Corrosion Resistance and Ultimate Shear Capacity of Weathering Steel High-Strength Bolts

Abstract This study evaluates how corrosion impacts the mechanical performance of various weathering steel bolts, focusing on Chinese Standard 10.9s NHL10 bolts (CS weathering bolts), American Standard A490M Type 3 bolts (AS weathering bolts), and double-shear connectors assembled with Q420qFNH weathering steel plates. The corrosion resistance and ultimate shear capacity of these bolts are evaluated through acetic acid salt spray accelerated corrosion tests and tensile tests. A finite element model is established to simulate the mechanical behavior. Experimental results show that, at the same level of corrosion exposure, weathering steel bolts possess slightly higher ultimate shear capacity than do Chinese Standard (CS) high-strength bolts (ordinary bolts). Among them, CS weathering bolts exhibit the highest shear strength in uncorroded conditions and after 60 and 120 d of corrosion exposure. The average weight loss rates after 60 and 120 d of corrosion are 2.49% and 4.60% for CS weathering bolts, 2.67% and 4.87% for AS weathering bolts, and 3.13% and 6.21% for ordinary bolts, respectively. As a dense and stable inner rust layer forms, the corrosion rate and weight loss rate of weathering steel decrease significantly, indicating superior corrosion resistance compared to ordinary bolts, whose corrosion rate remains almost constant. The error between finite element simulation and experimental results in predicting the ultimate shear capacity is less than 2%. The simulation results also indicate that the reduction ratio of ultimate shear capacity is positively correlated with the weight loss ratio, whereas bolt preload mainly affects the sliding load and has little influence on the ultimate shear capacity.