Experimental And Theoretical Analysis On Seismic Behavior Of Corroded Steel Frame Joints In Acidic Atmosphere

Long-term corrosion in the environment under the steel structure,it is also difficult to avoid its corrosioneven even with the corresponding anti-corrosion measures and structural measures,resulting in the steel surface random distribution of different sizes of rust pits,great weakness of steel plasticity and fracture toughness,greater impact of steel structure seismic performance.In this paper,the failure mode,seismic performance and fracture prediction of the steel frame beam-column joints in acidic atmosphere are studied by means of experimental study,theoretical analysis and numerical simulation.The main work and achievements of this paper include:(1)Using the outdoor cycle spray exposure test to simulate the urban acid atmospheric environment,14 kinds of Q235 B steel plates and four fully welded steel frame structure beam and column joints were subjected to acidic atmospheric corrosion,and the steel sheets with different degree of corrosion were obtained.Steel frame beam-column joint specimen.(2)The monotonic tensile constitutive model of corroded steel was established by the monotonous tensile test of seven different degrees of corrosion steel plates.The fracture toughness parametersmonη based on microscopic mechanism pore growth model(VGM)were calibrated by finite element simulation.This paper has researched the relationship between the fracture toughness parameters and the corrosion rate ?,and discussed the influence of the finite element mesh size on the fracture toughness parameters.(3)By studying the hysteresis tests of seven kinds of steel plates with differentdegree of corrosion,the experiment analyzed the impact of corrosion on the parameters of strengthened and mixed steel model.By embedding the programmed UVARM in ABAQUS software,the test verified the accuracy of the fractured prediction of corroded steel plate under the reciprocating load in the cyclic pore growth model(CVGM).Based on the calibration results of toughness parameters of corroded steel,this test established a relationship between parameters of corrosion damageCVGM? and the corrosion rate.(4)According to the low-cyclic reciprocating load test on five kinds of welded steel frame beam-column joints with different degrees of corrosion,the experiment analyzed the corrosion ? ’s impact of steel frame structure beam-column joints on the seismic performance indicators such as hysteresis curve,skeleton curve,strength degradation,stiffness and degradation.On the basis of the experiment,the parameters of the reinforced steel frame beam-column joint reinforced model were calibrated.Then introducing the calibrated mixed-model parameters and CVGM toughness parameters into ABAQUS,the test theoretically analyzed the seismic performance of the joints and revealed the degradation mechanism of seismic performance on the joint under the acid atmosphere.