An Experimental Study On The Seismic Behavior Of Recycled Concrete Frame Beam With Low Shear Span Ratio

Since the studies on seismic performance of recycled concrete frame beam ispoor now, six full-scale recycled coarse and fine aggregate concrete frame beams weretested under low cyclic loading. The ductility behavior, enery dissipation behavior,deformability and shear capacity after the yieling of longitudinal steel were mainlyinvestigated. Analysis and comparison of the failure patterns, characteristics loads anddisplacements, the proportion of bending deformation and shear deformation, stiffnessdegradation were conducted. The effect which includes different shear span ratio, amountof transverse reinforcement, amount and configuration of longitudianl reinforcement on theload-carrying capacity, ductility and energy dissipation, ultimate deformability and shearcapactiy after the yielding of longitudinal steel were discussed. The results show that:(1)Due to the water absorption of the recycled coarse and fine aggregate is high, the slumploses rapidly. It is suggested that on-site mixing, on-site casting and construction areadopted when recycled concrete is used in structures. High performance recycled concreteis advised if commercial recycled concrete is used. Additionally, it is suggested to reducetransport and pouring time in order to ensure the construction quality of the recycledconcrete.(2) In the loading process, it was observed that the inclined cracks developedconsiderably in the end of beams. The final failure of all specimens was caused by theobvious degradation of shear capacity.(3) The requirement on the length of confinementregion for normal concrete frame beams in Chinese code GB50010-2010could be used forrecycled concrete beams.(4) Since the shear span of the specimens is relatively small, theshear deformation accounted for a large proportion. The pinching of the hysteresis loopswas exhibited. It is found that the pinching of the specimen with a shear span of1.5ismore obvious than that of the specimens with a shear span ratio of2.(5) The recycledconcrete frame beams could acheive good load-carrying capacity, ductility and energydissipation after rational design.