Journal articles: 'Tendons (Prestressed concrete) – Evaluation'

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Cai, Jiang Yong, Zhi Feng Tu, Su Min Gong, and Li Zhuang. "Evaluation of Flexural Performance for Prestressed Concrete Beams with FRP Tendons." Advanced Materials Research 383-390 (November 2011): 3128–33. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.3128.

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Prestressed concrete beams with vertically distributed FRP tendons possess some flexural performance obviously different from prestressed concrete beams with steel tendons. This paper provides a complete theoretical approach to analyze and evaluate the flexural behavior of prestressed concrete beams with FRP tendons. Calculation and analysis results show that a prestressed concrete beam with FRP tendons designed at balanced ratio reaches the maximum of its deformability. The increase of prestressing ratio and number of reinforcement layer will increase, respectively, its moment capacity but simultaneously decrease its deformability.

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Wang, Xiao Dong, Wen Zhong Zheng, and Ying Wang. "Research on Stress Increase of Unbonded Tendons at Ultimate in Prestressed Concrete Continuous Beams." Applied Mechanics and Materials 166-169 (May 2012): 1554–57. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.1554.

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Rational evaluation for stress increase of unbonded tendon at ultimate is the basis to exactly compute flexural load bearing capacity of unbonded prestressed concrete beams. Moment-curvature nonlinear analysis method is adopted to compile programs for calculating stress increase at ultimate in unbonded prestressed continuous beams. The precision of the method is proved by comparing results of 16 experimental two-span unbonded prestressed continuous beams to the prediction value of stress increase at ultimate. Based on the simulation analysis, law of the influence of some basic factors to stress increase at ultimate in unbonded tendons in continuous beams is obtained, such as non-prestressed reinforcement index, prestressed reinforcement index, ratio of span to depth and loading type. Then formulas for calculating stress increase at ultimate in unbonded tendons in prestressed concrete continuous beams were established.

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Jo, Byung-Wan, Ghi-Ho Tae, and Byung-Yun Kwon. "Ductility Evaluation of Prestressed Concrete Beams with CFRP Tendons." Journal of Reinforced Plastics and Composites 23, no. 8 (2004): 843–59. http://dx.doi.org/10.1177/0731684404033492.

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Shin, Kyung-Joon, Young-Ung Park, Seong-Cheol Lee, Yun Yong Kim, and Hwan-Woo Lee. "Experimental Evaluation of Prestress Force in Tendons for Prestressed Concrete Girders using Sensors." Journal of the Computational Structural Engineering Institute of Korea 28, no. 6 (2015): 715–22. http://dx.doi.org/10.7734/coseik.2015.28.6.715.

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WATANABE, Ken, Toshiya TADOKORO, and Yukihiro TANIMURA. "Evaluation for Flexural-load Capacity of Prestressed Concrete Girders with Broken Tendons." Quarterly Report of RTRI 52, no. 4 (2011): 224–29. http://dx.doi.org/10.2219/rtriqr.52.224.

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Aziz, Mohamad Abdel, George Abdel-Sayed, Faouzi Ghrib, Nabil F. Grace, and Murty K. S. Madugula. "Analysis of concrete beams prestressed and post-tensioned with externally unbonded carbon fiber reinforced polymer tendons." Canadian Journal of Civil Engineering 32, no. 6 (2005): 1138–51. http://dx.doi.org/10.1139/l05-071.

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Fiber reinforced polymer (FRP) tendons are being increasingly used nowadays in prestressing and (or) post-tensioning concrete structures. However, designers are faced with lack of practical analysis procedure that leads to proper evaluation of their structural performance, especially when bonded prestressing is combined with unbonded post-tensioning. This paper presents an analytical procedure for these beams. It examines the load–defelction characteristics and proceeds to estimate the ultimate load carrying capacity by taking into consideration the change of stress that occurs in the externally unbonded tendons during different stages of loading. The analytical procedure uses the concept of effective moment of inertia of concrete beams. The equations used are developed by ACI Committee 440, the Intelligent Sensing for Innovative Structures (ISIS) Canada Research Network, and the Comité Euro-International du Béton - Fédération International de la Précontrainte (CEB-FIP), for calculating the deflection of beams reinforced with carbon fiber reinforced polymer (CFRP) tendons. Finite element analyses have been conducted to verify the proposed analytical method. Two experimental programs were used to validate the proposed analytical method. The experimental findings of two box beams reinforced with bonded and unbonded external tendons are compared with finite element analyses and the analytical results. A full-scale test for an internally and externally prestressed double-T beam was undertaken at Construction Technology Laboratories Inc., Skokie, Illinois. The results from this experimental work were used to validate the analytical procedure.Key words: bonded CFRP tendons, concrete, post-tensioning, unbonded CFRP tendons.

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Yang, Ze Ying, Yu Zhao, and Zhi Sheng Liu. "Research on Stretching Order of Tendons in PC Curved Box Girder Bridge." Advanced Materials Research 219-220 (March 2011): 487–91. http://dx.doi.org/10.4028/www.scientific.net/amr.219-220.487.

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This paper is based on an existed bridge---ramp bridge A of Mu-Shi interlinked flyover on Zao-Mu Freeway. The model of curved Box Girder Bridge was built using finite element method to simulate the stretching of prestressed tendons. To start with, several different alternative stretching orders were proposed, and afterwards, mechanical reflection of bridge under different stretching orders was calculated and evaluated respectively by commonly used finite element analysis software Midas. Additionally, evaluation principle was to avoid the appearance of tension in the concrete and to minimize stress fluctuation during stretching. To sum up, optimal stretching sequence was put forward after comparison of the calculation results based on the proposed evaluation principle. Moreover, the optimum sequence referred in this paper and the research approach can provide some valuable referential information about the stretching of prestressed tendons of bridges in the same style.

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Klier, Tomáš, Tomáš Míčka, Michal Polák, Tomáš Plachý, Milan Hedbávný, and Lenka Krejčíková. "New information about practical application of the modified magnetoelastic method." MATEC Web of Conferences 310 (2020): 00026. http://dx.doi.org/10.1051/matecconf/202031000026.

