Prediction of Residual Buckling Strength in Corroded Steel Bridge Members

Abstract

Abstract: At present, degradation process of steel bridges has become major problem in all over the world. Steel bridges are exposed to numerous degradation processes during long year operation period, which causes various types of defects. Corrosion is one of major cause of deterioration process of steel bridge structures. Because of the corrosion, remaining load carrying capacities of steel bridge structures are gradually decreased. So it is very important to carefully evaluate the remaining strength of steel bridges in order to understand the feasibility of those steel structures for the current usage and to evaluate the necessity of retrofitting of selected corroded members to strengthen the existing structures. There are lots of researches have been conducted in order to find out remaining tensile strength of corroded steel bridge members. To find out remaining buckling strength of corroded steel, previously conducted tensile test results are not accurate. So evaluation of buckling strength is an essential source of information for carrying out a comprehensive evaluation of its current buckling strength capacity and also the parameters involve in the method should be easily measurable. There is a need of more brisk and accurate assessment method which can be used to make reliable decisions affecting the cost and safety. This study proposes a new method to calculate the remaining buckling strengths by using minimum thickness ratio based on the results of many buckling strength tests conducted on specimens of corroded steel bridge plates with different corrosion conditions based on the results of many compression coupon tests of actual corroded plates. And also, it is an impossible task to predict remaining buckling strength capacities of each and every aged bridge structure by conducting experiments and so nowadays, the finite element analysis method has become the most common, powerful and flexible tool in structural analysis and makes it possible to predict the strength of complex structures more accurately than existing classical theoretical methods. Further, since it is not easy to measure several thousands of points, to accurately reproduce the corroded surface by numerical methods and to predict their buckling behaviors , a simple and reliable analytical model is proposed by measuring only the maximum corroded depth (Tc,max), in order to estimate the remaining strength capacities of actual corroded members more precisely.