LAUSR

Abstract To investigate the seismic behavior of corroded steel frames in chloride environment, accelerated corrosion tests and lateral low cyclic loading tests were carried out on four steel frames. Firstly, a deterioration model of mechanical property with mass loss rate for corroded Q235B steel was proposed. Then, the failure process and mechanism of test steel frames were observed, the strain developments of potential plastic hinge sections at beam ends and column bases were analyzed, and the effects of corrosion level on the hysteretic curves, bearing capacity, stiffness degradation, ductility and energy dissipation capacity were studied in detail. The test results indicated that in relatively slight corrosion level, all specimens exhibited a hybrid yield dissipation mechanism, with the “beam end - column bottom - beam end” sequence of the plastic hinges occurring. However, an increase in corrosion level tended to accelerate plastic hinge formation and aggravate structural damage degree. Additionally, with the increase of corrosion level, the lateral bearing capacity reduced, stiffness degradation intensified, ductility and energy dissipation capacity decreased. Base on test data, the structural performance levels and performance index quantified thresholds of corroded steel frame were preliminarily determined. Moreover, a finite element model adopting a time-varying constitutive model of corroded steel and a stress triaxiality dependent failure criterion, was established using ABAQUS, and then verified to be valid by comparing the numerical and experimental results. The research results lay an experimental and theoretical foundation for the seismic performance evaluation of in-service steel frame structures in chloride environment.