Reliability Analysis of a Suspension Bridge Affected by Hydrogen Induced Cracking Based upon Response Surface Method

Abstract

This paper deals with the Hydrogen Induced Cracking (HIC) of wires in a cable of a suspension bridge. The main objective is to compare the safety of a bridge system locally and globally. In a deterministic analysis stage, HIC in cable wires is calculated in order to evaluate the local safety of the main cable of suspension bridge. In the local analysis, a decoupling technique has been developed for the evaluation of crack propagations in a wire section driven by the hydrogen diffusion to a wire section, in terms of two 2-dimensional finite element models. One is for the fracture analysis in a longitudinal section, and the other is for a hydrogen diffusion model in a horizontal section. In a stochastic analysis stage, an ultimate limit state function for the cracking in cable wires is considered for the local safety of main cable. Using the ultimate limit state, the reliability of time-dependent and crack depth-dependent HIC of a cable wire has been calculated in component and parallel system reliability analysis. Globally, a serviceability limit state based on the global responses of a stiffening girder is also evaluated. Based on the observed difference of safeties between the global and local behaviors of the suspension bridge system, the proposed solutions are discussed.KEY WORDS: hydrogen induced cracking; crack propagation; cable wires; suspension bridges; reliability. axial strength of twisted strand wires. 11)Those previous studies may predict the fatigue crack growing in a wire or provide a monitoring criterion for corroded cable wires. However, the crack propagation is mainly caused by hydrogen induced cracking in a main cable of a suspension bridge.The main objective of this study is to investigate the safety of an example suspension bridge considering local reliability of the corrosion assisted crack growth in cable wires, and the global safety of a suspension bridge affected by HIC in main cables as follows:(1) Application of the developed analytical model for the fracture analysis in a cable wire by utilizing the developed analytical model for the diffusion analysis by the infiltrated hydrogen atoms. 4) (2) Reliability analysis for the HIC of a cable wire for a crack growth as a time dependent function for the evaluation of local safety in main cables, based on the fracture analysis for crack growing with transient hydrogen diffusion analysis.(3) Reliability analysis for the global behavior of suspension bridge system in order to compare global safety with the local behavior based on FE analysis. Cable Wire Attacked by Hydrogen Induced Crack 2.1. Decoupling the Diffusion Analysis and FractureAnalysis for HIC in Wire The authors have decoupled the hydrogen diffusion analysis from the fracture analysis for crack growing in prestressed wires due to HIC. 4) As the conservative and practical design of a structure regarding HIC, two 2-dimensional simplified finite element analysis (FEA) models have been proposed. As shown in Fig. 2, in the longitudinal section, the SIF is calculated by a fracture analysis...

Bayesian Correlation Prediction Model between Hydrogen-Induced Cracking in Structural Members

“…As a mixture of corrosion and crack growth deterioration in structural steel, Hydrogen-Induced Cracking (HIC) has been present in the cable wires of many suspension bridges [1][2][3][4][5][6][7][8][9]. Because it may become the primary cause underlying abrupt failure of structural systems, HIC of cable wires is a critical issue in cable-supported structures.…”

“…However, very few studies have attempted to quantify the correlation between HIC and structural components. The quantification of this correlation is essential for developing an optimized maintenance plan in terms of budget management, leading to the design of bridge systems have been compared by the authors of this study and by other researchers [3,4,11,13]. With regard to the local safety analysis, a decoupling technique based on two-dimensional finite element models has been developed for evaluating hydrogen-diffusion-driven crack propagation in a wire section.…”

“…Parallel system reliability analyses have also been carried out. While the proposed solutions show local and global risks successfully and separately calculated based on observed differences in the global and local safety behaviors of the suspension bridge system, a quantitative correlation between the two behaviors has not been modeled [3,4].…”

“…This, combined with the stress applied to the metal, can result in crack propagation. Diffused hydrogen atoms can recombine to form hydrogen molecules, which can exert pressure on the surrounding steel, resulting in the crack propagation in wires under high tensile stress [3,4].Such corrosion can happen under exposure to carbonated and bicarbonated, caustic, nitrate, cyanide, anhydrous ammonia (liquid), mixture of nitric and sulfuric acid, mixture of magnesium chloride and sodium fluoride, or CO/CO 2 /H 2 O mixtures, and under hydrogen attack. Some mechanisms have been proposed in the literature for explaining the phenomenon; these can be classified as either anodic Stress Corrosion Cracking (SCC) mechanisms or mechanical fracture processes.…”

“…This, combined with the stress applied to the metal, can result in crack propagation. Diffused hydrogen atoms can recombine to form hydrogen molecules, which can exert pressure on the surrounding steel, resulting in the crack propagation in wires under high tensile stress [3,4].…”