Test And Analysis Of Mechanical Properties Of Corroded Weathering Steel Connections

Ordinary steel is easy to be corroded,which will seriously affect the safety and reliability of steel structures.New high-quality Weathering steel can effectively solve this problem.This paper focuses on the mechanical properties of corroded Weathering steel connections.The effects of corrosion cycle,steel plate type,and other factors on the failure mode and mechanical properties of material specimens and butt weld connections were studied through experiments.The effects of corrosion cycle,steel plate surface treatment method,and high-strength bolt type on the failure mode and mechanical properties of highstrength bolt connections were analyzed.Through the numerical simulation software,the influence of longer corrosion cycles on the failure mode and mechanical properties of high-strength bolt connections was studied,and the static performance of Weathering steel bolted welded beam column connections was explored by the factors such as the thickness of steel plate,the size of high-strength bolts,the anti slip coefficient,and the preload of high-strength bolts.The main content of this article includes:(1)Neutral salt spray corrosion tests with corrosion cycles of 0 days and 30 days were carried out on Q355 B ordinary steel performance test piece(PC test piece)and S355J2 W weathering steel performance test piece(NC test piece)respectively,and tensile tests were carried out on the corroded test pieces.The results showed that the surface of the two test pieces after corrosion had two mixed colors of brown yellow and black,and the thickness of the corrosion layer on the surface of the test piece increased with the increase of the corrosion cycle.Under the same corrosion cycle,the corrosion products of NC specimens are less than those of PC specimens,and the black corrosion products of NC specimens are less than those of PC specimens.After 30 days of corrosion,the yield load,ultimate load,nominal yield strength,and nominal ultimate strength of both specimens decreased compared to the non corroded specimens.(2)The Q355 B ordinary steel butt weld connection test piece(PD test piece)and S355J2 W weathering steel butt weld connection test piece(ND test piece)were subjected to neutral salt spray corrosion tests with corrosion cycles of 0 days,10 days,20 days and30 days respectively,and the corroded test pieces were subjected to tensile tests.The results showed that the fracture failure mode of the two test pieces was mostly 45 ° inclined shear failure,and the fracture surface of some test pieces was flat.The yield load and ultimate bearing capacity of both specimens decrease with the increase of corrosion cycle,and the decrease in yield load is greater than that of ultimate load.The decrease in yield load and ultimate load of PD specimens is greater than that of ND specimens.(3)Neutral salt spray corrosion tests with corrosion cycles of 0 days,10 days,20 days,and 30 days were conducted on weather resistant high-strength bolt connections and ordinary high-strength bolt connections considering two different surface treatment methods of steel plates.The corroded specimens were subjected to tensile tests,and the results showed that the failure and failure modes of the specimens were basically consistent,that is,the failure of the specimens occurred at the outer bolt holes of the core plate.The load displacement curve obtained from the experiment can be divided into five stages: friction force stage,sliding stage,pressure bearing stage,strengthening stage,and failure stage.The anti slip load and full slip load of specimens(NP specimens)connected with weather resistant high-strength bolts and treated with steel plate surface shot blasting are greatly affected by the corrosion cycle,and show a trend of increasing first and then decreasing.The yield load and ultimate load of NP specimens are less affected by the corrosion cycle.The anti slip load of specimens connected with weather resistant highstrength bolts and untreated steel plate surfaces(NW specimens)is greatly affected by the corrosion cycle,showing a trend of increasing first and then decreasing.The yield load and ultimate load of NW specimens are less affected by corrosion cycles.The anti slip coefficients of both NP and NW specimens show a trend of increasing first and then decreasing.Based on the experiments in this article and existing literature,a function model for the anti slip coefficient of NP and NW specimens is proposed.(4)On the basis of experimental research and theoretical analysis,the performance of high-strength bolt connection specimens with longer corrosion cycles was supplemented and analyzed using ANSYS numerical simulation software.The results showed that the load displacement curve trend and failure mode of finite element simulation were similar to those of actual tests.The correlation between the initial anti slip load of specimens with different corrosion cycles and the anti slip coefficient of specimens is significant,while the correlation between the ultimate load of specimens and their geometric dimensions is significant.(5)Based on the data and results of previous corrosion tests,tensile tests and numerical simulation analysis,the mechanical properties of bolted welded connections of weathering steel in different corrosion states were analyzed using finite element software.Comparing and analyzing the numerical simulation results of bolted welded beam column joints in different corrosion states,it can be found that factors such as thinning of steel plate thickness,reduction of high-strength bolt size,reduction of high-strength bolt preload,and first increasing and then decreasing anti slip coefficient caused by corrosion have a significant impact on the load-bearing performance of the joints.As the corrosion cycle increases,the load at which the first sliding occurs in the beam column node gradually decreases,and the load at which the node fails also gradually decreases.