Behaviour of over-reinforced concrete beams

The behaviour of over-reinforced concrete beams isinvestigated experimentally. Tests are reported on theinfluence of stirrup spacing in pure bending zone and thetension reinforcement ratio on the deformational character-istics and ultimate strength of concrete beams.Twenty-four simply supported reinforced concrete rect-angular beams were tested. The tested beams were arrariged inthree series within each of the three series, all specimenshad the same stirrup spacing in the middle zone, the mainvariable being the proportion of the tension reinforcement.Empirical expressions for stress distribution parameters(e and K ) and for the ultimate flexural strength of overo 3reinforced beams are presented.The proposed stress block for concrete in flexuredescribed by the paramete 3 and K and the empiricalexpression for the ultimate flexural strength ofreinforced beams are checked on the basis of experimentalinformation of the tested beams and those given in some otherworks. The results show a good agreement with the experimentaldata.