| The appearance of retractable roof structure breaks the boundaries between traditional indoor space and outdoor space.It can be converted between indoor environment and outdoor environment according to the use function and weather conditions,making the stadium more flexible,more functional and more comfortable.However,the emergence of new systems and new models not only makes architectural works unique,but also makes it difficult to summarize the structural forms.Retractable roof structure has movable characteristics,and its design involves many disciplines such as architecture,structure,machinery,automation control,etc.Compared with ordinary long-span space structure,its technical complexity is much greater.At present,there are many research results on key technologies such as design and construction of retractable roof at home and abroad,but the traditional research on retractable roof system is basically aimed at the static state of fully open,fully closed and semi-closed.In fact,the upper movable roof is a low-speed,heavy-duty movement process in the process of opening and closing.The excitation of wheel-rail vibration and collision has a great impact on the force and deformation of the structure in the process of moving.The research on the collision mechanism of large retractable roof system based on the concept of moving structure is still scarce.Firstly,the method of converting Foldable Bar Structure(FBS)based on Hoberman element into Radially Retractable Plate Structures(RRPS)is introduced.After determining the open-close mode and wheel-rail arrangement method,the motion characteristics of movable roof in the process of opening and closing are studied.Then,the finite element analysis model is constructed.The refined wheel-rail model considers track irregularity,wheel-rail friction,wheel-rail contact and other factors.The wheel-rail contact characteristics are investigated by using dynamic theory.Based on the basic theory of NURBS,Grasshopper modeling method and isoparametric meshing method,the reticulated shells with different shapes are constructed.Based on the theory of vehicle-bridge coupling,a simplified analysis model of movable roof-track-fixed roof is established,and the numerical integration process is given.The dynamic response of retractable roof structure includes wheel-rail vibration response and reticulated shell dynamic response.The effects of irregularity,roof load,travel speed and friction coefficient on the acceleration,contact force,stress and reaction force of roller and track are analyzed by parameterization.The structural characteristic nodes are selected for the dynamic response of reticulated shells,starting with single-point excitation and multi-point excitation.Single-point excitation is used to study the influence of excitation at each constraint on the dynamic response of reticulated shells.The maximum dynamic response of reticulated shells under wheel-rail excitation is obtained by multi-point excitation.Comparing with the requirements of the code,the relationship between impact load and travel speed and irregularity is summarized.The stability of reticulated shells is studied.Using ABAQUS finite element software and Riksarc length method,the whole load-displacement curve is obtained.Based on the load-displacement curve,the plastic development process of reticulated shells is analyzed,the static instability modes of reticulated shells are summarized,and parametric analysis is carried out for initial defects,cross section of members and uneven distribution of live loads.Based on the criterion,the failure modes of reticulated shells under various parameters are investigated.It is considered that dynamic instability and strength failure of reticulated shells may occur under wheel-rail excitation.Typical examples are selected to analyze the changing process of displacement,deformation,strain energy and plastic distribution of reticulated shells with the increase of dynamic load,which is compared with static stability. |
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