Effect of Prestress Levels and Jacking Methods on Friction Losses in Curved Prestressed Tendons

Hong, Sung-Jong

doi:10.3390/app7080824

Cited by 5 publications

(4 citation statements)

References 5 publications

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“…In ACI 318 [32], f cr is defined via Equation (6). Therefore, by assuming that the flexural stress in the outermost concrete fiber below the neutral axis in Equation ( 4) is equal to the flexural tensile strength of the concrete, and that the moment generated by an external load is equal to the initial cracking moment, the initial crack moment and the initial crack load (P cr ) can be obtained from Equations (7) and (8), respectively:…”

Section: Effect Of the Amount Of Fe-sma Rebarmentioning

confidence: 99%

“…Because bulkheads are required in the process of introducing prestress with this method, this method is mostly used in precast concrete (PC) factories rather than on-site [5]. On the other hand, the post-tension method entails tensioning and anchoring the tendon after the concrete has been cured [6]. Unlike the pre-tension method, it can be easily applied in the field because separate support is not required.…”

Section: Introductionmentioning

confidence: 99%

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Flexural Behavior of Self-Prestressed RC Slabs with Fe-Based Shape Memory Alloy Rebar

Yeon

Hong

2022

Applied Sciences

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A lot of studies have been conducted to introduce self-prestress to structures using Fe-based shape memory alloys (Fe-SMAs). Technology to introduce self-prestress using Fe-SMAs can resolve the disadvantages of conventional prestressed concrete. However, most of the research to introduce a self-prestress force to a structure using Fe-SMAs has been focused on using Fe-SMAs for the repair and strengthening of aging structures. Therefore, in this paper, a study was conducted to introduce self-prestress into a new structure. To this end, in this paper, an experimental study was conducted to evaluate the flexural behavior of self-prestressed concrete slabs with Fe-SMA rebar. Nine specimens were built with consideration of the amount and activation of Fe-SMA rebars as experimental variables. The Fe-SMA rebars used in the specimens exhibited recovery stress of about 335 MPa under the conditions of a pre-strain of 0.04 and a heating temperature of 160 °C. Activation of the Fe-SMA rebars by electrical resistance heating applied an eccentric compression force to the specimen to induce a camber of 0.208–0.496 mm. It was confirmed through a 4-point bending test that the initial crack loads of the activated specimens were 40~101% larger than that of the non-activated specimens. However, the ultimate loads of the activated specimens showed a difference within 3% from that of the non-activated specimens, confirming that the effect of activation on improving the ultimate strength was negligible. Finally, it was confirmed that repetitive activation of the Fe-SMA rebar could repeatedly apply compressive force to the slab.

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Section: Effect Of the Amount Of Fe-sma Rebarmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flexural Behavior of Self-Prestressed RC Slabs with Fe-Based Shape Memory Alloy Rebar

Yeon

Hong

2022

Applied Sciences

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“…There are no specific regulations or guiding documents for the design and construction of bridge misalignment, and the methods to address misalignment mainly rely on previous construction experience. The study on the stress characteristics and deformation extent of the beam during jacking and translation processes is not clear, especially for complex bridge structures with large spans, long distances, and heavy loads, which lack indepth exploration [9][10][11][12]. Moreover, during construction, there is a lack of state monitoring and effective control measures for the jacking and translation processes, which poses risks to both construction and the subsequent operation of the bridges [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Research on construction monitoring of curvilinear continuous beam bridge jacking and horizontal moving construction

Zheng

2024

Archives of Civil Engineering

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This article investigates the issue of beam misalignment in continuous curved beam bridges. Taking the D0–D6 spans of the Gongbin Road elevated bridge as a basis, real-time monitoring of the stress and displacement of the beams is carried out during the jacking and shifting construction process. At the same time, the reaction forces of each support are monitored. The jacking force of the hydraulic jacks is controlled to ensure the stability and safety of the beam during the construction process. Finally, the jacking and shifting monitoring data is organized and compared with theoretical values. It is found that the stress values generated during the jacking phase of the bridge are below the stress control standard. No uplift phenomenon occurs at the supports, and the jacking height is controlled within a reasonable range. The construction process does not cause damage to the beams, and it is safe and reliable. During the shifting construction, the whole bridge was displaced using the jacking method, and the three working conditions were monitored throughout the process. The stress increment at the 2# and 4# sections was relatively small, and the measured stress increments for the entire bridge were all below the stress control standard. The displacement of the bridge abutment during the jacking process was minimal, with no contact with the abutment blocks, and no significant elastic deformation occurred. The jacking displacement was successfully achieved.

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“…The Anchorage-Measurement-Access (AMA) system is the main experimental idea proposed for estimating the pre-stress friction loss [16]. Two full-scale pre-stressed concrete girders were constructed [17] and the influence at various pre-stress levels was discussed. The actual Friction loss is conveniently considered in terms of the effect of length and curvature [27].…”

Section: Introductionmentioning

confidence: 99%

Experimental Analysis on Pre-Stress Friction Loss of Crushed Limestone Sand Concrete Beams

Xiao

Zhang

et al. 2018

Applied Sciences

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This paper presents an experimental research work that evaluates the pre-stress loss caused by friction in crushed limestone sand (CLS) concrete members with post-tensioning. A total of 26 full-scale pre-stressed concrete beams were constructed and tested for the friction loss experiment. The considered variables mainly included the duct-forming materials, wires of tendons and arrangement of ducts. The tensile forces at both active and passive ends of specimen were recorded by steps, and then the pre-stress friction loss for each case was calculated. The result shows that the proportion of pre-stress friction loss in specimen with multi-wire tendons is in the range of 10-40%, with the trend first increasing before decreasing. The pre-stress friction loss in specimen with curve duct accounts for 10-30%. The pressure on the curved part definitely increases the friction when compared with the straight duct. The pre-stress friction loss in specimen with rubber hose reaches nearly 40%, which is larger than the metal bellow and plastic bellow. The suggested values for each case are proposed for a deviation coefficient κ of 0.0017-0.007 and a friction coefficient µ of 0.108-0.858. This can provide reliable theoretical support for the design and construction.

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Effect of Prestress Levels and Jacking Methods on Friction Losses in Curved Prestressed Tendons

Cited by 5 publications

References 5 publications

Flexural Behavior of Self-Prestressed RC Slabs with Fe-Based Shape Memory Alloy Rebar

Flexural Behavior of Self-Prestressed RC Slabs with Fe-Based Shape Memory Alloy Rebar

Research on construction monitoring of curvilinear continuous beam bridge jacking and horizontal moving construction

Experimental Analysis on Pre-Stress Friction Loss of Crushed Limestone Sand Concrete Beams

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