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1
Huang, Min Yuan. "A Survey on Project Application of External Prestressing Technology." Advanced Materials Research 368-373 (October 2011): 1469–72. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.1469.
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This article mainly introduce the major effect factor of external prestressing technology, for instance: The reasonable external prestressing’s transmission system chiefly includes two aspects of prestressing size and prestressing function position; The tendon steering system is to solve the centralized solution of local stress and the grasp stress of weak link ; The external prestressing anchor system must guarantee multiplicity and construction security; In construction monitoring process，it must grasp the monitor parameter of the prestressing and the deflection and so on; The anti-vibration localization of the external prestressing is to enhance the structure durability etc., which have provided the advantageous technical guidance for the actual projects.
2
Batchelor, B. deV, and Jayanth Srinivasan. "Calculation of stress in prestressing steel at ultimate conditions." Canadian Journal of Civil Engineering 16, no. 4 (1989): 576–82. http://dx.doi.org/10.1139/l89-088.
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This paper reviews different methods available for the calculation of stress in prestressing steel at ultimate, ƒps, and the methods are evaluated using a nonlinear analysis computer program. The development of a nonlinear model for the analysis of partially prestressed concrete flexural members is described. The model takes the material nonlinearities into account by the use of appropriate stress–strain relationships for steel and concrete. A parametric study of partially prestressed beams was conducted to study the effect of various parameters on stress in prestressing steel at ultimate conditions. Two types of sections, rectangular and T sections, were studied. The prediction equation, recommended in the Canadian Code Can3-A23.3-M84, for calculating the stress in prestressing steel at ultimate is found to be very conservative for all the cases studied, which covered all possible ranges of partial prestressing ratio. The present restriction in the Canadian Code, for the use of their prediction equation only when the ratio of the neutral axis depth, Cu, to the depth of the centroid of prestressing steel, dps, is less than or equal to 0.3, is found to be too restrictive. An alternative equation for ƒps, suggested by Loov, is found to be more suitable than the present equation in the Canadian Code; however, a more practical upper limit for cu/dps ratio is suggested in the paper. It is shown that the proposed equation can be used conservatively over the complete range of partially prestressed concrete. Key words: analysis, concrete (prestress), flexure, partial prestressing, prestressing, strain, stress, steel.
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Zamaliev, F. S., and D. Yu Filippov. "Numerical and Experimental Investigations of Prestressed Steel-Concrete Beams." Reinforced concrete structures 9, no. 1 (2025): 18–25. https://doi.org/10.22227/2949-1622.2025.1.18-25.
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The idea of prestressing in reinforced concrete structures is widely used. Peculiarities of stress-strain state of prestressed reinforced concrete elements are described in many scientific articles, recommendations on prestressing methods are developed. The use of prestressing in steel-concrete structures is quite a new phenomenon. In SP 266.1325800.2016 there are no recommendations on prestressing of steel-reinforced concrete structures.The aim of the study is to evaluate the effect of prestressing on the stress-strain state of steel-concrete beams.Application of prestressing in steel-concrete beams allows to optimize their material intensity. The methodology and results of numerical investigations on the basis of computer modeling are given. Experimental studies of steel-concrete beams are carried out. The results of full-scale tests are analyzed and compared with the data of numerical experiments.
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Su, Jian, Nan Gai Yi, Zong Guang Sun, Yang Bai, and Ai Guo Zhang. "Experimental Study on Mechanical Performance of Unbonded and Bonded Prestressed Concrete Beams." Applied Mechanics and Materials 178-181 (May 2012): 2387–92. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.2387.
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The experiment which based on the stress performance of unbonded and bonded prestressed concrete beam, has made a systematically research on the stress and strain variation law of pretressing tendon in the aforementioned reinforcement prestressed concrete structure. When the bonded prestressed concrete beam bearing load, there is a larger variation in stress and strain of prestressing reinforcement along the length. The maxima of stress and strain of prestressing reinforcement in bonded prestressed concrete beam appears in midspan, it is achieved the yield stress and yield strain, the minima appears in bearing, the stress and strain of prestressing reinforcement in bonded prestressed concrete beam is proportional to the distortion. The stress and strain of prestressed reinforcement in unbonded prestressed concrete beam is almost the same along the length.
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Tian, Zhongchu, Zujun Zhang, Wenping Peng, Ye Dai, Yue Cai, and Binlin Xu. "Research on the Method of Temporary Prestressing to Regulate the Stress in the Section during the Construction of the Main Arch Ring of the Cantilever Cast Arch Bridge." Applied Sciences 12, no. 19 (2022): 10070. http://dx.doi.org/10.3390/app121910070.
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To control the level of tensile stress in the section of reinforced concrete arch cantilever construction, a construction control method of temporary prestressing reinforcement is proposed in this study. The influence law of temporary prestressing on the arch ring section stress is revealed based on the engineering background (Shatuo Special Bridge in Guizhou). Meanwhile, a temporary prestressing test is carried out on the ring section of the main arch to verify the effectiveness of the method. The results show that the prestressing configuration during the construction of the main arch ring of the suspension arch bridge has obvious influence on the control of tensile stress. The method can also effectively improve the force uniformity of the buckle cables, reduce the variation range of cable forces during construction, and improve the safety of arch ring construction.
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Zhang, Xiaojie, Jiayu Wu, Chao Hou, and Jian-Fei Chen. "An Analytical Solution for Stress Transfer between a Broken Prestressing Wire and Mortar Coating in PCCP." Materials 15, no. 16 (2022): 5779. http://dx.doi.org/10.3390/ma15165779.
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A prestressed concrete cylinder pipe (PCCP) consists of a concrete core, a steel cylinder, prestressing wires, and a mortar coating. Most PCCP failures are related to the breakage of prestressing wires. It is thus expected that the load-bearing capacity of PCCP is significantly affected by the length of the prestress loss zone and the stress distribution in the broken wire. Based on a tri-linear bond-slip model, the length of prestress loss zone and the stress transfer mechanism between a broken wire and a mortar coating are analysed in this paper. During the breaking (unloading) process of a prestressing wire, the interfacial bondline exhibits the following three stages: elastic stage, elastic-softening stage, and elastic-softening-debonding stage. The closed-form solutions for the interfacial slip, the interfacial shear stress, and the axial stress in the broken wire are derived for each stage. The solutions are verified by the finite element predictions. A parametric study is presented to investigate the effects of the size of the prestressing wires, the prestressing level, the interfacial shear strength, and the residual interfacial shear strength on the interfacial stress transfer. For an example PCCP with an inner diameter of 4 m, the length of prestress loss zone increases from 500 mm to 3300 mm as the radius of prestressing wire increases from 1 mm to 7 mm. It increases from 2700 mm to 7700 mm when the interfacial shear strength reduces from 3.94 MPa to 0.62 MPa and reduces from 13,200 mm to 7300 mm as the residual interfacial shear stress factor increases from 0.1 to 0.9.
7
Ghallab, A., and A. W. Beeby. "Calculating stress of external prestressing tendons." Proceedings of the Institution of Civil Engineers - Structures and Buildings 157, no. 4 (2004): 263–78. http://dx.doi.org/10.1680/stbu.2004.157.4.263.
