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Nonlinear Analysis of Friction Effect in Externally Prestressed Beams

DOI：

 作者 单位 E-mail 方德平 福建省厦门市集美区华侨大学土木工程学院 fdp@hqu.edu.cn

构造了简单的体外预应力梁的摩擦单元，摩擦单元位于转向块和体外筋之间的角平分线上，能模拟转向块和体外筋之间的有摩擦或摩擦滑移。考虑混凝土、钢筋和体外筋应力-应变的非线性关系，采用梁截面弯矩-轴力-曲率的三折线模型，探讨了体外预应力梁的性能。对简支梁和连续梁的不同因素进行计算，包括不同摩擦系数、不同体外筋和钢筋面积、不同偏心距、对称和非对称荷载形式。计算结果表明：对于简支梁和对称荷载下的连续梁，承载力的摩擦效应可以忽略，最大预应力增量和挠度的摩擦效应不宜忽略，最小预应力增量的摩擦效应明显；对于非对称荷载下的连续梁，承载力、最大和最小预应力增量、挠度的摩擦效应不可忽略。

A concise friction element located at angle bisector between the external tendon and deviator was constructed, which can simulate the slip with or without friction between the tendon and deviator. The nonlinear stress-strain relationships of concrete, steel bar and external tendon were taken into consideration, the tri-linear model of the bending moment-axial force-curvature of beam section was adopted, the behavior of externally prestressed beam was investigated. The calculations of simply supported beams and continuous beams for various factors were conducted, including different friction coefficients, different areas of external tendon and steel bar, different eccentricities, symmetric or asymmetric load patterns. The calculation results indicate: for the simply supported beam and continuous beam under symmetric load, the friction effect on load carrying capacity is negligible; the friction effect on maximum prestress increment and deflection may not be negligible, the friction effect on minimum prestress increment is obvious; for the continuous beam under asymmetric load, the friction effect on load carrying capacity, maximum and minimum prestress increments, and deflection cannot be neglected.
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