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Effect of corrosion on degradation of mechanical behavior of prestressing strands
Published in Airong Chen, Xin Ruan, Dan M. Frangopol, Life-Cycle Civil Engineering: Innovation, Theory and Practice, 2021
L.Z. Dai, T. Li, L. Wang, Z. Hu, S.C. Yi, J.R. Zhang
Prestressed concrete has the significant advantages in strength and crack resistance, which becomes an important structural form in engineering. However, in recent decades, some failure accidents of prestressed concrete structures due to the strand corrosion have been reported, such as the Ynysy-Gwas bridge (Wilson & Woodward 1991). Strand corrosion has become one of the main diseases of prestressed concrete bridges (Biondini & Frangopol 2018). Corrosion will reduce the mechanical behavior of prestressing strand and lead to corroded wire fracture unevenly, which affects the safety performance of prestressed concrete structures (Nakamura et al. 2004).
The Problem
Published in Warren Green, Paul Chess, Durability of Reinforced Concrete Structures, 2019
Prestressed concrete is used in a wide range of buildings and civil structures where its improved performance can allow longer spans, reduced structural thicknesses, and material savings compared to conventionally reinforced concrete. Applications can include high-rise buildings, residential buildings, foundation systems, bridge and dam structures, silos and tanks, industrial pavements and nuclear containment structures.
Inspection Methodology
Published in Mohamed Abdallah El-Reedy, Assessment, Evaluation, and Repair of Concrete, Steel, and Offshore Structures, 2018
Prestressed concrete is usually a form of concrete used in construction of bridges, which is prestressed be being placed under compression prior to supporting any loads beyond its own dead weight. Therefore, its reliability is very sensitive to any reduction on steel section.
Analytical study for prediction of stress distribution on orthodontic archwire considering short-term stress loss
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Yeonju Chun, Yeokyeong Lee, Hyunju Lee, Minji Kim, Heesun Kim
In this study, initial stress means stress on archwire right after engaging bracket and archwire and short-term stress means stress considering instantly induced loss after engagement. According to the prestressed concrete design, (1) elastic shortening of concrete, (2) slip at anchorage, and (3) friction between the concrete and prestressing tendon are the main causes of stress losses in the prestressing tendon in short term. In prestressed concrete, steel wired tendons placed inside the concrete are anchored at both ends of the concrete structure and stretched to apply stresses to the concrete beam. Based on the similarities between the mechanisms of the stretched tendon in prestressed concrete and deformed archwire in orthodontic treatment, as shown in Figure 5(a, b), formulations are adopted in this study to estimate the stress losses occurring on prestressing tendons. Formulations to calculate the stress losses are needed to replace the modeling brackets and can be adopted from the concepts of prestressed concrete design (Raju 2018).
Pseudo-Ductility Through Progressive Failure of Multi-Layered Carbon-Fiber-Reinforced Polymer (CFRP) Prestressed Concrete Beams
Published in Structural Engineering International, 2023
Ali Alraie, Nikhil Garg, Vasant Matsagar, Arndt Goldack, Mike Schlaich
The use of prestressed concrete systems has increased in the construction of bridges, high-rise buildings, etc. to achieve longer unsupported spans and elegant slender structures. However, the corrosion-induced deterioration of the prestressing steel tendons used in these structures is one of the major concerns that seriously reduce their service life. Advances in material science have enabled engineers to enhance the strength and long-term behavior of concrete structures.1 One possible solution is to use non-corrosive carbon-fiber-reinforced polymer (CFRP) reinforcements in place of the conventional steel reinforcements. The salient features of CFRP reinforcements are their non-corrosiveness along with high strength, light weight and ease of installation, which have made them appealing alternatives to steel reinforcements, especially for structures exposed to severely harsh environments. Tendons made from composite materials are not only suitable for replacing conventional steel prestressing systems, but there are also many areas where their application will be justified and increase efficiency, such as external prestressing in difficult environmental conditions.2 This is due to the excellent durability exhibited by CFRP under extreme environmental conditions.3 However, CFRP reinforcements have one major limitation, i.e. they do not deform plastically, unlike steel reinforcements, and thereby lack ductility. This inability to deform plastically, and suddenly occurring brittle rupture, are major limitations to their structural engineering applications. A possible solution to this brittle failure is to design CFRP-prestressed concrete members so as to introduce a progressive rupture of the tendons under the application of incrementally increasing load. The increase in ductility of such a prestressed concrete beam thus leads to safer design by avoiding sudden/ catastrophic failure. Based on the energy dissipation approach of quantifying the ductility of such beams, the effectiveness of the progressive rupture of the CFRP tendons in prestressed concrete beams is investigated here. The main objectives of this study are: (a) to evaluate the ductility of CFRP-prestressed concrete beams designed as under-reinforced sections based on an energy dissipation approach; (b) to introduce a progressive failure-based pseudo-ductility by prestressing the CFRP tendons in a multi-layered system with sacrificial warning rebars; and (c) to introduce a solution to the compromised economy in a multi-layered system by using functionally-graded concrete with a higher grade in the compression zone and a lower grade in the tension zone.