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Yu, Yi Zhong, and Xiao Yu Zhou. "Experimental Research on Stress Relaxation of Diskspring Used for Laser Optical Mounts." Advanced Materials Research 129-131 (August 2010): 531–35. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.531.
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Diskspring was used in new type of laser optical mounts for reposition. Due to stress relaxation of diskspring after long period loading, the laser optical mount’s adjusting platform would have titling drift. When a mirror mounted on the platform drifts off the collimation axial in laser resonator, it will affect the laser from normal working. Generally, a complicated laser system has many optical mounts, accumulated drift of all adjustable elements will decrease laser’s output, even lead to stop lasing. In this paper, we proposed a method that is suitable for measuring stress relaxation of precision diskspring used for laser optical mounts, comparing with normal experimental facilities for diskspring’s stress relaxation test. We use a simple optical path design, which can not only be intuition, but also measure the diskspring’s creep deformation easily with high accuracy. Comparative experimental results for the creep deformation between no prestressing, treated by 5 short terms prestressing and treated by 24 hours prestressing are given. We found that the stress relaxation amount with prestressing is 1/12 of those without prestressing, and they change directly into the stable creep deformation stage, and can be used safely. This paper also gave a instruction to optical mount manufacturer that after the optical mount are assembled, tightening adjusting screw and keeping all the disksprings in a compacted state for 24 hours, then releasing before ex-factory, this is the best way to reduce stress relaxation in diskspring and will achieve higher stability of laser.
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Maes, M. A., X. Wei, and W. H. Dilger. "Fatigue reliability of deteriorating prestressed concrete bridges due to stress corrosion cracking." Canadian Journal of Civil Engineering 28, no. 4 (2001): 673–83. http://dx.doi.org/10.1139/l01-031.
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In this paper, an analysis framework is presented to develop a relationship between fatigue reliability in a prestressed concrete bridge and the progress of stress corrosion cracking (SCC) in prestressing steel. The fatigue limit state uses a cumulative damage model for prestressing steel wires, which is a function of both stress range and minimum stress. The SCC model takes into account varying degrees of material susceptibility, stress regimes, and environmental conditions and is structured around three stages: initiation of micro-cracking, propagation, and macro-crack instability using linear elastic fracture mechanics. The framework is an overall time-dependent analysis of the safety against fatigue of a prestressed concrete bridge. It involves a stochastic analysis of the evolution of prestressing wire corrosion as a function of time and a time-dependent probabilistic analysis of the fatigue reliability of the prestressed concrete bridge suffering a certain degree of deterioration. The uncertainties involved in the fatigue model, the SCC model, and traffic actions are considered. The updating of uncertainties is simplified by considering a limited number of classes representative of the severity of SCC exposure. The framework is applied to three deteriorating highway bridges.Key words: fatigue analysis, prestressing strands, stress corrosion cracking, reliability assessment, prestressed concrete bridges, deterioration.
10
Fan, Yun Lei. "Collapse Behavior of RC Column-Beam Sub-Structure with External Prestressing Tendons." Applied Mechanics and Materials 847 (July 2016): 325–30. http://dx.doi.org/10.4028/www.scientific.net/amm.847.325.
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Previous studies indicated that the external prestressing tendons can effectively improve the deformability and bearing capacity of RC frames. However, how to utilize the external prestressing tendons to prevent the increase of deformation of the structure with catenary action in the process of collapse needs further study. Using an analytical method for the stress variations of external prestressing tendons based on structural deformation, the deflection and stress of beam-column sub-structureunder the failure of RC column during elastic and plastic stages are studied, the calculation of ultimate bearing capacity considering catenary action are also presented which provide a basis for collapse-resistant design of beam-column sub-structures.
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Svoboda, A., L. Klusáček, R. Nečas, J. Koláček, J. Strnad, and M. Olšák. "Anchorage length of patented wire cables in prestressed bridge girders." Koroze a ochrana materialu 65, no. 3 (2021): 92–96. http://dx.doi.org/10.2478/kom-2021-0012.
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Abstract This paper briefly describes the methodology, performance and the obtained results of unique experiments performed on original I-73 precast bridge girders. The main objective of the experiments was to determine the actual anchorage length of corroded-through fully grouted prestressing reinforcement (prestressing wires), which is important for determination of the residual load-bearing capacity of prestressed structures. Observation probes leading all the way to the prestressing wires were drilled on selected sections of the girders along the length of the prestressing reinforcement. Optical image acquisition devices were then installed at these probes. Subsequently, controlled breakage of the patented wires (corrosion failure simulation) and observation of the changes that occurred in the prestressing wires after relief of stress were carried out. Evaluation of the experiments was then performed by analyzing the images obtained before and after the prestressing reinforcement failure.
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Park, Sang-Yeol. "Ultimate Stress of Prestressing Steel in Prestressed Concrete Beams Strengthened by External Prestressing." Journal of the Korea Concrete Institute 16, no. 5 (2004): 677–86. http://dx.doi.org/10.4334/jkci.2004.16.5.677.
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Toribio, Jesús, Miguel Lorenzo, and Diego Vergara. "Influence of Drawing Straining Path on Hydrogen Damage of Prestressing Steel Wires." Key Engineering Materials 488-489 (September 2011): 775–78. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.775.
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Residual stress and strain states, produced during cold drawing, play a key role in hydrogen embrittlement (HE) of prestressing steel wires, because of hydrogen accumulation in certain places of the material is affected by stress and strains fields. Taking into account that thedrawingstraining path directly affectsbothresidual stress and plastic strain distribution, the aim of the present paper is to clarify the influence of drawing straining path in the residual state and, consequently, its influence on the HE process of prestressing steel wires.
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Fracture, &. Structural Integrity Research Group. "Residual stress redistribution induced by fatigue in cold-drawn prestressing steel wires." Construction and Building Materials 114 (June 7, 2016): 317–22. https://doi.org/10.1016/J.CONBUILDMAT.2016.03.037.
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In this paper the evolution of diverse residual stress states (similar to the ones produced after a cold drawing process) during several fatigue loading schemes is analysed. Thus, numerical simulations by finite element method were carried out applying diverse fatigue loading schemes to several cold drawn wires with a residual stress state associated. Numerical results reveal the key role of plastic strains produced by fatigue loading causing a redistribution of the residual stress when tensile stresses are placed at the wire surface. However, a negligible effect is obtained for wires with a compressive residual stress associated.
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Lee, Bang-Yeon, K. T. Koh, M. A. Ismail, H. S. Ryu, and S. J. Kwon. "Corrosion and Strength Behaviors in Prestressed Tendon under Various Tensile Stress and Impressed Current Conditions." Advances in Materials Science and Engineering 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/8575816.
