| Since the last century,steel plate girder has been widely used in bridge engineering.However,steel-concrete composite structures have an advantage over the traditional steel or concrete structure,in which the most common composite flexural member is composed of concrete and I-steel.Besides,such composite structures take full advantage of their material properties to provide higher strength and stiffness.With the rapid development of transportation,rollover and leakage accidents about liquid transport vehicles on Bridges are common.Once an accident occurs in a corrosive liquid tank truck,the steel of steel plate composite beams is corroded rapidly and produced a large amount of acid mist,which seriously degraded the mechanical properties of the steel plate composite beam as well as the structural bearing capacity.Besides,not only does there is a great impact on road traffic with composite beams occur deflection or even collapsing,but also bring serious harm to the personnel at the scene of the accident and the surrounding environment.Therefore,it is worth attending to the influence of strong corrosive liquid on the mechanical properties of steel-concrete composite beams.Domestic and foreign scholars are mainly concentrating on simulation of atmospheric corrosion environment about corroded steel-concrete composite structures,where are few studies on the mechanical degradation performance and bearing capacity degradation of steel-concrete composite structures under strong corrosion.Based on the research of scholars at domestic and foreign,this paper adopts the method of combining experimental research,finite element simulation,and theoretical analysis likewise carries out the monotonic tensile test of different bridge steel under strong corrosion.So that the mechanical properties under strong corrosion are revealed considering corrosion degree of steel,and established the constitutive model of bridge steel.On the basis of studying the degradation model of mechanical properties,the finite element model of steel plate composite structure under the coupling effect of load and the corrosive liquid is established,which analyzes the attenuation law and failure mechanism of positive bending moment and bending capacity under different corrosion rates and corrosion time.In the following,the major contents and results are summarised :（1）By searching and studying related papers,master the basic situation of corrosion steel.The ordinary steel Q345 and weathering steel Q345 were immersed in 36 % hydrochloric acid for 0,1,2,4,8,12,24,48 and 72 h,respectively.Here,the 3D morphology of corroded steel plates was scanned to analyze the relationship between the maximum corrosion pit coefficient and mechanical properties,and establish the strong corrosion kinetics curve.（2）The quasi-static tensile test of two kinds of strong corrosion bridge steel was carried out,which measured the mechanical parameters of the material and obtained the constitutive relationship.At this time,it is also researched the relationship between fracture morphology,stress-strain curve,mechanical properties and corrosion degree of steel.（3）The nominal stress-strain curve of strong corrosion steel was transformed into the true stress-strain curve.Using Origin software to fit,get A,B,and n in different Johnson-Cook models,and substitute into ABAQUS to simulate the stress flow and necking failure of weathering steel Q345 considering flexible metal damage.Finally,the equivalent ductile fracture criterion of strong corrosion steel based on corrosion time was established.（4）A finite element model of a three-span double I-shaped steel plate girder was proposed by ANSYS finite element program to analyze the structural response of three kinds of strong corrosive bridge conditions.Moreover,the influence of steel plate beams under corrosive liquid was investigated,such as structural bearing capacity and deformation.And to explore the variation law of structural properties of steel plate beams under strong corrosion. |
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