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...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.展开更多
This paper studied the stress corrosion cracking(SCC)of EV31A in 0.1 M Na 2 SO 4 saturated with Mg(OH)2 using linearly increasing stress tests,compared with pure Mg and WE43B.All three materials were susceptible to SC...This paper studied the stress corrosion cracking(SCC)of EV31A in 0.1 M Na 2 SO 4 saturated with Mg(OH)2 using linearly increasing stress tests,compared with pure Mg and WE43B.All three materials were susceptible to SCC.SCC susceptibility increased with decreasing applied stress rate.The threshold stress was 0.3×(yield stress)for pure Mg,0.6×(yield stress)for EV31A,and 0.8×(yield stress)for WE43B.The SCC velocities at an applied stress rate of 7.3×10^(-4)MPa s^(-1)were 7.2×10^(-8)m s^(−1)for pure Mg,5.6×10^(-9)m s^(-1)for WE43B,and 1.5×10^(-9)m s^(-1)for EV31A.展开更多
基金Project supported by the National Natural Science Foundation of China (No.50178026)the New Century Excellent Talents in UniversityChangjiang Scholars Program of China (No.2009-37)
文摘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.
基金YL wishes to thank The University of Queensland,the University of Science and Technology Beijing,and China Scholarship Council for their support during his study abroad year.
文摘This paper studied the stress corrosion cracking(SCC)of EV31A in 0.1 M Na 2 SO 4 saturated with Mg(OH)2 using linearly increasing stress tests,compared with pure Mg and WE43B.All three materials were susceptible to SCC.SCC susceptibility increased with decreasing applied stress rate.The threshold stress was 0.3×(yield stress)for pure Mg,0.6×(yield stress)for EV31A,and 0.8×(yield stress)for WE43B.The SCC velocities at an applied stress rate of 7.3×10^(-4)MPa s^(-1)were 7.2×10^(-8)m s^(−1)for pure Mg,5.6×10^(-9)m s^(-1)for WE43B,and 1.5×10^(-9)m s^(-1)for EV31A.
