抄録
The report describes on the model of the beam grid system that each sides are quatered on the rectangular hollow slab, the basic equation was set up on the model by adaptation of a slope deflection method. Using this basic equation, in case of a square of slab depth of 20cm, bending and twisting moments were got from two cases that ratio η of slab depth to hollow diameter is 0 and 0.5. They were converted into moment per unit volume, compared with usual slab by section efficiency. The result is as follows. The admissible bending moment increases 24% and the admissible twisting moment decreases 2%. On case of slab depth 15cm, on the change of aspect ratio and the value of η, the bending and twisting moments were obtained from the basic equation by an electronic computer FACOM-231 and they were drawen on the chart. Thinking the ballance on the each joints, the movement of moments was summarized according to the chart. Then the bending strength on the hollow slabs was calculated by means of the sum of admissible bending moments and they were shown on the chart. As the result, it was found that the bending strengeh increased to a/b=1.6 and decreased over a/b=1.6, and that beam grid system became beam structure of one way at a/b=4.0. And the arched curves are drawn smoothly on the chart. When the strength of bending within η=0.5 : 0.7 is a/b=1.0〜4.0, it is the same value as η=0. Accordingly, within the limit of η=0.5〜0.7, the strength of bending on this hollow slab is not less than usual slab.
