Research On Mechanical Properties Of Bamboo Scrimber Flexural Members Reinforced With Steel Bars

When bamboo scrimber is used as a bent member,it has shortcomings such as insufficient bearing capacity,low bending rigidity and weak spanning ability.For these problems,this paper proposes a reinforced bamboo scrimber bending member,the basic mechani cal properties of the test material and the reinforcing bamboo scrimber.The mechanical properties of the flexural members were tested experimentally to achieve the desired results.For the test material,the axial stretching of the steel bar,the bamboo scrimber compression and tensile mechanical properties test,the ultimate stress,ultimate strain,elastic ultimate strain and elastic modulus of the material are analyzed,and the prestressed steel bar is determined.Based on the test results,a model that can describe the trend of stress-strain curve of steel bar and bamboo scrimber is proposed and compared.This paper presented the design and fabrication method of bamboo scrimber beams.By grooving the side of the beams,the common steel bars and prestressing bars were implanted into the tension area of the beams,and epoxy resin was used as binder to sthengthen the bamboo scrimber beams.Seven groups of restructured bamboo beams were designed,with 14 specimens in each group of two parallel specimens,and the comparison parameters were the diameter of steel bars and the prestressing.Four-point bending test was carried out to study the bending properties of bamboo scrimber.Author compared and analyzed the deformations,loaddisplacement curves,failure modes,load-strain curves and load distribution of mid-span section of the beam under prestressing tension.Compared with the comparison specimen,the ultimate bearing capacity of the beams strengthened by common steel bars was 65.16 k N～81.29 k N,which is increased by 3%～28.5%.The ultimate bearing capacity of the strengthened bamboo scrimber beams increased nonlinearly with the reinforcement ratio.The average ultimate bearing capacity of prestressed rebar strengthened beams was 74.43 k N and 77.19 k N.The ultimate bearing capacity of group B2S12 II with large prestress is higher than that of group B2S12 I.With the increased of reinforcement ratio,the bending stiffness increases from 4.73% to 36%,which was almost linear.The cross-section strain distribution also conformed to the law,and the steel bar and the bamboo scrimber beam can be ideally deformed under the synergistic force.Reinforcement can effectively improve the flexural mechanical properties of bamboo scrimber beams.Through the FEA software ABAQUS,author established and calculated the threedimensional model of reinforced bamboo scrimber beams and analyzed the deformation state of beams under prestressing tension,the cloud diagram of beams and prestressing steel bars under ultimate state,load-displacement curve,failure mode,load-strain curve and load distribution of mid-span section.Compared with the test specimens,the law was similar.The average absolute error of ultimate bearing capacity was 7.47%,the average error of bending stiffness calculation was only 2.94%.The change of neutral axis position was consistent with the test results.Therefore,the accuracy of the finite element model can be proved and the foundation for similar types of finite element simulation analysis can be laid.According to the principle of equivalent section and the simplified stress-strain model of material properties,the neutral axis position of reinforced bamboo scrimber beams in elastic stage was calculated by referring to the calculation formula of interface bending stiffness.Compared with the test,the maximum error was only 3.62%.Only when the drawing curve was compared with the test curve and the simulation curve,can the curve in the initial stage coincide completely.The theoretical formula and method of failure bending moment under ultimate state are presented.The average value of calculation results and test values was only 3.83%,and the maximum error was only 6.01%.Very good verification of the theoretical calculation,test results,finite element simulation of the three data accurate,theoretical calculation and the reliability of finite element simulation.