| Concrete filled steel tubular structure has been widely used in various engineering structures because of its high bearing capacity,beautiful appearance,convenient construction,good seismic performance,excellent ductility and plasticity,and remarkable economic benefits.With the increasing application of concrete filled steel tubular columns in the field of engineering,environmental corrosion of components is becoming more and more common,the safety and service life of the engineering structure have been seriously affected.Compared with the overall uniform corrosion,local corrosion is easy to cause stress concentration,leading to local sudden fracture or overall fracture failure of the component,which causes more deadly damage to the structure.At present,the research on the mechanical properties of concrete filled steel tube has been more extensive.However,there are relatively few studies on the influence of corrosion on concrete-filled steel tubular columns,and most of them focus on the study of overall uniform corrosion.Based on the above situation,this paper takes the volume loss rate of steel tube,the local corrosion position and the proportion of corrosion surface area as the change parameters to study the axial compressive properties of the concrete short column of round steel tube after local corrosion.The main work contents are as follows:（1）Forty-five concrete short columns of round steel tubes with different local corrosion types were designed and fabricated for axial compression tests.By observing the phenomenon of the test process and the final failure mode of the specimen,the following conclusions are drawn: the failure modes of the specimens can be mainly divided into shearing type and ring-drum type.The buckling failure sites of the steel tubes of the locally corroded specimens are all located in the locally corroded area,and there is no obvious change in the uncorroded area.（2）On the basis of the tests,the effects of volume loss rate of steel tube,local corrosion site and proportion of corrosion surface area on the mechanical properties of the specimens were further studied by load-displacement curve and load-strain curve.The results show that:the ultimate bearing capacity,initial stiffness and ductility of the specimens decrease with the increase of the volume loss rate of the steel tubes.The ultimate bearing capacity and ductility of corroded specimens at both ends are better than those at one end,while those in the middle are slightly lower than those at one end.The corrosion surface area ratio has no significant effect on the axial compressive properties of the specimens.With the increase of the steel tube volume loss rate,the difference of axial compressive properties of the specimens with different corrosion surface area ratio slightly increases.（3）The finite element model of concrete short column under axial compression of round steel tube after local corrosion was established by using the finite element software ABAQUS,and the establishment method of the model is expounded.The finite element simulation results are in good agreement with the experimental results by comparing the failure modes,load-displacement curves and ultimate bearing capacity of the specimens,which verifies the rationality of the finite element model established in this paper.（4）Based on the existing formulas for calculating the axial bearing capacity of concrete short columns with round steel tubes,regression analyses the available data,presented a simplified formula for calculating the ultimate bearing capacity of circular steel tube concrete short column under axial compression after local corrosion.By comparing the calculated values with the experimental values and the finite element simulation values,the results show that the bearing capacity calculated by the simplified formula is more accurate and generally safer. |
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