Mechanical properties of load-bearing beam with tree root type steel-concrete structure

In traditional design of anti-seismic steel-concrete structure, the strength of steel-concrete directly affected the shear capacity of load-bearing beam frame joints. The interfacial size and shear interface of the load-bearing beam decreased with the increasing of the steel-concrete strength when the joints were under a certain load. It was unfavorable to anti-seismic ability under a certain stirrup ratio. To solve the problem, one innovative bionic designing thought - structure of tree root type was introduced in this paper. Feasibility of this structural design was confirmed by studying on the composite effect of tree root type. Three kinds of different beam were prepared: common steel-concrete load-bearing beam, primary load-bearing beam with tree root type steel-concrete structure (bifurcation angle of 45°), secondary load-bearing beam with tree root type steel-concrete structure (bifurcation angle of 30°, 45°, 60° respectively). Microstructure of prepared steel-concrete sample was characterized by scanning electron microscope (SEM) and EDS. Mechanical properties were characterized by universal pressure experimental machine with a concentrated pressure. Results indicate that lateral branches of bionic rebar bear partial compressive press and tensile stress. Mechanical properties of bionic reinforcement concrete improved with the effect of shear interface between lateral branches and concrete, which anticompression ability is 135 percentages to common reinforced concrete. Compared with the primary, the secondary load-bearing beam with tree root type steel-concrete structure present the optimal mechanical properties and anti-seismic efficiency when lateral beam is located in the bottom and bifurcation angle is 45°.