Journal articles: 'Prestressed'

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MIRMIRAN, AMIR, AMDE M. AMDE, and ZEFANG XU. "ELASTO-PLASTIC BUCKLING OF PRESTRESSED ARCHES." International Journal of Structural Stability and Dynamics 02, no. 03 (September 2002): 295–313. http://dx.doi.org/10.1142/s0219455402000580.

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Intentional buckling as a fabrication technique for arch frameworks results in prestrains at every section of the arch, which in turn affect its strength and stability. A nonlinear corotational straight beam element with elastic, linear strain hardening material has been developed to study the elasto-plastic buckling of prestressed arches. The study indicates that for prestressed arches there is an interdependence between the slenderness and steepness ratios of the arch with the ratio of prestresses to the yield strength of the material, all of which control the magnitude and shape of buckling mode. While steeper arches are generally more stable in their elastic range, the effect of steepness ratio is reduced as the prestress exceeds 55% of the yield strength. Effects of loading and support conditions have also been considered. Although fixed supports result in more stable arches, their effectiveness depends on the steepness ratio and the level of prestresses. Finally, the effect of strain hardening on the plastic buckling of the arch is more pronounced for lower values of the plastic tangent modulus.

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Peng, Rui Tao, Fang Lu, Xin Zi Tang, and Yuan Qiang Tan. "3D Finite Element Analysis of Prestressed Cutting." Advanced Materials Research 591-593 (November 2012): 766–70. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.766.

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In order to reveal the adjustment principle of prestressed cutting on the residual stress of hardened bearing steel GCr15, a three-dimensional thermal elastic-viscoplastic finite element model was developed using an Arbitrary Lagrangian Eulerian (ALE) formulation. Several key simulation techniques including the material constitutive model, constitutive damage law and contact with friction were discussed, simulation of chip formation during prestressed cutting was successfully conducted. At the prestresses of 0 MPa, 341 MPa and 568 MPa, distributions of residual stress on machined surface were simulated and experimentally verified. The results indicated that residual compressive stress on machined surface were achieved and actively adjusted by utilizing the prestressed cutting method; meanwhile, within the elastic limit of bearing steel material, the higher applied prestress leads to the more prominent compressive residual stress in the surface layer and subsequently the higher fatigue resistance of the part.

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Li, Jian, Shanxiong Chen, Fei Yu, and Lingfa Jiang. "Reinforcement Mechanism and Optimisation of Reinforcement Approach of a High and Steep Slope Using Prestressed Anchor Cables." Applied Sciences 10, no. 1 (December 30, 2019): 266. http://dx.doi.org/10.3390/app10010266.

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Using prestressed anchor cables is one of the most common approaches for reinforcing slopes. By establishing a calculation model for a high and steep slope, the changes of displacement of slope foot and increment of force on the cables under different prestresses were calculated. Furthermore, the influence of prestress on the changes of displacement of slope foot and force on the cables was analysed. By analysing the changes in force on cables in different parts of the slope, the reinforcement mechanism of a prestressed anchor cable on the slope was attained. The result showed that the reinforcement effect of prestressed anchor cable on the slope was mainly attributed to it effectively restricting the displacement of sliding mass in the slope, while the effect of cables in the lower part of the slope was more significant than that of those in the upper part of the slope. Therefore, to reduce the number of cables, decrease the construction difficulty of cables and save money, it is feasible to remove cables in the range of the upper-third of the slope. Afterwards, by improving the cable prestress in the range of the lower-third and reducing the cable prestress in the middle, the safety factor of the slope can satisfy design requirements, thus reinforcing the slope.

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Li, Feng Ge, and Rong Li. "Experiment Study on Dynamic Characteristics of Unbounded Prestressed Concrete Beams." Applied Mechanics and Materials 166-169 (May 2012): 273–76. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.273.

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An experimental investigation on the dynamic characteristics of unbounded prestressed concrete simply support beams is presented in this study. A total of 3 unbounded prestressed concrete simply support beams were constructed and tested. The main variables considered in the test study were the prestress level, the position of prestressed steel and concrete damage. The test results shows that the natural frequencies and model shape of prestressed concrete beams change with the prestress level and the position of prestressed steel, and that the existence or not of concrete crack have certain effects on the dynamic characteristics of prestressed concrete beams.

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Lv, Qingfang, Ye Liu, and Yi Ding. "Analyses on Prestress Loss and Flexural Performance of the Laminated Bamboo Beam Applied with Prestressed BFRP Sheet." Advances in Civil Engineering 2019 (April 30, 2019): 1–13. http://dx.doi.org/10.1155/2019/2319814.

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Inspired by the studies about wooden beam applied with prestressed steel plate and bamboo beam strengthened by fiber-reinforced polymer (FRP), this paper aims to explore the applicability of the prestressed basalt fiber-reinforced polymer (BFRP) sheet to the laminated bamboo beam and the variation of the flexural performance of the laminated bamboo beam applied with prestressed BFRP sheet. Two series of tests were conducted in the present study. In the first series of tests, the prestress loss of the prestressed BFRP sheet was classified and analyzed based on measured strains and deflections, which led to a derivation of the effective prestressed force considering the prestress loss. Analyses showed that the recommended value of prestress loss compared with the initial prestressed force was 22.0% based on the existing test data in the specimen preparation stage. In the second series of tests, the static loading test was performed to investigate the flexural performance of the laminated bamboo beam applied with prestressed BFRP sheet and analyze the difference between the laminated bamboo beams applied with prestressed and non-prestressed BFRP sheets. Test results showed that the no significant variation of the ultimate load and a reduction of the ultimate deformation capacity were caused by the application of the prestressed BFRP sheet.

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Batchelor, B. DeV, Jayanth Srinivasan, and Mark F. Green. "Losses in partially prestressed concrete." Canadian Journal of Civil Engineering 15, no. 5 (October 1, 1988): 890–99. http://dx.doi.org/10.1139/l88-114.

