Study On Dynamic Response And Damage Of Solar Greenhouse Skeleton Under Wind And Snow Load

With the increasing span of solar greenhouse structures,safety issues are increasingly being taken seriously.The different force points and ranges of the load acting on the solar greenhouse will have varying degrees of impact on the overall strength of the greenhouse.With the increasing deterioration of the global natural environment,deformation and damage to solar greenhouses are becoming increasingly common under extreme weather conditions such as strong winds and blizzards.In the load calculation of solar greenhouses,as wind and snow load is the main load in the design of greenhouse structures,the current treatment method for wind and snow load is basically based on the standard method,which is calculated as the equivalent static load.When equivalent to static load,the calculated results do not match the actual deformation of the greenhouse structure.Therefore,considering wind load as dynamic load and combining it with snow load can better reflect its true situation and reflect the impact of the greenhouse structure in the time domain.This article is based on nonlinear finite element theory,numerical simulation theory,and fatigue cumulative damage theory to conduct dynamic response and damage analysis of greenhouse structures under wind and snow loads.Based on the AR model theory,a wind speed time history simulation program was developed using MATLAB tools to simulate the wind speed time history curve acting on the fluctuating wind on the greenhouse structure,and the load time history that can be directly imported into the finite element model was obtained.In the snow load analysis,the snow load is selected according to the agricultural greenhouse load code,and two forms of snow load,namely uniform and non-uniform distribution across the entire span,are arranged and combined with wind loads at 90 ° and 270 ° wind angles to obtain four load distribution forms.Use ANSYS software to analyze the displacement response,acceleration response,and stress response of the greenhouse structure under the combined action of wind and snow loads.Perform rain flow counting on the stress results obtained from transient analysis,calculate the rain flow matrix within the specified simulation time,and obtain its mean stress,stress amplitude,and stress cycle number.Finally,based on the structural form of the greenhouse and the specifications,the S-N curve parameters were determined,and the Miner linear fatigue cumulative damage theory was used to calculate fatigue damage.Taking a solar greenhouse in Yangling area as an example,the study found that when the snow load is the same,the displacement response values of the greenhouse structure under the action of a 90 ° wind angle are greater than those under the action of a 270 ° wind angle.The displacement response value under non-uniform snow load(90 ° wind angle)on the front and rear roofs is 14.5% higher than that under uniform snow load(90 ° wind angle)on the front and rear roofs;The displacement response value under non-uniform snow load(270 ° wind angle)on the front and rear roofs is 44.2% higher than that under uniform snow load(270 °wind angle)on the front and rear roofs.The fatigue damage value of the greenhouse skeleton under non-uniform snow load at a 90 ° wind direction angle increased by 142.1% compared to that under uniform snow load.The results show that the maximum time displacement of each node under the combined action of dynamic wind load and snow load is much greater than the static displacement when the wind and snow load is equivalent to static load.This indicates that when the wind load is considered as dynamic load and combined with snow load,it is closer to the structural deformation status,and the calculation results will be more accurate.When studying the dynamic response of greenhouse structures under the combined influence of wind and snow loads,it is necessary to consider the type of wind direction angle and the uneven distribution of snow cover.When dynamic wind load and snow load act together,the fatigue damage value under non-uniform snow load at a 90 ° wind direction angle is the highest,and this load combination is the most unfavorable for greenhouse structures.