Effect of soil-structure interaction on damping of structures

239A 846301 Eartlflill strives for safety Middelboe, S New Cio Engr N596, 28 June 1984, P14-15

846306 Underpinning. The undersold technique Smoltczyk, U

Considerable progress has been made in the last 40 years towards understanding the mechanics involved in embankment stability for large earthfill dams. The use of horizontal and vertical drains has greatly reduced problems of failure - but failures do still occur. Uncertainty in the estimation of strength and safety parameters appears to be the root cause.

Techniques for underpinning buildings include: deep underpinning by piles, tie-back anchoring, solidification of the bearing soil and underpinning grillages.

846302 Diffraction of torsional wave or plane harmonic compressional wave by an annular rigid disc Dhaliwal, R S; Singh, B M

Eartlu! Engng Struct Dynam Vl1, N5, Sept-Oct 1983, P595621

Soil Dynam gartlu! gngng V3, N3. July 1984, P150-156 Two problems are considered. The first problem is that of diffraction of normally incident SH waves by a rigid annular disc situated at the interface of 2 half spaces. The solution is reduced to the solution of triple integral equations involving Bessel functions. This is then reduced to Fredholm integral equations ofthe second kind. From this, the numerical values for the moment required to rotate the disc are obtained. The second problem is diffraction of plane harmonic compressional waves by an annular circular disc embedded in an infinite elastic space. The solution to the problem is reduced to solution o f a Fredholm integral equation of the second kind. This gives numerical values for the couple applied to the disc. 846303 Effect of depth of embedment on foundation settlement. Technical note Yamaguchi. H

Soils Found V24. N1, March 1984, P151-156 It is suggested that Fox's method of computing the settlement of an embedded foundation is not suitable. The method is based on Mindlin's first solution which does not conform to the actual stress state around the base of the foundation. A new settlement formula is proposed which considers such factors as the net foundation pressure, the modulus of deformation and the bearing capacity below the foundation level. Foundations

See a~o." 846342, 846344 8463O4 Expansive..shri-I,°hh. soils in China: Technical note Hou. S

Can Geotech J V21, N2, May 1984, P375-379 Describes the origin, mineralogy and engineering behaviour of the expansive-shrinkable soils in China. Deformation damage characteristics of buildings founded on these expansive soils are described. Examples of successful construction on the soils are presented. 846305 Heave of coal shale fill. Technical note Caldwell, J A; Smith, A; Wagner, J

Can Geotech J 1/21, N2, May 1984, P379-383 The cause of heave of a floor slab in a new dining/kitchen complex at a mine in Utrecht was investigated in the laboratory by examining the behaviour of the underlying fill which was a waste material from the mining operation. The cause of heave was shown to be: (1) absorption of water and (2) alteration by weathering and oxidation of sulphides in the fill to sulphates. Further heave was anticipated.

Civ Engng, London Feb 1984, P21-24

8463O7 Effect of soil-structure interaction on damping of structures Novak, M; El Hifnawy, L

Damping of structures resting on flexible foundations is affected by soil-structure interaction in 2 ways: (I) the structure gains damping through energy dissipation in the soil, and (2) the damping the structure would have on a rigid foundation is reduced. These effects are evaluated using 2 approaches: a simple, approximate method based on energy considerations, and a complex eigenvalue analysis. The 2 methods are compared and the accuracy of the energy approach is assessed. 846308 Transient flexural vibrations of a Timoshenko column supported by an elastic half-space Wada, H

Earthq Engng Struct Dynam V12. N2, March-April 1984, P169-179 Transient flexural vibrations of an elastic column supported on an elastic half space are investigated using an arbitrarily-shaped free-field lateral acceleration as input. The Timoshenko theory is applied to the column and making use of Laplace transformations with respect to time and numerical inverse Laplace transformations, the time histories of the column free end acceleration are presented. Results are compared with previous results obtained from applying the Bernouilli-Euler theory to the column. The effects of column slenderness and foundation stiffness are clarified. 846309 Soil-structure interaction effects on the steady-state response of torsionally coupled buildings Tsicnias, T G: Hutchinson, G L

EartiN Engng Struct Dynara VI2, N2, March-April 1984, P237-262 Investigates the effect of foundation flexibility on the coupled lateral-torsional response of single-storey buildings excited by translational ground motion. The eccentricity between the centre of mass and the centre of resistance is considered to be the only cause of coupling of the lateral and torsional response of the building. The effect of the controlling parameters on the lateral-torsional coupling is investigated. It is concluded that for a particular range of these parameters, representing most cases of actual buildings, their effect on the coupling is not qualitatively affected by increases in the flexibility of the foundation medium. 846310 Dynamic-stiffness matrix of soil by the boundary-element method: conceptual aspects Wolf, J P; Darbre, G R

Eartlul Engng Struet Dynam V12, N3, May-June 1984, P385 -400 Various boundary element methods - the weighted-residual technique, the indirect boundary element method and the direct boundary element method - are developed for the calculation of the dynamic stiffness matrix of an embedded foundation. The indirect boundary element method is found to give the best