Research On Dynamic Stability Of Spatial Latticed Structures

Large-span Space Latticed Shell Structures are used more and more in people's lives and industrial productions for they are aesthetically appealing with layout flexiblty and can satisfy the requirement of large space. Structural vibration control theory and method provides the technical support for solving the instability problem of large-span space latticed shell structures under seismic and other dynamic loads. Based on the implication of modern control theories, the use of new intelligent materials, and the integration of self-perception, self-judgement, self-diagnosis, and self-control functions together, active control is able to executive self-adaptive control on structures, and represents one of the directions of structural development in the future. Space reticulated shell structure has been a much-talked-about structure form, main characteristic is to make full use of material properties, adapt to the change of construction sculpt, need, and spatial dome structure is reasonable, light weight, force the low cost and lively form novel, can highlight human art creativity, etc. With the development of science and technology, this kind of earthquake is more and more big, the span, research shows that sensitivity strong spatial dome structure on the sensitivity of the earthquake as top and towering structure and long-span Bridges. Combination with structural vibration control results and large space reticulated shell structure characteristics, choose a feasible way to control vibration, spatial dome structure large-scale structural vibration control research, it is a kind of ideal way of studying, also is very necessary.This paper also introduces the active control technology in civil engineering structure damping control application, established the nets shell structure of the active control model, and only to build intelligent network shell model, analyzes the characteristics of the fuzzy control algorithm, design the lut type fuzzy control system, and puts forward the whole structure of local vibration control, thus reach on the structural control strategy. And in the Matlab environment of intelligent reticulated shell structure, active vibration control simulation research, the simulation results confirm when space reticulated shell by EL Centro wave structure, incentive effect by this control method can effectively restrain the reticulated shell structure vibration.After that, the intelligent algorithm based on the fuzzy control theory and the modal control method are both used to launch the theoretical study and experimental verification of active control on the dynamic stability of space latticed shell structures. The innovations of this research are as follows:(1) It makes a quantitative analysis on the random process of seismic shock with the signal processing method. First, it fits random seismic waves for mathematical functions and builds the finite-element model, unifying vibration and stability of the space structures. Then, it studies the dynamic stability of space structures from the persective of structural performance under dynamic actions quantitatively and further summarizes all intervals of dynamic instability of the structures. On the basis of these discussions, it finally explores the causing factors of the structual dynamic instability.(2) It analyzes the seismic shock's space coherence influence appearing in the aseismic design of large-span space structures by making use of advantages of both the random vibration theory and the time history method. Based on both 'the power spectrum model which is of statistical sinificance and the coherence model of the seismic shock, the time history curve which takes the space effect of the shock into considerartion and which is suited for time history analysis is attained. Relevant analysises are followingly made on different structural forms. Finally, it summarizes the law behind the structural dynamic instability.