Vibration Reduction Mechanism And Seismic Design Of Single-layer Reticulated Domes With Friction Pendulum Bearings

As a kind of typical large- span space structure, reticulated domes exhibit good development prospects and have been applied to many landmark buildings, owing to the large span, reasonable force and beautiful design. Because of their great significance of polit ics and economy, reticulated domes are often employed to some densely populated places, and hence their researches on vibration reduction mechanis m and seismic performance become particular important. At present, the studies of reticulated domes mainly concentrate on the stability, dynamic performance and failure mechanism. However, it is rare to investigate vibration control of reticulated domes.Friction pendulum bearing(FPB) is applied to reticulated domes as an effic ient and complete passive dry friction slid ing isolation device, which can cause a series of key urgent problems. These problems include the application feasibility of FPB, structural isolation effect, selection principle of FPB, influences of structure and FPB parameters, design and installation of support, and so on. In this paper, the refined finite element models are applied to reticulated domes and the vibration reduction mechanism and effects of FPB reticulated dome are systematically investigated for above problems. Firstly, the vibration reduction mechanism and effect of ground and column supporting reticulated domes with FPB are analyzed, and the significant isolation effects of FPB structures are proved and the selection principles of FP B are simultaneously given. Secondly, three kinds of new friction isolation bearings for reticulated domes are designed on the basis of traditional FPBs. Their isolation mechanisms are discussed by theoretical and numerical approaches, and their significant isolation performance s are verified by numerical examples. Finally, the installation and design of FPB are discussed through considering init ial design angle, arrangement form and installation location. Seismic design suggestions of reticulated domes with FPB are given, which can lay good foundations for the wide application of FPB in reticulated domes. The main research contents of the present paper are as follows:1. Vibration re duction me chanis ms of friction pe ndulum bearings and establishme nt of finite element modelsThe isolation mechanis ms of FPB are analyzed from two aspects of isolation and energy consumption. The motion equation of structures with FPB is provided. The refined finite element model of FPB is eatablished, and its reasonability and correctness are proved by the existing experimental results.2. Seis mic pe rformance research of reticulated domes with friction pendulum bearingsThe refined finite element models are used to the single- layer reticulated domes to investigate the influence of FPB on the performance of reticulated domes from internal force, deformation and stability views. The results show that the internal force and deformation of domes increase, while the stability is reduced. However, the negative influence caused by FPB can be weakened through reinforcing outermost ring bars. Moreover, the variations on seismic performances of are researched by means of changing parameters of earthquake waves and FPB. The influences of earthquake waves on seismic effects of reticulated domes with FPB are provided. The vibration reduction effect of FPB structures increases with the increase of ground motion intensity. As the frction coefficient increases, the vibration reduction effect enhance s firstly and then reduces. The bigger the radius of curvature is, the better the isolaton effect of FPB is. Furthermore, the feasibility of FPB as vibration damping device is verified by investigating the isolation effects of reticulated domes with different rise-span ratios, roof loads and span sizes.3. Seis mic pe rformance research of column s upporting reticulate d domes with friction pendulum bearingsFPBs are installed between the lower and upper structures, and the internal force, deformation and stability of column supporting reticulated domes are discussed. The seismic performances of reticulated domes are researched by considering the influences of earthquake wave, FPB and upper domes parameters. The results show that the influences of different parameters on dynamic mechanical performances are similar to the ground domes. In addition, the vibration reduction effects of domes with FPB are investigated under different height and sectional radius of columns, which shows that FPB can prolong the natural vibration period of reticulated domes to avoid resonance, and further reduce the seismic response.4. Research of new types of friction pendulum bearingsAccording to the influence rule of friction coeffic ient, a variable- friction friction pendulum bearing(VF-FPB) is designed, and its iso lation mechanism and effect are discussed through theoretical and numerical examples. Results show that this VF-FPB possesses a good adaptive characteristic, and reveals more significant isolation effect than a traditional FPB. Considering the characteristics of the large-span space structures, a spherical-cylindrical surface friction bearing(SCSFB) is designed, and isolation effects of structures with SCSFB are studied from theoretical and numerical analysis. O n the comparison with traditional FPB, SCSFB can markedly reduce the earthquake response of structures. Moreover, a new kind of variable- friction spherical-cylindrical fr iction bearing(VF-SCFB) is provided based on SCSFB and variable friction ideas. The isolation effect of VF-SCFB is better than SCSFB, which has been verified by theoretical and numerical analysis.5. Seismic design of reticulate d domes with friction pendulum bearingsSeismic design suggestions are given for single- layer spherical reticulated domes with FPB, and the influence laws of arrangement forms and installation positions of FPB on vibration reduction effect s of domes are given. Firstly, the concept of the initia l design angle of FPB is proposed. As the angle is less than 15 degrees, FPB can enhance the static performance of reticulated domes, and has less influence on the structural vibration reduction effect. Secondly, three arrangement forms are designed to research effects on mechanical properties of reticulated domes. The results give that the first form is more reasonable than others for seismic design. Addit ionally, the mechanical properties of structures are compared when FPBs are installed on the top and bottom of columns. It is found that the static performance is better for structure with FPBs installed on the bottom of columns, whereas the isolation effect has obviously reduction. FPB should be installed on the top of columns in the seismic design.