The Analysis On Mechanical Behavior Of Continuous Prestressed Composite Concrete Beams Using Non-linear Finite Element Study

After steel and concrete composite beam and prestressed reinforced concrete beams,prestressed steel and concrete composite beam is a new developed combination of prestressedsteel structures. Compared with the ordinary reinforced concrete beam, there are manyadvantages in the new components, such as lighted-dead weight, stiffness big, large bearingcapacity, crack resistance, seismic resistance; And for the purposes, the beam is suitable forlarge span and the structure of beam cross section have higher requirements. At present, thestudy of the prestressed steel and concrete composite beam is focused on single cross beam,single span large span beam. While, in practical engineering, the multi-span continuous beamis mainly used. Therefore, the study of prestressed steel and concrete composite beam remainsto be further developed and comprehensive.Using the nonlinear finite element software, to do systemic research on the mechanicalproperties of prestressed steel reinforced concrete continuous composite beams undermonotonous load, deformational properties was discussed, crack propagation and failuremechanism. The results show that the edge of beam tensile zone of concrete crack first, andthen steel, formed steel flange in tension and part of the web tension area yield, the beamflange on the tensile zone of concrete crushed, steel compression flange, steel bar, and a smallweb submission, damage before the beam has a larger bending deformation, shown as theplastic bending failure. The theoretical analysis results are in good agreement withexperimental result in the literature. Consided the parameters such as ratio of longitudinalreinforcement, prestress degree, span-depth ratio which effect on the mechanical behavior ofprestressed steel reinforced concrete continuous composite beams. Results show that the reinforcement ratio can effectively improve the ultimate bearing capacity of components,but it’s constraint effect is not obvious for the displacement controlling; And those stress stateare same with the ordinary steel reinforced concrete beam under the condition of onlychanging the reinforcement ratio. Prestressed degree can greatly enhance the usability ofbeam, but bending performance of beam does not change significantly with the increase of thedegree of prestress after cracking performance. We suggest the upper limit value ofspan-depth ratio of prestressed steel and concrete composite beam without deflectioncalculation:the side span is suit for16, the midspan is suit for22. With increasing ofspan-depth ratio, ultimate load and stiffness of the beam would be reduced; If the value ofspan-depth ratio is too high,the inclined section flexural shear capacity of normal sectionand midspan deflection would do not meet the requirements. If the value of span-depth ratio istoo low, it would cause dead weight is too large, and the crack width of the beam can’t satisfythe requirements of normal use, thereby the economic benefits of the whole structure wouldbe affected aslo, so it should be considered in engineering design.The mechanical properties of prestressed steel and concrete composite beam were deplyanalysised in different angles. The influence of different factors on the component stressperformance were analyzed, and the recommended value of span-depth ratio were putforward. The conclusion is helpful for promotion of prestressed steel and concrete compositebeam, and has certain reference value for further research.