Pretensioned pullout test of 18 mm (0.7 in.) diameter strand with different embedment lengths

Xin, Jiang; Gui, Qiang; John, Zhongguo

doi:10.1002/suco.201800215

Cited by 8 publications

(3 citation statements)

References 8 publications

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“…∆ ↓= 5ql 4 384E c I g (7) Accordingly, the predicted net cambers were 16.0 mm at 4 d detension and 15.2 mm at 6 d detension. In fact, the box girder was detensioned in the factory at the age of 6 days, and the measured camber was 15.3 mm.…”

Section: Cambermentioning

confidence: 90%

“…Morcous et al [1][2][3] demonstrated the specific problems of NU I-girders using 18-mm strands, and Ma et al [4] studied the transfer length and development length of AASHTO-PCI BT girders using two different high-capacity prestressing strands. Jiang et al [5][6][7] studied the bond properties of 18-mm strands through a pullout test of specimens with different embedment lengths and initial prestress forces. Dang et al [8][9][10], in the past ten years, have been studying the performances of pretensioned concrete beams using 18-mm strands.…”

Section: Introductionmentioning

confidence: 99%

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Prestressed Concrete Box Girder with High-Capacity Strands-Monitoring and Analysis during Fabrication

Xin

Ban

et al. 2022

Buildings

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Despite the attractive merits of high-capacity strands, the application in bridge girders is limited due to concerns, including concrete cracking, excessive stress, and cambers. An efficient and defect-free production is the first step to wide application. The objective of this research was to alleviate the production concerns of prestressed concrete bridge girders using high-capacity strands. A gigantic prestressed concrete box girder using 18-mm strands was produced; its entire fabrication process (from strand stressing to detension) was introduced. Sixteen temperature gauges were embedded in the girder to monitor the hydration of the large volume of concrete and the adjacent environmental temperature. Moreover, displacement transducers were used to measure the camber at detension; load cells were installed to monitor the variations of the prestressing strand tensile forces during fabrication. Monitoring and analysis showed that the timing of the detension is determined by the hydration of the concrete, the compressive strength of the concrete, and its modulus of elasticity or age. Since the tensile forces in strands are affected by the concrete’s internal temperature, the detension is conducted after the concrete temperature falls back (close to its initial value); otherwise, unfavorable and considerable prestress losses are caused. Finally, a 4-d detension was suggested since the hydration was not a concern at the time; the predicted prestress loss and camber were acceptable and the concrete material properties at 4 d satisfied the requirements.

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Section: Cambermentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Prestressed Concrete Box Girder with High-Capacity Strands-Monitoring and Analysis during Fabrication

Xin

Ban

et al. 2022

Buildings

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“…Dang et al [9][10][11] systematically measured a large number of transfer lengths while studying the bonding performance of 18 mm strands. Jiang et al [12,13] conducted a study on the transfer length of 18 mm strands with pull-out tests, in which the failure mode, the relationship between the slip of strand and the pull-out force, and the relationship between the embedment length and the transfer length were analyzed.…”

Section: Introductionmentioning

confidence: 99%

Transfer Length and Prestress Losses of a Prestressed Concrete Box Girder with 18 mm Straight Strands

Jiang,

Chen,

Zhou

et al. 2023

Buildings

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Despite the potential advantages of 18 mm strands, the limited research on the behavior of girders with larger-diameter strands hinders the application in bridges. Transfer length and prestress losses are two important indicators. In this research, a 32.6 m long prestressed concrete box girder with 18 mm straight strands and 15 mm harped strands was produced, and the transfer length and the prestress losses were studied. The transfer length was calculated based on the existing equations in codes and previous research. Three beam specimens were fabricated, and strain gauges were pasted on the concrete surface to measure the transfer length of 18 mm strands. It indicated that the average measured transfer length was 700 mm. This value was smaller than the transfer lengths predicted by AASHTO LRFD 2017 and ACI 318-19, while Mitchell’s equation offered the closest prediction to the average measured transfer length. Additionally, the prestress losses at different stages were evaluated. A one-end stressing test was conducted to analyze the effect of strand harping on the loss of tensile force. In comparison with the actual measured loss based on the concrete strain and the longitudinal shortening, the instantaneous prestress loss calculated using the AASTHO LRFD 2017 alternative equation was appropriate. The time-dependent prestress losses due to shrinkage, creep, and relaxation were predicted using two different methods addressed in AASHTO LRFD 2017. The time-dependent predicted losses of 69.2 MPa at 28 d using the refined method were 37% higher than the measured losses 47.4 MPa at 28 d, indicating an overestimation of AASHTO LRFD 2017. The accumulation of the total losses over time revealed that the prestress losses developed in the first two months occupied the majority of the total losses in the long term. The research may provide guidelines for the design of a pretensioned concrete box girder with 18 mm strands.

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Modeling of bond stress-slip relationships of mono-prestressing strands with H-anchorage dead end

Aly

Maree

Kohail

et al. 2023

Ain Shams Engineering Journal

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Pretensioned pullout test of 18 mm (0.7 in.) diameter strand with different embedment lengths

Cited by 8 publications

References 8 publications

Prestressed Concrete Box Girder with High-Capacity Strands-Monitoring and Analysis during Fabrication

Prestressed Concrete Box Girder with High-Capacity Strands-Monitoring and Analysis during Fabrication

Transfer Length and Prestress Losses of a Prestressed Concrete Box Girder with 18 mm Straight Strands

Modeling of bond stress-slip relationships of mono-prestressing strands with H-anchorage dead end

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