scholarly journals Assessment of Mechanical Properties of Corroded Prestressing Strands

2020 ◽  
Vol 10 (12) ◽  
pp. 4055 ◽  
Author(s):  
Chi-Ho Jeon ◽  
Cuong Duy Nguyen ◽  
Chang-Su Shim
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Prestressed Concrete ◽  
Critical Issue ◽  
Concrete Bridges ◽  
Structural Behavior ◽  
Maximum Deformation ◽  
Prestressing Steel ◽  
External Tendons ◽  
Governing Factor

The corrosion of prestressing steel in prestressed concrete bridges is a critical issue for bridge maintenance. To assess structures with corroded strands, it is necessary to define the mechanical properties of the strands and their influence on the structural behavior. In this study, corroded strands were taken from external tendons in existing post-tensioned concrete bridges and tested to determine the effects of corrosion on their tensile properties. Empirical equations for the tensile strength and ductility of the corroded strands were proposed using test results. The most corroded wire governs the mechanical properties of the strand. Experiments on prestressed concrete beams with a single corroded strand were conducted to investigate their structural behavior. A reduction in the flexural strength and maximum deformation was observed in these experiments. According to the section loss of a wire in a strand and its location in a beam, the flexural capacity can be evaluated using the proposed equation. The reduced ultimate strain of the corroded strand can be the governing factor of the flexural strength.

scholarly journals Assessment of Mechanical Properties of Corroded Prestressing Strands

2020 ◽  
Author(s):  
Chi-Ho Jeon ◽  
Cuong Duy Nguyen ◽  
Chang-Su Shim
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Prestressed Concrete ◽  
Critical Issue ◽  
Concrete Bridges ◽  
Structural Behavior ◽  
Maximum Deformation ◽  
Prestressing Steel ◽  
Governing Factor ◽  
Existing Bridges

The corrosion of prestressing steel in prestressed concrete bridges is a critical issue for bridge maintenance. To assess structures with corroded strands, it is necessary to define the mechanical properties of the strands and their influence on the structural behavior. In this study, corroded strands are taken from external tendons in existing bridges and tested to define the effects of corrosion on the tensile properties of the strand. Empirical equations for the tensile strength and ductility of the corroded strand are proposed using test results. The most corroded wire governs the mechanical properties of the strand. Experiments on prestressed concrete beams with a single corroded strand are conducted to investigate the structural behavior. A reduction in the flexural strength and maximum deformation is observed from the experiment. According to the section loss of a wire in a strand and its location in a beam, the flexural capacity can be evaluated using the proposed equation. The reduced ultimate strain of the corroded strand can be the governing factor of the flexural strength.

Reliability-Based Assessment of Flexural Strength of High-Speed Rail PC Box Beam in Marine Environment

2013 ◽  
Vol 405-408 ◽  
pp. 678-683
Author(s):  
Zhao Hui Lu ◽  
Hai Li ◽  
Yan Gang Zhao
Keyword(s):  
Flexural Strength ◽  
Marine Environment ◽  
Prestressed Concrete ◽  
High Speed ◽  
High Speed Rail ◽  
Prestressing Steel ◽  
Box Beam ◽  
Maintenance And Rehabilitation ◽  
Structural Engineers ◽  
Asset Managers

This paper examines the effect of pitting corrosion of prestressing steel strands on flexural strength of prestressed concrete (PC) beams in marine environment. A reliability-based methodology for the prediction of time to structural failure after corrosion initiation was proposed and probabilities of failure are evaluated using FORM as exampled by a high-speed rail PC box beam. The methodology presented in this paper can be used as a tool for structural engineers and asset managers to assess a corrosion-affected concrete infrastructure and make decisions with regard to its maintenance and rehabilitation.

Fatigue reliability of deteriorating prestressed concrete bridges due to stress corrosion cracking

2001 ◽  
Vol 28 (4) ◽  
pp. 673-683 ◽  
Author(s):  
M A Maes ◽  
X Wei ◽  
W H Dilger
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Prestressed Concrete ◽  
Corrosion Cracking ◽  
Concrete Bridges ◽  
Concrete Bridge ◽  
Fatigue Reliability ◽  
Prestressing Steel ◽  
Prestressed Concrete Bridges ◽  
Prestressed Concrete Bridge

