Construction Control And Cable Force Optimization Of Cable-stayed Bridge Built On Temporary Supports

Cable-stayed bridge is quite competitive in modern bridge due to its large span and beautiful line shape.Construction control is an important part in the construction of cable-stayed bridge.At present,there are few researches about the construction control of cable-stayed bridge by bracket method.In this paper,the author studies the reasonable construcing state of cable-stayed bridges built on temporary supports.For the cable-stayed bridge constructed by the second-round adjustment method,there is a problem that the tension and the tension sequence are determined by relevant experience.In this paper,the purpose is to solve the problems by establishing a corresponding mathematical model that the tension and the tension sequence are determined by relevant experience in the second pretension.And the purpose is to solve the problems of excessive stress in local locations and insufficient bearing capacity of temporary supports in the construction process.There are three main aspects including the frequency method for cable force measurement,the method for determining the cable tension of interlude reasonable state and the optimization method of tension sequence in the construction phase.The main contents and achievements are as follows:(1)Based on the vibration equation of tensile beam,the model of practical formula between the cable force and ?n is created,which can be used for any constraint conditions.Through numerical calculation,the function ?n is precisely fitted to a dimensionless parameter ? and the frequency order n.Finally,the improved formula for calculating the cable force is obtained.And a method for identifying the cable force using two cable tension to calibrate parameters is proposed for practical engineering.The formula and method are testified in actual engineering.Under non-ideal boundary conditions,the precision of this paper is less than 4% relative to the accuracy of other documents,which meets the requirements of construction control in actual projects.(2)For the second-round adjustment method,the state of one round of tension state is artificially determined.Using the displacement change which is minimal when the main girder is breaked away from brackets,the author solves the cable tension of interlude reasonable state.In this paper,the author unifies the optimization of the cable tension to the multi-objective optimizing mathematic model.The combination of square sum weighted method,the active set cutting plane method and finite element method is proposed to optimize interlude reasonable state.The optimization results showed that the main beam just get off the emporary supports and the bending moment is evenly distributed.(3)A function of profit and loss value is established about the number of main beams breaked away from brackets and construction costs according to the requirements of the optimization of tension sequence.In this paper,the optimization problem of tension sequence is attributed to the mathematical model of multi-objective and multi-stage optimization.Then it uses linear weighting method and main target method to convert the problem of multi-objective optimization into a mono-objective one.And the multi-stage problem is solved by using breadth-first search and dynamic programming method.Finally,a mathematical model of dynamic programming model is established.Combined with an example t o analyze the optimization,the force of the supports after optimization is reduced by 80%.(4)Low memory problems can occur when the problem is solved by using dynamic programming method.In this papar,the author applies mountain climbing algorithm to solve this problem and the tension sequence is optimized.Impacts of using the optimization method are also analyzed through example analysis.The optimization results show that the main girder and supports are safe under stress.This solves the problem of simply designing the tensioning sequence based on experience.