Research On Shear Characteristics Of ECC-Steel-Epoxy-Aggregate Composite Cohesive Layer

Cracking,transposition,upheaval and insufficient shear strength due to the failure of interlayer bonding and so on,generally which are main problems considering the structure of steel bridge deck.In this thesis,based on domestic and international research results about the form of steel bridge deck,respecting to the deficiency of flexible pavement,the ECC is selected as pavement materials,designing the composite structure of bridge deck.Regarding size and spreading quantity of aggregate and different waterproof binding materials as experiment parameters,under dead load,the oblique shear experiment of ECC-steel-epoxy-aggregate composite cohesive layer is accomplished with respect to the damage course of interface analyzing sensibility of experiment parameters when damage morphology,shear strength τ,the curve of τ-δ(shear slip),shear modulus K,tangential cohesive energy ?0,and shear-clip energy ?f are different,as well as the development law of τ-δ curve and stress-strain curve of ECC pavement is researched.As follows,there are main research contents and results in this thesis.(1)The shear damage morphology mainly includes that stripping damage of interlayer between the waterproof cohesive material and steel deck,cohesive failure of interface between the waterproof cohesive material and aggregate,or they happen together.(2)The curve of τ-δ at interlayer can be divided into three stages including increase,yielding and softening.When spreading quantity of aggregate is determined,τ,K,?0,?f and ε(cohesive interlayer strain)have distinctly increased trend with increase of aggregate size;δ0,displacement corresponding to the maximum shear strength,gradually decreases with increase of aggregate diameter;when aggregate size is determined,τ,δ0,?f and εfirstly increase then decrease,and the optimal spreading quantity is 4.5~5.5kg/m2;with increase of spreading quantity,K gradually increase;the curve of τ-ε is full circularity,mainly dividing into liner stage,curvilinear increase stage,and curvilinear decrease stage.(3)The design of composite size from 4.75~9.5mm to 9.5~13.2mm and spreading quantities of aggregate for 4.5~5.5kg/m2 to ECC-steel-epoxy-aggregate composite cohesive layer is suggested.(4)Based on the experimental results,using Popovics model to research the bond slip law of interlayer.Analyze the damage course of interface cohesion through cohesive damage variables combining with Popovics model,Dτ and DB,based on shear strength and shear stiffness.Results indicate that popovics model can be applied to represent theshear-slip law of the interface.Dτ fits the facts of the damage course of interface better than DB.(5)Grey theory is employed to set up damage prediction model about Dτ and δ.Results indicate that prediction of model has relative high precision,and can be applied to represent the damage law of interface with the increase of shear displacement.