Study On Flexural Behavior Of Steel Plate-UHPC Composite Deck

The structural system of the bridge ortho tropic steel deck(OSD)system is complex,and there are many welds.The repeated action of the wheel load arouses the fatigue issue,which eventually leads to structural cracks.In addition,the asphalt overlays over OSD are prone to rutting and cracking,which has a great unfavorable impact on OSD,in terms of serviceability and durability.Compared with normal concrete,UHPC shows obvious excellent performance.When UHPC is applied to bridge structures,the structural strength,rigidity,and durability can be greatly improved.Recently,the application of UHPC in civil engineering has increasingly attracted attention,including the application of steelUHPC composite deck in bridge engineering.A large number of studies and engineering practices have shown that replacing the traditional OSD structure with a steel-UHPC composite deck can effectively solve the two problems mentioned above.The Fulong Bridge in Foshan,Guangdong Province develops a new steel plateUHPC composite deck with perfobond rib shear connectors.The height of the steel plate is 8mm and that of the UHPC overlays is 150mm.In this new structure,PBL perforated steel plate replaces the longitudinal ribs of the steel box girder.UHPC layer is considered a load-bearing component.As a result,the bridge deck system is greatly simplified,and the structural stiffness is improved.This new composite deck can solve the traditional OSD problems of fatigue and pavement cracks as well.To investigate the flexural performance of this new composite deck,this paper conducted an experiment with six steel-UHPC composite slabs(three for positive bending test and three for negative bending test).The dimensions of the tested slabs are based on the design of the Fulong Bridge.In the experiment,the effects of PBL holes spacing and steel bars diameter on the flexural properties were investigated.The test results show that the hole spacing has little effect on the bending resistance of the specimens under positive bending.All the tested slabs show the damage pattern of bending failure,which demonstrates the good performance of PBL in shear resistance.The diameter of longitudinal rebars has an obvious influence on the mechanical properties of the specimens under negative bending.The cracking load,ultimate load,and flexural stiffness obviously increase as the diameter increases.Based on the test results,three different methods were used to simulate the interface behavior of the steel plate and UHPC using ABAQUS.It is found that the results of the finite element model with the surface-to-surface contact(frictionless)method are in better agreement with the experimental data.Therefore,this model was further used for parameter analysis to explore the influence of factors on the flexural performance of the composite slab,such as the thickness of UHPC and steel plate,and the diameters of longitudinal steel bars.The results show that the thickness of UHPC and steel plate are the key factors affecting the flexural performance of specimens under positive bending.The diameter of steel bars and thickness of UHPC have a great impact on the mechanical properties of specimens under a negative bending moment.This paper also calculates the cracking moment and ultimate load of composite slabs using a simplified theory.The overall error between the calculated value and the experimental data is small,and the calculated value is relatively safe,which has a certain reference value for engineering applications.