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In the technical practice there is very often a need of axial force determination in the important structural elements of a building during its construction or operational state with adequate precision. The magnetoelastic method is one of the five experimental techniques usually used for that purpose in civil engineering practice. The modified magnetoelastic method is especially aimed on experimental evaluation of the axial forces in the prestressed steel reinforcements on prestressed concrete structures and it is usable not only for newly built structures but in particular for existing ones. New information and knowledge about practical application of the new approach based on the magnetoelastic principle is introduced in the paper. The results of three experiments are summarized, which were realized on the full locked cable PV 150 standardly used as a cable stay strand, on the MUKUSOL threadbar 15FS 0000 generally applied as a temporary prestressed reinforcement and on some prestressed tendons of an existing concrete road bridge, which is about thirty years old.

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Cao, Zhiliang, Hao Wang, and Tong Guo. "Fragility analysis of self-centering prestressed concrete bridge pier with external aluminum dissipators." Advances in Structural Engineering 20, no. 8 (2016): 1210–22. http://dx.doi.org/10.1177/1369433216673376.

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A novel self-centering prestressed concrete pier with external energy dissipators has been developed to realize seismic resilient performance and enhanced corrosion-resisting property. Self-centering capacity of the pier is provided by the unbonded post-tensioned tendons and damage is mostly concentrated on the replaceable dissipators. To investigate the seismic behavior of the proposed pier, a detailed analytical model considering interface opening and dissipator deformation was developed and verified through existing cyclic load tests. Based on the proposed model, a prototype reinforced concrete pier and a self-centering prestressed concrete pier with similar backbone curves are designed, and fragility analyses are conducted on the two piers through incremental dynamic analysis. One maximum drift-based performance limit state (i.e. collapse prevention) and two residual drift-based performance limit states (i.e. emergent usage and reconstruction) are defined for seismic capacity evaluation. Fragility curves indicate that the self-centering prestressed concrete pier has a slightly higher peak drift demand owing to its inferior dissipating capacity as compared with the reinforced concrete pier, while sustains a much lower residual drift demand due to its inherent self-centering characteristic.

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Della Sala, Lucio, Rosario Cerone, Alberto Gennari Santori, and Mauro Tommasini. "Assessment, Strengthening and Validation of Prestressed Damaged Beams." Key Engineering Materials 413-414 (June 2009): 359–66. http://dx.doi.org/10.4028/www.scientific.net/kem.413-414.359.

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The paper describes the evaluation of the actual conditions, the repairing design criteria and procedures, and the final validation tests carried out on a severely damaged prestressed bridge in southern Italy. In the first phases several release tests have been performed on damaged and, for comparison, on sound beams, with the aim of evaluating the residual prestressing stress acting both on concrete and on tendons. In particular, the tests on concrete have been carried out by extracting cores which have been previously instrumented with strain-gages; in a similar way, the strands were tested by gluing a micro strain-gage on a singular wire of a strand and the cutting the wire itself. The test results were used for optimising the design of an adjunctive prestressing system, consisting in 6 external unbounded cables and in a continuous FRC reinforcing of the bottom wing. The tensioning procedure of the external cables of each beam was then monitored by means of 12 strain-gages installed on concrete at mid span and at the two support sections, and by measuring the vertical deflection using laser optical levels. The validation of the repairing works was finally performed by a static load acceptance test, performed using the same apparatus previously adopted for the tensioning monitoring.

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Lou, Tiejiong, and Theodore L. Karavasilis. "Numerical evaluation of prestressed steel-concrete composite girders with external FRP or steel tendons." Journal of Constructional Steel Research 162 (November 2019): 105698. http://dx.doi.org/10.1016/j.jcsr.2019.105698.

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Oh, Chang Kook, Changbin Joh, Jung Woo Lee, and Kwang-Yeun Park. "Corrosion Detection in PSC Bridge Tendons Using Kernel PCA Denoising of Measured MFL Signals." Sensors 20, no. 21 (2020): 5984. http://dx.doi.org/10.3390/s20215984.

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The construction of prestressed concrete bridges has witnessed a steep increase for the past 50 years worldwide. The constructed bridges exposed to various environmental conditions deteriorate all along their service life. One such degradation is corrosion, which can cause significant damage if it occurs on the main structural components, such as prestressing tendons. In this study, a novel non-destructive evaluation method to incorporate a movable yoke system with denoising algorithm based on kernel principal component analysis is developed and applied to identify the loss of cross-sectional area in corroded external prestressing tendons. The proposed method using denoised output voltage signals obtained from the measuring device appears to be a reliable and precise monitoring system to detect corrosion with less than 3% sectional loss.

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Breen, John E., Michael E. Kreger, Christopher D. White, and Gordon C. Clark. "Field evaluation and model test of a composite wing-girder bridge." Canadian Journal of Civil Engineering 14, no. 6 (1987): 753–62. http://dx.doi.org/10.1139/l87-113.

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This paper presents the key observations and conclusions from the evaluation of an innovative "loose-fit" composite, post-tensioned concrete wing-girder bridge proposed for an elevated interstate highway expansion in an urban environment. The evaluation program included both testing to destruction of a 1/2-scale model of a partial span as well as construction monitoring and field testing at service load levels of a full-scale prototype two-span bridge. Results of both construction measurements and loading tests were compared with analytical predictions. Laboratory tests showed the composite behavior of the wing-girder joint to be fully effective and a high level of load transfer between wings to be present. Recommendations for modification of the prototype design are made to improve constructibility, durability, structural performance, and economy. Key words: box girder, bridge, post-tensioned, prestressed concrete, reinforcement, stresses, temperature, tendons.

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Naito, Clay. "Construction and Field Evaluation of Electrically Isolated Tendons in a Prestressed Concrete Spliced Girder Bridge." Journal of Bridge Engineering 25, no. 7 (2020): 05020001. http://dx.doi.org/10.1061/(asce)be.1943-5592.0001551.