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Corrosion occurs more rapidly under high tensile stress and this leads to several problems like degradation of serviceability and structural performance in PSC (prestressed concrete) structures. In this paper, impressed current method, so-called ICM, was applied to tendons under tensile loadings of 0.0, 20.0, 40.0, and 60.0% of ultimate load. With induction of 20 volts for 24 hours to tendon under tensile stress, loading was induced to failure and the ultimate load was evaluated with varying corrosion behaviors. The changing mechanical behaviors in the same corrosive conditions were evaluated under different initial prestressing levels. With increasing initial prestressing load, corrosion occurred more rapidly and corrosion amount also increased linearly. The ultimate load accordingly decreased with increasing initial prestressing and corrosion amount. The relationships between prestressing levels and corrosion behaviors were quantitatively obtained through regression analysis. The measured current during applied voltage and the related corrosion amounts were also dealt with in this work.
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Yao, Rong, Heng Hong Liang, and Ping Hua Zhu. "Mechanical Behavior of the Slab on Prestressing Tendons Concentrated Arranged along the Columns." Advanced Materials Research 163-167 (December 2010): 1343–48. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1343.
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The internal-force distributing of the slab computed according to the existing design methods is different from that of the bidirectional slab supported on beam. The mechanical characteristic of the slab on unbonded prestressing tendons concentrated arranged along the columns is analyzed. The results show that the hidden beams of prestressing tendons couldn’t replace the role of the actual beam. Therefore, the prestressing tendons layout in the beam-less slab should not be disposed according to the internal stress distribution of the two-way slab supported on actual beams. Based on the FEM, a accurate method for calculating the amount of two-way prestressing tendons is put forward according to the bearing counterforce that existe in beam-supported two-way slab. The linear of the prestressing tendons is deduced and reasonable value of the equivalent load of prestressed tendons is suggested.
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Bahleda, František, Ivan Drevený, Martin Pitoňák, Miroslav Neslušan, and Peter Koteš. "Employment of Barkhausen Noise Technique for Assessment of Prestressing Bars Damage with Respect of Their Over-Stressing." Metals 11, no. 5 (2021): 770. http://dx.doi.org/10.3390/met11050770.
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This paper investigates the potential of a non-destructive magnetic technique based on Barkhausen noise emission for the monitoring of prestressing bars with respect to their undesired over-stressing. Barkhausen noise signals are correlated with tensile stress, residual stresses, and microhardness measurements. It was found that prestressing bars exhibit strong magnetic anisotropy which becomes more pronounced along with the increasing degree of the bar’s over-stressing. Barkhausen noise emission becomes strongly attenuated in the direction of the tensile stress at the expense of the perpendicular direction. However, the Barkhausen noise emission in the direction of the tensile stress exhibits a continuous and remarkable decrease, whereas the Barkhausen noise steep increase for lower degrees of over-stressing is followed by early saturation for higher over-stressing. This study demonstrates that the Barkhausen noise technique is capable of distinguishing between the prestressing bars loaded below yielding, and those which are over-stressed.
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Huang, Min Yuan, and Zong Ren Zou. "Research and Application of External Prestressing Curved Beam’s Tendons." Advanced Materials Research 639-640 (January 2013): 1245–48. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.1245.
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With continuous development of the structural engineering, a perfect theoretical foundation and construction means is the key to its development. Combined with characteristics of the curved beam, it will be closely integrated together with external prestressing technology. The associated design and construction research can be carried out, in order to fully meet the need of the prestressing development. In this paper, the advantages of external prestressing curved beam was studied, and relevant contents are as follows: reasonable adjustment of external prestressing tendon’s diameter makes the structural force to become more uniform and prevents inappropriate use to tendon; reasonable external prestressing tendon and anchorage is the premise of good structure connection. The crucial problems should to be solved are the lower anchor position and stress concentration treatment. Considering the security need of prestressing curved beam’s tendon connection, attention should be paid not only to its materials and mechanical properties, but also to the convenience of construction. The external reinforcement work of prestressing curved beam is to ensure reasonable control parameters, as well as to ensure the optimal design of reinforced construction. As for the technical grasp on the theory and construction of external prestressing curved beam structure, it will make them have broader development space.
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Huang, Min Yuan, and Zong Ren Zou. "Engineering Application of External Prestressing Curved Beam." Advanced Materials Research 639-640 (January 2013): 1249–52. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.1249.
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Using the finite element software ANSYS to analyze dynamic characteristics of external prestressing structure, reasonable control parameter, as well as external prestressing reinforcement joints of security, the main research contents and results are as follows: Dynamic performance analysis is about variation law and internal feature. With the increase of external prestressing, on the contrary, the natural vibration frequency will reduce. However, external prestressing effects on the structural dynamic performance improvement that is not obvious in general. Based on sensitivity analysis, control parameter of external prestressing reinforcement curved beam must be analyzed and the reasonable value range of sensitive control parameter can be found. For the control parameter of external prestressing process, its reasonable control parameter’s range should be about 6% in the theoretical calculation. While simulating of anchoring system, local force on anchoring system must be analyzed finely and accurately. A comprehensive understanding should be mastered on variation law, which is about the internal forcing and stress response of special area. The setting of anchoring device shall be arranged at 1/3 place of original prestressing position. To ensure the safety, it should guarantee the mechanical continuity of anchor joints.
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Jia, Li, Zhi Fang, Zhengmeng Huang, Kypros Pilakoutas, Qiwu Wang, and Xingyu Tan. "Flexural Behavior of UHPC Beams Prestressed with External CFRP Tendons." Applied Sciences 11, no. 19 (2021): 9189. http://dx.doi.org/10.3390/app11199189.
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This paper presents an experimental investigation on the flexural behavior of ultra-high-performance concrete (UHPC) beams prestressed with external carbon fiber-reinforced polymer (CFRP) tendons. A total of eight T-shaped beam specimens were fabricated and tested, and the effects of the effective prestressing stress, partial prestressing ratio, deviated angle, and loading condition on the flexural behavior were analyzed. The experimental results indicate that the fully prestressed beams experienced a brittle failure, and the shear capacity of these beams was mainly controlled by the effective prestressing stress in CFRP tendons and the ultimate tensile strength of UHPC, whereas the partially prestressed beams failed in a ductile manner. The presence of internal steel reinforcement could significantly improve the flexural capacity and deformation ability. Thus, internal reinforcements should not be omitted from UHPC beams with CFRP tendons. A higher effective prestressing stress resulted in enhanced cracking load and flexural capacity. The deviated angle enhanced the utilization efficiency of high strength CFRP tendons. The loading condition exerted a slight influence on the flexural behavior of the specimens. Moreover, a method considering the effect of steel fibers was proposed and verified to predict the flexural capacity of UHPC beams prestressed with external CFRP tendons.
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Oukaili, Nazar K. Ali, and Iqbal Fadhil Peera Al-Hawwassi. "SHORT TERM DEFLECTION OF ORDINARY, PARTIALLY PRESTRESSED AND GFRP BARS REINFORCED CONCRETE BEAMS." Journal of Engineering 16, no. 01 (2010): 4631–52. http://dx.doi.org/10.31026/j.eng.2010.01.19.