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The calculation of prestress losses by the age-adjusted effective modulus method is analyzed and compared with the Ontario highway bridge design code predictions for partially prestressed concrete. Specifically, the effect of nonprestressed reinforcement on prestress losses is studied. The age-adjusted effective modulus method for calculating prestress losses is outlined, and plots of prestress losses versus partial prestressing ratio are presented and analyzed. It is shown that prestress losses decrease with increasing amounts of nonprestressed reinforcement. Also, the Ontario highway bridge design code expressions, which are intended for use with fully prestressed sections, are not suitable for use in the design of partially prestressed concrete members. Key words: concrete (prestress), design, partial prestressing, prestress losses.

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Xue, Gang, and Chong Ge Wang. "Experimental Study on Natural Frequency Variation Regulations of Simply Supported Externally Prestressed Concrete Beams." Applied Mechanics and Materials 351-352 (August 2013): 1043–46. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1043.

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In order to study the relationship between prestress and natural frequencies and the factors of influence natural frequence change, a dynamic test on three simply supported externally prestressed concrete beams of different prestressed level was carried out. The results showed that the eccentricity and arrangement of externally prestressed tendons and the constraints have more influence on natural frequencies than prestress itself. The prestressed effect comes from combined action of the several factors, and the natural frequencies of beams were found to agree well with the prestress. It appears that higher order frequencies have greater increment usually.

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Li, Chen, Kai Yin Zhang, and Zhong Lin Fan. "Research on Prestressed Loss in Curving Hole of Prestressed Concrete Structure Caused by Frictional Resistance." Applied Mechanics and Materials 587-589 (July 2014): 1668–71. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.1668.

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Excessive prestressed loss in prestressed concrete continuous beam bridge and continuous rigid frame bridge causes structures appearing different types of diseases. By theoretical analysis on computational expression of effective prestress in curving hole, and distribution of contact stress and experiment about prestressed loss caused by frictional resistance, this paper points out the disadvantages of current effective prestress formula in curving hole. According to the research on the major influencing factors of prestressed loss in curving hole-contact status and friction coefficient μ, it plays a remarkable role on the further analysis of prestressed loss in curving hole.

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Shi, Luning, Haoxiang He, and Weiming Yan. "Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies." Mathematical Problems in Engineering 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/840937.

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A prestress force identification method for externally prestressed concrete uniform beam based on the frequency equation and the measured frequencies is developed. For the purpose of the prestress force identification accuracy, we first look for the appropriate method to solve the free vibration equation of externally prestressed concrete beam and then combine the measured frequencies with frequency equation to identify the prestress force. To obtain the exact solution of the free vibration equation of multispan externally prestressed concrete beam, an analytical model of externally prestressed concrete beam is set up based on the Bernoulli-Euler beam theory and the function relation between prestress variation and vibration displacement is built. The multispan externally prestressed concrete beam is taken as the multiple single-span beams which must meet the bending moment and rotation angle boundary conditions, the free vibration equation is solved using sublevel simultaneous method and the semi-analytical solution of the free vibration equation which considered the influence of prestress on section rigidity and beam length is obtained. Taking simply supported concrete beam and two-span concrete beam with external tendons as examples, frequency function curves are obtained with the measured frequencies into it and the prestress force can be identified using the abscissa of the crosspoint of frequency functions. Identification value of the prestress force is in good agreement with the test results. The method can accurately identify prestress force of externally prestressed concrete beam and trace the trend of effective prestress force.

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Zhang, Shan, Kai Yin Zhang, Bing Yang Xie, and Zhong Lin Fan. "Research on the Mechanism of Prestressed Loss for Curving Hole of Prestressed Concrete Structure Caused by Frictional Resistance." Applied Mechanics and Materials 351-352 (August 2013): 156–63. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.156.

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Excessive prestress loss in Prestressed Concrete (PC for short) continuous beam bridges and continuous rigid frame bridges cause structures to be different types of diseases. Based on theoretical analysis and experiment , this paper points out the imperfection of the effective prestress formula in Curving Hole at present. According to the research on the influencing factor of prestressed loss in Curving Hole of friction coefficient, it plays a remarkable role on the analysis about the prestressed loss in Curving Hole of prestressed concrete structure.

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Wei, Fang Fang, Jin Bo Wang, Ben Wei Zou, and Hao Sun. "FEM Research on Static Mechanical Performance of Twice Prestressed Composite Curved Beam." Advanced Materials Research 243-249 (May 2011): 1038–42. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1038.

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The conception of twice prestressed composite structures (TPCS) was proposed in order to solve great distortion problems in prestressed concrete structures. Through decomposition of the total prestress, we define the 1st stage as one part of the prestress acting on a prefabricated beam, and the 2nd as the other part on a post-pouring structure. This kind of structure could substantially decrease its distortion and enhance the efficiency of prestress, at the same time contributing to flexibly laying the prefabricated concrete. A continuous curved prestressed concrete box girder bridge was modeled with the FEM software ANSYS, taking into account the ordinary steel and prestressed losses. The aim is to analyze the deformation, stress performance, the impacts of the primary prestressed force value on the anti-deforming performance as well as bearing load performance of the twice prestressed composite curved beam. The conclusion could provide a basis for the application and promotion of the structure.

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12

Bai-jian, Tang, Wang Fei, and Chen Song. "Effect of Prestress Force on Natural Bending Frequency of External Prestressed Steel Beams." Open Civil Engineering Journal 12, no. 1 (April 26, 2018): 62–70. http://dx.doi.org/10.2174/1874149501812010062.

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Introduction: Natural bending frequencies of externally prestressed steel beam have certain sensitivity to prestress force, so they can be used to find the magnitude of prestress force. Methods: To answer the question if the existence of externally prestressed tendons increases or decreases the natural bending frequencies of a simply supported steel beam, the calculating formula for natural frequencies is deduced by using the energy method from the view point of prestress mechanism and further verified by the finite element method. Using this formula of universal property, the influence of prestress force, eccentricity and cross-sectional area of tendons on natural bending frequencies of prestressed steel beam is clearly revealed. Results and Conclusion: For external prestressed steel beams with straight tendons, their natural frequencies increase with the eccentricity and cross-sectional area of the prestressed tendon, and the eccentricity has a much larger effect on natural frequencies than the cross-sectional area does. The prestress force has no influence on the oven-order frequencies but decreases the odd-order frequencies. With the increasing order number, the prestress effect is much weaker than the effects caused by the eccentricity and cross-sectional area of the tendon.

