Research On The Construction Control Of Large Span Asymmetric Beam-arch Combination Bridge

With the development of construction technology, the traditional bridge construction control theory has been unable to meet the requirements of the more and more complicated modern bridge construction control. For the complex structure and various construction procedure of Beam-Arch Combination Bridge, the displacement and stress of the bridge changes with the various system conversions. It is of great significance in the research of construction control of the Beam-Arch Combination Bridge. In this paper, the construction control process of a(73.9+148+128+148+73.9) m continuous beam arch composite bridge is studied. The main research contents and conclusions are as follows.The finite element model of this bridge is established with considering the construction process of the bridge structure by the forward calculation method. The cumulative displacement and stress of the main girder and arch rib of each construction stage are obtained, and are compared with the design results. The parameters(concrete density and elastic modulus) of finite element model are refined according to the field test data during the construction process in order to improve the control precision. The finite element model is with high consistency with the construction process according the monitoring process resists, and can provide effective guidance for the construction.Aiming at the deficiency of GM(1,1) prediction model of grey theory, the background value and initial value of the GM(1,1) prediction model are refined by using least squares theory and automatic optimization. And the original sequence of the prediction is optimized by multipoint moving average, then an improvement construction grey control system of bridge is put forward. Compared with the traditional GM(1,1) model, the improved grey control system becomes more precise. Then applied to the linear control of the bridge, the ideal alignment is obtained.The influencing factors of stress control in construction control are analyzed, and the relative measures are adopted to weaken the temperature and theoretical calculation errors. Emphasized on the shrinkage and creep error analysis, the related theory of separation of shrinkage and creep on non-load strain measured strain is used to get closer to the actual value of stress. The MATLAB program is compiled to separate the shrinkage and creeping strain, and is applied to the bridge stress control, a more accurate results is obtained.Tension force of rod influences the stress state of the whole structure, it is necessary to determinate the tension force of rod to ensure that meet the requirements. The frequency method is the most widely used method to determinate of tension force of rod. The two deferent methods have an obvious difference on the rod force measurement of short rod. By measuring the basic frequency of the boom, the tension value of the boom is calculated by the two ends of the hinge method or both ends of the consolidation method. In actually, for the elastic stiffness of the short rod should not be neglect or simplified to consolidation. And the actual suspender constraint is elastic stiffness of elastic constraint. Therefore, this paper put forward a mothed based on the elastic boundary condition of multi frequency identification method for suspender tension, tear down the corresponding frequency equation and using the genetic algorithm to solve. The numerical examples and the accuracy of the method is verified.