Experimental investigation of ultimate bearing capacity of corroded welded hollow spherical joints

Abstract

The basis for analysing and evaluating the safety performance of space structures in service is investigating the effect of corrosion on the residual bearing capacity of welded hollow spherical joints. Thus, accelerated corrosion tests were conducted in this study on five types of welded hollow spherical joints, where the longest corrosion time is 283 d. Subsequently, axial tension, axial compression, and eccentric compression tests were performed after corrosion. The effects of the corrosion time, joint size, steel strength, and eccentric load on the mechanical properties of the corroded joints were then considered. The test results show that the failure mode and strain distribution of the joints are not influenced by corrosion. For the axial force, the ultimate bearing capacity of the corroded joints fluctuates with the corrosion rate (less than 10%); and under the combined action of the bending moment and axial force, the ultimate bearing capacity of the corroded joints decreases with a decrease in the corrosion rate (maximum reduction of approximately 22%). Finally, a simplified calculation method for the ultimate bearing capacity of welded hollow spherical joints after corrosion was proposed. For the atmospheric environment in Qingdao (over a 50 year period), the corrosion coefficient under axial force is 0.87 considering the joint size and comprehensive corrosion influences. Under the combined action of the axial force and bending moment (within 40 mm of the initial eccentricity), the corrosion coefficient is 0.73.