弹性阻尼支撑装置设计及性能试验

Design and Experimental Study on Elastic-damping Support Device

为克服两端刚接的大跨度钢箱梁桁架式纵隔板斜腹杆疲劳性能不足,提出一种弹性阻尼支撑装置(Elastic-damping Support Device, EDSD)。其主要原理是将已开裂斜腹杆局部切除后安装EDSD,通过端部铰接消除斜腹杆次内力,通过阻尼元件耗散斜腹杆在荷载作用下的伸缩变形能量,通过弹性元件控制桥面板竖向变形量,实现外载输入能量的合理分配。在大跨度斜拉桥正交异性钢箱梁运营期,经合理设计的EDSD可以有效消除其桁架式纵隔板斜腹杆端部疲劳裂损病害的发生。为探明EDSD的静力特征和滞回性能,制作了3个试件进行静动载试验研究。结果表明:(1)EDSD的刚度在静载加载时呈线性,约为206 kN/mm;而卸载时呈非线性,且刚度先大后小。卸载刚度值变化拐点出现在位移量±1.3 mm处,变化前后的刚度值分别约为508 kN/mm和90 kN/mm。(2)EDSD是一种与加载速率无关的非线性位移型阻尼支撑装置。(3)动载试验中随着位移幅值的增加,EDSD单位循环耗能以二次多项式规律不断增大,等效刚度以乘幂规律不断减小,等效阻尼比线形增大。(4)50 000个加载循环后的EDSD单位循环耗能比初始值下降了8%,等效刚度比初始值下降了8%,等效阻尼比基本保持不变。工程实践表明,研制的EDSD装置可有效增加纵隔板疲劳寿命,施工及维护便捷,桥梁全生命周期内的运维综合成本约为现有技术的70%。

To overcome the insufficient fatigue performance of diagonal web members of long-span steel box girder truss-type diaphragm with rigid connections at both ends,the elastic-damping support device(EDSD)is proposed.The main principle is to install EDSD after partially removing the cracked diagonal web members,to eliminate the secondary internal force of diagonal web members through end hinge connection,to dissipate the expansion and contraction deformation energy of diagonal web members under load through damping elements,and to control the vertical deformation of bridge deck through elastic elements.It will achieve the reasonable distribution of external load input energy.The properly designed EDSD can effectively eliminate the fatigue crack damage at the ends of diagonal web members of orthotropic steel box girder of long-span cable-stayed bridge during its operation period.Clarifying the mechanical properties of EDSD is the necessary prerequisite for the rational design.To investigate the static characteristics and hysteretic performance of EDSD,three specimens were made for static and dynamic load tests.The result indicates that the stiffness is linear during static loading,approximately 206 kN/mm,and is nonlinear during unloading with the unloading stiffness value first increasing and then decreasing.The inflection point of unloading stiffness value appears at the displacement of±1.3 mm;and the stiffness values before and after variation are approximately 508 kN/mm and 90 kN/mm respectively.The EDSD is the nonlinear displacement-type damping support device,which is independent of loading rate.In the dynamic load test,as the displacement amplitude increasing,the energy consumption per unit cycle of EDSD continuously increases according to the quadratic polynomial.The equivalent stiffness continuously decreases according to the power method.The equivalent damping ratio increases linearly.After 50000 loading cycles,the energy consumption per unit cycle of EDSD decreases by 8%compared with the initial value.The equivalent stiffness decreases by 8%compared with the initial value.The equivalent damping ratio remains basically unchanged.The engineering practice shows that the developed EDSD device can effectively increase the fatigue life of diaphragm.It is convenient for construction and maintenance.The comprehensive cost of operation and maintenance during the entire life cycle of bridge is approximately 70%of the existing technology.