Experimental Investigation of Prestress Losses in Full-Scale Bridge Girders

Garber, David; Gallardo, José M.; Deschenes, Dean; Bayrak, Oguzhan

doi:10.14359/51687909

Cited by 29 publications

(18 citation statements)

References 6 publications

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“…Testing methods are in general required for estimating prestress losses, and include five typologies (Table 3): (1) static load testing to determine crack initiation or crack re-opening loads to obtain the available compressive stress in the bottom flange of a PC girder [23,28,54,55]. (2) Severing the prestressing tendon by cutting it into a representative exposed length after placing strain gauges on the tendon [23,56].…”

Section: Testing Methodsmentioning

confidence: 99%

“…To overcome this problem, Caro et al [26] used the ECADA+ method [27] to measure the effective prestress forces in a number of PC specimens for over 1 year and, consequently, compared the results with prestress losses estimated by several codes. Although design code-based predictions can be considered as quite satisfactory, they are very conservative [28]. Accordingly, there are difficulties in determining prestress losses related to factors including, inter alia, assumptions about the properties of prestressing systems and time-dependent phenomena, such as long term degradation processes, tendon relaxation, creep and shrinkage of concrete, and parameters of the real environment [29,30].…”

Section: Introductionmentioning

confidence: 99%

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State-of-the-Art Review on Determining Prestress Losses in Prestressed Concrete Girders

2020

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Prestressing methods were used to realize long-span bridges in the last few decades. For their predictive maintenance, devices and dynamic nondestructive procedures for identifying prestress losses were mainly developed since serviceability and safety of Prestressed Concrete (PC) girders depend on the effective state of prestressing. In fact, substantial long term prestress losses can induce excessive deflections and cracking in large span PC bridge girders. However, old unsolved problematics as well as new challenges exist since a variation in prestress force does not significantly affect the vibration responses of such PC girders. As a result, this makes uncertain the use of natural frequencies as appropriate parameters for prestress loss determinations. Thus, amongst emerging techniques, static identification based on vertical deflections has preliminary proved to be a reliable method with the goal to become a dominant approach in the near future. In fact, measured vertical deflections take accurately and instantaneously into account the changes of structural geometry of PC girders due to prestressing losses on the equilibrium conditions, in turn caused by the combined effects of tendon relaxation, concrete creep and shrinkage, and parameters of real environment as, e.g., temperature and relative humidity. Given the current state of quantitative and principled methodologies, this paper represents a state-of-the-art review of some important research works on determining prestress losses conducted worldwide. The attention is principally focused on a static nondestructive method, and a comparison with dynamic ones is elaborated. Comments and recommendations are made at proper places, while concluding remarks including future studies and field developments are mentioned at the end of the paper.

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Section: Testing Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

State-of-the-Art Review on Determining Prestress Losses in Prestressed Concrete Girders

2020

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“…Assuming a perfect bond between the prestressing strands and surrounding concrete, the strain changes measured in the concrete can be assumed to be equal to the strain changes in the prestressing strands at the same location, and Equation can be used to estimate the stress change, as illustrated in Figure . This type of instrumentation has been used by many researchers employing vibrating wire strain gauges() (see Figure a), demountable mechanical gauges,() electrical strain gauges, or fiber optic sensors (see Figure b). ()…”

Section: Strain‐based Methodsmentioning

confidence: 99%

“…Different types of strain sensors used in monitoring concrete: (a) vibrating wire gauge, (b) distributed and discrete fiber optic sensors, (c) electrical strain gauge, and (d) metal‐coated fiber optic sensor…”

Section: Strain‐based Methodsmentioning

confidence: 99%

Monitoring of prestressing forces in prestressed concrete structures—An overview

Abdel-Jaber

Glišić

2019

Struct Control Health Monit

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This paper presents an overview of currently available methods for monitoring prestressing forces in prestressed concrete structure. Structural health monitoring has become an increasingly important tool for assessment of structural performance. Additionally, the value of the prestressing force represents an important parameter in prestressed concrete structures. Thus, several methods for monitoring prestress forces have emerged. This paper aims to consolidate the work performed in the area of prestressing force monitoring by presenting the most important advances and the directions for future research. The methods presented in this paper are based on indirect monitoring of the prestressing force through monitoring of another relevant parameter. They are divided into five general classes based on the relevant parameter they monitor:(a) vibration-based methods (based on acceleration), (b) impedance-based methods (based on electrical impedance), (c) acoustoelastic methods (based on wave velocity), (d) elasto-magnetic methods (based on magnetic permeability), and (e) strain-based methods (based on strain). The paper presents a table summarizing the comparison between the methods based on defined criteria.

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“…In case of short-term loss, when a prestress force is applied to a PS member, elastic deformation occurs to the extent of the compressive force received by the member [ 3 ]. In addition, the behaviors of the sheath pipe and PS steel are not completely in consonance, resulting in friction between them; accordingly, when a prestress force is applied to the PS steel, the PS steel anchorage slips owing to the force [ 4 , 5 ]. In case of long-term loss, creep causes deformation owing to the continuous stress generated during the curing process.…”

Section: Introductionmentioning

confidence: 99%

Experimental Evaluation of PSC Structures from FRP with a Prestressing Strengthening Method

Kim

Park

et al. 2021

Materials

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A prestressed concrete (PSC) structure is subject to prestress losses in the long and short terms, and the structure ages over time. The structure is susceptible to corrosion from exposure to environmental factors such as moisture, chloride, and carbonation, thus causing prestress loss. Therefore, strengthening the structure is needed to address this problem. Here, the near surface mounted (NSM) method and the external prestressing (EP) method were selected because they are capable of applying additional prestressing. Further, we used fiber-reinforced plastics or polymers, or carbon fiber-reinforced plastics or polymers because of their high tensile strength and noncorrosive properties. For EP tests, prestressed strands were used. Accordingly, this study performs four-point flexural tests and evaluations for 12 types of specimens fabricated with different PSC methods. All specimens fabricated with the NSM (prestressing, no prestressing) and EP methods achieved stiffness that was 50–60% higher than that of the control PSC specimen. It was observed that the EP method in conjunction with prestressing yielded the best strengthening effect. It is expected that the results of this study will be applied to real structures for strengthening them and improving their performances.

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Experimental Investigation of Prestress Losses in Full-Scale Bridge Girders

Cited by 29 publications

References 6 publications

State-of-the-Art Review on Determining Prestress Losses in Prestressed Concrete Girders

State-of-the-Art Review on Determining Prestress Losses in Prestressed Concrete Girders

Monitoring of prestressing forces in prestressed concrete structures—An overview

Experimental Evaluation of PSC Structures from FRP with a Prestressing Strengthening Method

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