Prediction of Long-Term Prestress Losses

Youakim, Samer A; Ghali, Amin; Hida, Susan E.; Karbhari, Vistasp M.

doi:10.15554/pcij.03012007.116.130

Cited by 16 publications

(6 citation statements)

References 3 publications

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“…The minimum clearance is particularly important to detect changes caused by support settlement or repaving and to avoid vehicular collisions of structures that are exposed to traffic. Furthermore, the long-term measurement of beam geometry can provide information about the effects of creep and shrinkage on prestressed concrete girders [8,9]. However, the acquisition of this metric value is traditionally accomplished by means of contact measurement systems with 0263-2241/$ -see front matter Ó 2012 Elsevier Ltd. All rights reserved.…”

Section: Introductionmentioning

confidence: 99%

Validation of terrestrial laser scanning and photogrammetry techniques for the measurement of vertical underclearance and beam geometry in structural inspection of bridges

et al. 2013

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Section: Introductionmentioning

confidence: 99%

Validation of terrestrial laser scanning and photogrammetry techniques for the measurement of vertical underclearance and beam geometry in structural inspection of bridges

et al. 2013

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“…In order to consider the uncertainties in creep model and shrinkage model, two coefficients, ψ 1 and ψ 2 , are adapted in this study. For the CEB-FIP90 model, the statistical characteristic values of ψ 1 and ψ 2 can be taken as E(ψ 1 ) � 1, V(ψ 1 ) � 0.339 and E(ψ 2 ) � 1, V(ψ 2 ) � 0.451 [18], respectively; φ 0 is the nominal creep coefficient; β c (t, τ) is the coefficient to describe the development of creep with time; ε sh0 is the nominal shrinkage strain; β s (t, τ) is the coefficient to describe the development of shrinkage with time; σ pr (t) is the reduced relaxation loss and equals to λ r σ pr (t); λ r denotes the reduction factor, and a value of 0.75 [19] is adopted in this study, and the calculation method of intrinsic relaxation, σ pr (t) by Youakim et al [20], is adopted in this paper. e coefficients A p , B p , C P , and D P are as shown in the following equation:…”

Section: Probabilistic Model Of Long-term Prestress Lossmentioning

confidence: 99%

EM‐Based Monitoring and Probabilistic Analysis of Prestress Loss of Bonded Tendons in PSC Beams

Chen

Zhang

2018

Advances in Civil Engineering

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The prestress level is a key factor of prestressed concrete (PSC) beams, affecting their long-term serviceability and safety. Existing monitoring methods, however, are not effective in obtaining the force or stress of embedded tendons. This paper investigates the feasibility of elastomagnetic (EM) sensors, which have been used for external tendons, in monitoring the long-term prestress loss of bonded tendons. The influence of ambient temperature, water, eccentricity ratio, plastic duct, and cement grouts on the test results of EM sensors is experimentally examined. Based on the calibrated EM sensors, prestress loss of a group of PSC beams was monitored for one year. In order to further consider the high randomness in material, environment, and construction, probabilistic analysis of prestress loss is conducted. Finally, the variation range of prestress loss with a certain confidence level is obtained and is compared with the monitored data, which provides a basis for the determination of prestress level in the design of PSC beams.

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“…Based on their test results and for ease of calculation, Cao et al [ 18 ] used the least squares method to fit the long-term prestress losses. Samer et al [ 19 ], using equilibrium and compatibility principles based on solid mechanics, presented an analytical method for predicting the long-term prestress losses of precast, pre-tensioned, or post-tensioned concrete members. It can be used for multi-stage loading and prestressing.…”

Section: Introductionmentioning

confidence: 99%

Long-Term Prestress Loss Calculation Considering the Interaction of Concrete Shrinkage, Concrete Creep, and Stress Relaxation

Han

Tian

et al. 2023

Materials

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In order to accurately calculate the long-term prestress losses of prestressed tendons, a time-varying model of long-term prestress loss considering the interaction between concrete shrinkage, creep, and the stress relaxation of prestressed tendons was constructed. Then, a method for calculating the long-term prestress losses of concrete structures was developed. A long-term prestress loss test of a prestressed concrete T-beam in a long-term field test environment was carried out. The measured values of long-term prestress losses are compared with the calculated results of JTG 3362-2018, AASHTO LRFD-2007, and the time-varying law model. The results show that the long-term effective tension of the T-beam decreases gradually with the increase in the load holding time. At the beginning of loading, the tensile force changes rapidly and then gradually slows down. The later the tensile age or the higher the initial loading stress level, the smaller the long-term prestress losses of the prestressed tendons. The long-term prestress loss values calculated by JTG 3362-2018, AASHTO LRFD-2007, and the time-varying law model increase with the increase in the load holding time. In the early stage of loading, the rate of change slows down and tends to be stable. The calculated results of JTG 3362-2018 and AASHTO LRFD-2007 are significantly different from the measured values. However, the calculated results of the time-varying law model are in good agreement with the measured values. The average coefficients of variation of the long-term prestress loss calculated by JTG 3362-2018, AASHTO LRFD-2007, and the time-varying law model are 17%, 10%, and 5%, respectively. The time-varying law model of the long-term prestress losses of prestressed tendons is accurate, and the long-term prestress loss of prestressed reinforcement can be predicted effectively.

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Prediction of Long-Term Prestress Losses

Cited by 16 publications

References 3 publications

Validation of terrestrial laser scanning and photogrammetry techniques for the measurement of vertical underclearance and beam geometry in structural inspection of bridges

Validation of terrestrial laser scanning and photogrammetry techniques for the measurement of vertical underclearance and beam geometry in structural inspection of bridges

EM‐Based Monitoring and Probabilistic Analysis of Prestress Loss of Bonded Tendons in PSC Beams

Long-Term Prestress Loss Calculation Considering the Interaction of Concrete Shrinkage, Concrete Creep, and Stress Relaxation

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