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The behavior of structural concrete beams is studied under short-term loading. A computer program developed originally by Oukaili to evaluate curvature is modified to evaluate the deflection for flexural structural concrete members. The program deals with actual stress-strain relationships of concrete and steel. The analysis is based on requirements of equilibrium and compatibility of strain in concrete and reinforcement. The proposed model is used in conjunction with the step by step analysis for small loading increments that allows the determination of the history of strain and stress in concrete with prestressing steel or non-prestressing reinforcement only or prestressing and non-prestressing reinforcement together. The evaluation of curvatures for the structural member involves iterations for computing the strains vectors at each analysis step. Newmark's numerical integration is used to evaluate the deflection of the member depending on the curvature values. The stress-strain model that was proposed by (Korpenko et al. 1986) is used and compared with experimental data and other analytical models for each of concrete and steel. The comparison showed good agreement between the model used and the experimental data. This relationship is used in SECTION program and presented in this study. The analytical results for load-deflection diagram are compared with available experimental data. The comparison has shown good agreement.
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Lu, Si Ping, and Ming Jian Zhao. "Experimental Research on the Permanent Prestress of Transverse Prestressing Bundle for the Xiangjiang Yinpenling Bridge." Applied Mechanics and Materials 90-93 (September 2011): 1054–60. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.1054.
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In order to assess the service states of the permanent prestress of transverse prestressing bundle for the Xiangjiang Yinpenling Bridge (XYB), the permanent prestress values are measured. Appearance census of the diseases of transverse prestressing bundles for the cable-stayed part, the east and west incremental launching girder parts of the XYB are carried out. Three transverse prestressing bundles of the most serious corrosion are investigated by windowing damage inspection. The measured results and the analysis of the permanent prestress for the XYB show that the average permanent prestress of the three transverse prestressing bundles is about 300MPa to 550MPa, which do not meet the requirements of the design tension stress. It suggests that the appropriate treatment measures should be taken.
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Mohamed, Mahmoud, Siddhartha Brahma, Haibin Ning, and Selvum Pillay. "Development of beneficial residual stresses in glass fiber epoxy composites through fiber prestressing." Journal of Reinforced Plastics and Composites 39, no. 13-14 (2020): 487–98. http://dx.doi.org/10.1177/0731684420916534.
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The undesired residual stresses in fiber reinforced polymer composites are developed during their manufacturing processes due to the thermal and chemical shrinkage of the polymer matrix, which negatively affect the performance of the composites. Applying tensile stress to the reinforcement fibers during the curing of the matrix can reduce or eliminate the undesired residual stresses. Furthermore, the undesired tensile residual stress within the matrix can be replaced with beneficial compressive residual stress which can improve the mechanical properties of the composites. In this study, theoretical stress analysis was performed in order to determine the value of the optimum compressive residual stress that is associated with the highest tensile strength. This value was determined based on the tensile testing result of prestressed composites with a 40% fiber volume fraction. For the composites with different fiber volume fractions, a new approach was introduced to estimate the optimum fiber prestressing level which generates the optimum compressive residual stress within the matrix and consequently, the highest tensile strength can be achieved. In order to validate this approach experimentally, prestressed composites with 25 and 30% fiber volume fraction were prepared by applying the estimated optimum fiber prestressing levels during curing of matrix and tensile testing was performed. The result of the stress analysis showed that the value of the optimum compressive residual stress corresponding to the highest tensile strength is 2.5 MPa approximately. The tensile testing results confirmed the validity of the new approach in estimating the optimum fiber prestressing level for the composites with different fiber volume fractions. For both prestressed composites with 25 and 30% fiber volume fraction, the highest tensile strength was achieved when the theoretically estimated optimum fiber prestressing level was applied to the fibers during the curing of the matrix.
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Zhao, Bao Jun, Guo Rui Zhu, and Liang Yin. "Analysis on Stress State of Box-Girder Web under Prestressing." Applied Mechanics and Materials 602-605 (August 2014): 33–36. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.33.
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In order to study the stress of box-girder web under prestressing, and confirming the internal stress distribution of the web, analyzing of vertical prestressed box girder, curved beam prestressed sensitivity under the webs. Establishing finite element model of the box-girder webs vertical prestressing effect is analyzed, results show that the principal tensile stress of the web is sensitive to the vertical prestress, applying the vertical prestress can effectively reduce the principal tensile stress of the web; with the decrease of the effective vertical prestress, the neutral axis above the principal compressive stress decreases rapidly, while below the neutral axis decreases relatively slow; Under the same vertical preloading stress level, the roots of cross section of the compressive stress of web reserves than L/4 section of the web.
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Zhao, Yong Ming, Hong Xue Li, and Xue Wei Wang. "Estimation Method for Prestress Loss of Externally Prestressed Composite Girder Bridges." Advanced Materials Research 919-921 (April 2014): 547–50. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.547.
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To accurately calculate the prestress of externally prestressed composite girder bridges, the six critical factors (the prestressing tendon withdrawal and anchor deformation, friction between prestressing tendon and deviator, prestressing tendon relaxation, concrete creep, concrete shrinkage and temperature changes) that cause the prestress loss of such type of the bridges are summarized and the corresponding simplified calculation methods are respectively derived on the basis of the existing researches. The prestressing tendons ability has an important influence on the mechanical behavior of prestressed composite girder bridges, which is the key design parameters. Prestress loss will occur in the process of long-term use, so that the whole beam stress redistribution occurs. How to accurately calculate the value of the prestressing loss is an issue of great concern to engineers. And at present there is few research for prestressed composite girder bridges. On the basis of existing research, this paper summarizes the key factors that lead to loss of prestress and derives the corresponding simplified calculation method for design reference.
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Mohammed M. Rasheed, Dr, Mr Ali F. Atshan, and Mr Kamal Sh. Mahmoud. "Flexural Behavior of Steel Beam Strengthening by Prestressing Strands." International Journal of Engineering & Technology 7, no. 4.20 (2018): 572. http://dx.doi.org/10.14419/ijet.v7i4.20.26421.
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Seven simply supported steel beams were tested to explain the effect of strengthening by external prestressing strands. All of the beams have the same steel section, clear span length and the strengthening samples which implemented by two external prestressing strands. The tested beams are divided into two categories according to existing of external prestressing strands, the first category consists of one steel beam as a reference, while, the second group deals with steel beams strengthening by external prestressing strands and consists of six steel beams divided according to the eccentricity location of prestressing strand with jacking stress (815 MPa). From experimental results, it was found that the moment curvature curves behavior for the tested beams are stiffer and with less ductility than the reference beams and the ultimate moment capacity is increased with increasing the eccentricity location. While, the maximum radius of curvature at bottom flange decreases with increasing the eccentricity location as compare with the reference beam.
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Lee, Seon Yeol, Huy Viet Le, Min Kyoung Kim, Dong Joo Kim, and Jongwoong Park. "An Innovative Smart Concrete Anchorage with Self-Stress Sensing Capacity of Prestressing Stress of PS Tendon." Sensors 21, no. 15 (2021): 5251. http://dx.doi.org/10.3390/s21155251.