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13

Liu, Han Bing, Long Lin Wang, Guo Jin Tan, and Yong Chun Cheng. "Effective Prestressing Force Testing Method of External Prestressed Bridge Based on Frequency Method." Applied Mechanics and Materials 303-306 (February 2013): 363–66. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.363.

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A practical project is taken for the example to analyze the application of frequency method in the effective prestress test of external prestressed bridge. In the process of solving the dynamic differential equation of tension cable, the effects of boundary conditions on the natural frequencies of external prestressed tendons are analyzed. The analysis results show that the fundamental frequency of the prestressed tendons under fixed boundary condition is higher than that under hinged-support support boundary condition, and the relative variance decreases with the increase of tensioning force. With the same tensioning force, the relative variance decreases with the increase of cable length. In the practical test, only the upper and lower bound limits can be obtained according to the measured prestressed tendon frequencies, while the real effective prestress values are between them. For external prestressed tendons, a kind of short tension cable, the frequency method can produce certain error in calculating the effective prestress.

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14

Wang, Bo, and Guang Xin Men. "Study of Flexural Property of Prestressed Carbonfiber-Reinforced Plastics (CFRP) Reinforced Concrete Beams." Applied Mechanics and Materials 351-352 (August 2013): 1503–8. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1503.

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To study the effect of prestress level on beam for its flexural property, through comparing of the stress property of non-reinforced beam, non-prestressed fiber beam, and prestressed fiber beam. The experimental results show that non-prestressed fiber makes little difference in improving beams flexural property, while prestressed fiber has improved beams cracking load, yield load, bending rigidity greatly.

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Guo, Nan, Mingtao Wu, Ling Li, Guodong Li, and Yan Zhao. "Bending Performance of Prestressed Continuous Glulam Beams." Advances in Civil Engineering 2021 (June 25, 2021): 1–16. http://dx.doi.org/10.1155/2021/5512350.

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The limited transferring moment capability of Glulam (glued laminated wood) joints results in insufficient joint stiffness. Therefore, most of the connections are hinged joints. Based on the previous studies, one novel end-connection device was proposed to form prestressed continuous Glulam beams. The prestressed beams were composed of prestressed low-relaxation steel bars, the deviator block, the anchorage device, and the novel end-connection apparatus. These prestressed steel bars were tensioned by the deviator block to exert prestress. Then, 18 prestressed continuous beams and two prestressed simply supported beams were subject to the bending tests to explore the impact of reinforcement ratio and prestress on the prestressed Glulam beams from aspects such as failure modes, bearing capacity, load-deflection relationship, and load-strain relationship. The results show that, given the same prestress level, compared with beams with a reinforcement ratio of 1.92%, the bearing capacity of beams with a reinforcement ratio of 3.84% and 5.76% is increased by 20.3%–29.4% and 30.51%–36.36%, respectively. Given the same reinforcement ratios, compared with beams without prestressing, the bearing capacity of beams with a prestressing force of 7 kN and 14 kN is increased by 2.39%–10.14% and 6.49%–13.26%, respectively. In addition, compared with simply supported beams, the bearing capacity of continuous beams is increased by 40%, and the deformation is reduced by 13%. Therefore, as a novel prestressed beam, the bending performance of Glulam beams can be improved effectively.

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Li, Feng Ge, and Rong Li. "Theoretical Analysis of Natural Vibration Frequency for Unbonded Prestressed Concrete Beams." Advanced Materials Research 594-597 (November 2012): 882–85. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.882.

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This papers deals with the study of the influence of prestress force on the natural frequencies for unbonded prestressed concrete beams. A total of 5 unbounded prestressed concrete simply support beams were constructed and tested. The test results show that the prestress force has little effect on the nature frequencies of unbonded prestressed concrete beams. A model of variable stiffness is proposed to calculate the natural frequencies of prestressed concrete beams with unbonded tendons, which assumed that the flexural rigidity of the beam is changing when beams vibrating. The calculate results show that the calculation results by the proposed model agree well with experimental ones.

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Wang, Yongguang. "Determination of Bridge Prestress Loss under Fatigue Load Based on PSO-BP Neural Network." Computational Intelligence and Neuroscience 2021 (July 12, 2021): 1–10. http://dx.doi.org/10.1155/2021/4520571.

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During the service period of a prestressed concrete bridge, as the number of cyclic loads increases, cumulative fatigue damage and prestress loss will occur inside the structure, which will affect the safety, durability, and service life of the structure. Based on this, this paper studies the loss of bridge prestress under fatigue load. First, the relationship between the prestress loss of the prestressed tendons and the residual deflection of the test beam is analyzed. Based on the test results and the main influencing factors of fatigue and creep, a concrete fatigue and creep calculation model is proposed; then, based on the static cracking check calculation method and POS-BP neural network algorithm, a prestressed concrete beam fatigue cracking check model under repeated loads is proposed. Finally, the mechanical performance of the prestressed concrete beam after fatigue loading is analyzed, and the influence of the fatigue load on the bearing capacity of the prestressed concrete beam is explored. The results show that the bridge prestress loss characterization model based on the POS-BP neural network algorithm has the advantages of high calculation efficiency and strong applicability.

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Vincent, Thomas. "Influence of Prestress on Axial Compressive Behavior of High-Strength Concrete-Filled FRP Tubes." Applied Mechanics and Materials 744-746 (March 2015): 173–78. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.173.

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This paper presents an experimental investigation on the influence of prestress on axial compressive behavior of concrete-filled fiber reinforced polymer (FRP) tubes (CFFTs). A total of 12 aramid FRP- (AFRP) confined high-strength concrete (HSC) specimens with circular cross-sections were tested under monotonic axial compression. All specimens were cylinders with 152 mm diameter and 305 mm height and their unconfined concrete strengths were approximately 100 to 110 MPa. The influence of FRP prestress was examined by applying 3 different levels of lateral prestress ranging from 4.29 to 7.27 MPa. In addition to the prestressed specimens, companion specimens with no applied prestress were manufactured and tested to establish reference values. Results of the experimental study indicate that the influence of prestress on compressive strength is significant, with an increase in ultimate strength observed in all prestressed specimens compared to that of non-prestressed specimens. On the other hand, the influence of prestress on axial strain was found to be minimal, with prestressed specimens displaying a slight decrease in ultimate strain, compared to their non-prestressed counterparts. The results also indicate that prestressing the AFRP shell prevents the sudden drop in strength, typically observed in FRP-confined HSC specimens, that initiates at the transition point which connects the first and second branches of the stress-strain curves.