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Han, Sun-Jin, Jae-Hoon Jeong, Hyo-Eun Joo, Seung-Ho Choi, Seokdong Choi, and Kang Su Kim. "Flexural and Shear Performance of Prestressed Composite Slabs with Inverted Multi-Ribs." Applied Sciences 9, no. 22 (2019): 4946. http://dx.doi.org/10.3390/app9224946.

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Half precast concrete slabs with inverted multi-ribs (Joint Advanced Slab, JAS), which enhance composite performance between slabs by introducing shear keys at connections between the slabs and improve structural performance by placing prestressing tendons and truss-type shear reinforcements, have recently been developed and applied in many construction fields. In this study, flexural and shear tests were performed to verify the structural performance of JAS members. Towards this end, two flexural specimens and four shear specimens were fabricated, and the presence of cast-in-place concrete and the location of the critical section were set as the main test variables. In addition, the flexural and shear performance of the JAS was quantitatively evaluated using a non-linear flexural analysis model and current structural design codes. Evaluation results confirmed that the flexural behavior of the JAS was almost similar to the behavior simulated through the non-linear flexural analysis model, and the shear performance of the JAS can also be estimated appropriately by using the shear strength equations presented in the current design codes. For the JAS with cast-in-place concrete, however, the shear strength estimation results differed significantly depending on the way that the shear contributions of the precast concrete unit and cast-in-place concrete were calculated. Based on the analysis results, this study proposed a design method that can reasonably estimate the shear strength of the composite JAS.

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Kim, Tae-Hoon. "Hollow precast segmental prestressed concrete bridge columns with a shear resistant connecting element." Canadian Journal of Civil Engineering 44, no. 6 (2017): 472–84. http://dx.doi.org/10.1139/cjce-2016-0276.

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The purpose of this study was to investigate the performance of hollow precast segmental prestressed concrete (PSC) bridge columns with a shear resistant connecting element. A model of hollow precast segmental PSC bridge columns was tested under a constant axial load and a cyclically reversed horizontal load. The computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used. Non-dimensional P-M interaction diagrams were developed to predict the design resistance of precast segmental PSC bridge columns. Among the numerous parameters, this study concentrates on concrete compressive strength, prestressing reinforcement ratio, effective prestress, diameter of circle passing through tendon centerlines-to-outside diameter of section ratio (Ds/Do) and inside diameter of section-to-outside diameter of section ratio (Di/Do). This study documents the testing of hollow precast segmental PSC bridge columns under cyclic loading and presents conclusions and design recommendations based on the experimental and analytical findings.

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Uesaka, Mitsuru, Jian Yang, Katsuhiro Dobashi, Joichi Kusano, Yuki Mitsuya, and Yoshiyuki Iizuka. "Quantitative Evaluation of Unfilled Grout in Tendons of Prestressed Concrete Girder Bridges by Portable 950 keV/3.95 MeV X-ray Sources." Applied Sciences 11, no. 12 (2021): 5525. http://dx.doi.org/10.3390/app11125525.

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We have developed porTable 950 keV/3.95 MeV X-band (9.3 GHz) electron linear accelerator (LINAC)-based X-ray sources and conducted onsite prestressed concrete (PC) bridge inspection in the last 10 years. A T-shaped PC girder bridge with a thickness of 200–400 mm and a box-shaped PC girder bridge with a thickness of 200–800 mm were tested. X-ray transmission images of flaws such as thinning, fray, and disconnection caused by corrosion of PC wires and unfilled grout were observed. A three-dimensional structural analysis was performed to estimate the reduction in the yield stress of the bridge. In this study, we attempted to evaluate the unfilled grout quantitatively because it is the main flaw that results in water filling and corrosion. In the measured X-ray images, we obtained gray values, which correspond to the X-ray attenuation coefficients of filled/unfilled grouts, PC wires (steel) in a sheath, and concrete. Then, we compared the ratio of the gray values of the filled/unfilled grouts and PC wires to determine the stage of the unfilled grout. We examined this quantitative evaluation using the data obtained from a real T-shaped PC girder bridge and model samples to simulate thick box-shaped PC girder bridges. We obtained a clear quantitative difference in the ratios for unfilled and filled grouts, which coincided with our visual perception. We synthesized the experience and data and proposed a quantitative analysis for evaluating the unfilled grout for subsequent steps such as structural analysis and destructive evaluation by boring surveys.

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Anderson, Patrick, Martin Hansson, and Sven Thelandersson. "Reliability-based evaluation of the prestress level in concrete containments with unbonded tendons." Structural Safety 30, no. 1 (2008): 78–89. http://dx.doi.org/10.1016/j.strusafe.2006.09.003.

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Bartoli, Ivan, Salvatore Salamone, Robert Phillips, Francesco Lanza di Scalea, Stefano Coccia, and Charles S. Sikorsky. "Monitoring Prestress Level in Seven Wire Prestressing Tendons by Inter Wire Ultrasonic Wave Propagation." Advances in Science and Technology 56 (September 2008): 200–205. http://dx.doi.org/10.4028/www.scientific.net/ast.56.200.

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Researchers at UCSD are investigating, in collaboration with Caltrans, the combination of ultrasonic guided waves and embedded sensors as an approach to provide both prestress level monitoring and defect detection capabilities in concrete-embedded PS tendons. This paper will focus on the prestress level monitoring by first discussing the behavior of ultrasonic guided waves propagating in seven-wire, 15.2-mm diameter twisted strands typically used in post-tensioned concrete structures. A semianalytical finite element analysis is used to predict forced wave solutions as a function of the applied prestress level. A feature shown sensitive to load levels is the inter-wire energy leakage. In order to monitor such feature, piezoelectric sensors were experimentally employed to probe the individual, 5-mm wires comprising the strand. Results of load monitoring in embedded strands during laboratory tests will be presented and a statistical approach will be used to enhance the evaluation of prestress loss in the strands.

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Wang, Zhi Feng, and Xian Yan Zhou. "Impact-Echo Based Nondestructive Evaluation of Grout Condition in Post-Tensioned Bridge Ducts." Advanced Materials Research 168-170 (December 2010): 1122–25. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1122.

