| Prefabricated steel and concrete composite beams are commonly used in large span beam and bridge structures or in high-rise buildings,and are commonly available as cast-in-place steel and concrete composite beams or as prefabricated steel and concrete composite beams with "bearded bars".The disadvantages of cast-in-place girders are obvious: more wet work processes and more moulding work,while prefabricated assembled girders with reinforcement in the base plate take up a larger area of the moulding platform and are very inconvenient to transport to site,and the bending bars protruding from the base plate lead to more refinement in design.In order to solve the above-mentioned problems of traditional composite beams,this paper proposes an assembled composite beam with pre-built angle steel connections at the precast base plate of the laminated slab,and compares it with the assembled composite beam with angle steel at the precast base plate by means of footprint specimen tests,finite element simulation and parametric analysis,theoretical calculations,etc.The cast-in-place concrete composite beam is added as a control group when investigating the mechanical properties of the composite beam in the positive moment zone,the specific work is as follows.(1)Two sets of prefabricated H-shaped steel and concrete composite beams of different configurations were fabricated to simulate the stresses in the negative moment zone of the composite beams in actual engineering by inverting the beams and applying uniaxial static loading in the middle of the span.The test data such as load-deflection curves,damage patterns,crack development,mid-span deflection variation curves,slip curves and load-strain curves of the two sets of composite beams were analysed and found that the mechanical properties of the two sets of composite beams in the negative moment zone were similar,with the composite beam with angles showing greater initial stiffness.(2)The results of the finite element analysis were compared with the test results and the results showed a good agreement between the two,which proved the reliability of the finite element model.according to the test model,a parametric analysis was carried out to investigate the effect of different lengths of angles on the load carrying capacity of the composite beam,and the results showed that the length of the angles was positively related to the ultimate load carrying capacity of the composite beam.(3)The loading method of the finite element model was changed to simulate the mechanical properties of the combined beam in the positive moment section,and the cast-in-place combined beam was added as a control group to derive the load-deflection curves and Mises stress graphs of the three groups of combined beams,and the parametric analysis of the finite element model in the positive moment section was carried out,and the theoretical calculations were carried out with reference to the formulae in the code and literature,and the error between the theoretical calculation results and the finite element analysis results was small.In this paper,the structural characteristics of the angle steel connectors are used to solve the problems of inconvenience in transportation and the large amount of design refinement caused by the outgoing bars.The mechanical properties in the negative moment section are similar to those of the outgoing bars through tests,finite element analysis and theoretical calculations,and in the investigation of the mechanical properties in the positive moment section,the composite beam with pre-buried angle steel connectors shows better shear resistance and can meet the load-bearing requirements of conventional composite beams.Figure [43] table [11] reference [76]... |
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