Research On Structure Optimization And Engineering Control Method Of Asymmetric Self-anchored Suspension Bridge With Single Tower

Compared to ground anchored suspension bridge,the self anchored suspension bridge has saved the huge anchorage and anchored the main cable directly on the stiffening beam.The structure is beautiful and the span of the bridge is varied.It occupies a great advantage in the city bridge competition.However,due to the construction sequence and nonlinear construction process of the first girder and cable,the structural system has become a difficult point in the design and construction of this type of bridge.In this paper,a single tower unsymmetrical self anchored suspension bridge is combined to optimize the cable force of the full bridge sling first,then the influence of the temperature on the cable alignment and the control of the cable stringing precision under the state of the air cable are studied and discussed.Then the influence of the construction error on the cable clamp positioning and the unstressed length of the sling is analyzed.Finally,the suspension tension of the bridge is made.The design and optimization of the pull plan is carried out.The specific research contents are divided into the following aspects.1.In order to optimize the suspension force of the self anchored suspension bridge,the minimum bending energy method and the uniform mass method are used to first determine the constant load sling force,and then some unreasonable suspending forces are adjusted.Then the finite element model of the full bridge is set up by the finite element software,and the stress state of the bridge components is calculated and analyzed.The linear finite displacement method is used to calculate the enveloping graph of constant live load bending moment of stiffened beams.Finally,the feasible region of bending moment is drawn according to the internal force balance method,and the bridge state is checked and adjusted by using it until the required bridge forming state is obtained.2.On the basis of this,the relationship between the temperature and the sag is calculated by the parabolic analysis method,and the results of the finite element calculation are compared with the results of the finite element calculation,and the results of the parabola method are accurate enough to be used for the aerial cable erection.In the end,the construction control of the benchmark cable strands is studied.In order to accurately determine the temperature of the bridge environment and the temperature of the cable strands,the relevant temperature measurement scheme is formulated.Then,according to the measured temperature,the standard cable shares are adjusted to make the erection precision meet the requirements.3.Due to the fact that the measured air cable shape is not exactly the same as the theoretical empty cable shape,there will be some error between them.First,the error source is analyzed and determined,and the effect of the error on the bridge alignment is analyzed.According to the offset error of the main cable saddle,the height error of the main cable span is calculated.In order to ensure that the linear shape of stiffened beam is close to the design line shape,the position of the cable clip is re calculated and the length of the sling has no stress under the change of the line shape of the main cable.The vertical state of the sling after the bridge is kept,and the alignment of the stiffening beam meets the design requirements.4.First of all,according to the parameters of each component,the tensioning control principle is determined,and then 4 tensioning schemes are drawn up,one of which is to pull the whole bridge sling at one time,and the other schemes are optimized on the basis of this.Through the simulation analysis of each stage during the construction stage,the safety,construction period and economy of each plan are compared,and the optimal sling tension plan is finally determined.