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Zhang, Ji Mei, Jing Long Pan, and Hong Bo Dong. "Analysis of Prestressing Loss on Construction of External Prestressed Wooden Buildings." Advanced Materials Research 594-597 (November 2012): 914–20. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.914.

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Wooden buildings which has a long history, is one of the earliest forms of building structures by mankind.The structure form and construction method of are different from the common prestressed structure,therefore,the prestressing loss caused by the external prestressed structures is different from that of the common prestressed structure.It is an effective method to reduce the large deflection of large-span wooden structure by external prestress method.Through the real model test of the external prestress tension at scale of 1:2,and after long-term observing on parabolic wooden beam of external prestress with initial pretension force,we can quantitatively analyse the effections of prestressing loss of prestressed rebar due to the creep of wood.At the same time,this paper gives the deflection calculation formula during the term of test.The conclusion obtained is useful to designers.

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Du, Xian He, and Xin Pu Shen. "Three Dimensional Numerical Simulation of LNG Prestressed Tank." Advanced Materials Research 433-440 (January 2012): 1324–32. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.1324.

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The purpose of this paper is to observe the distribution of displacement and stress of LNG prestressed tank when under the normal condition and the LNG divulging. The Abaqus software has been used to analyze the three dimensional LNG prestressed tank with finite element method, a numerical simulation is carried out by modeling the prestressed rebar with three dimensional elements, meanwhile, the prestress is applied for rebar with the falling temperature method. By coupling the condition of dead load, live load, prestress, gas pressure, hydraulic pressure and the low temperature, the conclusions indicate that: 1) the valid prestress has been applied by the prestressed rebar for LNG tank model. 2) the effect of live load for the tank can be ignored but the effect of gas pressure cannot. 3) the effect of highly temperature difference between the internal and external of LNG tank is great when the template lining of LNG tank divulging. The maximum displacement of cylinders shell is 28.22mm, and the maximum stress is 13.97MPa, the safety can be enhanced by modifying the arrangement of prestressed rebar.

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Hussin, Manal, Tommy H. T. Chan, Sabrina Fawzia, and Negareh Ghasemi. "Identifying the Prestress Force in Prestressed Concrete Bridges Using Ultrasonic Technology." International Journal of Structural Stability and Dynamics 20, no. 10 (September 2020): 2042014. http://dx.doi.org/10.1142/s0219455420420146.

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In this research, ultrasonic tests were performed on a prestressed concrete box-girder model to identify the prestressed force according to the acoustoelastic theory. During the tests, the ultrasonic wave was generated using piezoelectric transducers and emitted to the prestressed concrete bridge model. The concrete bridge model was subjected to three different levels of prestress force (PF), which were limited to about 30%, 50% and 80% of the ultimate tensile strength. The experimental results showed the increase in prestress force level leads to an increase in the relative change in the wave velocity and the amplitude energy of the ultrasonic wave which proved the acoustoelastic effect theory. This study contributes to the knowledge of the acoustoelastic behavior of the prestressed concrete and presents the capability of the ultrasonic system in evaluating the stress state in the prestressed concrete bridge.

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Xie, Jun, Yi Shu Zhou, and Xiao Hua Zheng. "Influence of Prestress Degree to Long-Term Response of the Long Span Prestressed Concrete Bridges." Applied Mechanics and Materials 256-259 (December 2012): 1542–47. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.1542.

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Though the prestress degree that is selected under control of the specified stress limit is a key design parameter in design of the prestressed concrete bridges, study on long-term deformation of the long span prestressed concrete beam bridges is not popular both here and abroad. This paper reveals the time-dependent regularity of long-term stress and deformation effect to the critical sections of the long span prestressed bridges from various prestress degrees, thereby the necessity of stress and deformation control consideration during design of the long span prestressed bridge structures is verified, and the prestressing expression based on stress and deflection control for relative study and design reference is given.

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Yang, Yi, Pei Yan Huang, and Jun Deng. "Experimental Study on the Fatigue Properties of RC Beam Strengthened by Prestressed CFL." Advanced Materials Research 33-37 (March 2008): 169–73. http://dx.doi.org/10.4028/www.scientific.net/amr.33-37.169.

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Bonding prestressed CFL to strengthen reinforced RC structures can improve the bending capability of structures and the working efficient of CFL. Base on the fatigue experiments of 4 RC beams strengthened by prestressed CFL, the present paper analyzes the fatigue properties of prestressed CFL reinforced RC beams. Comparing with the experimental results of strengthened RC beams without prestress, it can be concluded that the prestressed technology can improve the reinforcing effect and fatigue lives.

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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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Song, Chaojie, Gang Zhang, Wei Hou, and Shuanhai He. "Performance of prestressed concrete box bridge girders under hydrocarbon fire exposure." Advances in Structural Engineering 23, no. 8 (January 3, 2020): 1521–33. http://dx.doi.org/10.1177/1369433219898102.

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This article presents an approach for investigating performance of prestressed concrete box bridge girders under hydrocarbon fire exposure. A three-dimensional nonlinear finite element model, developed in computer program ANSYS, is utilized to analyze the response of prestressed concrete box bridge girders under combined effects of fire exposure duration and simultaneous structural loading. The model validation is performed using a scaled prestressed concrete box girder exposed to ISO834 fire in furnace. Subsequently, the validated model is used to investigate fire performance of prestressed concrete box bridge girders through taking into consideration some variables, namely concrete cover thickness to prestressing strands, prestress degree, load level, fire exposure length, and position. Through a case study, results from numerical analysis show that concrete cover thickness to prestressing strands and load level has significant effect on fire resistance of prestressed concrete box bridge girders. Increasing prestress degree in prestressing strands can speed up the progression of deflection (sudden collapse) in prestressed concrete box bridge girder toward the final fire exposure stage. Reducing fire exposure length or preventing fire exposure on mid-span zone can highly enhance the fire resistance of simply supported prestressed concrete box bridge girders. Failure of prestressed concrete box bridge girder, under hydrocarbon fire exposure conditions, is governed by rate of deflection failure criterion in particular cases.

