Research On The Ultimate Bearing Capacity Of Unstiffened Space DKT Type Steel Circular Hollow Section Joints In Corrosive Environments

Large span spatial structures located in industrial atmospheric environments are prone to corrosion due to environmental influences,especially at the joints of the structure.The impact of corrosion on their bearing capacity cannot be ignored.In addition,the joint forms in large-span spatial structures are becoming increasingly complex,and the application of space DKT type steel circular hollow section joints has also begun to rise.Therefore,it is of great significance to conduct research on the impact of corrosive environment on the bearing capacity of space DKT type steel circular hollow section joints in this paper.This article adopts finite element simulation methods to substitute the mechanical properties of corroded material specimens into the finite element model to explore the ultimate bearing capacity of corroded space DKT type steel circular hollow section joints.The specific content is as follows:（1）Indoor accelerated corrosion tests on coupon test specimens to simulate the corrosion of steel in industrial atmospheric environments were conducted.Uniaxial tensile tests on corroded specimens were conducted to obtain their mechanical properties,including ultimate bearing capacity,yield strength,ultimate strength,and elastic modulus.The variation law of mechanical properties of Q345B steel was investigated and the effect of one-sided corrosion and two-sided corrosion on mechanical properties of joints was studied.（2）The existing joint test was selected to establish the finite element model,and the finite element analysis results were compared with the test results and the code calculation results to verify the rationality of the finite element modeling method in this paper.The finite element model of non-corroded space DKT type steel circular hollow section joints was established.（3）By replacing the non-corroded model with the mechanical properties and reducing the thickness,the finite element model of the corroded joint was established,the ultimate bearing capacity of corroded joints was obtained,and a degradation model of the ultimate bearing capacity of joints with corrosion weight loss rate was established.The prediction model of atmospheric exposure corrosion depth established by predecessors in typical environments was introduced,and a degradation model of the ultimate bearing capacity of actual joints over time was obtained,providing a basis for predicting the ultimate bearing capacity life of actual engineering joints.（4）The ABAQUS finite element model was used for parametric analysis of space DKT type steel circular hollow section joints（Control variates were used to change a single parameter to achieve）.The parameters involved included the diameter thickness ratio of the main tubeγ,diameter ratio of inclined branch tube to main tubeβ₁,Vertical branch to main tube diameter ratioβ₂,angle between branch and main tubeθAnd spatial angleφ.The variation law of the ultimate bearing capacity of corroded space DKT type steel circular hollow section joints under different parameters was explored.