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The field of Nondestructive Evaluation (NDE) is a very broad, interdisciplinary field that plays a critical role in civil engineering for controlling new structures (quality control) as well as for assessing the internal grout condition of prestressed pipes in post-tensioned concrete structures. Because it allows voids in grouted tendon ducts to be inspected and measured without damaging them, impact-echo based NDE provides an excellent balance between quality control and cost-effectiveness. This paper focuses on the nondestructive evaluation of internal injection quality in post-tensioned bridge ducts, and the developments in civil engineering NDE in China are also introduced.

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Kwahk, Imjong, Kwang-Yeun Park, Ji-Young Choi, Hungjoo Kwon, and Changbin Joh. "Non-Destructive Evaluation for Sectional Loss of External Tendon of Prestressed Concrete Structures Using Total Flux Leakage." Applied Sciences 10, no. 21 (2020): 7398. http://dx.doi.org/10.3390/app10217398.

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A non-destructive evaluation method is proposed to identify the sectional loss of the external tendon of prestressed concrete structures by detecting the change of the magnetic flux in the external tendon exposed to a magnetic field. The method uses a solenoid-shaped device with two coils: a primary coil for producing magnetic field and secondary coil for damage detection, wrapping the external tendon. A current applied to the primary coil in the device causes the magnetic field. Then, the change in the magnetic flux by the damage in the external tendon is detected by the variation of the voltage in the secondary coil in the device as the device moves along the tendon. An alternating current is applied to the primary coil to minimize the effect of the moving speed of the device. As a result, the damaged area can be detected with a low-level energy current. In addition, a wrapping solenoid-shaped device that is easy to disassemble and assemble was developed for in situ inspection. The measured signal from the secondary coil has a sinusoidal form with the same frequency as the applied current to the primary coil, and the peak curve of the measured signal provides enough information to detect the damage. It is shown that the proposed method can quantitatively identify one or multiple damaged-tendon locations as well as damages of at least 2 cm.

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Liu, Zhengyu, Brent M. Phares, Weizhuo Shi, and Behrouz Shafei. "Full-Scale Evaluation of an Innovative Joint Design between Adjacent Box Beams." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 2 (2020): 33–44. http://dx.doi.org/10.1177/0361198120902695.

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The longitudinal joints on adjacent precast, prestressed box beams used in bridge construction are vulnerable to cracking. These cracks provide a direct path for water and deleterious agents to enter the structural system, causing corrosion of the embedded steel bars and tendons. To avoid significant maintenance costs, safety concerns, or both, an innovative longitudinal joint between two adjacent box beams was designed in the current study. This joint is 6½ in. wide with roughened surfaces, filled with shrinkage compensating concrete and reinforced by steel bars. The joint was evaluated on a small-scale basis and satisfactory performance was obtained in resisting early-age cracks. In the current paper, the joint design is further evaluated through experiments on a 31 ft long specimen during the joint’s early age, and when it is subjected to multiple levels of cyclic loads. A finite element (FE) model that is capable of simulating the early-age concrete hardening was also developed and validated against the experimental data. The early-age, time-dependent stress development in the joint and at the interface of the joint and box beam was investigated using the FE model. Based on the results of laboratory tests and FE simulations, the innovative joint was found to remain crack free without the utilization of a shear key or transverse post-tensioning. The “compression-dominate” joint created by the expansive joint material and transverse reinforcing bars across the interface is expected to address the issues associated with early age, while ensuring the long-term durability and performance of box-beam bridges.

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Liu, Kit Fook, Hwa Kian Chai, Nima Mehrabi, Kobayashi Yoshikazu, and Tomoki Shiotani. "Condition Assessment of PC Tendon Duct Filling by Elastic Wave Velocity Mapping." Scientific World Journal 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/194295.

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Imaging techniques are high in demand for modern nondestructive evaluation of large-scale concrete structures. The travel-time tomography (TTT) technique, which is based on the principle of mapping the change of propagation velocity of transient elastic waves in a measured object, has found increasing application for assessing in situ concrete structures. The primary aim of this technique is to detect defects that exist in a structure. The TTT technique can offer an effective means for assessing tendon duct filling of prestressed concrete (PC) elements. This study is aimed at clarifying some of the issues pertaining to the reliability of the technique for this purpose, such as sensor arrangement, model, meshing, type of tendon sheath, thickness of sheath, and material type as well as the scale of inhomogeneity. The work involved 2D simulations of wave motions, signal processing to extract travel time of waves, and tomography reconstruction computation for velocity mapping of defect in tendon duct.

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Yon, Jung-Heum, and Do-Goon Kim. "Design of Additional Tendon Force and Evaluation of Resistant Moment for Prestressed Concrete Composite Section." Journal of the Korea Concrete Institute 16, no. 3 (2004): 335–44. http://dx.doi.org/10.4334/jkci.2004.16.3.335.

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KAMADA, Toshiro, Shinya UCHIDA, Hotaru TSUNODA, and Koji SATO. "NON-DESTRUCTIVE EVALUATION METHODS FOR GROUTING CONDITION IN TENDON DUCTS IN EXISTING PRESTRESSED CONCRETE BRIDGES." Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures) 68, no. 4 (2012): 238–50. http://dx.doi.org/10.2208/jscejmcs.68.238.

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PARKHATS, Vadzim, and Rafał KRZYWOŃ. "EVALUATION OF TIME DEPENDENT PRESTRESS LOSSES IN PRETENSIONED CONCRETE MEMBER WITH TOP AND BOTTOM TENDONS." Architecture, Civil Engineering, Environment 12, no. 3 (2019): 105–12. http://dx.doi.org/10.21307/acee-2019-040.

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Yuyama, S., K. Yokoyama, K. Niitani, M. Ohtsu, and T. Uomoto. "Detection and evaluation of failures in high-strength tendon of prestressed concrete bridges by acoustic emission." Construction and Building Materials 21, no. 3 (2007): 491–500. http://dx.doi.org/10.1016/j.conbuildmat.2006.04.010.

