| As a new type of composite structure with good performance,steel-concjrete composite beams have many advantages,such as large bearing capacity,high stiffness,good ductility and material saving,combined with the characteristics of good corrmpressive performance of concrete and good tensile performance of steel.In view of the above characteristics,this paper proposes a new type of composite beam,which is different from the traditional reinforced concrete composite bcam in that on the basis of widening the upper flange of the composite beam,the concrete above the upper flange plate is plain concrete,and is tightly combined by shear connectors.This new type of composite beam can maintai.n the overall work,bearing capacity and ductility of mechanical properties,so this paper carried out loading tests on the composite beam,and then demonslrated the test by finite element simulation,and finally optimized the mechanical propernies by changing the parameters.Firstly,th.e loading test of the new composite beam is carried out.In order to verify whether this new type of composite beam can meet the rcquirements of mechanical properties such as overall work,bearing capacity and ductil.ity,two groups of plain concrete composite beams with flange widhs of 150 mm and 300 mm were designed in this paper.Three-point bending loading tests were carried out on them.Through the tests,we measured their load-displacement curves,load-strain curves and control sections,The results show that in the elastic stage,the load-displacement curve is linear and the height of strain-elongated section is linear.It shows that steel and concrete can work together,conform to the assumption of flat section,have no relative displacement and have good ductility.Ater entering the plastic deformation stage,there is an obvious yield stage and the plastic development is sufficient,which shows that the beam has good which shows that the beam has good plasticity and is not easy to occur brittle fracture failure,which is equivalent to the failure of the ordinary composite beam with suitable reinforcement.Then,the experiment is demonstrated by finite element simulation.According to the characteristics of the composite beam,the non-linear finite element method is used to simulate the composite beam.Through the finite element analysis,the load-displacement curve is also obtained,and the results of the finite element model are compared with the experimental results.The results show that the failure modes of the specimens are identical,and the load-displacement curves and the flexural capacity of the specimens are in good agreement.It can be seen that the established finite element model is reasonable and can accurately reflect the flexural performance of the composite beam.Finally,the mechanical properties are optimized by changing the parameters using the non-linear finite element method.The mechanical properties of the specimens were optimized by changing the four parameters of the steel beam’s tension flange thickness,steel strength,concrete strength and width of the concrete flange plate.The effects of the four parameters on the ductility and bearing capacity of the specimens were obtained.In summary Through the experimental study and the results of finite element analysis,it is expected that this new type of composite beam will play a positive role in promoting the practical application. |
