Mejoras en la apreciación de cargas sísmicas

Abstract

Deformations u of buildings due to the acceleration of earthquakes are investigated. Two suppositions are made: a) the deformations are principally due to shear; and b) they are principally due to bending. In both cases it is found that u may be expressed by an uniformly convergent series of eigenfunctions. Except for a variable factor, the Fourier coefficients of these series are the same as the values X obtained recently by Alford, Housner and Martel, by means of the electrical analog computer of the California Institute of Technology. Using mean values of what they call the spectrum of earthquakes, it is found that the seismic charge is constant on buildings less than about 30 m height. On buildings heigher than 30 m and lower than about 85 m it becomes decreasing with height if they are not far from 30 m. When height is far from 30 m q is first decreasing till cero and is afterwards increasing. Numerical investigations on the greatest period T₁, on the elasticity modulus E, and on the rigidity modulus μ of buildings, lead up to the conclusion that E is a growing function of the ratio Γ of hight to width μ. changes with Γ but little; and T₁ changes lineary with height. This allows to think that assumption a) fits up better to the facts than assumption b).