基于频率法的理论计算吊杆索力研究

Theoretical calculation of suspender tension based on frequency method

为提高工程中吊杆索力计算精度,引入系杆拱桥吊杆一端铰支一端固支的边界条件,并考虑叉耳对吊杆振动的影响,采用能量法推导出吊杆索力和吊杆自振频率之间的显式表达式。在此基础上,进一步推导出考虑温度影响的吊杆索力和自振频率之间的显式表达式,依据温度修正计算吊杆索力值,并与设计索力值对比。以新城大桥为实例,利用本文方法与传统方法进行计算,并与大桥实测索力进行比较,本文方法计算结果与实测值更为接近;且采用本文考虑温度影响的计算式二次计算索力后,结果表明吊杆索力值随温度降低而增大。研究结果表明:采用本文方法计算吊杆索力能提高计算精度。

In order to improve the calculation accuracy of cable forces of suspenders in engineering,the boundary condition of one end hinged and one end fixed for the tied arch bridge is introduced,and the influence of the fork on the vibration is considered in this paper.The energy method was used to derive the explicit expression between the cable force of suspenders and the natural vibration frequency.On this basis,the explicit expression between the cable force and the natural frequency of the suspenders by considering the temperature influence was further derived,and the cable force of the suspenders was calculated according to the temperature correction,and compared with the design tension value.Taking the Xincheng Bridge as an example,the calculated results of this method are closer to the measured ones comparing with the traditional method.The results show that the cable forces increase with the decrease of temperature.The above results show that using this method to calculate the cable force of the boom can improve the calculation accuracy.