Instrument to Evaluate Remaining Prestress in Damaged Prestressed Concrete Bridge Girders

Civjan, Scott A.; Jirsa, James O.; Carrasquillo, R L; Fowler, David W.

doi:10.15554/pcij.03011998.62.71

Cited by 16 publications

(12 citation statements)

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Section: Introductionmentioning

confidence: 99%

“…Also it is known that the loss of the prestress force occurs due to damage or severing of prestress strands. In this case, a prestressed concrete structure is considered as irreparable as it is seriously damaged on the condition of the prestressing strands [1].These losses of the prestressing force lead to the safety problem of prestressed concrete structures. In this case, it is very important to estimate the prestress loss, because the prestressed concrete must keep effective prestressing force during the service life of the concrete structure.…”

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confidence: 99%

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Numerical investigation in detection of prestress losses in prestressed concrete slab by modal analysis

Kovaļovs

Akishin

Ruchevskis

2018

Engineering for Rural Development

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Abstract. The paper presents a non-destructive method to detect prestress loss in prestressed hollow core slabs using a few modal frequencies. Loss of prestress is investigated by the 3D finite element model, using ANSYS software. A numerical model is used to estimate the percentage change in modal frequencies of prestressed slabs under various initial stresses induced in the tendon. Applicability and effectiveness of the proposed method are investigated by using various span lengths of slabs and elastic modulus of concrete. The parametric study shows that the minimal length of slab and maximal elastic modulus has the smallest influence on the percentage change in the modal frequencies. The results of this investigation thus indicate that proposed method can potentially be used to identify the initial stress reduction in concrete structures with minimal elastic modulus of concrete and the largest length of span.Keywords: prestress, concrete slab, frequencies, ANSYS, FEM. IntroductionToday prestressed concrete elements are widely used in many civil constructions for commercial and industrial buildings. Prestressing force in tendons is used to reduce the cross-section and deflections of prestressed concrete structures. However, the prestressing force decreases over time due to time dependent deformation of concrete, steel relaxation in strands, creep of concrete and other factors. Also it is known that the loss of the prestress force occurs due to damage or severing of prestress strands. In this case, a prestressed concrete structure is considered as irreparable as it is seriously damaged on the condition of the prestressing strands [1].These losses of the prestressing force lead to the safety problem of prestressed concrete structures. In this case, it is very important to estimate the prestress loss, because the prestressed concrete must keep effective prestressing force during the service life of the concrete structure.One of the methods to detect a possible loss of the prestressing force in prestressed concrete structures is implementation of dynamic monitoring. Loss of prestress can change the stiffness of the structure, which causes changes of the dynamic parameters. It is possible to identify loss of prestress by comparing the frequencies of the reference structures and the frequencies of the structure with reduced prestressing forces.In recent years, development of damage detection techniques based on modal parameters was extensively studied. It is possible to identify damage of a structure by comparing the typical dynamic properties of the damaged and undamaged structure. This method is being widely used, because it is very simple in use. Many algorithms for damage detection were developed by many researchers over the three decades in the field of vibration based damage detection [2; 3].However, there are many disagreements about how the prestressing force in tendon affects the modal frequencies of prestressed concrete structures: 1. The modal frequency decreases with increasing the prestressing force [4;...

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Numerical investigation in detection of prestress losses in prestressed concrete slab by modal analysis

Kovaļovs

Akishin

Ruchevskis

2018

Engineering for Rural Development

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“…However, there are substantial difference between the desired and the in-service prestress forces in existing PSC bridge; hence, this differences leads to severe and critical serviceability and safety problems [1,10] . In other words, a PSC girder is considered as irreparable as it is seriously damaged on the condition of the prestressing strands [2] . It is known that the loss of the prestress force in tendon occurs due to elastic shortening and bending of concrete, creep and shrinkage of concrete, steel relaxation, anchorage take-up, and frictional loss between tendon and its surrounding materials.…”

Section: Introductionmentioning

confidence: 99%

“…Lin (1963) showed that the loss of the prestress force in PSC bridge is related to the change in structural stiffness, Saiidi et al (1994) and Miyamoto et al (2000) presented that the loss of the prestress force changes vibration characteristics of PSC bridge. In addition, Civjan et al (1995) presented a method to evaluate remaining prestress in damaged PSC bridge. Especially, Kim et al (2004) suggested a method to nondestructively detect the loss of prestress force using a few natural frequencies, and they successfully verified the method by experimental and numerical models of beam-type PSC bridges [9] , which are reinforced by internal tendons.…”

Section: Introductionmentioning

confidence: 99%

Monitoring cracks and prestress-loss in PSC girder bridges using vibration-based damage detection techniques

et al. 2007

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In this study, a vibration-based method to simultaneously predict prestress-loss and flexural crack in PSC girder bridges is presented. Prestress-loss and flexural crack are two typical, but quite different in nature, types of damage which can be occurred in PSC girder bridges. The following approaches are implemented to achieve the objective. Firstly, two vibration-based damage detection techniques which can predict prestress-loss and flexural crack are described. The techniques are prestress-loss prediction model and mode-shape-based crack detection method. In order to verify the feasibility and practicality of the techniques, two different lab tests are performed. A free-free beam with external unbonded tendons is used to verify the feasibility of the prestress-loss prediction model. In additional, a PSC girder with an internal unbonded tendon is used to evaluate the practicality of the prestress-loss prediction model and the modeshape-based crack detection method.

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“…Several companion papers are available in addition to the published reports. These papers include Jones (1996) ;Feldman, Jirsa and Kowal (1998) ;Zobel, Carrasquillo and Fowler (1997): and Civjan, Jirsa, Carrasquillo and Fowler (1998).…”

Section: 2 Beam Testing and Repairmentioning

confidence: 99%

Experimental and analytical assessment of prestressed concrete bridges damaged by overheight vehicle impact

Russo¹

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This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be f^ any type of computer printer.The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction.In the unlikely event that the auttior dkJ not send UMI a complete manuscript and there are missing pages, tiiese will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overiaps.

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Instrument to Evaluate Remaining Prestress in Damaged Prestressed Concrete Bridge Girders

Cited by 16 publications

References 0 publications

Numerical investigation in detection of prestress losses in prestressed concrete slab by modal analysis

Numerical investigation in detection of prestress losses in prestressed concrete slab by modal analysis

Monitoring cracks and prestress-loss in PSC girder bridges using vibration-based damage detection techniques

Experimental and analytical assessment of prestressed concrete bridges damaged by overheight vehicle impact

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