Reasonal Suspender Force And Stretching Optimization Of Multi-span Prestressed Continuous Beam-Arch Composite Bridge

With reasonable force structure, beautiful and novel shape, good economic performance, highly adaptable to foundation, and many other advantages, beam-arch composite bridge has becoming one of the chief types of 60-200m span range in modern bridge engineering. Derrick is the key active force-transfer component in the complex structure system, its construction procedures and tension directly affect reasonable structure situation of internal force and figure in the bridge state. Therefore, making detailed research and analysis which is about the rational suspender force and stretching optimization of this type of bridge is particularly important.The paper is based on the Wolonghe bridge as the engineering background, and based on suspender force optimization theory, through finite element simulation calculation of the construction period, determines reasonable final hanger force and derrick force under construction, optimizes the tensioning sequence of derrick, and researchs derricks force variation in construction period and tension control error, the main contents include:1. Through finite element simulation and calculation, adjust and optimize final hanger force, and determines reasonable final hanger force by minimum bending energy method and influence matrix principle. We adopt normal assembly method and influence matrix adjustment principle to determine suspender tension in different stages of suspender tension. And analyze the stress and displacement of structure. The calculation results show that according to the certain tension force and construction process, main girder and arch rib have reasonable force and small vertical deformation, and structure achieves the reasonable force and figure in the bridge state.2. Through finite element simulating calculation of different derrick tensioning sequence, contrastively analyze the change of internal force and figure which is critical part of main girder and arch rib under various tensioning procedure. The results show that we adopt the sequence to construct uniformity and symmetry all spans suspender tension in longitudinal direction, it ensures construction safety and behavior rationality of main girder and arch rib during the construction process, optimizes the tensioning sequence of derrick. The sequence is that according to the direction from small span to large span, we conduct suspender tension in 1/4 span and conduct suspender tension in the midspan. And it also verifies the tensioning sequence of derrick what is adopted to determine reasonable derrick force under construction in this paper is reasonable.3. On the basis of the identified derrick tensioning sequence and tensioning force in each stage, research and analyze derrick force change in stages of suspender tension and the influence degree of structure result in the bridge state under different derrick force accidental error and system error. So we obtain changing rule of derrick force, and if we control derrick force error within 15% in the boom tensioning construction, it will have smaller effect on linear and internal force of structure in the bridge state and control effect is remarkable. Finally, structure achieves the more ideal linear and internal force in the actual bridge state.