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Wu, Jian Qing, Hong Bo Zhang, Xiu Guang Song, Yi Fan Yu, and Chao Li. "Numerical Simulation on the Stress Characteristics of Prestressed Retaining Wall." Applied Mechanics and Materials 477-478 (December 2013): 596–99. http://dx.doi.org/10.4028/www.scientific.net/amm.477-478.596.

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With the highway subgrade fill increasing, traditional retaining wall cannot meet the requirements for supporting. To meet this requirement, the prestressed opposite-pull retaining wall was put forward. Due to the anchor pull of the new-style retaining wall, its bearing capacity was enhanced, but the stress is not clear. In order to reveal the stress distribution of the prestressed opposite-pull retaining wall, FLAC3D was adept to do numerical simulation on the new-style retaining wall. It simulated three conditions of the wall with no anchor, with anchor but without prestress and with prestressed anchor. The results showed that, after the layout of prestressed anchor, the lateral earth pressure of the region near the anchor increased with the increase of prestress, the lateral earth pressure of the wall is parabola distribution. The lateral earth pressure was larger than that of the wall with no anchor and with anchor but without prestress. The bearing capacity of the retaining wall was effectively improved.

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Quenneville, Pierre, and Karl Van Dalen. "Relaxation behaviour of prestressed wood assemblies. Part 1: Experimental study." Canadian Journal of Civil Engineering 21, no. 5 (October 1, 1994): 736–43. http://dx.doi.org/10.1139/l94-079.

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Transverse prestress has been found to increase significantly the strength and stiffness of laminated timber bridge decks and timber joints using timber connectors. A fundamental requirement to the successful use of prestressing with timber is the ability to predict the reduction of prestress with time for transversely prestressed timber applications. The loss of prestress with time for transversely prestressed assemblies was studied analytically and experimentally. In the experimental study, Douglas fir specimens were subjected to two different relative humidity levels and to various stressing histories. The relaxation behaviour and the moisture content of the specimens were continuously monitored for 9 months. Results show that the relaxation behaviour of transversely prestressed wood is affected by the relative humidity level in the surrounding environment and by the stressing frequency. The magnitude of the observed prestress losses and the graphs showing prestress levels and moisture content of specimens as a function of time under various externally imposed conditions are presented. Key words: connections, wood, prestress, Douglas fir, rheology.

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Zhou, Xiang Ling. "Research on Stability Calculation Methods for Grillage Supporting Structure with Pre-Stressed Anchor." Applied Mechanics and Materials 686 (October 2014): 666–70. http://dx.doi.org/10.4028/www.scientific.net/amm.686.666.

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Aiming at prestressed anchor cable frame in the presence of reinforcement landslide problem, through the selection of test points, the paper study and tested soil pressure, frame internal force and prestress losses under prestressed anchor cable frame beam, reveal the law of internal force distribution, and provides a theory basis for the rational design of prestressed anchor cable in landslide..

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An, Jing Bo. "Unified Design of Tensile-Compression Prestressed Concrete Structure." Applied Mechanics and Materials 193-194 (August 2012): 970–75. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.970.

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Structural characteristics of tensile-compression prestressed concrete are introduced briefly in this paper. Firstly, with current concrete structure design code（GB50010）, requirements for materials used in tensile-compression prestressed concrete structure are put forward; and for prepressing stress steel pipe, strength value and basic types for structure design are determined. Secondly the calculation method of prestress loss is given during each work stage of tensile-compression prestressed concrete; and the basic measures of cracking control are concluded. Thirdly, bearing capacity formula of tensile-compression prestressed concrete structure and stress checking formula of menbers in construction stage are provided. Finally structure design of tensile-compression prestressed concrete is unified

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Sabastony, Mulsen, and Koespiadi Koespiadi. "Precast Work Planning Tribun Jakarta International Stadium." ADRI International Journal of Civil Engineering 6, no. 2 (August 31, 2021): 63–68. http://dx.doi.org/10.29138/aijce.v6i2.44.

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This study aims to re-calculate the ratio of non-prestressed iron precast stands to prestressed/prestressed precast stands, which are designed forcon precast concrete stands using non-prestressed iron which results in increased loads from a large iron ratio and the production process will take longer. Recalculate non-prestressed stands precast into precast concrete prestressed stands. The benefits of this research can change non-prestressed iron to prestressed iron which can change the iron ratio to be more efficient and the implementation process to be faster. And also calculate the strength of the precast concrete stands prestress in accordance with predetermined standards. The location of this research was carried out at the Jakarta International Stadium project in North Jakarta. The results of the research found that the presence of a prestressing system in the stadium stands can save the iron ratio so that the weight of the structure obtained is lighter and optimal

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Wang, Wei Ling. "Static Finite Element Analysis of Large Liquefied Natural Gas Prestressed Storage Tank." Applied Mechanics and Materials 578-579 (July 2014): 173–76. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.173.

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Finite element analysis of LNG prestressed storage tank which was under various load conditions was carried out. The calculation results show that the low temperature load and prestress force are the control load which affect the storage tank stress. Further,some recommendations on the configuration of the prestressed reinforcement have been made so as to provide the basis for the design optimization of prestressed LNG tanks.

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Przygocka, M., and R. Kotynia. "Pre-Stress Losses in FRP Pre-Stressed Reinforced Concrete – Subject Overview." Archives of Civil Engineering 64, no. 4 (December 1, 2018): 257–68. http://dx.doi.org/10.2478/ace-2018-0073.

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AbstractFiber reinforced polymers (FRPs) due to their specific high-strength properties become more and more popular and replace traditional structural materials like conventional steel in prestressed concrete structures. FRP reinforced structures are relatively new when compared to structures prestressed with steel tendons. For that reason only several studies and applications of pre-tensioned FRP reinforcement have been conducted until now. Moreover, researchers only considered short-term behavior of FRP reinforced concrete members. The precise information about long-term behavior of FRP reinforcement is necessary to evaluate the prestress losses, which should be taken into account in the design of prestressed RC structures. One of the most important factor influencing long term behavior of FRP reinforcement is stress relaxation. The overview of experimental tests results described in the available literature considering the prestress losses obtained in FRP prestressed concrete members is presented herein.

