Calculating stress of external prestressing tendons

This paper presents a simple method to calculate the increase in stress of the external prestressing tendons used to strengthen the concrete beams at any loading. First, the previous equations used to calculate stress of unbonded or external prestressing tendons are briefly reviewed, and then a new design method is proposed by considering deformation of the member. The steps of this method are simple and can be used for any loading. Experimental results obtained from several sources are compared with those calculated using the proposed method and the Harajli, Naaman et al., ACI-318 and BS 8110 code equations. The proposed equation showed good agreement and better accuracy.

[1]  Mohamed H. Harajli,et al.  STRENGTHENING OF CONCRETE BEAMS BY EXTERNAL PRESTRESSING , 1993 .

[2]  Jeong-Ho Moon,et al.  PROPOSED METHODOLOGY FOR COMPUTING OF UNBONDED TENDON STRESS AT FLEXURAL FAILURE , 1999 .

[3]  Angel C. Aparicio,et al.  Testing of externally prestressed concrete beams , 2002 .

[4]  Mohamed H. Harajli,et al.  EFFECT OF SPAN-DEPTH RATIO ON THE ULTIMATE STEEL STRESS IN UNBONDED PRESTRESSED CONCRETE MEMBERS , 1990 .

[5]  F. N. Pannell,et al.  The ultimate moment of resistance of unbonded prestressed concrete beams , 1969 .

[6]  Antoine E. Naaman,et al.  Stress at Ultimate in Unbonded Post-Tensioning Tendons: Part 1--Evaluation of the State of the Art , 1991 .

[7]  Antoine E. Naaman,et al.  New Methodology for the Analysis of Beams Prestressed With External or Unbonded Tendons , 1990, SP-120: External Prestressing in Bridges.

[8]  F. N. Pannell,et al.  The ultimate moment of resistance of unbonded partially prestressed reinforced concrete beams , 1976 .

[9]  睦好 宏史,et al.  Flexural Behavior of Externally Prestressed Beams with Large Eccentricities , 1998 .

[10]  James L Noland,et al.  Computer-Aided Structural Engineering (CASE) Project: Decision Logic Table Formulation of ACI (American Concrete Institute) 318-77 Building Code Requirements for Reinforced Concrete for Automated Constraint Processing. Volume 1. , 1986 .

[11]  Chee Khoon Ng,et al.  Effects of Deviators and Tendon Configuration on Behavior of Externally Prestressed Beams , 1997 .

[12]  Antoine E. Naaman,et al.  STRESS AT ULTIMATE IN UNBONDED POST-TENSIONING TENDONS: PART 2 - PROPOSED METHODOLOGY , 1991 .

[13]  A. Ghallab,et al.  ULTIMATE STRENGTH OF EXTERNALLY STRENGTHENED PRESTRESSED BEAMS , 2002 .

[14]  Antoine E. Naaman,et al.  STRESSES IN UNBONDED PRESTRESSING TENDONS AT ULTIMATE: RECOMMENDATION , 2002 .