Seismic response of multiple-story structures on flexible foundations

1969 ◽  
Vol 59 (3) ◽  
pp. 1061-1070
Author(s):  
Richard A. Parmelee ◽  
David S. Perelman ◽  
Seng-Lip Lee
Keyword(s):  
Seismic Response ◽  
Half Space ◽  
Dynamic Properties ◽  
Equations Of Motion ◽  
Elastic Half Space ◽  
Rigid Foundation ◽  
Flexural Response ◽  
Flexible Foundations ◽  
Constant Coefficients ◽  
Shear Buildings

abstract A method is presented for investigating the seismic response of multiple-story shear buildings on flexible elastic foundation media which are represented by an elastic half space. It is shown that the frequency dependent dynamic properties of the foundation medium may be assumed to be constant with respect to the frequency. This assumption leads to equations of motion with constant coefficients which are solved numerically. A study of several structure-foundation systems indicates that the flexibility of the foundation medium can increase or decrease the flexural response of the structure compared to the case of the rigid foundation.

Seismic response for self-strained structures

1974 ◽  
Vol 64 (6) ◽  
pp. 1809-1824
Author(s):  
Mario Paz ◽  
Michael A. Cassaro ◽  
Steven N. Stewart
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Dynamic Properties ◽  
Equations Of Motion ◽  
The Self ◽  
Mode Shapes ◽  
Strain Effect ◽  
Structure Changes ◽  
Superposition Technique ◽  
Initial Strains

abstract The seismic response of multistory building and other structural systems is affected by the existence of self strains which may be induced by temperature gradients, mechanical actions, or prestraining. The fundamental dynamic properties such as natural frequencies and mode shapes are influenced by the presence of these strains. As a consequence, the response of the structure changes to the extent that the self strains change its dynamic characteristics and to the extent that these characteristics are relevant in the interaction of a particular structure with a given ground motion. This paper presents a detailed study of some simple structures such as beams and frames whose members are subjected to initial strains. The homogeneous differential equations of motion are expressed in terms of the stiffness, mass, and geometry matrices and a parameter accounting for the self-strain effect. The solution of the resulting eigenvalue problem is used to write the modal equations into which the desired ground motion is applied. The final response is obtained from the appropriate shock spectrum and the application of root-mean-square superposition technique. The disturbing action produced by the ground motion of the well known El Centro earthquake of 1940 is applied to several structures in which the amount of self-strain is varied as a parameter.

scholarly journals Simplified Analysis of Dynamic Structure–Ground Interaction

1975 ◽  
Vol 2 (3) ◽  
pp. 345-356 ◽  
Author(s):  
J. H. Rainer
Keyword(s):  
Dynamic Properties ◽  
Dynamic Structure ◽  
Elastic Half Space ◽  
Mode Shapes ◽  
Soil Material ◽  
Modal Damping ◽  
Flexible Foundations ◽  
Simplified Method ◽  
Simplified Analysis

A simplified method of analysis is presented for the determination of dynamic properties of single-story structures founded on flexible foundations. The general equations for natural frequency, mode shapes, and modal damping are applied to structures founded on an elastic half-space and on piles. The results of parameter studies, including the effects of hysteretic soil material damping, are presented for these two cases.

scholarly journals The use of modelling of impacts exerted by means of transport on the environment for ensuring safety

2018 ◽  
Vol 188 (2) ◽  
pp. 162-175
Author(s):  
Joanna Bril ◽  
Edward Rydygier
Keyword(s):  
Rigid Body ◽  
Half Space ◽  
Dynamic Properties ◽  
Elastic Half Space ◽  
Transport Systems ◽  
Concentrated Force ◽  
Foundation Soil ◽  
Infinite Mass ◽  
Model Research ◽  
Surface Rayleigh Wave

The article presents the model research on impacts exerted by means of transport on the structures. In modelling the dynamics of transport systems the dynamic properties of the ground forming the foundation soil for tracks or roadways have been taken into account. The ground has been modelled as an elastic half-space. The dynamics of an infinite mass band being in contact with an elastic half-space has been investigated. As part of the research on impacts exerted by means of transport on structures a model of a problem has been examined where an automotive vehicle, representing a concentrated force in motion, is in contact with a roadway described as a rigid body coupled with an elastic half-space. It has been demonstrated that a surface (Rayleigh) wave propagates in the ground, being a continuous (elastic) medium, and acts on a structure modelled as a rigid body. The research results have been presented in the form of vertical and horizontal transmittances of the ground for different frequencies of loading with different unit forces.

Dynamic Response of a Rigid Foundation Subjected to a Distance Blast

2012 ◽  
Author(s):  
Deji Ojetola ◽  
Hamid R. Hamidzadeh
Keyword(s):  
Dynamic Response ◽  
Half Space ◽  
Integral Transform ◽  
Numerical Technique ◽  
Formal Solution ◽  
Elastic Half Space ◽  
Numerical Results ◽  
Rigid Foundation ◽  
Transform Method

Blasts and explosions occur in many activities that are either man-made or nature induced. The effect of the blasts could have a residual or devastating effect on the buildings at some distance within the vicinity of the explosion. In this investigation, an analytical solution for the time response of a rigid foundation subjected to a distant blast is considered. The medium is considered to be an elastic half space. A formal solution to the wave propagations on the medium is obtained by the integral transform method. To achieve numerical results for this case, an effective numerical technique has been developed for calculation of the integrals represented in the inversion of the transformed relations. Time functions for the vertical and radial displacements of the surface of the elastic half space due to a distant blast load are determined. Mathematical procedures for determination of the dynamic response of the surface of an elastic half-space subjected to the blast along with numerical results for displacements of a rigid foundation are provided.

scholarly journals Dynamic Response of a Circular Tunnel in an Elastic Half Space

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
İrfan Coşkun ◽  
Demirhan Dolmaseven
Keyword(s):  
Boundary Conditions ◽  
Half Space ◽  
Dynamic Pressure ◽  
Equations Of Motion ◽  
Surrounding Medium ◽  
Elastic Half Space ◽  
Polar Coordinates ◽  
Wave Number ◽  
Circular Tunnel ◽  
Tunnel Wall

The vibration of a circular tunnel in an elastic half space subjected to uniformly distributed dynamic pressure at the inner boundary is studied in this paper. For comparison purposes, two different ground materials (soft and hard soil) are considered for the half space. Under the assumption of plane strain, the equations of motion for the tunnel and the surrounding medium are reduced to two wave equations in polar coordinates using Helmholtz potentials. The method of wave expansion is used to construct the displacement fields in terms of displacement potentials. The boundary conditions associated with the problem are satisfied exactly at the inner surface of the tunnel and at the interface between the tunnel and surrounding medium, and they are satisfied approximately at the free surface of the half space. A least-squares technique is used for satisfying the stress-free boundary conditions at the half space. It is shown by comparison that the stresses and displacements are significantly influenced by the properties of the surrounding soil, wave number (i.e., the frequency), depth of embedment, and thickness of the tunnel wall.

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