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An innovative smart concrete anchorage (SCA) has been developed for monitoring the stress of prestressing (PS) tendons by utilizing smart ultra-high-performance concrete (UHPC). The smart UHPC contained 2 vol% steel fibers and fine steel slag aggregates instead of silica sands. The effects of different electrode materials, arrangements, and connectors on the self-stress sensing capacity of the SCA are discussed. A prototype SCA demonstrated its feasibility and sufficient self-stress sensing capacity to be used in monitoring the prestressing loss of the PS tendon. As the tensile stress of the PS tendon increased from 0 to 1488 MPa, the fractional change in resistivity (FCR) of the prototype SCA, with horizontally paired copper wire electrodes and a plug-in type connector, decreased linearly from 0% to −1.53%, whereas the FCR increased linearly from −1.53% to −0.04% as the tensile stress of the PS tendon decreased from 1488 to 331 MPa.
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Mostafa, Nawras H., ZN Ismarrubie, SM Sapuan, and MTH Sultan. "Fibre prestressed polymer-matrix composites: a review." Journal of Composite Materials 51, no. 1 (2016): 39–66. http://dx.doi.org/10.1177/0021998316637906.
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This article reviews the literature studies based on improving the mechanical properties of fibre-reinforced composites using fibre-prestressing method. The idea is characterized by pretensioning the fibres either elastically or viscoelastically prior matrix curing. The beginnings of the studies in this field were focused on reducing fibre waviness and breaking the weaker fibres by pretensioning the fibres to a relatively high stress level prior moulding process. In the last three decades, the concept of fibre prestressing had been developed to include its ability to reduce the effect of undesired residual stresses existence accompanying manufacturing process of fibre-reinforced composites. The main advantage of fibre prestressing method is to generate a desired and controlled residual stress state within the matrix in order to obstruct the initiation and propagation of cracks. Various techniques of fibre prestressing have been reviewed to show their scope of applications, developments and limitations. Therefore, the findings drawn from this review can be used for further studies in the field of fibre prestressed composites in order to select the most suitable methodology and develop it to fit the manufacturing process requirements towards a production of high-performance composites without a considerable additional cost.
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Sari, Nur Purnama, Irwan Irwan, and Hermansyah Hermansyah. "Analisis Kehilangan Gaya Prategang Girder Pada Jembatan Proyek Pembangunan Jalan Tol Tebing Tinggi – Inderapura." Jurnal Ilmiah Teknik Sipil dan Arsitektur (JITAS) 1, no. 2 (2022): 112–17. http://dx.doi.org/10.31289/jitas.v1i2.1456.
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Currently, the construction of toll roads in several regions of Indonesia is being carried out. One of them is the construction of the Tebing Tinggi-Inderapura Toll Road. In this project there are several bridge constructions as a link between roads or as a pedestrian bridge. This bridge uses prestressed beams in which there are steel wires. The steel wire is tensioned by pulling it using a hydraulic jack. When stress is applied, the beam loses its prestressing force. The purpose of this study was to determine the percentage loss of prestressing forces that occurred in the bridge beam. Loss of prestressing force must not exceed the maximum that has been determined. There is some loss of prestressing force which is taken into account. Short-term prestress losses include elastic shortening of the concrete, friction along the tendons and anchor slippage. Furthermore, the loss of long-term prestressing forces is creep in steel, shrinkage in concrete and relaxation of steel. After all the loss of prestressing force is calculated, the total loss of prestressing force is 21.62%. To find out the maximum percentage of loss of prestressing force using calculations from the book Design of Prestressed Concrete Structures by T. Y. Lin H. Burns with the formula Pe/Ac and the value is 8.98 MPa. Where 8.98 MPa is 25%, so 21.62% is smaller than 25%, so it is still safe. In addition, an implementation method for installing girders on bridges is introduced..
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Yin, Haijun, Ziqing Li, Xianwu Hao, and Baojun Zhao. "Analysis on stress state of box-girder web under prestressing effect." ITM Web of Conferences 17 (2018): 03007. http://dx.doi.org/10.1051/itmconf/20181703007.
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In order to study the effect of prestressed box girder webs stresss state, determining the stress distribution within a web, research and analysis of vertical prestressed box girder, curved beam prestressed sensitivity under the web. Establishing the finite element model of the box girder web vertical prestressing effect is analyzed, results show that the principal tensile stress of the web is sensitive to the vertical prestress, applying the vertical prestress can effectively reduce the principal tensile stress of the web; with the decrease of the effective vertical prestress, the neutral axis above the principal compressive stress decreases rapidly, while below the neutral axis decreases relatively slow; Under the same vertical preloading stress level, the roots of cross section of the compressive stress of web reserves than L / 4 section of the web. Calculation and analysis of curved beam under bending point, different bending angles and bending radius of principal stress effect on the web, Results show that the set of curved beam web when the curved beam bending stress concentration easily, appear the main tensile stress; Increase the bending radius can effectively reduce beam cross-section of web principal tensile stress, along with the rising of the next corner, principal tensile stress peak value increases gradually, thus setting bending beam, should try to reduce the bending angle.
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König, G., R. Krumbach, and A. Heyn. "Spannungsrißkorrosion von Spannstahl - Vorstellung einer neuen Untersuchungsmethode / Stress corrosion of prestressing steel reinforcement - Presentation of a new test method." Restoration of Buildings and Monuments 6, no. 1 (2000): 73–86. http://dx.doi.org/10.1515/rbm-2000-5448.
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Abstract The origin of the susceptiblility of prestressing steel reinforcement with respect to stress corrosion and the observed failure mechanisms can be described 'in detail. So far, however, no precise method exists to determine the sensitivity of prestressing reinforcement or to distinguish different types of steel with respect to their susceptiblility for stress corrosion. This fact leads not only to prejudices in practice but also to additional safety measures (f.e. robust reinforcement), which implies economical consequences. The aim of a cooperation project between the Institute of Concrete Structures and Building Materials Technology at Leipzig University and the Institute for Materials Technology and Testing at Otto-von-Guericke- University Magdeburrg is to develop a general acceptable test method which provides us quickly with meaningful results. It turned out that the observation of electrochemical noise is a promising method to study stress corrosion of prestressing steel reinforcement. This method can be applied both in laboratory testing and under site conditions and can therefore also serve as a basis for corrosion monitoring.
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Toribio, Jesús, and Miguel Lorenzo. "Influence of the Straining Path during Cold Drawing on the Hydrogen Embrittlement of Prestressing Steel Wires." Metals 13, no. 7 (2023): 1321. http://dx.doi.org/10.3390/met13071321.
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Cold drawing is a commonly used technique for manufacturing the prestressing steel wires used as structural elements in prestressed concrete structures. As a result of this manufacturing process, a non-uniform plastic strain and residual stress states are generated in the wire. These stress and strain fields play a relevant role as the main cause of the in-service failure of prestressing steel wires in the presence of an aggressive environment, hydrogen embrittlement (HE). In this paper, hydrogen susceptibility to HE is compared in two different commercial cold-drawn wires with the same dimensions at the beginning and at the end of manufacturing that follow different straining paths. To achieve this goal, numerical simulation with the finite element (FE) method is carried out for two different industrial cold-drawing chains. Later, the HE susceptibility of both prestressing steel wires was estimated in terms of the hydrogen accumulation given by FE numerical simulations of hydrogen diffusion assisted by stress and strain states, considering the previously obtained residual stress and plastic strain fields generated after each wire-drawing process. According to the obtained results, the hardening history modifies the residual stress and strain states in the wires, affecting their behavior in hydrogen environments.
