Experimental Study On Mechanical Performance Of Prefabricated Partially Encased Composite Beam

Prefabricated partially encased composite(PPEC)beam means to precast the girder web and slab part of the concrete beam in the factory,and finish the cast-in-site concrete part on the construction site.As a new type of composite structure PPEC beam combines the advantages of precast concrete structure and steel reinforced concrete structure.The current studies on PPEC beams are all based on the material limits of current codes.With the continuous development of high strength steel and high strength concrete,howing excellent mechanical performance,ombining the two,through reasonable design,can achieve good mechanical performance,reduce the cost and other characteristics,has a good application prospect.In this paper,seven PPEC beams specimen are designed.The section steel part is welded from Q690 high strength steel plate,and the underside is composite with ultra-high performance concrete(UHPC).This paper conducted monotone concentrated load test to study the mechanical performance of PPEC beams.By analysing the test results,the mechanical performance of PPEC beams are studied thoroughly.The main works are as follow:(1)involveing several parameters To study the mechanical performance of PPEC beams,this research involves several parameters,which includes thickness of the steel flange(6 mm,10 mm,14 mm),stirrup forms(link closed stirrup,rectangular stirrup,C shape stirrup),the flange forms(angle steel connection full precast slab,steel truss composite plate)and the strength grade of concrete flange plate(C40,C120).Besides,this research contrast the failure mode,crack resistance,bending stiffness and bearing capacity of PPEC beams.The test results show that the flexural capacity of PPEC beam can be significantly improved by increasing the flange thickness.Stiffness is less affected by stirrup form,flange plate form and flange plate concrete strength;(2)Based on the experimental study,this paper establishes the crack load calculation method of PPEC beam.The formula of crack width,flexural stiffness,flexural bearing capacity and longitudinal shear bearing capacity are derived,and the calculated results are in good agreement with the test results.The research shows that the Prefabricated partially encased composite beams combine the advantages of precasted structure and steel reinforced concrete structure,reduce construction difficulty and on-site wet work,save energy and protect environmrnt;at the same time,they have good mechanical performance and corrosion resistance,fire resistance have been further improved.