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Jin, Kiwoong, Linfei Hao, and Kazuhiro Kitayama. "Direct evaluation method for load-deformation curve of precast prestressed concrete frame with different tendon forces." Bulletin of Earthquake Engineering 19, no. 9 (2021): 3597–626. http://dx.doi.org/10.1007/s10518-021-01109-w.

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Gong, Shilin, and Xin Feng. "Detection of grouting defects in prestressed tendon ducts using distributed fiber optic sensors." Structural Health Monitoring 19, no. 4 (2019): 1273–86. http://dx.doi.org/10.1177/1475921719880318.

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To compensate for the shortcomings of the existing point detection methods for grouting defects in prestressed tendon ducts, such as low detection efficiency, stringent detection environment, and easy omission of grouting defects, this article presents a distributed detection approach to detect the grouting defects in tendon ducts. The main objective of the research pertained to the development of a method for accurate identification and location of grouting defects and qualitative evaluation of the size of grouting defects using distributed fiber optic sensors with active heating. Using the thermal analysis of grouting defects in the tendon duct and the research on distributed fiber optic sensors measurement characteristics, our work proposed a method for identifying and locating grouting defects and explored the effect of the grouting defect length and the grouting compactness on the temperature rise of distributed fiber optic sensors. The feasibility of the proposed approach is evaluated through an experimental program. The experimental program involved use of heating distributed fiber optic sensors for the distributed measurement of temperature after the heating and detection of grouting defects in tendon ducts in a concrete beam. The results indicate that distributed fiber optic sensors can monitor the temperature distribution of the tendon duct during a temperature rise in real time. Grouting defects in the tendon duct can be quickly detected and located by identifying temperature anomalies in the temperature contour of the distributed fiber optic sensors. Furthermore, there is a linear relationship between the defect length and the abnormal temperature length on the distributed fiber optic sensors, and the defect length can be identified based on the abnormal temperature length obtained by the measurement. Plane-equivalent thermal conductivity can be used to evaluate the grouting compactness of the tendon duct. When the grouting compactness is greater than 70%, the smaller the plane-equivalent thermal conductivity is, the lower the grouting compactness is. The plane-equivalent thermal conductivity is basically the same when the grouting compactness is less than 70%.

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Wang, Xin Ding, Hang Dai, and Yong Chao Zhang. "Study on Shear Behaviour of Concrete Beams Prestressed with External CFRP Tendons." Applied Mechanics and Materials 275-277 (January 2013): 1167–71. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.1167.

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Based on independent research and development of a CFRP tendons wedge-type anchorage, the shear tests of six CFRP external prestressing concrete beams were done. Among them, CFRP external tendons of three pieces were installed in straight line while other pieces were installed in curved line. The results of experimental research show that shear behaviour of concrete beams prestressed with CFRP external tendons are the similar process to the traditional prestressed reinforced concrete beams. They go through the elastic stage, the stage of crack extension, the yield stage of internal hoop reinforcements at the intersection of inclined cracks and the failure stage. When external CFRP tendons are arranged in the same situation, the cracking load and the shear capacity of concrete beams prestressed with CFRP external tendons reduce gradually along with the increase of shear-span ratio,.When shear-span ratio is equal, the cracking load and the shear capacity of concrete beams prestressed with curved arrangement of CFRP external tendons are larger than those of concrete beams prestressed with straight arrangement of CFRP external tendons. Compared with traditional concrete beams prestressed with external steel bars, due to elasticity modulus and shear modulus of CFRP tendons are both smaller than those of steel bars, the mid-span deflection of concrete beams prestressed with CFRP external tendons at the time of shear failure is bigger than that of traditional concrete beams prestressed with external steel bars under the same circumstance.

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Du, Xiu Li, Zuo Hu Wang, and Jing Bo Liu. "Flexural Capacity of Concrete Beams Prestressed with Carbon Fiber Reinforced Polymer (CFRP) Tendons." Advanced Materials Research 168-170 (December 2010): 1353–62. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1353.

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Fiber reinforced polymer (FRP), particularly those incorporating carbon fiber (CFRP), has high strength, high stiffness-to-weight ratio and high resistance to corrosion, which shows potential for use as prestressing tendons in corrosive environment. However, concrete beams prestressed with FRP tendons have showed brittle flexural failure due to the elastic rupture of FRP tendons. In order to improve the ductility, a combination of bonded and/or unbonded prestressing tendons was used. Nine prestressed concrete beams were tested up to failure to study the effect of bonded and unbonded FRP tendons on their flexural capacity. Three factors were taken into consideration; the bonding condition of CFRP tendons, the location of CFRP tendons and the prestressing ratio. Also an analytical investigation was carried out to extend some flexural capacity calculation equations to this beam type. The results of the experimental showed that under the same condition, the carrying capacity of concrete beam prestressed with bonded FRP tendons was 20% higher than that of internal unbonded prestressed beam, and was 40% higher than that of external unbonded prestressed beam without deviators. By combination of bonded and unbonded FRP tendons, the ductility of prestressed concrete beams can be improved.

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Ju, Yan Zhong, Dong Xu Yu, and Wang Dehong. "A Study of the Partially Prestressed Tendons RPC Concrete Pole Connection Design." Applied Mechanics and Materials 166-169 (May 2012): 534–37. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.534.

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In order to study and solve the problem of connection on the part of the prestressed tendons RPC concrete pole engineering. Design connecting flange suitable for the existing part of the prestressed tendons RPC concrete pole developed by our group used the connection flange in Steel tower as the prototype.Through the ABAQUS software to establish the finite element model between the connection flange and part of the prestressed tendons RPC concrete pole, and carry out finite element analysis.Through the finite element analysis to get results whether the design of connecting flange can meet the strength requirements when the prestressed tendons RPC concrete pole is under ultimate load, so to get the practical design method of the 500kv part prestressed RPC concrete pole connecting flange.

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Fu, Qiang, Xia Cao, Ling Zhi Jin, Wan Xu Zhu, Hui Xian Yang, and Zhu Bai Shu. "Experimental Study on the Stress Increment of Prestressed Tendons of Retard-Bonded Prestressed Concrete Continuous Beams." Advanced Materials Research 163-167 (December 2010): 1431–35. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1431.