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Ding, Yuqing, and Shahzma Jaffer. "THE IMPACT OF CONCRETE AND POST-TENSIONING CABLE DEGRADATION ON STRAIN MEASUREMENTS OF CONCRETE CONTAINMENT BUILDINGS." CNL Nuclear Review 8, no. 1 (2019): 17–33. http://dx.doi.org/10.12943/cnr.2017.00012.
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Concrete containment buildings (CCBs) are important safety structures in nuclear power plants; however, degradation may occur in CCBs as they age. For post-tensioned CCBs, prestressing losses could occur and may affect the CCBs’ performance under accident conditions. CANDU CCBs contain cement-grouted post-tensioning (P-T) cables. The grouting of P-T cables prevents direct monitoring of prestressing losses by traditional lift-off testing. Instrumented monitoring has been recommended as an indirect approach by some guidelines for integrity evaluation of CCBs with grouted prestressing systems. As part of the investigation on the relationship between instrumentation data and the integrity of CCBs, sensitivity analyses have been performed using finite element models to develop an understanding of the sensitivity of strain changes to degradation factors that contribute to prestressing losses, such as creep and shrinkage of the concrete, stress relaxation, and deterioration of prestressing systems. Strain measurements from a CANDU CCB were analysed to assess the measurement noise, which was compared with the predicted strain changes due to degradation to evaluate whether the degradation of concrete and prestressing systems can be captured by strain instrumentation. The analysis reveals that the strain changes due to degradation, except the creep and shrinkage during the early years of CCBs, were comparable with the level of noise observed in the measured strain data. Degradation mechanisms related to prestressing losses have conflicting effects on strain changes and are difficult to assess individually. Therefore, it could be difficult to detect the prestressing losses and the effect of individual degradation issues using strain instrumentation.
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Toribio, J., and A. M. Lancha. "Anisotropic stress corrosion cracking behaviour of prestressing steel." Materials and Corrosion 49, no. 1 (1998): 34–38. http://dx.doi.org/10.1002/(sici)1521-4176(199801)49:1<34::aid-maco34>3.0.co;2-a.
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A.M., Elhashimy, and A.Abbas. "Behavior of Confined Concrete using Prestressing Skew Bars." International Journal of Engineering and Advanced Technology (IJEAT) 11, no. 3 (2022): 12–16. https://doi.org/10.35940/ijeat.C3354.0211322.
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This paper presents the results of an experimental study on the biaxial compression behavior of concrete prism confined using pre-stressed bars. The pre-stressed bars could provide passive confinement stress, that preventing the lateral strain of the prism from increasing leading to an increase in both the initial modulus of elasticity and prism compressive strength. The confined concrete had a higher compressive strength that was directly proportional to the confinement bar pressing force and lower ductility than the plain prisms. The concrete initial modulus of elasticity is directly proportioned to the confinement lateral pressure of the prestressing bar and inversely proportion with the spacing between prestressing bars. It was simple to find out that the best pre-stressing stress was 10 N/mm2, also the compressive strength of the confined concrete with pre-stressed skew bars was greater than the compressive strength of the unconfined concrete by more 3.3 times.
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Guo, Nan, Yunan Zhang, Lidan Mei, and Yan Zhao. "Experimental Study on Flexural Performance of the Prestressed Glulam Continuous Beam after Long-Term Loading." Buildings 12, no. 7 (2022): 895. http://dx.doi.org/10.3390/buildings12070895.
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The study of the long-term behavior of the prestressed continuous beam is vital for the design and the appliance of wood structures in engineering. In this study, long-term experiments were first conducted to determine the long-term creep behavior. Afterward, the prestress of the long-term beam was regulated to the initial state, and we carried out short-term flexural experiments to explore the effect of prestressing regulation. The influences of prestressed value and the number of prestressed steel wires on the mechanical properties of the continuous beam were investigated and discussed. The experimental results demonstrate that the creep reduced the stress in the steel wires, weakened the effect of prestressing, and increased the tensile stress at the bottom of the beam, which led to a reduction in the bearing capacity of the beam. The prestressing regulation could increase the moment arm, so the bearing capacity of the beam was improved.
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Tanjung, Darlina. "The Main Structure of the Prestress Bridge: Ultimate Calculation Analysis Using Bridge Management System (BMS 1992) Planning Method." International Journal of Research and Review 9, no. 3 (2022): 127–37. http://dx.doi.org/10.52403/ijrr.20220317.
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One of the functions of the bridge is as a medium between two parts of the road that are cut off, the existence of a bridge construction facility is very beneficial for the local community from an economic and social perspective. This analysis aims to determine the dimensions of the structure that will be used in determining the forces acting on the main structure of the bridge, especially the ultimate force in controlling the beams in the main structure. The main beam uses AASHTO standard prestressed beam type V, with a beam height of 1600 mm, with an initial prestressing force of F = 691943,478 Kg and after calculating the initial prestressing loss of 20%. By controlling the stress that occurs at the time of transfer (jacking) on the top fiber of 24,457 Mpa and on the bottom fiber of -130.618, the stress when the load is off when the top fiber is -13,033 Mpa and at the bottom fiber is -7,653 Mpa, the stress when the load is on at the top fiber of -13.033 Mpa and at the bottom fiber of -7.653 Mpa. Keywords: Beam dimensions, prestressing force, ultimate load.
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Liu, Qi Wei, Shu Wen Huang, Yong Hong, and Wen Lin Luo. "Research of Loop Pre-Stress Tension Test for Cable-Stayed Bridge Pylon Based on Full-Scale Sectional Model." Applied Mechanics and Materials 275-277 (January 2013): 1141–46. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.1141.
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Based on full-scale sectional model experiment for cable pylon anchorage zone of cable-stayed bridge, this research tested the friction factor and deviation factor of the duct. The reason that tension elongation of loop prestressing tendon exceeded the provision of ±6% in specification was analyzed systematically. A correctional calculation formula was proposed, with quantitative analysis for influencing factors of tension elongation. The formula shows good applicability in practical engineering and has reference value for similar loop prestressing tendon.
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Masėnas, Vilius, Adas Meškėnas, and Juozas Valivonis. "Analysis of the Bearing Capacity of Reinforced Concrete Dapped-End Beams." Applied Sciences 13, no. 9 (2023): 5228. http://dx.doi.org/10.3390/app13095228.
