Abstract
In the present paper, the horizontal rigidity of a precast concrete slab is analyzed theoretically by reference to the experimental studies which have been represented with respect to this problem, and when this precast concrete slab is used in one-storeied buildings provided with rigid frames and rigid ones with walls, the effects of the deformation and rotation of this slab on the lateral force distribution are dealed with theoretically in consideration of the resistances of the rigid frames of the longitudinal direction as well as the bending and shearing deformations of this slab. The conclusions obtained from this analysis are as follows. (1) The fact which the horizontal rigidity of a precast concrete slab becomes smaller than that of a concrete slab in the corresponding size is caused by the decrease of the moment of inertia of area (Jn) in the modulus of flexural rigidity (EJn) of the precast concrete slab. (2) The horizontal rigidity of a precast concrete slab is smaller than that of a concrete slab and when tins precast concrete slab is used in one-storeied buildings acted upon the lateral forces the deformation of this slab between the rigid walled-frames of the transverse direction becomes larger than that of the concrete slab, in consequence, the lateral force distribution among the rigid frames of the transverse direction becomes larger and the lateral forces carried by the rigid walled-frames of the transverse direction smaller. In the case which the shape of this slab between these rigid walled-frames, is slender in the longitudinal direction, therefore, the lateral force distribution method based on the conventional principle, that is, the principle that a slab is perfectly rigid and the torsion of buildings is considered, can not be accepted in structural design. So the limitation which can be accepted above mentioned lateral force distribution method are presumed as the followings. n≦(1〜2) spans n: the number of the span between rigid walled-frames or [numerical formula] G_W: the rigidity of the rigid walled-frames G_F: the rigidity of the rigid frame (3) The shearing force distribution among the columns of rigid frames of the longitudinal direction and the torsional moment distribution among the columns and walls of the transverse direction, which are caused by the deformation and rotation of precast concrete slabs, become larger than those in the case of using the concrete slab. But they are not so large that they can be neglected in structural design. Where transverse direction: direction of the action of the lateral force longitudinal direction: direction perpendicular to the transverse direction transverse walls: walls of the transverse direction longitudinal walls: walls of the longitudinal direction horizontal rigidity: in the horizontal direction
