Research On Mechanical Behavior And Strengthening Method Of Existing Double Hyperbolic Paraboloid Shell Structures

Shell structure is widely used in civil and industrial building. With the time going, the design codes and analysis methods are improved, the bars are rusty, and the loads are changing. Thus, it is much necessary to research the mechanical behavior and strengthening method of existing shell structures in actual projects.In this paper, the analysis methods of existing shell structure are introduced, and the strengthening methods of steel structure are detailed. On the basis of these theories, The specific project—the hyperbolic paraboloid shell structure named Shijingshan Gymnasium is introduced, and the finite element model is established, including calculation of load, simplification of node nature and simplification of support.The structure is analyzed on the aspects of static and dynamic, then the unallowable components will be found. The dynamic analysis is processed with Elcentro wave of United States, seismic records of Tianjin, China (1976) and a group of artificial acceleration-time curve. The acceleration peak is adjusted in accordance with 8 degrees district. The time-history results are compared to the response spectrum results. In the process, the impacts on the self-vibration characters by joint stiffness and support stiffness are discussed, and the effect of damping ratio on the time-history response of the structure is analyzed.After analysis, there are two kinds of problems in the structure: the strength of some bars is inadequate and the stiffness of some bars is not enough.Based on the strengthening principles, the intensity of bar is increased with methods of unloading and FRP. The Approach of changing structure's force system-additional braces is used to change the slenderness ratio of bars. The changes of structure's internal force are detailed in the process of unloading and after changing bars. The effects on bars' buckling load by FRP paste length and thickness are analyzed and the needed length and thickness in the structure is provided.After reinforcenment, the structure is analyzed again, and the results indicate that: both of the strength and the stiffness meet the requirments.