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The dapped-end beam is a widely utilized structural component that offers many benefits in real-world applications. However, abrupt changes in the geometry result in complex stress flows, rendering conventional calculation methods unreliable. The estimation of the bearing capacity becomes particularly challenging when such elements are designed with prestressed reinforcement. Previous studies have identified that prestressing can have a negative impact on the behavior of dapped-end beams in specific configurations; however, this effect remains inadequately studied. This study employed both analytical and numerical parametric analyses to compare the behavior of prestressed and non-prestressed dapped-end beams. The results show that prestressing has a significant impact on the crack formation and bearing capacity of dapped-end beams. The intensity of this effect is dependent on various parameters, including shear reinforcement, concrete strength, height of the dap, and the distance between the support and the re-entrant corner. A reduction of approximately 50% in the cracking load was observed when the compressive stress ratio fell within the 0.20–0.25 range. At elevated prestressing levels, cracks emerged in the re-entrant corner prior to the beam being subjected to an external load. The analysis conducted revealed a decline of up to 8.81% in load-bearing capacity attributable to prestressing. The study highlights the importance of assessing reductions in bearing capacity and proposes an analytical calculation model for evaluating such reductions.
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Liao, Aihua, Xiaodong Chai, and Jian Yang. "A Numerical Simulation of Elastoplastic Contact Analysis of Compressor by Overspeeding." Advances in Mechanical Engineering 6 (January 1, 2014): 176897. http://dx.doi.org/10.1155/2014/176897.
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This study analyzes the stress distribution of 3D elastoplastic contact problems by using the FE parametric quadratic programming (PQP) method derived from a 3D FE model based on parametric variational principle (PVP). We numerically analyze a 24-blade compressor by combining centrifugal loading with interference-fit one. To accelerate computation, calculation is simplified by structural modeling via multisubstructuring, aiming to deal with FE-simulated computer aided design (CAD) conveniently. We then analyze the relationships between the maximum residual stresses of the compressor posterior to prestressing and overspeed rpms, and we also study the distribution and magnitude of the contact stresses of the compressor in working conditions after overspeed prestressing. Moreover, we thoroughly discuss the distribution and magnitude of the contact stresses of shaft-shaft sleeve-impeller in working conditions. Relative displacement can be prevented and contact stress can be kept uniform due to the nonuniform initial amount of interference in overspeed prestressing. This paper summarizes the FEM simulation results and provides reference data for improving the design and processing of compressor impellers, indicating that overspeed is indispensable in manufacture.
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Asadolahi, Seyyed Morteza, and Nader Fanaie. "Performance of self-centering steel moment frame considering stress relaxation in prestressed cables." Advances in Structural Engineering 23, no. 9 (2020): 1813–22. http://dx.doi.org/10.1177/1369433219900940.
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Buildings can be designed to limit the earthquake-induced damage to members that can easily be repaired. Self-centering moment-resisting frames can be used as effective structural systems for this purpose. Self-centering moment-resisting frames with prestressed cables are able to return the structure to its original position after the earthquake. The internal forces in self-centering moment-resisting frames are transferred between the beam and the column by post-tensioned cables. As a main member of self-centering connections, prestressed cables play a significant role in such systems. Cable tension decreases over time due to the effect of stress relaxation on the performance of the system. Stress relaxation is a time-dependent phenomenon causing stress reduction over time in the members prestressed at a constant strain. Therefore, the effect of stress relaxation on the performance of self-centering moment-resisting frames can be significant. In this article, after simulating and validating a moment-resisting frame with self-centering connections, stiffness and moment–rotation hysteresis diagrams were analyzed after 0, 1, 5, 10, and 20 years of cable prestressing. According to the results, two equations were presented to estimate the reduction in the connection stiffness and dissipated energy by the system based on prestressing level and the time after prestressing. The proposed equations could be used to model semi-rigid connections.
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Shiranov, A. M., and A. L. Nevzorov. "INCREASING THE STABILITY OF THE SAND CUSHION BY PRESTRESSING THE REINFORCING LAYERS OF GEOSYNTHETICS." Construction and Geotechnics 11, no. 1 (2020): 30–40. http://dx.doi.org/10.15593/2224-9826/2020.1.03.
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The use of prestressing of geosynthetics allows accelerate their inclusion in work, reduce deformations and gaining bearing capacity of artificial foundation. The article presents results of research of two methods of construction reinforced sand cushions. In the first case, the effect of prestressing is achieved due to a certain order of layer-by-layer soil compaction of the cushion, in the second - by laying of the swellable material between the contours of the foundations. The experiments were carried out in a laboratory tank with a pneumatic loading device. There are three stamps united by a common frame on the surface of the cushion. To assess the stress-strain state of the soil foundation, the non-contact digital tracer imaging method was used. The experimental results are presented in the graphs form of the dependence of the stamp settlement on pressure and vector fields of particle movements. Modeling has confirmed the high efficiency of prestressing. The ultimate pressure on the soil foundation with two-layer horizontal reinforcement and prestressing of the reinforcing layers in the first method was 195 kPa, in the second method - 165 kPa, whereas in the absence of prestressing this value was 110 kPa. Foundation deformations also decreased significantly.
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Liu, Can, Bo Wu, and Kai Yan Xu. "Finite Element Analysis of Reinforced Concrete Beams with Transversely Prestressed Bars." Advanced Materials Research 368-373 (October 2011): 108–13. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.108.
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This paper presents a method that using inner transverse prestressing bars to enhance the shear capacity of concrete beams, which can be used in new transformer beams to decrease the sectional dimensions. Four transversely prestressed concrete beams and one ordinary reinforced concrete beam were tested. The nonlinear finite element method was applied to analyze them, and the following conclusions can be drawn: (a) The transverse prestressing bars can efficiently increase the shear capacity and failure load of the reinforced concrete beam, the improvement effect is more obvious when exerting the prestressing force on them properly. (b) On the whole, the simulated load-deflection relationships and failure loads of the five specimens agree well with the corresponding tested load-deflection relationships and failure loads. It indicated that the FE models used in this paper predict the structural behavior of the transversely prestressed concrete beams satisfactorily. (c) From the contour of first principal stress, it can be seen that the transverse prestressing bars can efficiently enhance the shear crack resistance of the reinforced concrete beams, if the area of transversely prestressing bars is almost same, the transverse bars with smaller diameter and smaller spacing will be better. It agrees well with the test results.
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Rogowski, Janusz, and Renata Kotynia. "Comparison of Prestressing Methods with CFRP and SMA Materials in Flexurally Strengthened RC Members." Materials 15, no. 3 (2022): 1231. http://dx.doi.org/10.3390/ma15031231.
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Over the years, prestressing concrete has become a well-known technique to improve the ultimate and serviceability state of RC members. Besides steel reinforcement, relatively new materials such as carbon fiber reinforced polymers (CFRP) or especially shape memory alloys (SMA) can be used to active strengthening. The main scope of this paper is to compare various prestressing methods using carbon composites and memory steel alloys. A description of SMA, shape memory effect, its utilization for prestressing, and CFRP materials are presented in the paper. Moreover, current state-of-the-art developments in the field of both materials, considering prestressing systems and available anchorage, material behavior, creep and stress relaxation, durability issues, thermal compatibility with concrete, and fire behavior, are described. A general revision of previous studies based on flexural strengthening using both materials is conducted and the selected results of these studies are briefly presented. The behavior of RC beams after strengthening with mentioned techniques is compared and discussed. Selected on-site applications are described to confirm the feasibility and practicality of the strengthening systems. Finally, the main advantages and disadvantages of CFRP and SMA materials for prestressing concrete structures are summarized and further recommendations for the future research are listed.
