Practical Formulas to Calculate Suspender Tension Based on Frequency
-
摘要: 为了分析频率对吊杆张拉力的影响,根据吊杆的振动力学特性,考虑到吊杆在振动过程中处于动平衡状态,建立吊杆的运动偏微分方程,推导出考虑抗弯刚度、转动惯量、剪切变形、转动惯量和剪切变形耦合影响下频率与索力的计算公式.通过不同吊杆长度及各自不同阶频率进行对比及频率差拟合分析,分析认为通过高阶频率差求基频会造成基频值识别变大,从而导致索力识别值偏大,得出基于一阶频率的频率修正值,同时得出了索力计算实用公式.通过算例,分析对比了弦振动公式、考虑抗弯刚度公式和本文公式.计算表明:采用实用公式确定的索力与实际张拉力相比,误差可控制在5%以内.证明了实用公式的正确性和实用性.Abstract: In order to analyze the influence of frequency on suspender tension, a partial differential equation of motion is established for the suspender according to its vibration mechanical properties and dynamic equilibrium. Then, a computational formula for the frequency and suspender force is built taking into account the influence of flexural rigidity, rotational inertia, shear deformation, and the coupling of rotational inertia and shear deformation. Comparing frequencies of different orders and fitting frequency difference for various lengths of suspenders leads to the finding that the fundamental frequency worked out using high-order differential frequency will contain a positive error and thus causes a positive deviation in the cable force. On this basis, the modified value for the first-order frequency is then obtained and practical formulas for calculating the cable force are proposed. In a case study, the proposed formulas are compared with the string vibration formula and the formula that takes the bending stiffness into consideration. The result show that using the practical formulas, the error between the calculated suspender tension and the measured value is no more than 5%, which validates the practical formulas.
-
Key words:
- bridge projects /
- suspender /
- coupling effects /
- frequency /
- suspender force /
- practical
-
RUSSELL J C,LARDNER T J. Experimental determination of frequencies and tension for elastic cables [J]. Journal of Engineering Mechanics, ASCE, 1998, 24(10): 1067-1072. KIM B H, PARK T. Estimation of cable tension force suing the frequency-based system identification method CEBALLOS M A,PRATO C A. Determination of the axial force on stay cables accounting for their bending stiffness [J]. Journal of sound and Vibration, 2007, 304(3/4/5): 660-676. MA Haitao. Exact solutions of axial vibration problems of elastic bars MEHRABI A B, TABATABAI H. A unified finite difference formulation for free vibration of cables 孙永明,李惠. 端部性质对频率法测量竖直拉索索力影响分析 [J]. Journal of sound and Vibrationg, 2008, 317(1/2): 127-141. 孙永明,孙航,任远. 频率法计算匀质竖直拉索索力的实用公式 [J]. International Journal for Numerical Methods in Engineering, 2008, 75(2): 241-252. ZUI H, SHINKE T, NAMITA Y. Practical formulas for estimation of cable tension by vibration method 任伟新,陈刚. 由基频计算拉索拉力的适用公式 ARMIN B, HABIB T. Unified finite difference formulation for free vibration of cables [J]. Journal of Structural Engineering, ASCE, 1998, 124(11): 1313-1322. 田广宇,郭彦林,张博浩,等. 车辐式屋盖结构的一种索力识别方法的误差研究 [J]. 工程力学,2013,30(8): 10-17. SUN Yongming, LI Hui. Effect of extreme properties of vertical cable on the cable force measurement by frequency-based method YOZO Fujino. Design formulas for damping of a stay cable with a damper 刘钊. 基于能量法的系杆拱桥最优吊杆内力的确定 [J].Engineering Mechanics, 2013, 30(8): 10-17. NAM Hoang, YOZO Fujino. Analytical study on bending effects in a stay cable with a damper [J]. 工程力学,2013,30(4): 211-218. SUN Yongming, SUN Hang, REN Yuan. Practical formulas to calculate tensions of vertical cable with uniform properties by frequency method 张戎令,王起才,马丽娜,等. 考虑转动惯量和剪切变形耦合的铰接吊杆索力实用计算公式 [J]. Engineering Mechanics, 2013, 30(4): 211-218. [J]. Journal of Structural Engineering, ASCE, 1996, 122(6): 651-656. [J]. 土木工程学报,2005,38(11): 26-31. REN Weixin, CHEN Gang. Practical formulas to determine cable tension by using cable fundamental frequency [J]. China Civil Engineering Journal, 2005, 38(11): 26-31. [J]. Journal of Structural Engineering, 124, 11: 1313-1322. [J]. 工程力学,2013,30(3): 126-132. TIAN Guangyu, GUO Yanlin, ZHANG Bohao, et al. Research on error of a cable force estimation methodfor spoke structural roofs [J].Engineering Mechanics, 2013, 30(3): 126-132. [J]. Journal of Structural Engineering, 2008, 134(2): 269-278. [J]. 工程力学,2009(8): 168-173. LIU Zhao. Determination of the optimal hanger forces for tied-archbridges based on energy methods [J]. Engineering Mechanics, 2009(8): 168-173. [J]. Journal of Engineering Mechanics, 2007, 133, 11: 1241-1246. [J]. 中国铁道科学,2014,35(5): 30-37. ZHANG Rongling, WANG Qicai, MA Lina, et al. Practical formulas for cable force of hinged suspender considering the coupling effects of moment of inertia and shearing deformation [J]. China Railway Science, 2014, 35(5): 30-37.
点击查看大图
计量
- 文章访问数: 1632
- HTML全文浏览量: 81
- PDF下载量: 474
- 被引次数: 0