4 軟弱地盤における建築物の不同沈下対策に関する基礎的考察

抄録

This paper contains fundamental discussions to restrain the differential settlements of structures due to consolidation of clay strata. At first, results of a investigation on the differential settlements of structures in Osaka city are stated in Chapter 2. As structural members are more or less in state of plasticity, the effect of the plastic rigidity and that of creep of members are taken into consideration in the theory. From the numerical calculation on the structure shown in Figure 3, we can see it is in such a state that yield hinges would take place・in the base beam at the value of deflection angle θ≒2×10^<-3> under the design load. The principle of the method to restrain the differential settlements is lead as follows. 1. The deflection angle θ of upper-structure must be restricted within the allowable value θ_A. 2. For the purpose, the followings ought to be taken into consideration. a) the increase of rigidity of base beam or wall of the basement, b) the decrease of effective pressure in clay strata, accordingly of the quantity of settlement. 3. The maximum allowable value of θ_A might be in the range of 0.8〜1.5×10^<-3> as shown in Figure 17, for the quantity of reinforcement, the rigidity of column and the depth of beam. 4. The rigidity of base beam must be restricted in the limit that its maximum moment does not reach to the yield moment.