Experimental Research On Seismic Behavior Of Energy-consuming Joints For Steel-bamboo Hybrid Frame Structures

The steel-bamboo hybrid frame system has good application prospects in multi-story buildings because of the characteristics of assembly,environmental protection and light weight.At present,there are few studies on beam-column joints used in steel-bamboo hybrid frame structures.Therefore,it has important theoretical significance and practical value to carry out the research on beam-column joints of this structural system.In this paper,a new type of energy dissipation joint was proposed to connect steel columns and bamboo beams based on the requirements of assembling ability and energy consumption.Through the combination of experimental research and finite element analysis,the seismic performance of the new energy-dissipating joint was studied.The main research work and achievements of this paper are as follows:The transmission mechanism of the energy dissipation joint was analyzed,and the calculation method of the bearing capacity of the joint was given,then the joint was designed with an example.The mechanical properties of the glued laminated bamboo and joint steel plates were tested,including the tensile strength with grain,the compressive strength with grain and the modulus of elasticity of the bamboo,the yield strength,tensile strength,modulus of elasticity and elongation after fracture of the steel plates,which provided the parameters for the calculation of the bearing capacity of the test joints and the finite element modelling.Pseudo-static tests on four groups of eight energy-dissipating joints were conducted.The influence of the span to thickness ratio of the energy dissipation plates on the seismic behavior of the joints was studied.The test results showed that the joints failure occurred at the energy dissipation plates,and the hysteretic curves were bow shaped.The study showed that the elastic stiffness of the joint was independent of the span to thickness ratio of the energy dissipation plates,and the peak bending moment of the joint increased with the decrease of the span to thickness ratio of the energy dissipation plates.The ductility and energy dissipation performance of the joint with the span to thickness ratio more than 10 were better than that of the joint with the span to thickness ratio less than 10.By using the finite element analysis software ABAQUS,the three-dimensional solid modeling of four groups of joint specimens was established.The rationality of the finite element model was verified by comparing the skeleton curves and the strain of the energy dissipation plates of the specimens.Furthermore,the mechanical characteristics of the shear bolt were analyzed.The results showed that the horizontal force of the shear bolt increased with the increase of the span to thickness ratio of the energy dissipation plates.The energy dissipation joint was optimized,and the improved joint was tested under low cyclic loading.By comparing the dynamic hysteresis performance of the improved joint and the original joints,the improved joint was more economical and it had higher bearing capacity and better energy dissipation performance.The shear key cross section height of the improved joints was analyzed by the parametric finite element analysis.The study showed that the shear key bending moment distribution coefficient was close to the ratio of the section inertia moment.The shear key shear distribution coefficient in the elastic stage increased with the increase of the height of the section,and the shear key in the plastic stage assumed all the shear forces.With the increase of the shear key cross section height,the contribution of the shear key to the energy consumption of the joints was increasing.According to the theoretical derivation,the end bending moment of the shear key of the joint after failure of the energy dissipation plate was obtained.A Summary of the mechanical characteristics of the energy dissipation joint was done,thus the joint design suggestions were given.