In this paper, an analysis framework is presented to develop a relationship between fatigue reliability in a prestressed concrete bridge and the progress of stress corrosion cracking (SCC) in prestressing steel. The fatigue limit state uses a cumulative damage model for prestressing steel wires, which is a function of both stress range and minimum stress. The SCC model takes into account varying degrees of material susceptibility, stress regimes, and environmental conditions and is structured around three stages: initiation of micro-cracking, propagation, and macro-crack instability using linear elastic fracture mechanics. The framework is an overall time-dependent analysis of the safety against fatigue of a prestressed concrete bridge. It involves a stochastic analysis of the evolution of prestressing wire corrosion as a function of time and a time-dependent probabilistic analysis of the fatigue reliability of the prestressed concrete bridge suffering a certain degree of deterioration. The uncertainties involved in the fatigue model, the SCC model, and traffic actions are considered. The updating of uncertainties is simplified by considering a limited number of classes representative of the severity of SCC exposure. The framework is applied to three deteriorating highway bridges.Key words: fatigue analysis, prestressing strands, stress corrosion cracking, reliability assessment, prestressed concrete bridges, deterioration.

scholarly journals DAMAGE TO CONCRETE BRIDGES DUE TO REINFORCEMENT CORROSION

Transport ◽  
2002 ◽  
Vol 17 (4) ◽  
pp. 137-142 ◽  
Author(s):  
Zenonas Kamaitis
Keyword(s):  
Prestressed Concrete ◽  
Poor Quality ◽  
Concrete Cover ◽  
Concrete Bridges ◽  
Prestressing Steel ◽  
Existing Structures ◽  
Concrete Carbonation ◽  
Prestressed Reinforcement ◽  
Segmental Bridge

Corrosion of reinforcement initiated by concrete carbonation and chloride contamination is the most common type of deterioration of concrete bridges. Based on the author's experience a number of cases is reported in which the corrosion of ordinary and prestressed reinforcement as well as the causes and consequences of deterioration observed are presented. Investigations have shown that the main reasons are: insufficient concrete cover, poor quality of concrete, and ingress of aggressive salts. The carbonation depth must be related to the histogram ofrebar cover depths and the probability of their coincidence can be predicted. The monitoring of tendon conditions in prestressed concrete precast post-tensioned segmental bridge decks shows that the voids and the water are often present in the ducts leading to the local rusting of tendons. The wires used in tendons are liable to fail in tension that was observed in some prestressed concrete bridges. Unfortunately, no reliable procedures of determining the condition of prestressing steel in existing structures are available.

Analysis of the Effects of Fiber Gradient Distribution on the Mechanical Properties of Moso Bamboo

2014 ◽  
Vol 590 ◽  
pp. 13-18
Author(s):  
Kai Chen ◽  
Lian Chun Long
Keyword(s):  
Mechanical Properties ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Axial Stress ◽  
Structural Behavior ◽  
Layer Model ◽  
Fiber Volume ◽  
Gradient Distribution ◽  
Maximum Deformation ◽  
Maximum Axial Stress

Bamboo is a fiber-reinforced bio-composite with superior structural behavior. For the purpose of analyzing the correlations between the mechanical properties of bamboo and fiber volume fraction, tensile tests were performed on bamboo test specimen, and the corresponding volume fractions of fiber and parenchymatous ground tissue were measured. Linear and curvilinear regressions were done from tested data of elastic modulus, tensile strength and volume fractions of fiber. The results display that there is an obvious correlation between bamboo tensile properties and fiber volume fraction. In order to analyze the effects of fiber gradient distribution on bamboo structural behavior, models composed of fiber and parenchymatous tissue were built based on different fiber distribution for comparative analysis. The analysis results show that the maximum deformation of 4 layers model is 3.86% less than 1 layer model, and the maximum deformation of 8 layers model is 8.87% less than 4 layers model. In the part of maximum axial stress, the maximum axial stress of 4 layers model is 3.27% less than 1 layer model, and the maximum axial stress of 8 layers model is 8.90% less than 4 layers model. Conclusion can be drawn from the comparison that the strength and stiffness of the model appear to be growing with the degree of fiber gradient distribution deepening from 1 layer model to 4 layers model, and 4 layers model to 8 layers model.It can be concluded that the mechanical properties of bamboo structure are significantly improved because of fiber gradient distribution.

Strengthening of Prestressed Concrete Bridges by External Tendons

2013 ◽  
Vol 99 (22) ◽  
pp. 662-669
Author(s):  
Balthasar Novák ◽  
Eberhard Pelke ◽  
Dieter Berger ◽  
Vazul Boros ◽  
Sven Priestaff ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Concrete Bridges ◽  
Prestressed Concrete Bridges ◽  
External Tendons
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