NEHRP Clearinghouse

Contribution of a Floor System to the Dynamic Characteristics of Reinforced Concrete Buildings.
Malik, L. R.; Bertero, V. V.
National Science Foundation, Washington, D.C., December 1976, 292 p.
Identifying Number(s)
A practicable and sufficiently accurate stiffness matrix method for estimating the contribution of a floor system to the overall elastic stiffness of moment-resisting space frames is developed. The floor system considered consisted of a two-way reinforced concrete slab supported on beams between columns. This stiffness matrix method is achieved by performing extensive parametric finite element analyses to identify the main parameters affecting and, therefore, controlling the stiffness of individual floor panels of the floor system. The stiffness of a two-way slab floor panel has been investigated by establishing an 8 x 8 panel stiffness matrix based on two rotational degrees of freedom (DOF) at each panel support. Stiffness matrix elements are determined by computing the moments necessary to produce a unit rotation at one support DOF while restraining the other seven DOF in the panel. Existing finite element computer programs are used in these computations. A series of rectangular finite elements models the bending and membrane stress-strain relations of the floor slab. The beams are modeled as uniaxial, prismatic members, connected by rigid links to the slab finite element nodes along the beam's centerline. Analytical tests confirm this method's accuracy in estimating the beam-slab composite action in flexible floors.
Floors; Reinforced concrete; Stiffness methods; Finite element analysis; Buildings; Earthquake engineering; Dynamic response; Computer aided analysis; Concrete construction; Earthquakes