Experimental Study And Engineering Application Of Composite Beam With U-shaped Groove At The Ends

Recently, rectangular precast beams and U-shaped precast beams have beenwidely used in the prefabrication of composite beams. However, many disadvantageswere found in the use of them. Therefore, a new type of precast beam with U-shapedgroove at the ends has been invented by our team. It combines the advantages of boththe rectangular precast beams and U-shaped precast beams and makes a significantimprovement in many aspects compared with the traditional U-shaped precast beams.As a new type of composite beam, this research attempts to verify the stressbehavior by means of test analysis. In the frame structure, the reliability of the beamend of beam-column joint is a key factor to ensure the safety of a structure. Therefore,this thesis has researched the shear behavior at the ends of new composite beams,ordinary composite beams and cast-in-situ beams based on the experiments of fourbeam components with a short column in its middle part under concentrated loads.Moreover, this thesis has made comparative detailed analysis of different specimensin the aspect of cracking load, ultimate shear capacity, deflection deformation,ductility, stirrup strain, and the property of composition, the development of crackand average width of crack. This thesis not only discovers the feasibility of the designof new type of composite beams by applying existing codes but also provides areference for the application and dissemination in the field of civil engineering.Admittedly, it exists some difference of the construction methods between thenew composite beams and cast-in-situ beams, however, according to the comparativeanalysis of this thesis, the new type of composite beams and cast-in-situ beams aresuperior to the traditional composite beams in the aspect of ultimate shear capacity,overall mechanical performance, ductility etc. Although U-shaped groove at the endshas been added in the new composite beams, comparing with rectangular precastbeams, it has significantly improved the connection between precast components andcast-in-situ components, and also enhanced the integrity and deformation behavior ofbeam-column joint under this combined modes. It strongly approves that the variousperformance of new composite beam is as good as that of cast-in-situ beam. Finally,this thesis summarizes the composition, manufacture and construction techniques ofthe new composite floor system and introduces the merits and characteristics to show economic growth and social benefits generated by the application.