Ultimate stress increase in unbonded tendons in prestressed concrete beams  

作　　者：Wen-zhong ZHENG Xiao-dong WANG 

机构地区：[1]Department of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China

出　　处：《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》2010年第12期998-1014,共17页浙江大学学报（英文版）A辑（应用物理与工程）

基　　金：Project supported by the National Natural Science Foundation of China (No.50178026);the New Century Excellent Talents in University;Changjiang Scholars Program of China (No.2009-37)

摘　　要：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,non-prestressed reinforcement index βp,prestressing reinforcement index βs,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.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,non-prestressed reinforcement index βp,prestressing reinforcement index βs,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.

关 键 词：Ultimate stress increase Unbonded tendons Loading type Non-prestressed reinforcement index Prestressed reinforcement index Span-depth ratio 

分 类 号：TU3[建筑科学—结构工程]