基于频率法的体外预应力桥梁有效预应力测试方法.docVIP

  基于频率法的体外预应力桥梁有效预应力 测试方法# 谭国金，刘寒冰，王龙林* 5 10 15 20 25 30 （吉林大学交通学院） 摘要：以工程实际为例，对频率法在体外预应力桥梁有效预应力测试的应用进行了分析。通 过求解张拉索的动力微分方程，分析了边界条件对体外预应力筋固有频率的影响。分析结果 表明，固支边界条件下预应力筋的一阶频率比铰支边界大，二者的相对差随着预应力筋的张 拉力的增大而减小。而在张拉力相同的情况下，二者的相对差则随着索长的减小呈现非线性 增大的趋势。在实际测试当中，利用实测的预应力筋频率，仅能得到有效预应力的上、下限 值，实际有效预应力值介于二者之间。对于体外预应力筋这种长度较短的张紧索，利用频率 法测试其有效预应力还存在一定的误差。 关键词：桥涵工程；体外预应力；自振频率；有效预应力；边界条件 中图分类号：U446.1 Effective Prestressing Force Testing Method of External Prestressed Bridge Based on Frequency Method TAN Guojin, LIU Hanbing, WANG Longlin (College of Transportation ,Jilin University) Abstract: A practical project is taken for the example to analyze the application of frequency method in the effective prestress test of external prestressed bridge. In the process of solving the dynamic differential equation of tension cable, the effects of boundary conditions on the natural frequencies of external prestressed tendons are analyzed. The analysis results show that the fundamental frequency of the prestressed tendons under fixed boundary condition is higher than that under hinged-support support boundary condition, and the relative variance decreases with the increase of tensioning force. With the same tensioning force, the relative variance decreases with the increase of cable length. In the practical test, only the upper and lower bound limits can be obtained according to the measured prestressed tendon frequencies, while the real effective prestress values are between them. For external prestressed tendons, a kind of short tension cable, the frequency method can produce certain error in calculating the effective prestress. Key words: beidge engineering; external prestressing; natural frequency; effective prestressing force; boundary condition. 35 0 引言 体外预应力结构是指预应力筋(索)布置在桥梁梁体之外的一种预应力结构。近年来，体 外预应力技术在新建桥梁和既有桥梁加固中得到了广泛运用。体外预应力桥梁中的有效预应 力是决定该类桥梁能否安全运营的主要因素之一。由于施工因素的影响，预应力筋的预应力 40 设计值和实际的有效预应力之间的存在一定的差异。这种差异过大则会影响桥梁的服务能 力，甚至会导致桥梁事故[1]。因此，检测该类桥梁的有效预应力，对评估桥梁安全性能和加 固效果具有十分重要的意义。 基金项目：高等学校博士学科点专项科研基金（