Anti-seismic Dynamic Analysis Of Chinese National Grand Theater

The engineering, anti-seismic analysis of Chinese National Grand Theater is assumed together by Taiyuan University of Technology and Beijing Institute of Architectural Design Research. This work is a portion of the whole design work of National Grand Theater.A first-rate building, National Grand Theater is designed and analyzed on account of the safety instead of the economy. The architecture area of this structure is 14952m2 and its height is 56m. The building is a multi-tower structure with a huge underground space and its structural shape is very complex, which is reflected by following items: big room width, long-span slabs, long-span beams, irregular slabs shape, slabs with big holes and many curved shear-walls. Main seismic members are reinforced concrete shear-walls, which is partially assisted by frames composed of concrete filled tubular columns. Considering the importance and complication of National Grand Theater, it is necessary that the analysis software be adopted apart from the normal software for engineering design. In this paper, the seismic analysis is performed by using software ANSYS, version 5.7.1.According to code for seismic design of buildings, the structural bearing and anti-deformed capacity should be calculated and evaluated under the normal earthquake. The main analyticalsubstances are shown as following.1. The Finite Element modelThe 3-Dimentional Finite Element model is adopted here.2. Anti-seismic analysisThe elastic analysis has been performed under normal earthquake. The response spectrum analysis and the time-history analysis are separately employed to check structural bearing and deformation capacity.3. Elastoplastic analysisThe Concert's tower structure is analyzed by push-over method under major earthquake.Above calculations have shown the structural dynamic characteristics as following: high fundamental frequency, dense spectra of frequencies and obviously partial modes. There are many secondary modes between two main modes and every mode is greatly correlative with its adjacent modes. The displacement distance of the adjacent stories is quilt small, which indicates that the seismic capacity of this structure is extremely strong. Additionally, the main weak parts have been found in this paper. There are many reasons to partial weak stiffness, such as sudden change of stiffness, big cantilever members, long-span thin slabs, long-span mega-beams, and so on.From the analysis, some new experiences can be drawn.1. Simplification of concrete filled tubular columnAccording to the equivalent lateral stiffness criterion, the concrete filled tubular column is converted into an equivalent reinforced concrete column. By using these methods, the degrees of freedom of the whole structure are reduced greatly as well as the accuracy of analysis can be ensured.2. Determination of the main modesIn the analysis of large-sized structures, the main modes can be determined by participation factor, modal coefficient, and characteristic of modes in the excitation direction.3. Determination of structural weak partsFor every element, such as beam, column and shell, the node's stress and displacement values are sorted, and then according to their order, locations of nodes within more values region would be found. Therefore, weak parts would be determined.4. Definition of horizontal loading formThe horizontal loading form is firstly presented and applied for 3-D Finite Element elastoplastic analysis. Under push-over loading, the distributions and development of hinges are obtained and then the weak parts are distinguished.The conclusions and experiences acquired in this paper provide some advices for seismic analysis of similar large-sized structures.