| Steel-concrete composite structures are widely used in civil buildings and bridges engineering by combining the advantages of their respective materials in terms of mechanical properties,which makes such structures have great advantages in large spans and spaces.In the traditional steel-reinforced joist concrete laminated slab system,the bent reinforcement is embedded in the end of the steel beam of the prefabricated base plate.However,the bending up of the reinforcement often causes collision problems during the construction process,which slows down the construction progress.What’s more,there have some safety loopholes because the prefabricated base plate does not form a solid connection with the steel beam.In order to make the construction of assembled steel-steel joist concrete laminated slab structure faster,safer and more efficient,this paper proposed a steel-steel joist concrete laminated slab structure with pre-embedded angle connections in the precast base slab,which has the advantages of fast construction progress and high safety,which has the significance in promoting the growth of prefabricated building.To study the mechanical performance of steel-laminated plate composite beams and beam-slab joints under negative bending moment and to verify the reasonableness of steel-laminated plate composite structure with prefabricated base plate with pre-embedded angle steel connections,the experimental analysis,finite element analysis and mathematical analysis were chosen to study the mechanical performance of these composite structures.It can provide a reference for the design and engineering practice of such composite structures.The main contents and conclusions of this paper are as follows:（1）.Experimental study of the mechanical performance under negative bending moment of a steel-laminated plate composite beam with prefabricated base plate projecting out the bent-up reinforcement and prefabricated base plate with pre-embedded new angle steel connections.The similarities and differences in load-deflection,deflection distribution,interface slip,crack distribution and section strain distribution of the two groups of composite beams were analysed and compared.The results of the study show that the damage patterns of the two sets of composite beams are serious cracking of the concrete slab and obvious buckling of the flange and girder web in the span,and the ultimate bearing capacity is similar.No shear damage occurred at the laminated surface,and the overall mechanical performance of the combined beams is good.The crack distribution of the two types of composite beams is similar,and the angle steel connectors have the effect of inhibiting the longitudinal splitting cracks of the steel-laminated plate composite beam.The steel-laminated plate composite beam with prefabricated base plate with pre-embedded new angle steel connectors has better combination performance and greater flexural stiffness.The slip of the steel-laminated plate composite beam with prefabricated base plate pre-embedded with new angle steel connections is much smaller than the slip of the prefabricated base plate projecting out of the bent-up reinforcement,and the maximum slip is only 1/2 of the prefabricated base plate projecting out of the bent-up reinforcement.（2）The stiffness of steel-laminated slab composite beam under negative bending moment is analyzed by applying the correction formula considering the additional deflection generated in the relative slip of the intersection interface.The analysis results show that the deflection values calculated by ignoring the concrete contribution to the stiffness in the negative moment zone of the composite beam deviate from the test values by a large margin,and the calculated values are too conservative.The deflection value calculated by equivalent stiffness is closer to the test value in the elastic phase,and the agreement of the deflection value in the elastic bearing capacity range is improved by about 5% compared with that of the deflection value calculated by ignoring the concrete action,and it is on the safe side.（3）The refined modeling analysis was carried out by combining the bending performance test of the steel-concrete laminated slab composite beam under negative bending moment.The model results are in good agreement with the test.On the basis of the experimental model,11 sets of finite element models were established for parametric analysis to investigate the influence of concrete strength,lap length of prefabricated base plate on the flange of steel beam,and the number of angle steel connectors on the flexural load carrying capacity and flexural stiffness of steel-laminated plate composite beam with prefabricated base plate with preembedded angle steel connectors.The results show that the concrete strength and lap length have almost no effect on the flexural load carrying capacity,and the number of angle steel connectors has a small effect on the flexural load carrying capacity.With the increaseing of concrete strength and the number of angle steel connectors,the initial stiffness and the later stiffness increase;the lap length has almost no effect on the stiffness.（4）In order to eliminate the influence of interaction between parameters in the finite element parametric analysis,an orthogonal table with three factors and three levels were designed,and a finite element model of bending under negative moment with uniform distribution of each factor and level were established for nine groups to determine the degree of influence of concrete strength,lap length and number of angle connectors on the initial stiffness and later stiffness.The results of the extreme difference and analysis of variance show that the number of angle connectors is the significant factor,followed by the concrete strength,and the lap length had no significant effect on the flexural stiffness.（5）In order to study the mechanical performance of the beam-slab joint formed by the laminated plate of prefabricated base plate with pre-embedded angle steel connections and steel beams,the mechanical performance of beam-slab joints of four different configurations is studied by means of finite element analysis,than the mechanical mechanism and transmission process of the angle steel connections are analyzed.On this basis,11 parametric analysis models were established for the influence law of bearing capacity of this joint on the diameter of upper web bearing reinforcement,concrete strength,number of angles,strength of angles and diameter of angles bending up reinforcement.The finite element study shows that the joints of the laminated plate and steel beam connection of the prefabricated base plate with pre-embedded angle connections have good load-bearing capacity and ductility and excellent working performance.The angle steel connectors have good safety performance during normal use.The flexural loading capacity of the beam-slab joint increases dramatically with the increase in the diameter of the upper web reinforcement.The concrete strength and the number of angles have less effect on the flexural loading capacity.Angle strength and angle bending up reinforcement diameter have no impact on the flexural loading capacity.Figure [65] table [20] reference [75]... |
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