| In the dynamic construction process of bridge rotation projects,the working conditions are complex and changeable,and there are many influencing factors,so in order to ensure the safety and reliability of the bridge in the process of rotation,the monitoring of rotation construction is very necessary.Based on the construction principle of bridge rotation,the stability indicators of the monitoring system in recent years have been analysed and the reliability and real-time monitoring of the bridge rotation has been found to be inadequate.This paper takes the stability of T-shaped bridges in the process of rotation as the research object,and uses intelligent control theory as the research method to put forward the demand for better monitoring functions and design a new rotation monitoring system.Firstly,the risk system of the rotation is analysed.Firstly,in order to further precise rotational speed monitoring of the turning body,the acceleration threshold index is derived from the effect of the accelerating phase of the turning body construction on the girder structure,enriching the risk monitoring term of the turning body over speed.Secondly,in order to monitor the stability indicators of the rotating structure,the theory of overturning angle and critical moment of the bridge rotating structure is studied,and fuzzy theory is used to fuse the two indicators.To address the problem that the critical moment cannot be collected and measured directly,this thesis proposes to use the ball-joint stress difference method with the ball-hinged rotation test method to complete the dynamic collection of the unbalance moment during the rotation process.Secondly,in accordance with the newly proposed functional requirements of the monitoring system,a general scheme for the integrated ball joint was designed for the lower computer,a modular ball joint acquisition box was built,and the installation locations of the individual sensors were also planned for the layout,laying the foundation for the software design of the upper computer.Then,based on the derived threshold theory and the built hardware acquisition system of the lower computer,the general design of the upper computer of the bridge rotation construction anti-overturning monitoring system is proposed.Based on LabVIEW,it completes the consistency check of multi-sensors and the weighted fusion of multi-sensors,realises the monitoring of acceleration by integrating the calculation of displacement sensors,realises the monitoring of critical moments by the stress difference method with the help of formula nodes,designs the fuzzy controller to realise the dual-input fuzzy inference of the unique integrated overturning hazard value,and realises the embedded time series prediction model by using MATLAB hybrid programming technology.Finally,the results show that the least squares method outperforms the BP neural network method in the prediction of displacement,velocity and tilt angle,with the prediction model having a minimum goodness of fit of 0.887 and a maximum of 0.999;at the same time the sampling interval is upgraded to 50 ms and the sampling density is improved.The overturning factor was upgraded from a single factor of deflection angle to two factors of deflection angle plus unbalance moment,and the risk of overspeed was extended from velocity to both velocity and acceleration.The system is capable of fulfilling the basic requirements of bridge rotation monitoring and visualisation,realising the interaction between human and machine information such as data visualisation,overturning alarm,3D attitude visualisation,etc.The system has been verified and tested for each functional module of the bridge rotation construction anti-tilt monitoring system.In the future,the system can also be extended by replacing the 3D model to monitor the rotation of cablestayed bridges,extending the hardware channel to monitor the cable force,and iterating and upgrading the algorithm to expand into a common rotation monitoring system for the industry. |
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