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Li, Feng Ge, and Yan Zhao. "Finite Element Analysis of Natural Vibration Frequency for Unbounded Prestressed Concrete Beams." Applied Mechanics and Materials 351-352 (August 2013): 1034–37. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1034.

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An experimental investigation on the dynamic characteristics of unbounded prestressed concrete simply support beams is presented. A total of 5 unbounded prestressed concrete simply support beams were constructed and tested. The influence of prestressing on natural vibration frequency of concrete beams is studied by applying prestress gradually. A model of variable stiffness is proposed to calculate the natural vibration frequency of unbounded prestressed concrete beams. The finite element program Sap2000 is used to calculate the frequency of unbounded prestressed concrete beams. The results show that the calculating results agree well with experimental ones.

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Sun, Qiang, Wei Tian, and Ding Tang Wang. "Analysis of Mechanics Characteristics of Prestressed Steel Beam in High Temperature (Fire) Condition." Applied Mechanics and Materials 351-352 (August 2013): 519–23. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.519.

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According to the requirements of fire science theory and structural fire resistance design, and the situation of possible disasters that may occur in the building based on practical project, this paper analyzes the mechanical characteristics of prestressed steel beam under high temperature (fire) circumstances. It puts forward how to consider the effects of parameters of different steel categories, the magnitude of prestress tension control forces and prestressed loss of steel cables on the structural bearing capacity in prestressed steel beam design, which can provide references for the fire resistance design of prestressed steel structures.

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35

Zhang, Qishu, Wuming Leng, Fang Xu, Qi Yang, and Xi Ai. "ADDITIONAL STRESS IN SOIL EMBANKMENTS SUBJECTED TO A NEW PRESTRESSED REINFORCEMENT DEVICE." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 25, no. 7 (July 16, 2019): 700–714. http://dx.doi.org/10.3846/jcem.2019.10532.

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Theoretical solutions were derived to calculate the additional stress/prestress in a newly-developed prestressed embankment (PE), and the diffusion characteristics of the prestress in a PE with a lateral pressure plate (LPP) having width of 0.9 m were clarified using the theoretical solutions and a 3D finite element analysis. The results show that (1) the application of the theoretical solutions requires the net spacing between the LPP and the embankment shoulder is greater than the LPP width; (2) the maximum prestress appears in the upper part of the loading area of a LPP, and the maximum and minimum prestresses present an order of magnitude difference at the shallow depth, but the difference attenuates and the prestress gradually tends to be uniform with increasing depth; (3) the prestress propagates to the core zones that mainly bear the train loads with certain peak stress diffusion angles, and the values for the analyzed case are 50° and 58° in the external regions of the LPP along the slope and longitudinal directions, respectively; and (4) a continuous, effective and relatively uniform prestressing protective layer with a prestress coefficient greater than 0.1 can be formed above the core zones when the LPP spacing is properly designed.

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36

Hou, Wen Yu, Lian Guang Wang, and Peng Liu. "Bending Capacity of T Beam with Prestressed Concrete-Filled Steel Tube." Applied Mechanics and Materials 368-370 (August 2013): 1048–51. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.1048.

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The prestressed composite T beam with concrete-filled steel tube is made through welding with half I-beam to connect the concrete-filled circular steel tube. The prestressed reinforcement was equipped on the T-beam. The load-bearing capacity and rigidity of the composite beam was enhanced by using prestressed force. In consideration of applying prestress, the corresponding parts stress and strain from the beginning of applying prestress to the phase of elimination of the pressure is calculated through the process of applying prestress; establish the equation of elastic flexural capacity with different location of neutral axis according to the theoretical analyses. Also use the superposition method to build the equation of the deflection. The computational results show that applying prestress reduces the deformation of the composite structure and the mechanic performance has improved which provide important theoretical basis with practical application in engineering.

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Yolanda, Devy, and Priyanto Saelan. "Studi Analisis Batasan Persentase Prategang Parsial pada Struktur Balok Prategang (Hal. 48-59)." RekaRacana: Jurnal Teknil Sipil 4, no. 3 (September 25, 2018): 48. http://dx.doi.org/10.26760/rekaracana.v4i3.48.

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ABSTRAKPengurangan gaya prategang yang diperlukan pada suatu penampang beton prategang penuh (full prestressed) menyebabkan diperlukannya baja tulangan, dan beton prategang berperilaku menjadi beton prategang parsial. Pengurangan gaya prategang akan menimbulkan tegangan tarik yang bilamana tegangan tarik yang terjadi melampaui kuat tarik lentur beton maka akan terjadi retak. SNI 03-2847-2002 membolehkan penggunaan beton prategang parsial namun belum mensyaratkan batasan persentase prategang yang harus digunakan. Oleh karena itu dilakukan studi analisis untuk mengetahui persentase prategang minimal yang dapat digunakan. Studi kasus dilakukan pada persentase prategang 50, 60, 70, 80, dan 90. Dari hasil studi kasus didapatkan bahwa persentase prategang yang semakin kecil akan berakibat tegangan tarik dan lebar retak yang terjadi semakin besar. Persentase prategang harus dipilih sedemikian rupa sehingga lebar retak yang terjadi tidak melampaui lebar retak yang diizinkan. Pada kelima variabel penelitian, batasan minimal persentase prategang yang lebar retaknya tidak melebihi lebar retak yang diizinkan adalah 60%.Kata kunci: beton prategang parsial, persentase prategang, tegangan tarik, lebar retak ABSTRACTReducing the required prestressing force on a full prestressed concrete section requires the need for reinforcing steel, and prestressing concrete behaves to partial prestressed concrete. Reduction of the prestressing force will cause tensile stress when the tensile stress that goes beyond the tensile strength of the concrete will result in cracking. SNI 03-2847-2002 allows the use of partial prestressed concrete but does not require the limitation of the prestress percentage to be used. Therefore, an analytical study was conducted to determine the minimum prestressed percentage that can be used. The case study was carried out at 50, 60, 70, 80, and 90 prestressed percentages. From the case study it was found that the smaller the prestress percentage would result in greater tensile stress and crack width. The percentage of prestress shall be chosen so that the crack width does not exceed the allowable crack width. In the five research variables, the minimum limit of prestressing percentage whose crack width does not exceed the allowable crack width is 60%.Keywords: partial prestressed concrete, prestress percentage, tensile stress, crack width

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Li, Qing Song, and Shao Ping Meng. "The Finite Element Analysis of Fatigue Performance of Precracked Concrete Beams Strengthened with Prestressed CFRP." Advanced Materials Research 250-253 (May 2011): 3320–27. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.3320.

