Experimental Study on Behaviors of Unbonded Prestressed Concrete Beams Reinforced with CFRP Tendons

2008 ◽  
Vol 400-402 ◽  
pp. 567-573 ◽  
Author(s):  
Wen Zhong Zheng ◽  
Chong Xi Bai ◽  
Hui Dong Cheng
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Limit State ◽  
Plastic Hinge ◽  
Stress Increment ◽  
Intermediate Support ◽  
Strength Limit ◽  
Continuous Beams ◽  
Bending Capacity ◽  
The Law

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

Analysis of serviceability limit state of GFRP prestressed concrete beams

2015 ◽  
Vol 134 ◽  
pp. 450-459 ◽  
Author(s):  
Mantas Atutis ◽  
Juozas Valivonis ◽  
Edgaras Atutis
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Limit State ◽  
Serviceability Limit State

Research on Stress Increase of Unbonded Tendons at Ultimate in Prestressed Concrete Continuous Beams

2012 ◽  
Vol 166-169 ◽  
pp. 1554-1557
Author(s):  
Xiao Dong Wang ◽  
Wen Zhong Zheng ◽  
Ying Wang
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Simulation Analysis ◽  
Analysis Method ◽  
Stress Increase ◽  
Continuous Beams ◽  
Unbonded Tendons ◽  
Index Ratio ◽  
Prestressed Reinforcement ◽  
Rational Evaluation

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

scholarly journals Reliability assessment of the behavior of reinforced and/or prestressed concrete beams sections in shear failure

2021 ◽  
Vol 15 (57) ◽  
pp. 195-222
Author(s):  
Karim Benyahi ◽  
Mohand Said Kachi ◽  
Youcef Bouafia ◽  
Salma Barboura ◽  
Jia Li
Keyword(s):  
Prestressed Concrete ◽  
Shear Failure ◽  
Concrete Beams ◽  
Limit State ◽  
Shear Loading ◽  
The Real ◽  
Modeling Uncertainties ◽  
Reliability Method ◽  
Real Behavior ◽  
State Curve

The object of this article is to be able to simulate the behavior of reinforced and/or prestressed concrete beam’s section in the shear loading through a model allowing the evaluation of nonlinear strains caused by shear, while taking into account the real behavior of the materials. In this approach, we are often confronted with problems of modeling uncertainties linked to some insufficiencies of the mechanical model allowing to describe the physical phenomena in a realistic way. For that, it is necessary to use a reliability model making it possible to evaluate their probability of failure, by establishing failure curves according to the different transition zones of the limit state curve of the nonlinear behavior in the shear loading up to at section failure of reinforced and/or prestressed concrete beams. In this work, we also propose a coupling of the reliability method by response surface to carry out the reliability optimization on complex mechanical models, where the mechanical and reliability models developed have been implemented on the Fortran. This allows the estimation in an efficient way of the different reliability characteristics according to each transition zone from the limit state curve to the real behavior until failure in the shear loading.

scholarly journals Automation of the evaluation of bonded and unbonded prestressed concrete beams, according to brazilian and french code specifications

2013 ◽  
Vol 6 (1) ◽  
pp. 13-54
Author(s):  
P. M. Lazzari ◽  
A. Campos Filho ◽  
F. P. S. L. Gastal ◽  
R. A. Barbieri ◽  
R. C. Schwingel
Keyword(s):  
Prestressed Concrete ◽  
Geometric Nonlinearity ◽  
Computational Algorithm ◽  
Concrete Beams ◽  
Limit State ◽  
Ultimate Limit State ◽  
Flexural Members ◽  
Design Procedures ◽  
Planar Frames ◽  
Ultimate Limit

This paper presents a suggestion for the automation of the design procedures of bonded and unbonded prestressed concrete flexural members, according to the Brazilian (NBR 6118:2007) and French (Règles BPEL 91) norm specifications. Prestressing of concrete structures has been increasingly used, mainly due to its building advantages, as well as allowing reducing crack incidence and element dimensions by the use of more resistant materials. Structure is analyzed by a numerical model that employs a hybrid type finite element for planar frames, considering geometric nonlinearity, cyclic loading and composite construction. The computational algorithm implemented considers full, partial and limited prestressing situations, evaluating in each case decompression limit state, limit state of cracking, ultimate limit state and final prestressing state. Finally, two examples comparing design situations according to the Brazilian and French norms are presented.

