The earthquake to one folding plate space truss structure roof lower chord nodal displacement influence

Abstract

In the ANSYS environment, when the connection between the steel roof and bearing are rigid and hinged, do the modal analysis for this gird roof by using the subspace iteration method, get the former 50 order natural frequencies and mode shapes of this structure, and do time-procedure analysis to understand the seismic performance of the gird roof structure. By doing contrastive analysis of the former 50 order mode shapes, we find that the frequency distribution of the structure is relatively dense, so we not only need to consider the low order modes, and also should consider the impact of the higher modes of the structure during seismic analysis; under eight degree rare earthquake, we use revised EI-Centro earthquake wave to do time-procedure analysis for this structure, the result shows that: in high seismic intensity area, the influence of Vertical seismic to the large span structure is relatively obvious, so we can’t neglect the influence of Vertical seismic during the seismic analysis; the kinds of the bearing type has little effect on overall structural dynamic performance of this structure. Introduction As a new form of the spatial structure, the folded plate grid structure is the combination of plat-panel. With good mechanical properties, sleek figure, easy to construct features, the folded plate grid structure has been wildly applied to varieties of public buildings. This paper takes a newly built railway station as research object due to its folded plate truss roof structure and focus on the analysis of mechanical characteristic hoping to provide a reference for later design and construction .Finite element model of a roof. This paper analyze the grid structure between two expansion joints of a folded plate type latticed roof of a train station with the ANSYS finite element and simulates the structural Members in the grid structure with space beam element. Regarding to this station, the roof is supported on steel columns. This paper simulates the folded plate type grid structure with hinge support and fixed support and investigates the influence that different types of support to stress performance of grid structure. The roof bottom chord nodes as shown in Figure1: Under the influence of structure weight, all the materials which the model was built with are linear elasticity. And the steel structure’s elastic modulus E is 206-109, Poisson's ratio of 0.3, a density of 7850kg/m3 [23-24].Top view of finite element model of a roof showed in Figure 2. Analysis Model An 8-degree seismic fortification intensity and a 0.2g earthquake acceleration are applied in the construction. According to the Current China Seismic Design Code of building GB50011-2010, it is better to do Elasto-plastic time-history analysis of reinforced concrete structure and steel structure when soil type and with 7 III III -degree seismic fortification intensity or RC Category II Framework with 8-degree seismic fortification[12]. Meanwhile Seismic Design Code of building GB50011-2010 set up specific provisions that different intensity should take certain peak of earthquake acceleration time histories: peaks of earthquake acceleration in rare 6, 8, 9 degree of seismic intensity are 18cm/s2, 70cm/s2, 140cm/s2 separately; as for peak of frequent 6, 8, 9 degree 0468 2nd International Conference on Electronic & Mechanical Engineering and Information Technology (EMEIT-2012) Published by Atlantis Press, Paris, France. © the authors of seismic intensity are 125cm/s2, 400cm/s2, 620cm/s2 separate The paper is focus on time-history analysis in rare earthquake response. And the peak ground acceleration of 8 degree earthquake is 400cm/s2. The Imperial Valley earthquake happened in 1940 is the EI Centro waive with 0.02s time steps. Results and Analysis Tab.1 Node displacement of A axis of the roof lower boom Node UX(mm) UY(mm) UZ(mm) hinge fixed hinge fixed hinge fixed 67 -32.591 -32.842 12.134 12.037 31.911 32.893 68 -33.595 -33.873 11.551 11.541 16.378 16.899 69 -33.16 -33.422 10.888 10.887 25.328 25.34 70 20.494 19.994 7.9823 8.1968 23.357 23.634 71 16.61 15.973 6.7802 6.9707 26.268 26.021 72 14.827 14.164 5.4253 5.5575 23.789 23.116 73 13.429 12.755 4.3344 4.4297 15.025 14.772 74 12.616 11.773 3.1394 3.1851 4.6823 4.6937 75 13.435 12.374 2.1607 2.1641 -10.012 -9.5462 76 15.57 14.296 1.8798 1.8461 -17.795 -16.859 77 18.23 16.715 2.3216 2.5705 -16.249 -14.906 78 19.48 17.848 2.5075 2.7754 7.2994 7.2962