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The research conducts the numerical analysis of the fatigue performance of precracked concrete beams strengthened with prestressed CFRP, establishing the static analysis model (SM) and fatigue analysis model (FM) respectively, examining the change of the static loading and fatigue performance before and after CFRP strengthens precracked concrete beams in the different prestressed situations, and analyzing the relevant fatigue performance parameters through comparing FEM analysis with experimental results. The research results demonstrate that the method of strengthening concrete beams with prestressed CFRP can improve the static loading and fatigue performance; the increased rate of fatigue performance of precracked concrete beams is parallel to the CFRP prestress; the fatigue life of precracked concrete beams increases with the raising of the CFRP prestress; FEM analysis is in close agreement with experiment results; the fatigue properties of precracked concrete beams strengthened with prestressed CFRP can be analyzed effectively by the finite element method.

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Chen, Hua, Kan Kang, and Lang Ni Deng. "Construction Technology Research of RC Beams Strengthened with Prestressed CFRP Plates." Advanced Materials Research 268-270 (July 2011): 659–63. http://dx.doi.org/10.4028/www.scientific.net/amr.268-270.659.

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The method of applying prestress to CFRP plates can make full use of the characteristics of high-strength, enhance the force properties, prevent peeling damage and reduce the strain lag. Construction technology of prestressed CFRP plates strengthening reinforcement concrete beams was introduce in this paper, and bending test of 6 reinforcement concrete beams strengthened with prestressed CFRP plates were carried out based on the self-developed prestressed CFRP plates supporting anchorages. The test results indicate that the flexural capacity and crack resistance capacity can be increased compared with non-prestressed CFRP plates, and the construction technology can be adopted in practical projects.

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Shi, Lu Ning, Hao Xiang He, Wei Ming Yan, Yan Jiang Chen, and Da Zhang. "Study on Dynamic Characteristics and Parameter Sensitivity of Three Spans Prestressed Continuous Beam." Applied Mechanics and Materials 351-352 (August 2013): 386–91. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.386.

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Established the three spans prestressed continuous beam dynamic equation, obtained analytical expression of frequency equation. To solve the frequency equation for natural frequency, and compared with the finite element numerical analysis results, the frequency both with analytical expression and with finite element are in good agreement. The formula can be obtained accurately the dynamic parameters of three spans prestressed continuous beam such as frequency. At the same time, the paper also studied the natural frequency sensitivity analysis of three spans prestressed continuous beam, and focuses on the impact on the frequency with effective prestress and prestressed eccentricity.

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Jia, Jin Qing, Fang Yu, Da Li Yao, and Wei Qing Zhu. "Strain Analysis of Corrosed Prestressed Concrete Beams on Fatigue Test." Advanced Materials Research 255-260 (May 2011): 355–59. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.355.

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In order to study the relationship between strains and corrosion levels of prestressed concrete beams uder fatigue loading, accelerated corrosion method is used to make various corrosion rates of prestressed steel strands. The beams have the same designs and submitted to the same maximum and minimum load during the test. With the corrosion level as main parameter, strains at different position of the beams, such as non-prestressed steel strain, concrete strain in compressive region at mid-span and prestressed steel strain are studied. The test results show that beams with different corrosion rates have the same “three-stage“ law on the development of non-prestressed steel maximum and residual strain,as well as concrete strain and prestress strain. The significant increase of concrete strain is generated due to corrosion after concrete cracking.The increase of non-prestressed steel strain is nearly proportional to the growth of corrosion under the same fatigue load. A relationship was found to be a function. It can be obtained the corrosion rate of prestressed steel when the stress of non-prestressed steel strains are measured.

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42

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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43

Bai, Chongxi. "Analysis on Dynamic Response of Prestressed Concrete Slab Subjected to Blast Loading." E3S Web of Conferences 136 (2019): 03015. http://dx.doi.org/10.1051/e3sconf/201913603015.

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The dynamic response of prestressed concrete slab under blast loading was analyzed based on LS-DYNA. The laws of influence of degree of prestress, combined reinforcement index, weight of explosives, thickness of slab on the dynamic response of prestressed concrete slab under blast loading were discussed, and the failure modes were given. The analysis results showed that the peak displacement at mid-span increased with increasing of degree of prestress and weight of explosives, and reduced with increasing of combined reinforcement index and thickness of slab. All the parameters, the influence of weight of explosives on displacement response of slab was significantly. Rationalization proposals were provided for blast resistant design of prestressed concrete slab.

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Liu, Li, Fang Wang, and Kai Wang. "Finite Element Analysis on Contact Surface Slip of Profiled Steel Sheet and Composite Slab." Advanced Materials Research 568 (September 2012): 256–59. http://dx.doi.org/10.4028/www.scientific.net/amr.568.256.

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In order to evaluate correctly the load-bearing performance of the prestressed profiled steel sheet composite slab，according to actual loading conditions, finite element model of the prestressed profiled steel sheet and concrete composite slab is established. Numerical simulation is made to the slip of the prestressed composite slab. The calculation results show that the slip of the prestressed composite slab at ultimate status will be gradually reduced with the improvement of the concrete strength. When increasing the prestress, the slip value at ultimate status will be less reduced and increasing the thickness of the concrete can reduce the slip value at ultimate status, the deformation of the prestressed composite slab will be increased by over 10% when considering the slip of the bonding surface.

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Li, Chang Chun, and Li Yun Yi. "On Detection Technologies of Pre-Stressed Duct Grouting Fullness." Advanced Materials Research 933 (May 2014): 71–75. http://dx.doi.org/10.4028/www.scientific.net/amr.933.71.

