Analysis Of Mechanical Characteristics And Design Parameters Of A Single-span Asymmetric Suspension Bridge

On the basis of China's economic development needs and the continuous improvement of bridge construction technology,more and more large-span suspension bridges have been constructed in China.Especially in the mountainous areas of the Southwest Plateau,the suspension bridge has become the preferred bridge type for long-span bridges due to its super spanning ability and beautiful structure.In order to adapt to the special engineering terrain environment of plateau and mountain areas,asymmetric suspension bridges have appeared constantly.In order to explore the relevant mechanical characteristics of this type of bridge,this paper uses an asymmetric single-span suspension bridge with an asymmetric main cable side span and a high-asymmetric main tower as the engineering background.The static and dynamic characteristics of the asymmetric suspension bridge and the symmetrical suspension bridge are studied.Finally,based on the asymmetric suspension bridge,the side span of the main cable of a single-span suspension bridge is optimized with the goal of maximizing the stiffness of the main cable of the side span.The main research contents and conclusions of this article are as follows:?1?Research shows that under various loads,the internal force variation of the bridge is consistent with the characteristics of long-span single-span suspension bridges;When the structural asymmetry sensitivity parameter?₁is changed in the range of-0.3788?0.3636,it has almost no effect on the stress and unstressed cable length of the left and middle spans of the suspension bridge;With the increase of the asymmetric sensitivity parameter,the internal force of the main cable saddle across the middle side of the main cable and the left side of the main cable saddle on the side of the main cable increased linearly,while the right side of the main cable saddle on the side of the main cable increased It changes linearly,with a rapid decrease in the early stage and a slow decrease in the later stage,with an exponential development trend.?2?The research shows that the fundamental frequency of the background bridge accords with the vibration law of the flexible structure system of a general long-span suspension bridge;When the asymmetric sensitivity parameters of the side span are within a certain range,the influence of the asymmetric structural characteristics on the natural vibration characteristics of the suspension bridge can be ignored when rough estimates of low-order vibration frequencies;The change of the main cable's vector span ratio is sensitive to the natural frequencies of the first-order positively symmetric transverse bending and the first-order antisymmetric vertical bending than the first-order anti-symmetrical transverse bending and the first-order positive symmetrical vertical bending natural vibration frequencies;The asymmetric suspension bridge's first-order longitudinal drift,first-order positive symmetry,and antisymmetric vertical bending natural vibration frequency are basically not affected by the stiffness of the main tower,and the change in the stiffness of the main tower has a greater effect on the side-oscillation frequency of the tower than on the first-order positive symmetry and The influence of anti-symmetric transverse bending natural vibration frequency is large;The change of the overall stiffness of the stiffening beam has a more significant impact on the lateral stiffness of the suspension bridge,while it has a smaller effect on the vertical stiffness of the structural system;As the height of the pylon decreases,the overall stiffness of the structure increases,but the increase in stiffness is small.When the asymmetric parameters of the pylon change within a certain range,its effect on the overall stiffness of the suspension bridge is not significant.?3?The research shows that the axial stiffness of the main cable of the suspension bridge is related to the effective area of the main cable,the load concentration,the elastic modulus,the sagittal height of the main cable,the height difference between the saddle and anchor cable saddle and the inclination of the main cable;When the effective area of the main cable,load concentration,elastic modulus,sagittal height of the main cable and the height difference between the tower saddle and the anchor cable saddle are constant,there is an optimal value for the inclination of the main cable at the side span,which makes the axial rigidity of the main cable the largest.