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Based on the bending experiment for two-span continuous beams of retard-bonded prestress concrete, the analysis of the stress increment of prestressed tendons is made in the loading process. The theory that the working performance of retard-bonded prestressed concrete members is as same as unbonded prestressed concrete members during the retarding period is demonstrated. It is feasible to use the formulas for the reference (Technical specification for concrete structures prestressed with unbonded tendons) to calculate σputhe ultimate stress and Δσp the Stress increment of the retard-bonded prestressed tendons and the recommended formulas are advised to use. It is also demonstrated that retard-bonded prestressed concrete members have the same working performance as bonded prestressed concrete members after the retarding period. The conclusion of this paper can provide the reference date for the design of retard-bonded prestressed concrete continuous beam.

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Wang, Zuohu, Zhanguang Gao, Yuan Yao, and Weizhang Liao. "Experimental investigation on the seismic behavior of concrete beams with prestressing carbon fiber reinforced polymer tendons." Science Progress 103, no. 1 (2019): 003685041988523. http://dx.doi.org/10.1177/0036850419885235.

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Seven prestressed concrete beams and one normal concrete beam were tested to study the seismic performance of concrete beams with prestressing carbon fiber reinforced polymer tendons. The failure modes, hysteretic curves, ductility, stiffness degeneration, and energy dissipation capacity were studied systematically. This study shows that the partial prestressing ratio is the main factor that affects the seismic performance of carbon fiber reinforced polymer prestressed concrete beams. The beam is more resilient to seismic loads as the partial prestressing ratio decreases. Under the same partial prestressing ratio value, the energy dissipation capacity of prestressed concrete beams with unbonded carbon fiber reinforced polymer tendons was better than that of prestressed beams with bonded carbon fiber reinforced polymer tendons. When combining both bonded and unbonded prestressing carbon fiber reinforced polymer tendons, the ductility index of concrete beams was improved. Compared with that of fully unbonded and fully bonded carbon fiber reinforced polymer prestressed concrete beams, the ductility index of concrete beams with combined bonded and unbonded prestressing tendons increased by 26% and 12%, respectively.

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Du, Jin Sheng, Dong Yang, P. L. Ng, and Francis T. K. Au. "Response of Concrete Beams Partially Prestressed with External Unbonded Carbon Fiber-Reinforced Polymer Tendons." Advanced Materials Research 150-151 (October 2010): 344–49. http://dx.doi.org/10.4028/www.scientific.net/amr.150-151.344.

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To assess the behavior of concrete beams partially prestressed with external unbonded carbon fiber-reinforced polymer (CFRP) tendons, three specimens prestressed with CFRP tendons and one reference specimen prestressed with external steel tendons were tested to failure under third point loading. It was found that the load-deflection curve of all specimens exhibited three stages, namely, elastic, cracked-elastic and plastic. The transition from the elastic to the cracked-elastic stage was caused by the development of cracks at the bottom of the beam, while the transition from the cracked-elastic to the plastic stage was caused by yielding of the non-prestressed steel. For beams prestressed with external CFRP tendons and that with external steel tendons, the relationships between the stress increment in external tendons and the mid-span deflection of specimens were linear or approximately linear. Although CFRP materials are brittle in nature and behave linearly elastically until failure, proper combination of external CFRP prestress tendons with internal steel reinforcing bars can impart ductility to the beams.

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Ma, Haiying, Xuefei Shi, and Yin Zhang. "Long-Term Behaviour of Precast Concrete Deck Using Longitudinal Prestressed Tendons in Composite I-Girder Bridges." Applied Sciences 8, no. 12 (2018): 2598. http://dx.doi.org/10.3390/app8122598.

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Twin-I girder bridge systems composite with precast concrete deck have advantages including construction simplification and improved concrete strength compared with traditional multi-I girder bridge systems with cast-in-place concrete deck. But the cracking is still a big issue at interior support for continuous span bridges using twin-I girders. To reduce cracks occurrence in the hogging regions subject to negative moments and to guarantee the durability of bridges, the most essential way is to reduce the tensile stress of concrete deck within the hogging regions. In this paper, the prestressed tendons are arranged to prestress the precast concrete deck before it is connected with the steel girders. In this way, the initial compressive stress induced by the prestressed tendons in the concrete deck within the hogging region is much higher than that in regular concrete deck without prestressed tendons. A finite element analysis is developed to study the long-term behaviour of prestressed concrete deck for a twin-I girder bridge. The results show that the prestressed tendons induce large compressive stresses in the concrete deck but the compressive stresses are reduced due to concrete creep. The final compressive stresses in the concrete deck are about half of the initial compressive stresses. Additionally, parametric study is conducted to find the effect to the long-term behaviour of concrete deck including girder depth, deck size, prestressing stress and additional imposed load. The results show that the prestressing compressive stress in precast concrete deck is transferred to steel girders due to concrete creep. The prestressed forces transfer between the concrete deck and steel girder cause the loss of compressive stresses in precast concrete deck. The prestressed tendons can introduce some compressive stress in the concrete deck to overcome the tensile stress induced by the live load but the force transfer due to concrete creep needs be considered. The concrete creep makes the compressive stress loss and the force redistribution in the hogging regions, which should be considered in the design the twin-I girder bridge composite with prestressed precast concrete deck.

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Li, Hong Fang, Chang Gong, and Zhi Fang. "Behaviors of Concrete Beam Prestressed with External CFRP Tendons." Key Engineering Materials 400-402 (October 2008): 559–66. http://dx.doi.org/10.4028/www.scientific.net/kem.400-402.559.

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The purpose of present paper is to study the flexural behaviors of concrete T-beams prestressed with external carbon fiber reinforced polymer(CFRP) tendons. Tests were carried out on 5 beams under four-point load, of which four beams were reinforced with hybrid both external CFRP tendons and internal steel rebars and another one only reinforced with internal steel rebars. Such parameters as the different initial loading states at external CFRP tendon jacking and different jacking stress in tendon were considered in experiment. A program was developed to predict the behaviors of those beams prestressed with externally prestressed tendons and the parametric study was conducted using the program. The predicted results from the program were in good agreement with the test results. Such parameters as jacking stress, elastic modulus of external tendons, configuration of deviators and ratio of span to effective depth of beam were chosen as primary analytical factors for the study on the flexural behaviors of beams prestressed with external tendons. The initial loading state on the beam before tendon jacking has no significant influence on the ultimate loading capacity and deflection.

