Seismic Analysis Of Single-Layer Spherical Reticulated Shells With Semi-Rigid Joint

Concerning the design of spherical shells, usually, shells with weld-joint system are considered as rigid-joint system and shells with bolt-joint system are considered as pin-joint shells, so cannot be used in single layer spherical shells. In fact, bolt-joint has partial bend stiffness; it is semi-rigid system between rigid-joint and pin-joint. Further more, because of such shell's convenient construction, beautiful apearence and merit of engineering application, the pertinency study of the shells with semi-rigid system has important practice significance.Associate with lots of former studies, this paper summarizes the actuality on the single-layer reticulated shells with semi-rigid joint system and research methods on the dynamic behavior analysis of large span structures. The dynamic finite-element model of reticulated shells with bolt-joint has been set up based on bend stiffness of bolt-joint system in some literature. Then the theory of self-vibration characteristics analysis and time history analysis is summarized.The difference of self-vibration trait between semi-rigid reticulated shells and rigid reticulated shells is analyzed in detail, including the distribution of natural frequency and mode shape character. Then, the paper makes analysis on the self-vibration trait of reticulated shells at the parameters such as high-to-span ratio, load conditions, section size of bars, bend stiffness and span.The dynamic behavior of single-layer reticulated shells with semi-rigid joint system under small earthquake is analyzed with a large number of models using time-history analytical method. Based on the calculation method of seismic force coefficient considering axial stress and bending stress, the rule of seismic force coefficient of semi-rigid reticulated shells has been studied absolutely, including the influence of some parameters.In order to simplify the design process, the seismic force revised coefficient of shells with semi-rigid joint system is defined. Finally, suggested values of seismic force revised coefficient are given out.