架構剛性を考慮した群杭基礎建物の水平荷重時応力略算法

抄録

It is necessary to analyze piles and super-structure in the condition of those stress and movement at footings agreed with. The authors had expressed^<1)> the stress solution of group piles foundation in laterally loaded condition which was gained by joining the angle of footing's rotation to the pile's solution as elastic supported beam what was called Chang's equation. This analysis is complicated in a meaning of that the simultaneous equations have many unknowns and are solved by using an electric calcurator from the first to the end. Therefore, it is considered in the practical vision that a symple and convenient method for stress calcuration of group piles foundation with super-structure is expected. There was the symple methods^<2)〜5)> appiying an idea of the turnning point of bending-moment to a rahmen-column of finite length substituted for the piles of infinite length. But, the idea is rather illogical, because the turning point does not agree with the stress distribution of pile affected by reaction load of soil. The authors have made clear by the theoretical analysis^<1),6)> that the footing settlement had a little influence on the bending moment of pile top and super-structure. So, in the assumption of no subsidence of foundation and no projection of pile from ground, this study presents the symple stress calcurating method of group piles foundation with super-structure based on the theoretical solution.^<1)> The idea of shear stiffness at pile top per a footing D_j and coefficient α_<ej> multiplied by fix bending moment is introduced in this method. D_j and αe_j are expressed as equations by using the coefficient γ_j (=θ_j/y^^〜_nβη, θ_j : angle of footing rotation (rad), y^^〜_h : holizontal displacement (cm) and βη : a constant of group piles (cm^<-1>), named the movement coefficient of pile foundation. The γ_j values are accumulated by stress analysis of model frames and the relationship of γ_j and _TI_j/K_G is expressed nearly by curves (_TI_j : the inertia moment of piles per a footing (cm^4) and K_G : rigidity of footing's beam (cm^3)). Shear stress of pile top per a footing _TQ_<oj>' and bending moment of pile top per a footing _TM_<nj>' are obtained by using D_j and α_<ej> calculated by γ_j. In this method, bending moment of footing's beam is calcurated by substituting θ_j obtained from γ_j value in the equation of slope-deflection method. And the bending moment of column of 1st. floor at the end near the footing is calcurated by moment equilibrium at the footing. Stress exept the above mentioned is obtained by usual stress analysis of super-structure. It was sured that this method was proper by comparing the stress values of trial computation with the theoretical values.