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Wang, Zuo Hu, Xiu Li Du, and Jing Bo Liu. "Shear Behavior of CFRP Prestressed Concrete Beams without Stirrups." Advanced Materials Research 266 (June 2011): 126–29. http://dx.doi.org/10.4028/www.scientific.net/amr.266.126.

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Five beams were tested up to failure to study the shear behavior of concrete beams prestressed with fiber reinforced polymer (FRP). Different factors were taken into consideration: the type of prestressing tendons and the shear span ratio. The shear failure modes and the influence of different factors on shear behavior were investigated in details. The test results showed that FRP prestressed beams without stirrups had two shear failure modes: diagonal compression failure and shear compression failure; the shear span ratio was the most important factor to determine the failure mode and shear capacity of the prestressed beams. The shear capacity of concrete members prestressed with FRP tendons was lower than that of concrete beams prestressed with steel cables.

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Zheng, Wen Zhong, Chong Xi Bai, and Hui Dong Cheng. "Experimental Study on Behaviors of Unbonded Prestressed Concrete Beams Reinforced with CFRP Tendons." Key Engineering Materials 400-402 (October 2008): 567–73. http://dx.doi.org/10.4028/www.scientific.net/kem.400-402.567.

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In order to research behaviors of unbonded prestressed concrete beams reinforced with CFRP tendons, static load experiments on 4 partially prestressed simple beams with unbonded CFRP tendons and 9 two spans partially prestressed concrete continuous beams with unbonded CFRP tendons were performed. Based on the experiment results of simple beams, the law of ultimate stress increment in unbonded CFRP tendons in simple beams was obtained. Based on the experiment results of continuous beams, the law of stress increment in unbonded CFRP tendons in continuous beams was obtained at serviceability state and at strength limit state of bending capacity. The calculation formula of length of equivalent plastic hinge for this kind of continuous beam was presented. The calculation formulas of moment modification coefficient with composite reinforcement index for intermediate support as variable and relative plastic rotation for intermediate support as variable were given respectively.

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Novák, Balthasar, Eberhard Pelke, Dieter Berger, Vazul Boros, Sven Priestaff, and Jochen Reinhard. "Strengthening of Prestressed Concrete Bridges by External Tendons." IABSE Symposium Report 99, no. 22 (2013): 662–69. http://dx.doi.org/10.2749/222137813806735561.

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Dall'asta, Andrea, Luigino Dezi, Graziano Leoni, and Alessandro Zona. "Behaviour of Concrete Beams Prestressed by Unbonded Tendons." IABSE Symposium Report 86, no. 5 (2002): 51–60. http://dx.doi.org/10.2749/222137802815776487.

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Gao, Dan Ying, and Yu Bin Zhu. "Flexural Behavior of Concrete One-Way Slab Externally Prestressed with GFRP Tendons." Applied Mechanics and Materials 71-78 (July 2011): 988–94. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.988.

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To study flexural performance of one-way slabs externally prestressed with GFRP tendons, a series of experiments were carried out. Based on the results, the load-deflection responses and bending capacities were presented in this paper. Moreover, the influence factors, including the quantity of GFRP tendons and prestressing force, were discussed. Comparison tests proved that the slabs externally prestressed with GFRP tendons will be improved in some aspects, such as ultimate deflection, flexural stiffness, bending capacity, larger deformation before failure.

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Liu, Shu Yue, and Wei Ling Wang. "Research on Post-Tensioned Prestressed Concrete Construction Technology in Construction Engineering." Advanced Materials Research 700 (May 2013): 221–24. http://dx.doi.org/10.4028/www.scientific.net/amr.700.221.

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Study of bonded post-tensioned prestressed concrete construction technology, from materials, equipment, channel reservation, prestressed reinforcement material installation, concrete pouring, the prestressed tendons tension and grouting of anchor seal is described from the aspects of the construction of the link, the specific operation steps, summarizes the method of construction, improve the following prestressed concrete construction understanding.

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Savić, Adrijana, Robert J. Peterman, and B. Terry Beck. "Suggested Qualification Test Procedure to Secure Splitting Resistance in Pretensioned Concrete Members." Advanced Engineering Forum 41 (July 7, 2021): 75–84. http://dx.doi.org/10.4028/www.scientific.net/aef.41.75.

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Prestressed concrete ties could develop end-splitting cracks along tendons due to lateral bursting stresses. The lateral bursting stresses can form due to Hoyer effect (change in diameter of the prestressing tendons due to Poisson’s ratio), the jacking force in the tendons, geometrical features and indent characteristics of the prestressing tendons. End-splitting cracks can occur immediately after de-tensioning procedure in some cases, but they also can be developed during the first weeks after de-tensioning procedure due to sustained lateral stresses exerted by the prestressing tendons. The ability of concrete to resist these bursting stresses without cracking is primarily the function of the thickness of concrete cover, the type of concrete mixture used and the maximum compressive strength of the concrete. Qualification test will be great tool for prestressed concrete tie manufacturers to identify tie designs that may be susceptible to end-splitting cracks. This test was formally adopted as section 4.2.4 in Chapter 30 of the 2021 AREMA Manual for Railway Engineering.

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Chen, Ke, Jian Yong Song, and Shuo Zhang. "Simulation and Analysis for Externally Prestressed Concrete Bridge Based on ANSYS." Advanced Materials Research 243-249 (May 2011): 1737–42. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1737.

