有限要素法による正方形フーチングの鉛直荷重時応力解析-II

抄録

This paper is the second report in a series of studies on finite element analysis of square column footings under vertical load. In this paper, many square column footings with and without footing girders were analyzed by three dimensional finite element method within the limits of elasticity. In addition, two of those column footing specimens experimented by F. E. Richart were analyzed by three dimensional finite element method within the limits of elasticplasticity and the results of the analysis were compared with the experimental data. After examining the results of the analysis described above, the following items were confirmed : a) The magnitude of stresses and the stress distributions obtained by elastic finite element analysis change according to the condition of soil and footing slab. b) The ratios of the moment obtained by elastic analysis to the moment calculated on the assumption of uniform distribution of soil reaction have a tendancy to become small with decreasing the relative rigidity of footing slab to soil. Under certain circumstances, the stress change due to the variation of this relative rigidity is more than that produced by cracking. c) In the case of the footing slab with the footing girders of which the stiffnesses are large enough, it is considered that the footing slab can be designed as a thin plate with two adjacent free sides and two adjacent fixed sides on the theory of thin plates, but in that case the footing girders should be designed considering the soil reaction under the girders. d) As the results of elastic-plastic analysis of column footings on the assumption that the elastic coefficient of soil is 10 kg/(cm)^3, the relationships of load-average strain in bar close to the experimental data at small strain levels.