Dynamic Analysis Of Reticulated Shell Under Impact Loads And Earthquake

Because of its beautiful appearance, reasonable force, and large coverage space and other advantages, shell structure is used more and more widely in the buildings where is usually crowded with lots of people, such as various exhibition halls, railway stations, gymnasium and landmark special structures. And the security issues caused by the application of shell structure attract more and more attention. Especially after the9.11terrorist attacks, the analysis of shell structure under accidental or sudden impact load has very profound significance. At the same time, China is an earthquake-prone country and in recent years, Yushu and Wenchuan earthquakes have caused serious damage, so the aseismatic and vibration reduction problem of the spatial structure becomes much more prominent.This paper, at first, summarizes several common forms of impact loading, including the half-sine impact loading, rectangular impact load, impact load of jagged triangle, isosceles triangle impact load, trapezoid impact load and so on, and analyses of the factors of impact load:the impact load wave, impact load amplitude and time.The paper uses finite element analysis software ANSYS to analyze impact load’s effect on shell structure, and study the effect of load waveform, duration, and structural design parameters. And it draws the following conclusions:the larger area surrounded by shock wave-shaped, the more intense the reaction is; the larger the impact load magnitude is, the longer the impact time is, and the greater the structure reacts; the larger the span of the shell structure is, the greater the structure reacts; the larger the span ratio is, the less the structure reacts; the reaction of the shell structure without defects is less than that of the defective one; the higher the degree of structural safety is, the less the structure reacts; the heavier the roof loads, the less the shell structure reacts.Then, this paper studies the vibration reduction of shell structure by replacing double spherical shell structure in some parts of bottom chords with damper. And there are several conclusions as follow.(1) Damping vibration reduction method of replacement rods has good control effect on double-layer reticulated shell structure of the node displacement.(2) The stiffness of damper rods has little control effect on structure and the damping rod with different damping coefficients has quite different control effects on structure dynamic response.(3) Damping control can not improve the critical load of reticulated shell; the maximum node displacement of suspension structure reduces greatly and damping method has good control effect on its deformation; the limit load has been improved and the integral structure dynamic performance has also been improved greatly; based on the plastic development status analysis of reticulated shell structure dynamic process, it is known that the seismic amplitude of reticulated shell structure’s entering the plastic state has been improved greatly after the vibration reduction.