抄録
Slabs in deeply buried structures, such as underground substatuions, are affected by external walls loaded by soil and hydrostatic pressure, furthermore, they must carry shearing forces to external walls under earthquake. For this reason, stresses in slabs take great values and so slabs under the ground are thicker than those above the ground. On making openings in such slabs, the effect of openings on the stress distribution in slabs must be taken into consideration. As stress concentration generally occurs near an opening, slabs with openings are reinforced there with steel bars. When they are subjected to shearing forces, stress distribution in them are predominantly affected by openings. In order to reinforce such slabs, we can employ the advantage of braces. In this paper, the effects of braces as reinforcement are examined by obtaining the stress distribution of a slab which has a square openin and is loaded on its inern boundary. This examination is based on the theory of two-dimensional problem in elasticity. Then the magnitude of the effect of a brace can be determined by the condition for compatibility of deformation at the end of the brace. And the theoretical solutions are examined by means of experimental analysis based on photo-elasticity. Through this study we find that it is considerably efficient to reinforce slabs with openings with braces but not. very efficient in comparison with braces in a frame.
