RESEARCH ON THE DYNAMIC REDUCTION OF FINITE ELEMENT MODEL FOR HIGH-RISE BUILDING

Dynamic model reduction will be used in some special field like structural control considering the computation burden in the real time calculation. A finite element (FE) model of tens of thousands degrees of freedom (DOF) should be reduced to a small scale model, called reduced model, which is required to have the same dynamic properties with the original FE model and the same response under the same fluctuating wind load or seismic load. Several techniques such as Improved Reduced System (IRS) method, have been developed last century. Structural matrices of the FE model, namely stiffness matrix, mass matrix should be known for that method. However, some structural analysis software packages for design purpose always do not provide the whole structural matrices. We should extract the necessary information with static solutions based on the classical structural dynamics ideas like freedom selection, mass assembling etc. The general principles of that method are discussed within a example, a 60 storey 3-D frame FE model which to be reduced to a less than 50-DOF reduced model. Some significant evaluation indices including modal frequency, mode shape, and mass participate ratio are used to judge the similarity between the FE model and the reduced model. At last, the dynamic response is compared to testify the efficiency of the reduction principles and the evaluation indices. At the end of this paper, a complex FE model of a real constructing super high-rise building is reduced to a 56-DOF reduced model based on the principles presented above, and comparing with the FE model, it is indicated that those principles are feasible and reliable.