Study On Responses Of No-platform-column Canopy In High-speed Railway Station Under Combined Actions Of Wind And Rain

With the rapid development of China's railway construction,a large number of high-speed railway stations have been built,and most of the new high-speed railway stations adopt the form of no-platform-column canopy.The no-platform-column canopy is a large-span spatial structure and its surrounding is not closed.It has the characteristics of huge volume,novel shape,complex shape and large space.Because of these characteristics,the stiffness and damping of the structure are lower,and the sensitivity to wind is more prominent.This requires a higher wind and rain resistance capacity to ensure the safety of the no-platform-column canopy.At present,the wind load is the main design load in the theoretical research and structural calculation of the no-platform-column canopy structure,and the existence of rainfall is rarely considered.In fact,strong wind and rainstorm are often accompanied by each other.These two kinds of loads will couple to form extreme loads,which will have a great impact on the no-platform-column canopy.Therefore,the impact of wind and rain on the no-platform-column canopy cannot be ignored.In this paper,the South no-platform-column canopy of Kunming south railway station is selected as the research example,and Midas Gen is used to establish a three-dimensional finite element model to analyze its dynamic response characteristics under different wind and rain time histories,and the influence of rain load on the no-platform-column canopy of high-speed railway station is obtained.This paper mainly carried out the following research:First of all,this paper summarizes the development process,structural form and corresponding advantages of the no-platform-column canopy,expounds the research background and significance of the no-platform-column canopy under the joint action of wind and rain load,and illustrates the significance of the research on the dynamic response characteristics of the no-platform-column canopy under the joint action of wind and rain based on the research status and development trend of the same subject at home and abroad.Secondly,according to the basic characteristics of the wind,the harmonic superposition method is used to simulate the fluctuating wind speed,and the simulation wind speed spectrum is compared with the target power spectrum to verify the accuracy of the simulation method.According to the actual situation of rainshed without column,the calculation method of wind load is established.Combined with rainfall intensity,raindrop number density,raindrop spectrum,raindrop occupancy and simulated wind speed,the impact force ofraindrops is analyzed and the calculation method of rain load is established.Then,Midas Gen is used to establish a three-dimensional finite element model of the no-platform-column canopy,and the natural vibration characteristics of the no-platform-column canopy are analyzed.The natural vibration frequency and mode shape of the no-platform-column canopy are given.According to the actual model of rainshed without column and the calculation method of wind load,the wind load time history data under condition I and condition II are obtained;and the rain load time history data under condition I and condition II are obtained by the calculation method of rain load.At last,the nonlinear dynamic analysis under the first and the second working conditions is carried out.The wind and rain load time history data are applied to the structure to analyze the wind and rain interaction.It is found that the rain load has an increasing effect on the RMS acceleration and the maximum displacement along the wind direction and in the vertical direction,so the rain load should not be ignored in the wind resistance design of the no-platform-column canopy;under the same wind speed,the RMS acceleration and the maximum displacement of the side span are greater than those of the middle span,and the RMS acceleration and the maximum displacement of the rain load are greater than those of the side span Span: at the same level of wind speed,the root mean square of acceleration in the downwind direction is larger than that in the vertical direction,and the maximum displacement in the downwind direction is smaller than that in the vertical direction.The influence of rain load on the root mean square of acceleration and the maximum displacement in the downwind direction of no-platform-column canopy is greater than that in the vertical direction.At the same level of wind speed,the root mean square of acceleration in the downwind direction and the maximum displacement in the downwind direction in condition I are greater than that in condition II and that in condition II are vertical In case of heavy rainfall,the influence of rain load in case I on the maximum value of acceleration in the vertical direction and displacement in the vertical direction is greater than that in case II,and the influence of rain load in case II on the maximum value of acceleration in the downwind direction and displacement in the downwind direction is greater than that in case I.