SIMPLIFIED DESIGN METHOD MODELING EARTH PRESSURE DURING AND AFTER EARTHQUAKES ACTING ON SEMI-UNDERGROUND STRUCTURES

Abstract

 The conventional design methods could not represent the complex distribution of earth pressure acting on the semi-underground structure, of which most part is placed underground and stiffness is larger than the surrounding soil. Dynamic non-linear FEM is recently applied for inspecting the validity of seismic design. We propose a simplified design method to model the earth pressure during and after earthquakes acting on the semi-underground structure, redistributing the soil failure effects on the earth pressure obtained by the linear analysis, based on the equilibrium of the whole structure. The validity of the proposed method was examined for the effects of structural rigidity and weight, friction between the ground and the side wall of the structure, the ground profile and the input ground motion, based on the 16 cases of dynamic non-linear FEM analysis. It was confirmed that the proposed method can adequately estimate the distribution of earth pressure during and after earthquakes. Quantitative evaluations of the resultant force and moment obtained from the modeled distribution, which respectively influence the shear force and bending moment of the structural wall, are performed. It is shown that the proposed method is excellent for designing the semi-underground structure, giving 5 to 25% larger values than the FEM two-dimensional nonlinear dynamic analysis.