Wind Induced Stochastic Stability Analysis Of Double-Layer Cylindrical Reticulated Shell Roofs

The large span roof structure is widely used in engineering construction due to it's fashionable and attractive shapes and good mechanical properties.As the wind-sensitive structures tend to be more flexible,it's necessary to establish a more perfect method to study the effect of stochastic wind load on the stability of real large span roof structures,the analysis theory of wind induced dynamic stability of long-span roof structures ought to be more perfected.This paper intend to explore and analyze the wind-induced random dynamic instability of large span roof structure through theoretical derivation,numerical analysis and experimental testing.The double layer cylindrical lattice shell roof structure is taken as the engineering background,and the correlation effect was introduced based on the stochastic dynamic stability theory,and the fluctuating random wind load acting on the large-span roof structure was simulated as ergodic process,follow Hooke's law and the assumption of flat section in material mechanics,according to Schwarz inequality,the stochastic stability boundary equation of components under the action of fluctuating wind random load is derived.Then the wind load model is introduced into the stochastic stability theory of large wind sensitive structures through wind tunnel tests based on the derived stochastic wind vibration stability algorithm formula which is suitable for large wind sensitive structures,the dynamic stability of the structure under stochastic wind load is tested by means of excitation test and wind tunnel test.The engineering application method is established through practical structures based on the theory of wind-induced random stability of structures,it provides theoretical and technical support for the calculation of wind resistance stability of large span roof structures.The main conclusions of this paper are as follows:(1)The main parameters that affect the dynamic stability of long-span roof structures are damping ratio,elastic modulus,mean wind load,mean square root and section size of components.Among them,increasing the section size is most beneficial to improving the random stability of the structure.(2)Under different wind directions,the stochastic stability and static stability of roof members are different significantly.The bars with smaller static stability are unstable under the dynamic disturbance of wind load.(3)Under strong winds,the upper and lower surfaces of the long-span roof structure are subjected to the wind induced combination of "top suction bottom roof",making the roof top andsurrounding areas more vulnerable to wind induced damage.Although the top receives the wind's suction,but for the double-layer reticulated shell,the roof surface of the suction still causes partial compression of the bar.(4)Although the relation between damping ratio and random buckling critical load is linear,the relation between damping ratio and the number of unstable bars is nonlinear.A small reduction in damping ratio will result in a large increase in the number of bars,and the instability of the bar area along the roof top diffusion.(5)90° direction of buckling under bar along the axial symmetric distribution on the roof,instability area are mainly distributed on the roof surface.135° direction instability of pole number most in the most unfavorable wind direction,and the concentration of instability in the corners at the top of the roof and windward surface.180° direction is the most stable state,the instability of bar at least,and the distribution in the entrance to the edge of the roof.