Study On The Performance Of Special-shaped Footbridge Under Wind Load

With the development of economy and technology and the improvement of bridge design level,the design of urban pedestrian bridge not only widely applies new materials,new bridge types and new construction techniques,but also pays more attention to the aesthetic characteristics of the bridge in order to meet the increasing aesthetic requirements of people.Therefore,pedestrian bridges with unique shapes and novel structures often appear in busy cities.At the same time,with the improvement of life quality,people's requirements for footbridges are not limited to safety,but also put forward higher requirements for the sense of experience and comfort.However,this kind of landscape footbridge has large flexibility and small damping,and it is easy to generate large vibration under external load excitation,which makes the comfort problem increasingly prominent.However,there are currently few studies on vibration comfort in addition to crowd excitation loads.In this paper,a special-shaped footbridge in Shenzhen urban area with strong typhoon landing is used as the engineering background.The performance and comfort of the bridge under the wind load is studied.The main work and conclusions are as follows:1.Through the AR model of linear filtering method,the simulated pulsating wind field program is programmed with MATLAB.The pulsating wind speed time history of the bridge is obtained by combining the actual environmental parameters of the bridge site,and the accuracy of the program is verified by the power spectral density function and correlation function.And the effectiveness of the wind field simulation.2.The numerical simulation of the three-component force coefficient of the section is explored,and the numerical model parameter setting method suitable for the bluff body section is obtained.The feasibility of the method is verified by comparing the numerical simulation results of the main beam of the Jinma Bridge with the wind tunnel test data.Finally,the numerical simulation of the three-component force coefficient of the heterogeneous footbridge is carried out,and the variation of the cross-section and the angle of attack with the wind are obtained.The variation of the three-component force coefficient of-6°~+6°.3.The ANSYS finite element three-dimensional model of a special-shaped footbridge was completed,and the full-bridge dynamic characteristics analysis,static wind response analysis and buffeting response time domain analysis considering the influence of aerodynamic admittance were carried out.4.The variation of peak acceleration and root mean square acceleration of a special-shaped footbridge at-6°~+6° wind angle of attack is obtained by ANSYS.The comfort of the bridge is evaluated and graded by national codes.The results show that The bridge meets most of the specifications for comfort evaluation limits,but is generally comfortable and moderately comfortable.5.Combined with the regulations of national standards on comfort,this paper puts forward some reference opinions on the design rules of China's footbridges,and proposes a multi-level fuzzy comprehensive evaluation comfort model,which realizes the quantitative analysis of comfort under the consideration of various fuzzy factors.Through this evaluation model,a profiled footbridge scored 0.87 and the comfort was good.6.By designing the TMD system,the lateral vibration of the special-shaped footbridge is obviously suppressed,and the damping rate is 38.5%,which indicates that the reasonable design of the TMD damping scheme can effectively improve the performance of the heterogeneous footbridge under wind load.