechanisms – uncracked concrete zone, aggregate interlock and dowel action.
Failure is assumed to occur at the un-cracked concrete zone, subjected to a biaxial stress state, when the Kupfer failure envelope is reached and the stirrups are yielded.
For the investigated hybrid beams, approximately half of the shear force is taken by the uncracked concrete zone and aggregate interlock of the concrete and the remaining half by dowel action.
The development of the FAM for corroded RC beams strengthened by prestressed CFRP sheets depends on the following basic assumptions: The compressive strain variation of the concrete zone is linear from the neutral axis to the outer fiber, and the strains and stresses follow Hooke's law.
Lengths in the plastic hinge region involving rebar yielding zone, concrete crushing zone and curvature localization zone are studied systematically, under different parameters.
Failure modes for the original joint included anchorage failure of bottom steel beam bars, crushing of concrete nodal zones, diagonal joint shear failure, and for the retrofitted joint CFRP laminate delamination and crushing of joint core concrete.
It is found that both the lengths of the rebar yielding zone and the curvature localization zone increase first and then decrease as confinement increases, while the length of concrete crushing zone keeps decreasing with the increase in confinement.
In the intervening 21 years, this concrete, militarised zone has been overtaken by urban wilderness or rampant redevelopment.
