The Nonlinear Stability Analysis On Single-layer Spherical Reticulated Shell Considering The Effects Of Different Initial Imperfection And Temperature

Due to shell structures’ advantages such as light self-weight, beautifulappearance, ability to shape large space, they are generally the first choice ofdomestic and foreign architectures when designing a building. However, shellstructure, especially single layer spherical reticulated shell structure, as its spangetting larger and larger, the stability analysis have becoming more and moreimportant for engineers.To investigate the modeling and FEM analysis of a single layer sphericalreticulated shell structure, this paper developed a series of program with APDLlanguage using international advanced FEM software, ANSYS. And it came up witha series of load-deformation curve of shell structure considering the influencefactors such as initial imperfection and temperature. Furthermore, the structure’sloading capacity, stiffness, strength and its full process’s mechanical characteristicwere suggested.In addition, with different initial condition and asymmetric load distributionbeing considered, the shell structure’s parametric non-linear stability analysis hadbeen carried out. These variables could affect structure’s buckling form, ultimatebearing capacity and failure mode. Here are the conclusions: Firstly, initialimperfection had a very important affection on shell structure. Secondly, whenconsidering material nonlinearity, there was a very significant decline of shellstructure’s bearing capacity, which indicated that material nonlinearity is importantto consider. Thirdly, asymmetric load distribution had no obvious affection on singlelayer spherical reticulated shell structure’s elastic-plastic bearing capacity. Lastly,comprehensive analysis on shell structures’ buckling form showed that ideal anddefect structures’ buckling first developed in the main rib. For ideal structure, thefailure happened at the second and forth rings. For the defect structure, it happenedat the first and second ring. Moreover, grid density had no obvious affection tosingle layer spherical reticulated shell structure’s modal analysis results.This paper also had studied temperature’s affection to single layer sphericalreticulated shell structure’s stability. Considering different negative temperature,static analysis, linear stability analysis and non-linear stability analysis had beencarried out. Here are the conclusions: Firstly, the influence of temperature mainlyfocused on the axial force of the shell structure’s bars which was close to the support area. For those which were more far away from the support area, the temperaturehad less affection to them. Secondly, due to the increase of negative temperature, thebearing capacity of single layer spherical reticulated shell structure would decrease.Thirdly, when considering material nonlinearity, the elastic-plastic and elasticbearing capacity of single layer spherical reticulated shell structure would decrease.That means we need to consider the influence of material nonlinearity whendesigning shell structure, otherwise it would be not safe. Lastly, due to the absolutevalue of negative temperature difference getting bigger, for single layer sphericalreticulated shell structure which had considered elastic analysis and elastic-plasticanalysis, it came out that its bearing capacity would be negative. And when thenegative temperature increased, the absolute value of shell structure’s bearingcapacity increased. The reason was when the negative temperature was considerable,downward displacement occurred in single layer spherical reticulated shellstructure’s local position. So the suggestion was that engineers should take properactions to provide a certain upward force (the force value should be calculated) inthe main node to eliminate the negative effects of negative temperature difference.