Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies

Shi, Luning; He, Haoxiang; Yan, Weiming

doi:10.1155/2014/840937

Cited by 14 publications

(19 citation statements)

References 11 publications

(20 reference statements)

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“…(4) Determining the side pressure to close the induced crack in a small cylindrical hole drilled adjacent to the tendon in the bottom flange of a PC girder [55,58]. (5) Vibration testing to determine the natural frequencies and/or dynamic responses of a PC girder [59][60][61][62][63][64][65]. (2) Destructive [23,56] Severing the prestressing tendon by cutting it into an exposed length after placing strain gauges It causes damages Table 3.…”

Section: Testing Methodsmentioning

confidence: 99%

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%

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

2020

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“…14 A method combined by vibration equations and measured FRFs was applied in the prestress identifications of a beam for improving accuracy of ELI. 15 To solve the ill-conditioning problem in a TFM, a weighted regularization method for stochastic dynamical ELI was proposed by considering the estimated errors of FRFs. 7 Based on the measured TFM of acceleration, the Tikhonov regularization method was adopted for load identification.…”

Section: Introductionmentioning

confidence: 99%

Vibration load and transfer path identification of vehicle using inverse matrix method based on singular value decomposition

Yang

Wang

Guo

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part D:

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Based on the theory of inverse transfer matrix, a novel method for simultaneous load identification of vehicle vibration is presented in this paper. Some response, excitation, reference points (called key points) and their transfer paths, which have severe effects on the vibration of a whole vehicle, are defined. The transfer functions among the key points are measured by experiments, and thereby a transfer function matrix of vehicle vibration is established. To solve ill-conditioning problem in the transfer function matrix, the methodology of singular value decomposition is introduced into matrix inversion in the excitation load identification. To reduce the identification error, four transfer function matrices with different reference points and condition numbers are selected and discussed. The results show that the more the reference points are, the smaller the condition number of transfer function matrix is, the higher the accuracy of excitation load identification. The transfer function matrix with minimum condition number is used to identify the excitation loads at the vehicle key points. Experimental verifications suggest that the newly proposed method is effective and feasible for excitation load identification of vehicle vibration. Using the identified excitation loads, furthermore, the vibration causes of the steering wheel and seat rail are obtained, which is helpful for improving vibration performance of the sample vehicle. In applications, the excitation load identification method proposed in this paper may be applied not only to other types of vehicle, but also to other complex electromechanical products for load identification in engineering.

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“…Moreover, for an existed EPSB, it is hard to gauge its prestress force and therefore to acquire its stress and deformation. However, it is an alternative way to gauge its natural frequency only if the relationship between the natural frequency and the prestress force has already been known [2,3]. The natural frequency of an in-service EPSB will change when the prestress force changes over time.…”

Section: Introductionmentioning

confidence: 99%

Effect of Prestress Force on Natural Bending Frequency of External Prestressed Steel Beams

Baijian¹,

Fei²,

Song³

2018

TOCIEJ

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Introduction: Natural bending frequencies of externally prestressed steel beam have certain sensitivity to prestress force, so they can be used to find the magnitude of prestress force. Methods: To answer the question if the existence of externally prestressed tendons increases or decreases the natural bending frequencies of a simply supported steel beam, the calculating formula for natural frequencies is deduced by using the energy method from the view point of prestress mechanism and further verified by the finite element method. Using this formula of universal property, the influence of prestress force, eccentricity and cross-sectional area of tendons on natural bending frequencies of prestressed steel beam is clearly revealed. Results and Conclusion: For external prestressed steel beams with straight tendons, their natural frequencies increase with the eccentricity and cross-sectional area of the prestressed tendon, and the eccentricity has a much larger effect on natural frequencies than the cross-sectional area does. The prestress force has no influence on the oven-order frequencies but decreases the odd-order frequencies. With the increasing order number, the prestress effect is much weaker than the effects caused by the eccentricity and cross-sectional area of the tendon.

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Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies

Cited by 14 publications

References 11 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

Vibration load and transfer path identification of vehicle using inverse matrix method based on singular value decomposition

Effect of Prestress Force on Natural Bending Frequency of External Prestressed Steel Beams

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