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Abstract: Since the assumption of plane sections cannot be applied to the strain of unbonded tendons in prestressed concrete beams subjected to loadings, a moment-curvature nonlinear analysis method is used to develop analytical programs from stress increases in unbonded tendons at the ultimate limit state. Based on the results of model testing and simulation analysis, equations are proposed to predict the stress increase in tendons at the ultimate state in simple or continuous beams of partially prestressed concrete, considering the loading type, prestressed reinforcement index%29&ck%5B%5D=abstract&ck%5B%5D=keyword'>non-prestressed reinforcement index β_p, prestressing reinforcement index β_s, and span-depth ratio L/h as the basic parameters. Results of 380 beams studied here and test results for 35 simple beams obtained by the China Academy of Building Research were compared with those from prediction equations given in codes and other previous studies. The comparison reveals that the values predicted by the proposed equations agree well with experimental results.

[1]A23.3-94. Design of Concrete Structures. Canadian Standards Association. Rexdale, Ontario, Canada.

[2]ACI318-02. Building Code Requirements for Structural Concrete (ACI 318-02) and Commentary (ACI 318R-02). American Concrete Institute, Michigan.

[3]Ariyawardena, N.D., 2002. Design of precast prestressed concrete members using external prestressing. PCI Journal, 47(2):84-91.

[4]Barakat, S., Bani-Hani, K., 2004. Multi-objective reliability-based optimization of prestressed concrete beams. Structural Safety, 26(3):311-342.

[5]BS8110-1-1997. Structural Use of Concrete, Part 1—Code of Practice for Design and Construction. British Standards Institution, London.

[6]Chen, X.B., Zhao, G.F., 1993. Investigation and reliability analysis of ultimate strength of unbonded partially prestressed concrete beams. Journal of Dalian University of Technology, 33(5):548-551 (in Chinese).

[7]Du, G.C., Tao, X.K., 1985. A study of the ultimate stress of unbonded tendons in partially prestressed concrete beams. Journal of Building Structures, 6(6):2-13 (in Chinese).

[8]Harajli, M.H., 1990. Effect of span-depth ratio on the ultimate steel stress in unbonded prestressed concrete member. ACI Structural Journal, 87(8):305-312.

[9]JGJ 92-2004. Technical Specification for Concrete Structures Prestressed with Unbonded Tendons. China Academy of Building Research, Beijing.

[10]Jin, W.L., Zhao, Y.X., Lü, Z.T., 2000. Ultimate stress of unbounded prestressed tendons. Journal of Zhejiang University (Engineering Science), 34(4):393-397 (in Chinese).

[11]Liu, F., Chen, X.B., 2003. Experimental study of unbonded prestressed concrete beams under concentrated load. Journal of Hefei University of Technology, 24(5):880-884 (in Chinese).

[12]Naaman, A.E., Alkhairi, F.M., 1991. Stress at ultimate in unbonded prestressing tendons: part 1—evaluation of the state-of-art. ACI Structural Journal, 88(5):683-692.

[13]Tao, X.K., 1993. Unbonded Prestressed Concrete Structure Design and Construction. Earthquake Publishing Company, Beijing, China, p.20-50 (in Chinese).

[14]Tao, X.K., Wang, Y., Du, G.C., 1989. Deflection estimation for unbonded partially prestressed concrete flexural members. Journal of Building Structures, 10(1):20-27 (in Chinese).

[15]Wang, X.D., 2005. Research on Law of Stress Increase in Concrete Flexural Members. MS Thesis, Harbin Institute of Technology, Harbin, China (in Chinese).

[16]Xu, J.S., Lin, C.Z., Hong, W.E., 1995. Study on structural behavior of waffle slab floor with unbonded prestressed tendons and non-prestressed steel. Journal of Building Structures, 16(1):3-14 (in Chinese).

[17]Zheng, W.Z., Zheng, X., Wang, Y., 2005. Calculation of ultimate stress of unbonded tendons in continuous prestressed concrete beam. Building Structure, 35(7):67-71 (in Chinese).

[18]Zhou, W., 2005. Research on Three Fundamental Issues in Design of Prestressed Concrete Structures. PhD Thesis, Harbin Institute of Technology, Harbin, China (in Chinese).