Local Corrosion Effect On Mechanical Behavior Of Concrete-filled Steel Tubes

Concrete-filled steel tubes can give full play to the advantages of materials,and they have the advantages of high bearing capacity,ductility and convenient construction,as a consequence of which,they are widely used in var ious structures.In complex environments such as ocean,groundwater erosion,and industrial atmosphere,concrete-filled steel tube columns are prone to corrosion,leading to deterioration of the mechanical properties,which significantly affects the safety and durability of the structure.At home and abroad,a large number of experimental studies and theoretical analysis have been carried out on steel corrosion and concrete-filled steel tubes.However,there are still few studies on the performance of corroded concrete-filled steel tube columns.In this paper,the mechanical properties of locally corroded concrete-filled steel tube columns were studied by experimental research and finite element.Corrosion tests were carried out on 18 specimens of concrete-filled steel tube long columns,18 specimens of concrete-filled steel tube long columns after corrosion were subjected to eccentric compression tests,and three specimens of concrete-filled steel tube short columns were subjected to axial compression tests.Using the method of energizing to accelerate the corrosion and Faraday’s law which can calculate the time and current density required to reach the target corrosion rate,concrete-filled steel tube specimens with different degrees of corrosion were obtained.The main parameters are corrosion rate,hoop corrosion rate,eccentricity and slenderness ratio.The failure modes of specimens with different parameters are analyzed;The load-column deflection curve,column length-deflection curve and load-strain curve are obtained;The effect of parameters on the mech anical properties of components was explored.Finite element of ABAQUS was employed to develop three models to simulate the behavior of locally corroded concrete-filled steel tube columns,namely,Uniform corrosion model,macro-uneven corrosion model and micro-uneven corrosion model of concrete-filled steel tube.Through comparison with test results and literature,the accuracy of the finite element model is verified.Based on the finite element theory model,the bearing capacity degradation laws of locally corroded concrete-filled steel tubes under different corrosion rates,circumferential corrosion rates,corrosion areas,and corrosion positions are obtained.and the mechanical properties of the locally corroded concrete-filled steel tubes under different parameters are analyzed.Compare the calculated ultimate bearing capacity and test results of the three local corrosion models,the paper provides a reference for better fitting the ultimate bearing capacity of actual components after corrosion and establ ishing a locally corroded concrete-filled steel tube model.The test and theoretical analysis results show that the bearing capacity and deformation capacity of components will be significantly weakened by corrosion,and the ultimate bearing capacity will decrease with the increase of component corrosion rate,hoop corrosion rate,eccentricity and slenderness ratio.When the steel content of the component is 9.6% and the thickness of the steel tube is 2.0mm,as the corrosion rate increases from 0.0% to 50.0%,the ultimate bearing capacity decreases by 17.7%.The different corrosion parts will also have an effect on the bearing capacity of the components.The closer the corrosion area is to the column mid-section,the more obvious the bearing capacity degradation.The calculation results of the three types of locally corroded concrete-filled steel tube models are in good agreement with the test results.The three simplified models are all suitable for the study of the mechanical properties of concrete-filled steel tubes with local corrosion.