J. M. R. S. Appuhamy

Prediction of residual strength of corroded tensile steel plates

Recently, the damage due to deterioration of materials in many old steel bridge structures, which causes unavoidable strength reduction, is becoming a serious problem in Japan and all over the world. Therefore the remaining load-carrying capacities must be carefully evaluated 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 structure. This paper proposes a new method to calculate the remaining yield and tensile strengths by using a concept of representative effective thickness (teff) with the correlation of initial thickness (t0) and the maximum corroded depth (tc,max), based on the results of many tensile coupon tests of actual corroded plates. Further, the feasibility of establishing of an analytical methodology to predict the residual strength capacities of a corroded steel member with fewer number of measuring points is also discussed.

Development of an Efficient Maintenance Strategy for Corroded Steel Bridge Infrastructures

The potential for structural capability degrading effects caused by corrosion is of profound importance and must be both fully understood and reflected in bridge inspection and maintenance programs. As the number of steel bridge infrastructures increases throughout the world, it is an exigent task to conduct regular and detailed corrosion surface investigations to evaluate their residual strength capacities and to develop analytical models to understand their current conditions and critical locations, as well as yield and ultimate behaviors. This paper presents a simple, accurate, and rapid assessment method and an effective maintenance management strategy developed by using the results of tensile coupon tests conducted on numerous corroded plates obtained from a steel plate girder used for about 100 years with severe corrosion and an finite element method (FEM) analytical approach proposed by measuring only the maximum corroded depth, which can be used to make reliable decisions affecting cost and safety.

Development of Analytical Method for Predicting Residual Mechanical Properties of Corroded Steel Plates

Bridge infrastructure maintenance and assurance of adequate safety is of paramount importance in transportation engineering and maintenance management industry. Corrosion causes strength deterioration, leading to impairment of its operation and progressive weakening of the structure. Since the actual corroded surfaces are different from each other, only experimental approach is not enough to estimate the remaining strength of corroded members. However, in modern practices, numerical simulation is being used to replace the time-consuming and expensive experimental work and to comprehend on the lack of knowledge on mechanical behavior, stress distribution, ultimate behavior, and so on. This paper presents the nonlinear FEM analyses results of many corroded steel plates and compares them with their respective tensile coupon tests. Further, the feasibility of establishing an accurate analytical methodology to predict the residual strength capacities of a corroded steel member with lesser number of measuring points is also discussed.

Numerical Investigation of Residual Strength and Energy Dissipation Capacities of Corroded Bridge Members Under Earthquake Loading

Recent damage examples of aged steel bridge infrastructures around the world are so alarming. They intensified the importance of careful evaluation of existing structures for the feasibility of current usage and to ensure public safety. Corrosion and fatigue cracking may be the two most important types of damages in aging structures. Furthermore, recent earthquakes demonstrated potential seismic vulnerability of some types of steel bridges. Corrosion and its effects can trigger the damages caused by earthquakes, and it will be vital to understand the behavior of existing steel bridges which are corroding for decades in future severe seismic events as well. This article comprises the results of nonlinear FEM analysis of many actual corroded plates with different corrosion conditions and proposes a simple and reliable methodology to estimate remaining seismic strength and energy dissipation capacities by measuring only the minimum thickness of a corroded surface, which can be used to make rational decisions about the maintenance management plan of steel infrastructures.

Tensile Behavior Prediction of Steel Plates with Pitting Corrosion

We report the tensile behavior of corroded steel plates with huge corrosion pit. The behavior of corroded steel plates is not easy to predict because of its surface roughness. We therefore conducted tensile tests first to understand the behavior experimentally using the corroded steel plates taken from plate girder bridge. Before the testing, a 3D laser prove system was employed to measure the surface irregularity. In addition, finite element model was developed here to predict the behavior numerically. The model was validated by the tensile test results so that the finite element model can be reliably used for the parametric study. It is found from the parametric study that the location of huge corrosion pit affects the tensile strength, at most 15%.