斜拉桥节段纵移悬拼法足尺模型试验研究

Experimental Study on Full-scale Model of Cable-stayed Bridge Using Sectional Longitudinal Transport and Cantilever Installation Method

为验证节段纵移悬拼工艺的可行性、合理性及可操作性,研究施工过程中结构的动力响应,以北盘江大桥为背景进行了足尺模型试验,试验工况涵盖了工艺中每个不确定的、有待验证的状态;并基于耦合系统动力分析理论,将结构简化为两自由度的弹簧-质量块振动系统,建立了试验过程大系统动力学方程进行理论计算,动力模型包含了5个典型动力状态,即地面提升、运梁小车纵向运输、运梁小车与桥机吊点协同前进、桥机吊点前移、桥机整体提升。研究结果表明:各工序下运梁轨道及主桁架测点加速度幅值较小,桥面吊机吊点前移时结构响应最为显著,桥面吊机端部最大加速度为0.212g;轨道梁测点的最大加速度方向为纵向,下弦杆测点的最大加速度方向为竖向,高速挡下轨道梁测点的纵向、竖向加速度实测幅值较低速档分别增大约54%,51%,下弦杆测点的纵向、竖向加速度实测幅值较低速档分别增大约31%,36%,轨道梁应力峰值在高速挡时也有所增大,跨度最大位置的测点对车速最为敏感;测点理论竖向加速度幅值、理论轨道梁应力峰值与实测值吻合较好,验证了理论模型的准确性;试验过程平稳且连贯性较好,节段纵移速度快、整体对接耗时少,较散拼法有较明显的工期优势。

In order to verify the feasibility, reliability and maneuverability of sectional longitudinal transport and cantilever installation technique, and investigate the dynamic response of the structure during construction, the full-scale model test is performed based on Beipan River bridge. The test conditions contain every state which is uncertain and need to be verified. Based on the dynamic analysis theory of coupling system, the structure is simplified into a 2-DOF spring-mass vibration system, and the system dynamic equations in the test are set up to obtain the theoretical result. The dynamic model includes 5 typical dynamic states, i.e., ground lifting, longitudinal transport by transport car, transport car and pickup point on erection crane moving forward together, pickup point on erection crane moving forward, and deck erection crane lifting. The result shows that （ 1 ） the acceleration amplitudes of the transport track and the main truss under each process is small, the dynamic response of the structure is most significant when the pickup point on erection crane moving forward, and the maximum acceleration of the erection crane end is 0. 212g; （2） the maximum acceleration direction of measuring points on track is longitudinal, the maximum acceleration direction of measuring point on lower chord is vertical, the actual longitudinal and vertical acceleration amplitudes of measuring points on track increased by about 51% and about 54% respectively when vehicles walked in higher gear, and the actual longitudinal and vertical acceleration amplitudes of measuring points on lower chords increase by about 31% and about 36% respectively when vehicles walked in higher gear; （3） the peak stress of the track also increased when vehicles walked in higher gear, and vehicles＇ speed has the most sensitive impact on the measure point that located in the biggest span. The theoretical vertical acceleration amplitudes and theoretical peak stress on track are well agreed with the measurement, which verified the accuracy of theoretical model. The test process runs smooth and it has good continuity, and the segmental longitudinal transport is fast and the segmental docking is less time consuming, this technique has a decided advantage in saving construction period than scattered assembling method.