Estimation of Ultimate Tendon Stress in Reinforced Concrete Beams Prestressed with External FRP Tendons

2013 ◽  
Vol 798-799 ◽  
pp. 374-377
Author(s):  
Shuan Jiang
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Plastic Hinge ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Stress Increment ◽  
Hinge Zone ◽  
Good Agreement

The ultimate tendon stress is the key to calculation of flexural capacity in reinforced concrete beam prestressed with external FRP tendons (RCBPEFT). Based on the theory of equivalent plastic hinge zone, the general formulas for calculating the ultimate tendon stress increment and ultimate tendon stress in RCBPEFT are therefore proposed. Comparisons indicate that the predictions are in good agreement with the test results.

Experimental Study on Fatigue Behavior of Prestressed Concrete Beams with Manufactured Sand

2012 ◽  
Vol 517 ◽  
pp. 595-600
Author(s):  
Qian Qian Li ◽  
Li Xin Liu ◽  
Sheng Dong He
Keyword(s):  
Cyclic Loading ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Fatigue Behavior ◽  
Limit State ◽  
Flexural Behavior ◽  
Natural Sand ◽  
Manufactured Sand ◽  
Allowable Range ◽  
Prestressed Beams

This paper presents the test results of 2 prestressed concrete beams with manufactured sand under cyclic loading, the concrete is made of manufactured sand to replace natural sand with different replacement rates of 50% and 100%. The stress of re-bars and prestressed strands and the strain of manufactured sand concrete are discussed, the rigidity and cracking of the prestressed beams under cyclic loading are analyzed, and the flexural behavior of the beams after 2.5 million times cyclic loading are also discussed and analyzed. The results show that the fatigue behavior of the prestressed concrete beams with manufactured sand to replace the natural sand under cyclic loading is satisfied, the flexural bearing capacity of the prestressed beams after 2.5 million times cyclic loading is still sufficient. The results also show that the crack width and the mid-span deflection of the prestressed beams are in the allowable range at the serviceability limit state. This may be regarded as a reference for the applications of manufactured sand in the prestressed concrete structure .

scholarly journals Interactive graphics tool for the calculation and serviceability limit state stress check of bonded post-tensioned concrete beams according to brazilian codes via Autodesk Robot Structural Analysis Professional(r)

2015 ◽  
Vol 8 (3) ◽  
pp. 427-446
Author(s):  
P. K. K. NACHT ◽  
L. F. MARTHA
Keyword(s):  
Structural Analysis ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Limit State ◽  
Interactive Graphics ◽  
Prestress Losses ◽  
Serviceability Limit State ◽  
Permissible Stresses ◽  
State Stress ◽  
Post Tensioned

This work presents an interactive graphics computational tool for the verification of prestressed concrete beams with post-tensioned bonded tendons to the serviceability limit state (SLS) stress check according to the Brazilian code NBR 6118:2014. The tool is an add-in for Autodesk Robot Structural Analysis Professional(r), which serves as a structural modeling platform. With data supplied by the user through a graphics user interface, the program here developed calculates all relevant prestress losses that occur throughout the structure's life-cycle, along with the prestress' equivalent loads during this period. The traditional calculation methods, obtained in the NBR 6118, are presented along with the modifications which had to be implemented in order to allow for incremental loss calculations. Usage examples and results are presented, validating the adopted methodology. At the end of the software's calculation, the user receives two outputs: the prestress' equivalent loads in the Robot model and an Excel spreadsheet. The spreadsheet contains the resultant stresses in the beam and warns whether these are greater than the permissible stresses in the SLS stress check. The loads may then be used in other calculations, such as shear reinforcement.

Experimental Study on the Stress Increment of Prestressed Tendons of Retard-Bonded Prestressed Concrete Continuous Beams

2010 ◽  
Vol 163-167 ◽  
pp. 1431-1435 ◽  
Author(s):  
Qiang Fu ◽  
Xia Cao ◽  
Ling Zhi Jin ◽  
Wan Xu Zhu ◽  
Hui Xian Yang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Prestressed Concrete ◽  
Technical Specification ◽  
Continuous Beam ◽  
Stress Increment ◽  
Concrete Members ◽  
Continuous Beams ◽  
Unbonded Tendons ◽  
Working Performance ◽  
Made In

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.

PRESTRESSED CONCRETE BEAMS WITH A LONGITUDINAL CAVITY

PCI Journal ◽  
1973 ◽  
Vol 18 (1) ◽  
pp. 39-49
Author(s):  
A. A. Hamoudi ◽  
R. A. Bierweiler ◽  
M. K. S. Phang
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams
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