Ultimate Stress of Unbonded Tendons in Partially Prestressed Concrete Beams

PCI Journal ◽  
1985 ◽  
Vol 30 (6) ◽  
pp. 72-91 ◽  
Author(s):  
Xuekang Tao ◽  
Gongchen Du
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Ultimate Stress ◽  
Unbonded Tendons

Ductility analysis of prestressed concrete beams with unbonded tendons

2008 ◽  
Vol 30 (1) ◽  
pp. 13-21 ◽  
Author(s):  
J.S. Du ◽  
Francis T.K. Au ◽  
Y.K. Cheung ◽  
Albert K.H. Kwan
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Unbonded Tendons

Flexural ductility of prestressed concrete beams with unbonded tendons

2009 ◽  
Vol 6 (6) ◽  
pp. 451-472 ◽  
Author(s):  
F.T.K. Au ◽  
K.H.E. Chan ◽  
A.K.H. Kwan ◽  
J.S. Du
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Unbonded Tendons ◽  
Flexural Ductility

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.

Beams prestressed with unbonded tendons at ultimate

1996 ◽  
Vol 23 (6) ◽  
pp. 1220-1230 ◽  
Author(s):  
Marco Andrea Pisani ◽  
Emilio Nicoli
Keyword(s):  
Numerical Analysis ◽  
Key Words ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Experimental Tests ◽  
Safety Factors ◽  
Unbonded Tendons ◽  
External Tendons ◽  
Simplified Method ◽  
Good Agreement

This paper presents a numerical investigation on beams and slabs prestressed with either unbonded internal or external tendons. Twenty-three experimental tests (beams and slabs prestressed with unbonded internal tendons) were numerically simulated to verify the reliability of the numerical algorithm adopted. The good agreement established enables us to study the behaviour of these beams in depth and to compare it with the behaviour of similar beams prestressed with external tendons. The numerical analyses were then repeated after including the safety factors related to the materials. The outputs were then compared with the results adopted by making use of the simplified method suggested by Eurocode E.C.2 Part 1-5, to check the size of the error involved in the adoption of the latter. Key words: numerical analysis, unbonded internal tendons, external tendons, European Prestandard, prestressed concrete, beams, post-tensioned.

Theoretical Analysis of Natural Vibration Frequency for Unbonded Prestressed Concrete Beams

2012 ◽  
Vol 594-597 ◽  
pp. 882-885 ◽  
Author(s):  
Feng Ge Li ◽  
Rong Li
Keyword(s):  
Prestressed Concrete ◽  
Natural Frequencies ◽  
Concrete Beams ◽  
Flexural Rigidity ◽  
Variable Stiffness ◽  
Natural Vibration Frequency ◽  
Test Results ◽  
Unbonded Tendons ◽  
Proposed Model ◽  
Calculation Results

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.

Increase of stress in unbonded tendons in prestressed concrete beams and slabs

1981 ◽  
Vol 8 (2) ◽  
pp. 262-268 ◽  
Author(s):  
Perumalsamy N. Balaguru
Keyword(s):  
Prestressed Concrete ◽  
Ultimate Load ◽  
Concrete Beams ◽  
Regression Equation ◽  
Prestressing Force ◽  
Unbonded Tendons ◽  
Stress Strain Relation ◽  
Stress Changes ◽  
Tendon Strain ◽  
Suggested Formula

In the case of prestressed concrete beams with unbonded tendons, in order to design for strength and serviceability, one has to evaluate the effective prestressing force in the tendon, which is beam dependent rather than section dependent, both at ultimate and working loads. The formulae available in the published literature deal only with ultimate load conditions. A simple equation to predict the tendon stress changes for the complete loading range is presented in this paper. The formula was developed using the basic theory of flexure to obtain the equation for the elastic curve, and numerical integration to obtain the curve lengths. Using the computer generated results of the increase in tendon strain for various span lengths, eccentricities, and maximum deflections, a regression equation was developed. This regression equation predicts the increase in tendon strains as a function of the span–eccentricity and eccentricity – maximum deflection ratios. The recently published stress–strain relation which seems to be very accurate is then used to predict the tendon stress. The results are compared with a set of experimental results. The suggested formula is also consistent with some of the available equations for the prediction of the tendon stress at ultimate load.

scholarly journals Numerical Study of Using FRP and Steel Rebars in Simply Supported Prestressed Concrete Beams with External FRP Tendons

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2773
Author(s):  
Miao Pang ◽  
Zhangxiang Li ◽  
Tiejiong Lou
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Numerical Study ◽  
Fiber Reinforced Polymer ◽  
Simply Supported ◽  
Reinforced Polymer ◽  
Unbonded Tendons ◽  
Model Predictions ◽  
Steel Rebars ◽  
Gfrp Rebars

This study aimed at examining the feasibility of using fiber-reinforced polymer (FRP) rebars instead of steel ones in prestressed concrete beams (PCBs) with external FRP tendons. By applying an experimentally validated program, numerical tests were performed on simply supported PCBs, with investigated variables including rebars’ type and area. Three types of rebars were considered, i.e., carbon, glass FRPs (CFRP, GFRP), and reinforcing steel. The ratio of tensile rebars ranged from 0.22% to 2.16%. The results indicated that the beams with CFRP rebars exhibited better crack mode and higher ultimate load than the beams with GFRP or steel rebars. GFRP rebars led to considerably higher ultimate deflection and tendon stress increment than steel rebars. In addition, several models for calculating the ultimate stress in unbonded tendons were assessed. An analytical model was also proposed to predict the tendon stress at ultimate and flexural strength in externally PCBs with steel and FRP rebars. The model predictions agreed well with the numerical results.

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