A method to calculate seismic behavior of a corroded beam-to-column joint considering distribution randomness of corrosion depth

Abstract

When conventional uniform corrosion method and equivalent material property method are applied to predict the seismic performance of corroded steel beam-to-column joints, distribution randomness of corrosion depth can't be considered, once damage occurs at a position where there is a large corrosion pit, there will be a great error between the actual damage and the damage predicted by the two methods. The current work aims to overcome this problem. Firstly, accelerated corrosion test was conducted on mild steel coupons. Secondly, topography of the corrosion pits was scanned, and distribution characteristic of the corrosion depth was obtained. According to the distribution characteristic, a FE modeling method (namely, stochastic corrosion method) that considers distribution randomness of the corrosion depth was proposed. The proposed method, together with uniform corrosion method and equivalent material property method were then applied on the seismic performance prediction of a corroded steel beam-to-column joint. The results show that 1) The depth of the corrosion pits on the specimens subjected to accelerated corrosion approximately obeys lognormal distribution. 2) The corroded steel beam-to-column joints' hysteretic behavior predicted by stochastic corrosion method is more accurate than those predicted by the other two methods. Compared with uniform corrosion method, the maximum calculation accuracy improvement of stochastic corrosion method can reach 90%. 3) The reason which leads to prediction error of uniform corrosion method is that localized buckling of some positions on the structural member is overlooked, while the reason leads to prediction error of equivalent material property method is that the kinematic hardening parameter C is assumed to increase with the increase of corrosion time period. Both the prediction errors of the two methods increase with the increase of corrosion time.