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Aging and deterioration (such as weakening of concrete strength and loss of prestress) of various degree will inevitably happen to prestressed concrete beam in service. In making the prestressed concrete beam, it is of vital importance to ensure that the prestress tension is sufficient, duct grouting is compact enough and concrete pouring is in good quality. Otherwise, structure will deteriorate faster and safety hazard and even bridge collapse may ensue, causing considerable economic losses.

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46

Li, Yang, and Li Jiao Shen. "The Measuring Test and Finite Element Analysis for Prestressed Concrete Beams." Applied Mechanics and Materials 105-107 (September 2011): 1052–55. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.1052.

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Based on one prestressed frame beam in an actual project, both the indirect measuring test and the finite element numerical simulation about the reinforcement prestress are made. The test and simulation results show that the effect prestress obtained from indirect measure methods can reflect the prestress history relatively well. Meanwhile, the indirect measure method has the advantages of low cost and easy operation, which can be exploited and developed in general projects so as to get the stress history of the prestressed reinforcement in time and reduce potential security threat.

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Zhao, Lijun, Tiesheng Dou, Bingqing Cheng, Shifa Xia, Jinxin Yang, Qi Zhang, Meng Li, and Xiulin Li. "Theoretical Study and Application of the Reinforcement of Prestressed Concrete Cylinder Pipes with External Prestressed Steel Strands." Applied Sciences 9, no. 24 (December 16, 2019): 5532. http://dx.doi.org/10.3390/app9245532.

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Prestressed concrete cylinder pipes (PCCPs) can suffer from prestress loss caused by wire-breakage, leading to a reduction in load-carrying capacity or a rupture accident. Reinforcement of PCCPs with external prestressed steel strands is an effective way to enhance a deteriorating pipe’s ability to withstand the design load. One of the principal advantages of this reinforcement is that there is no need to drain the pipeline. A theoretical derivation is performed, and this tentative design method could be used to determine the area of prestressed steel strands and the corresponding center spacing in terms of prestress loss. The prestress losses of strands are refined and the normal stress between the strands and the pipe wall are assumed to be distributed as a trigonometric function instead of uniformly. This derivation configures the prestress of steel strands to meet the requirements of ultimate limit states, serviceability limit states, and quasi-permanent limit states, considering the tensile strength of the concrete core and the mortar coating, respectively. This theory was applied to the reinforcement design of a PCCP with broken wires (with a diameter of 2000 mm), and a prototype test is carried out to verify the effect of the reinforcement. The load-carrying capacity of the deteriorating PCCPs after reinforcement reached that of the original design level. The research presented in this paper could provide technical recommendations for the application of the reinforcement of PCCPs with external prestressed steel strands.

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Ma, Jia, and Qing Shan Yang. "Study on Prestressed Laminated Strand Lumber and its Load-Carrying Capacity." Advanced Materials Research 168-170 (December 2010): 1470–75. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1470.

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Owing to some problems in the existent plywood products such as weak shear capacity and weak wear intensity, as while as the large consumption of crude wood resources, prestressed laminated strand lumber (PLSL) is proposed in this paper, in which the multiple integration method and prestressed technology are adopted to obtain a higher strength. More significantly, used wood can be reused as the raw material of PLSL, then the crude wood will be conserved and the cost will be lowered. To study its mechanical properties, the commercial software ANSYS is adopted to establish the finite element models of PLSL. The diameter and spacing of prestressed steel wire, the magnitude of the prestress and the width of the lumber are some factors considered. Based on the nonlinear finite element buckling analysis of these lumbers, some major conclusions are summarized as follows: (1) The improvement of strength is comparatively obvious to use PLSL compared with the traditional plywood products; (2) The ultimate bearing load is rising along with the increase of the diameter of the prestressed steel wire and the width of the lumber; (3) The ultimate bearing load is descending with the increase of the spacing of the prestressed steel wire; (4) The ultimate bearing load is rising along with the increase of the magnitude of the prestress at first, but when the prestress reaches a certain level, the ultimate bearing load starts to descend.

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Lv, Qingfang, Yi Ding, and Ye Liu. "Effect of the Nonprestressed/Prestressed BFRP Bar on Flexural Performance of the Bamboo Beam." Advances in Polymer Technology 2019 (October 9, 2019): 1–13. http://dx.doi.org/10.1155/2019/7143023.

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Until now, the systematical and comprehensive strengthening techniques have not been formed for the bamboo structure. Under such background, this paper aims to explore the effects of the application of the nonprestressed and prestressed basalt fiber-reinforced polymer (BFRP) bars on the flexural performance of the beams made of the laminated bamboo and reconstituted bamboo materials. Two series of four-point bending tests were thus conducted. In the first series of tests, the pure laminated bamboo beam and the laminated bamboo beam applied with nonprestressed BFRP bar were compared. Test results showed that the ultimate load and deformation capacity of the laminated bamboo beam was improved due to the existence of the BFRP bar. In the second series of tests, the reconstituted bamboo beams applied with nonprestressed and prestressed BFRP bars were compared. It is found that the ultimate load of the reconstituted bamboo beam was not improved by the application of the prestressed force. The further analysis related to the prestress loss demonstrated that the prestress loss before the release of the prestressed BFRP bar could reach up to 31.8–37.3% compared with the design initial prestressed stress. The prestress loss caused by the elastic deformation of the bamboo beam can be neglected. For all tested specimens, the plane section assumption was acceptable and the position of the neutral axis of the beam gradually moved down with the increase of the applied load.

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Gao, Wei, Chun Li, Quan Liu, and Yu Chen. "The Design and Prestressed Modal Analysis for Megawatt-Class Wind Turbine Rotor." Applied Mechanics and Materials 226-228 (November 2012): 295–98. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.295.

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The blade is an important component of the wind turbine, which is essential to proper blade design. This paper summarizes the process of the blade design, the selection of the design parameters, and the design of megawatt-scale blades. The finite element method was applied on the model generated in 3D graphics software. After selecting the material parameters of the blade, the modal analyses under prestresses were conducted so as to determine the modal shapes, frequency, maximum deflection and maximum stress at different orders of vibration. Thus the results were compared with those of modal analysis under the non-prestressed condition. Thus the conclusion on the effect of gravity and rotation-prestress on the modal frequency, maximum deflection and maximum stress in modal analysis will be drawn.

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Journal articles on the topic 'Prestressed'

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