Evaluation of residual flexural capacity of existing pre-cast pre-stressed concrete panels—A case study

The residual flexural capacity of 28 existing pre-cast, pre-stressed, ribbed concrete ribbed panels was studied. Four-point bending was applied into the middle third of the panel. Fifteen panels of the 28 conformed to the strength and rigidity requirements of new factory-issued panels.  In the study, all of the studied existing panels have retained sufficient residual flexural capacity to carry the design loads applied in service. Probably, it is likely that pre-stressing steel of an inferior strength mark was applied onto five of the panels studied. This, which could explain the poor flexural capacity of those panels of in good visual condition and the insignificant corrosion level on the pre-stressing bars. Twenty-two out of 28 panels exhibited flexural ductile failure. Three panels failed as a result of an anchorage (weld) rupture and three panels failed in shear. It is likely that the corrosion deterioration of the panels were probably neither carbonation nor chloride induced.