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Zahuranec, Michal, Peter Koteš, and Jakub Kraľovanec. "The Influence of the Prestressing Level of the Fully Threaded Anchor Bar on the Corrosion Rate." Buildings 13, no. 7 (2023): 1592. http://dx.doi.org/10.3390/buildings13071592.
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The article presents experimental research on the corrosion of prestressing steel bars with denotation CKT (fully threaded anchor bars), which are composed of high-quality prestressing steel of the grade Y 1050 (1050 MPa). The experiment was performed using an electrochemical accelerated test. The aspects of the electric current value influence, time dependence on the degree of corrosion, and especially the influence of the prestressing level in the prestressing steel bars on the degree of corrosion were observed and examined. The results of the experiment showed that if the sample was in a stressed state, its degree of corrosion increased. Specifically, for the maximal stress equal to 90% of the tensile strength, the corrosion degree was increased by approximately 7.3%, in comparison to the unstressed specimen. In this case, a 7.3% corrosion degree corresponds to a weight loss of 350 g. The theoretical degree of corrosion was calculated using Faraday’s Law, which allowed the prediction of a rough estimate of the corrosion degree obtained with known input data. The experimental results showed that there was no apparent difference in the corrosion morphology of the sample during the same time-dependent corrosion influence at the same prestressing level in the sample with the same electric current value.
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Gao, Jian Hua. "The Mechanic Analysis and Construction Method on Damaged Beam of External Prestressing Reinforcement." Applied Mechanics and Materials 501-504 (January 2014): 1039–42. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.1039.
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In order to investigate the feasibility of reinforcement transformation schemes for actual engineering, Combined with the characteristics of the project, the reinforcement transformation designs of the roof beams is carried out, three kinds of reinforcement transformation design schemes are put forward, they are carbon fiber reinforced polymer strengthening, internal prestressing strengthening and external prestressing strengthening. The external prestressing reinforcement scheme is selected after comparing. Numerical simulation analysis of the reinforcement system is done by ANSYS software, and nonlinear finite element model of simply supported beam with crack is built, through analysis deformation, cracks and stress distribution of reinforced beam are obtained. The results show that the using function of beam is improved obviously. The rationality and feasibility of this reinforcement scheme is validated. These can provide references for reinforcement transformation of similar existing buildings.
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Chepurnenko, Anton, Andrei Lipovich, Alexey N. Beskopylny, and Besarion Meskhi. "Reinforced Concrete Columns with Local Prestressing Rebars: A Calculation Theory and an Experimental Study." Buildings 12, no. 8 (2022): 1152. http://dx.doi.org/10.3390/buildings12081152.
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Local prestressing of reinforcement can be effective for slender reinforced concrete columns with large longitudinal force eccentricities. This article deals with columns with prestressed reinforcement on the side opposite to the eccentricity of the longitudinal force. Prestressing is created with the help of turnbuckles. The aim of the work is to develop a model for determining the stress–strain state of columns with local prestress and its experimental verification. The article presents the derivation of a resolving equation for the increment of deflection, which considers the non-linearity of the concrete and reinforcement work, the presence of creep and shrinkage of concrete. The solution of the resulting equation was performed numerically by the finite difference method in a MATLAB environment. Experimental studies were carried out according to the hinged support scheme for eight eccentrically compressed samples, four of which had been prestressed. Experiments and numerical modeling of columns with local prestressing showed a significant increase in crack resistance (by 1.3–2.5 times) and bearing capacity (by 12.5–30%) compared to similar structures without prestressing.
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Huang, Fei Xin, Hai Bo Jiang, Chun Gen Wei, Shi Wu Ouyang, and Xiang Long. "The Finite Element Analysis of the End Anchorage under Larger Prestressing Load in Rehabilitation Engineering." Advanced Materials Research 97-101 (March 2010): 4395–98. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.4395.
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Anchorages are the most important structure in the bridge’s rehabilitation engineering under external prestressing load, whose stress distribution is complex, it is necessary to carry out a detailed and careful structure analysis of anchorages. The inspection and strengthening design of an extra-large Bridge in Dongpu of Guangzhou City was taken for the background in the paper, the longitudinal stress, transverse stress and vertical stress of the end anchorage were given before and after adding concrete block, through finite element analysis of the end anchorage under larger prestressing load and the results of calculation of the anchorage were analyzed, it was showed that the strengthened effect of the end anchorage had been very obvious after concrete block was added. At the same time it was found that there were still some deficiencies on the end anchorage after concrete was added and the suggestions of the local strengthening of the end anchorage were proposed. It is helpful and referenced for the design of similar anchorage.
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Rasheed, Mohammed M., Kamal Sh Mahmoud, Saad Khalaf Mohaisen, and Mohammed Z. Yousif. "The Behavior of a Strengthened Steel Beam Section Under Eccentric Loadings." E3S Web of Conferences 318 (2021): 03007. http://dx.doi.org/10.1051/e3sconf/202131803007.
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Thirteen simply supported steel samples have been tested to explain the effects of strengthening steel beams using an external prestressing strand. The samples have the same cross-sectional dimensions and overall length. One steel beam without strengthening was taken as a reference, while the other twelve of them had been strengthening by two external strands at various eccentricity locations and jacking stresses. The strengthening by external prestressing strands is sub-divided into two series according to jacking stress. Each series consists of six steel samples divided according to the eccentricity location of prestressing strand. During tests, it was found that the Load deflection response for the strengthened samples is stiffer as compared with the reference. The increasing percentage in ultimate load capacity was increased to 0.347, 2.758, 3.921, 8.898, 9.326, and 10.256% for beams under jacking stress of 1120 MPa, while increasing percentage in ultimate load capacity were increased to 0.17, 26, 33, 48.5, 13.7, and 69.56% for beams under jacking stress of 815 MPa. On the other hand, the maximum percentages of deflection were decreased to 4.88, 2.44, 20.62, 15, and 9.7% when the jacking stress increase from 815 to 1120 MPa and the ratio of the quarter to mid-span deflection (δ quarter / δ mid) is about 0.528 and 0.497 when jacking stress is 1120 and 815 MPa respectively. So, the increase in jacking stresses from 815 to 1120 MPa will not be preferable because it has a little increasing percentage in stiffening and behaviors compared with other tested beams at the same condition.
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Liu, Qing Wen, and Fu Qiang Wu. "Finite-Element Analysis of Prestressed Concrete Frame Joints with Spread-Ended Beams." Applied Mechanics and Materials 638-640 (September 2014): 115–19. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.115.
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On the basis of the joint model experiment, the non-linear performance of joints is analysed by using finite element program. The concrete stress distribution, stirrups stress and dangerous area of joints with spread-ended beams are discussed. Finite element analysis shows that effective prestressing tendons through the joint core region play a beneficial role in concrete and can improve the compressive strengths of concrete, and help to improve the shear strength of joints. Finally, according to experiments and theoretical analysis, the beginning of the haunched region is the dangerous area of joint. In order to avoid concrete tension failure when exerting prestress, the beginning of the haunched region must have enough transverse U-shaped bars to resist the prestressing tension.