【摘要】 本文针对偏心直线作用下预应力混凝土梁桥的快速评估问题提出了一种基于结构强迫振动响应测试的桥梁承载力估计方法。首先,文章分析了在时域内结构的预应力对结构在外载作用下动力响应的影响的正问题。特别得到了受偏心预应力作用下预应力混凝土梁的几何刚度矩阵。接着,文章研究了由结构动力响应的变化来识别预应力的方法。本文运用了基于敏感度的优化计算方法。在得到了预应力值之后,预应力混凝土梁桥的抗裂承载力即可算得。文章以京秦高速公路上的青龙河桥为例,进行了数值模拟。研究了该桥数值模型在冲击荷载,简谐荷载和随机白噪声三种荷载作用下的承载力评估效率。数值计算结果表明,本文所提出的方法具有较高的计算效率和精度。更多还原

【Abstract】 The aging of thousands of prestressed concrete(PC) bridges in Chinese highway systems calls for fast condition evaluation methods to assess the load carrying capacity.In the paper a method for simply supported PC beam bridges eccentrically prestressed with straight tendons using measured structural forced vibration responses is presented.The forward mapping from structural prestress force to forced vibration responses is analytically derived firstly.The Special focus is put on the derivation of the geometrical stiffness matrix of an eccentrically prestressed PC beam.The inverse mapping technique of identifying the prestress force from structural forced vibration responses and solving sensitivity based optimization problem,is presented.According to the identified prestress force,the crack resistant load carrying capacity of the PC bridges can be assessed.A numerical study is conducted on a typical PC highway bridge--Qinglong-River Bridge on Beijing-Qinghuangdao Highway.The forced vibration responses of structure under impulse,harmonic and white noise random excitations are simulated for the load carrying capacity assessment purpose.The results verified the effectiveness and accuracy of the proposed method.更多还原