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The externally prestressed bridge finite element analysis module redeveloped based on ANSYS software is introduced，realizing finite element analysis method for externally prestressed concrete bridge. It is able to build the externally prestressed bridge finite element model, combined with Solid65 and Solid45 simulated concrete, and Link8 or Link10 simulated prestressed tendon. It is also able to bring material and geometric nonlinear effects into the analysis, for analyzing ultimate bearing capacity and local stress characterization of the externally prestressed structure. A bridge model is generated as an example for verifying the application of the module. Based on it, the model then is equipped with different allocation arrangements of internal and external tendons to analyze the mechanical characteristics of externally prestressed concrete bridge. Research is conducted for the effect on ultimate bearing capacity by allocation arrangement of tendons, and providing design suggestion and theoretic basis.

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Wang, Zhong Qiang, and Zhi Wu Yu. "The Experimental Research and Theoretical Analysis of Unbonded Prestressed Concrete Flat Beams at High Temperature." Advanced Materials Research 250-253 (May 2011): 2242–52. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.2242.

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The experiments of 26 unbonded prestressed concrete flat beams under fire with elevating the temperature according to the ISO time-temperature standard curve were accomplished in the large structures electrical heating furnace that was manufactured independently. The macroscopical phenomena of water penetration, the lube flowing, the spalling of concrete and the corlor change of aspect were observed. The laws of behaviors such as temperature distribution on section,the deformation characteristic and stress varieties of prestressed tendons were investigated through the tests. The experiments indicated that temperature distribution was not uniform, the dynamic continuous deformation and the complicated varieties of prestressed stress occurred at high temperature. Based on the increment temperature-stress coupling constitutive models and chief deformation compatibility of the unboded prestressed tendons, the nonlinear finite element calculation formula took the unknown nodes displacements and the tensile forces in the unbonded tendons as unsolved column matrix simultaneously. The Increment format of nonlinear finite element method and calculation model for whole process analysis of unbonded prestressed concrete flexural members at high temperature were presented. The solution of nonlinear equilibrium equations for unboded prestressed concrete flexural members at high tempure was proposed, and a FORTRAN program named NAUPCLF was developed also and the results were in good agreement. The conclusions can supply the way and basis for further fire-resistant design and analysis of prestressed concrete structures.

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Zhao, Zixiang, and Xiaozu Su. "Seismic Response Analysis of Prestressed Concrete Rocking Frame." Applied Sciences 11, no. 2 (2021): 585. http://dx.doi.org/10.3390/app11020585.

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In order to investigate the seismic performance of prestressed concrete rocking frame (PCRF), a theoretical model based on rigid body is established for a one-story single-span PCRF. The PCRF studied in this paper has the connecting interfaces set at the column feet and at the inner faces of the beam–column joints, allowing the columns to be uplifted with the accompanying separation of the beam–column interface and rotation of the beam and column around the interface. The tendons are arranged along the centerline of the beam and columns. The connections between the beam and columns and the anchoring of columns are accomplished by prestressing the tendons. The theoretical model consists of a rigid beam, rigid columns and elastic tendons. The governing motion equation of the PCRF is derived based on the model and a numerical solution of the equation of motion is obtained. The energy dissipation of the PCRF is analyzed and the calculation method for the coefficient of restitution is derived. Time history analysis and parameter analysis of seismic response of the PCRF are conducted and the results show that the PCRF has promising seismic behavior.

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Zhao, Zixiang, and Xiaozu Su. "Seismic Response Analysis of Prestressed Concrete Rocking Frame." Applied Sciences 11, no. 2 (2021): 585. http://dx.doi.org/10.3390/app11020585.

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In order to investigate the seismic performance of prestressed concrete rocking frame (PCRF), a theoretical model based on rigid body is established for a one-story single-span PCRF. The PCRF studied in this paper has the connecting interfaces set at the column feet and at the inner faces of the beam–column joints, allowing the columns to be uplifted with the accompanying separation of the beam–column interface and rotation of the beam and column around the interface. The tendons are arranged along the centerline of the beam and columns. The connections between the beam and columns and the anchoring of columns are accomplished by prestressing the tendons. The theoretical model consists of a rigid beam, rigid columns and elastic tendons. The governing motion equation of the PCRF is derived based on the model and a numerical solution of the equation of motion is obtained. The energy dissipation of the PCRF is analyzed and the calculation method for the coefficient of restitution is derived. Time history analysis and parameter analysis of seismic response of the PCRF are conducted and the results show that the PCRF has promising seismic behavior.

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Pandey, M. D., and M. A. Nessim. "Reliability-based inspection of post-tensioned concrete slabs." Canadian Journal of Civil Engineering 23, no. 1 (1996): 242–49. http://dx.doi.org/10.1139/l96-025.

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In unbonded, post-tensioned prestressed concrete slabs and beams, corrosion of prestressed tendons due to moisture ingress and their subsequent breakage has been identified as a major problem raising serious concern over the safety of aged structures. The paper presents a practical Bayesian approach to reliability assessment of such structures based on the inspection of a randomly selected sample of prestressing tendons. To minimize inspection costs, clear guidelines are presented for selecting the minimum sample size necessary to demonstrate that the annual probability of failure of an existing structure is below the target value of 10−5, implied in the Canadian Standards Association concrete design code CAN3-A23.3-M84. A systematic and cost-effective incremental strategy is developed for inspection of existing prestressed concrete structures. Key words: reliability, Bayes theorem, prestressed concrete, unbonded post-tensioned system, inspection, corrosion, probability distribution, CSA Standard CAN3-A23.3-M84, slab.

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Liu, Qing Wen, and Fu Qiang Wu. "Characteristic Analysis of Prestressed Concrete Frame Joints with Spread-Ended Beams." Applied Mechanics and Materials 578-579 (July 2014): 648–52. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.648.

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Three joints of prestressed concrete frame are studied under low frequency reversed loading. The failure and cracks feature, damage characteristics and mechanical properties under seismic loads are comparatively analysed between joints with spread-ended beams and conventional joints. Studies show that the layout of prestressing tendons and joints with spread-ended beams have little influence on the bearing capacity and ductility. Prestressing tendons through the joint core region can improve the shear strength of joints, but tendons through the joint outer region can not. We need to only consider the influence on the area of prestressing tendons through joint core region when calculating the shear strength of joints.

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Journal articles on the topic 'Tendons (Prestressed concrete) – Evaluation'

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