Dynamic boundary element analysis of multi story buildings

The present paper develops a new technique for dynamic analysis of structures using the boundary element method where a free vibrations analysis is considered. a new technique is developed to derive the stiffness matrix of each floor slab using the boundary element method. each slab is considered as a super finite element and its stiffness matrix is computed at the degrees of freedom which are assigned at the connections between the vertical elements and the slab. the stiffness matrices of the frame elements and the slabs are then assembled and a diaphragm constraint is applied to all slab degrees of freedom. a new technique is developed to compute the diagonal mass matrix,where the boundary element method is used to compute the load vector for the case of own mass only resulting by locking all the active degrees of freedom of the slab,these forces together with the diaphragm masses represent the diagonal elements of the mass matrix. a numerical technique is used to compute the eigen values of the structure. the present formulation results are compared to those obtained from the finite element method in order to verify the present formulation.