Study On Bond Slip Behavior Of Interface Between Steel And Recycled Concrete After High Temperature

To study the interfacial adhesive performance of steel-recycled concrete after high temperature, taking the temperature and recycled coarse aggregate replacement percentage of concrete as running parameters,60 recycled concrete samples in total of square steel tube, circular steel tube and fashioned steel had been designed and then their short-column sample had been tested by the static push-out test after high temperature, the stressed destruction process and shape of the sample had been observed to obtain its loading end and free end’s load-slip curve, adhesive strain and stress distribution, characteristic load and other important data.The law of influence on interfacial adhesive performance of steel-recycled concrete after high temperature by various running parameters had been analyzed, the failure mechanism of interfacial adhesive performance of steel-recycled concrete after high temperature had been discussed in detail, the calculation formula of ultimate adhesive strength and residual adhesive strength after high temperature had been proposed, besides, the sample tested by the push-out test had been studied with axial compression experiment, the law of change in bearing capacity of axial compression of sample had been analyzed, the effect of replacement percentage and temperature on the ultimate bearing capacity had been obtained.It was shown by the findings that:the temperatures experienced had different effects on the interfacial adhesive strength of steel tube sample and fashioned steel sample, the interfacial adhesive strength of steel tube sample was increased as the temperature went up, while the interfacial adhesive strength of fashioned steel sample was decreased as the temperature went up, the effect of recycled coarse aggregate replacement percentage on adhesive strength presented a great discreteness.The interfacial adhesive destruction process of sample was equally postponed and slowed down as the temperature went up, the interfacial adhesive energy-dissipating capacity of steel tube sample was decreased as the temperature went up, the counterpart of fashioned steel sample was increased as the temperature went up. As far as the different shaped-steel layout is concerned, in the case of a heating temperature below 200 ℃, fashioned steel sample peaked in its adhesive strength, followed by the circular steel tube sample, while the square steel tube sample had the lowest adhesive strength of all.In the case of a heating temperature above 400 ℃, the circular steel tube sample peaked in its adhesive strength, followed by square steel tube sample, while the fashioned steel sample had the lowest adhesive strength of all. The steel tube filled with recycled concrete(after interfacial slip) was rapidly brought down in its axis bearing capacity after the temperature exceeded 600 ℃, the axis bearing capacity of square steel tube sample respectively equaled to 93%、 104%、72% of that of the sample under room temperature when the temperature went up from the room temperature to 200 ℃、400 ℃、 600 ℃, while the axis bearing capacity of circular steel tube sample respectively equaled to 98%、 96%、77% of that of the sample under room temperature,The relevant conclusion about the interfacial adhesive slipping performance of steel-recycled concrete after high temperature drawn by this paper had a certain referential significance to the performance evaluation and reinforcement and repair technique of steel-recycled concrete composite structure after fire.