Journal of Engineering Mechanics

Two‐dimensional elastic wave theory is utilized to investigate the steady‐state dynamic response of a cylindrical structure of elliptic cross section surrounded by an ice sheet of infinite extent. Fixed and frictionless boundary conditions at the ice‐structure interface are considered under both plane stress and plane strain conditions. Numerical results are presented which show the effect of structural geometry, direction and frequency of vibration, and choice of boundary conditions on the dynamic characteristics of the ice‐structure system. The analysis shows that the behavior of the ice‐structure system is primarily controlled by the associated damping effects rather than the added mass. These results provide a measure of ice sheet resistance to the vibrational motion of structures surrounded by floating ice sheets and are applicable to the dynamic and seismic analysis of arctic offshore platforms.

A new technique is proposed to develop constitutive models for the drained/undrained creep deformation of normally consolidated clays. Based on the general concept, an explicit constitutive model is presented for the multiaxial undrained creep deformation. This is then reduced to a form that can be used to describe undrained biaxial creep deformation. It is shown that the current model contains a number of available creep constitutive model as a special case. The model is then verified using a number of triaxial creep test data reported by Sekiguchi.

Using a “systematic relaxation of constraints” technique, a plane‐strain solution is derived for stresses in an elastic orthotropic quarter space loaded by a normal concentrated line load at a distance a from the edge. The formulation is also specialized to the case of cross‐anisotropic material behavior. Results are presented in the form of distribution of normal and shear stresses for a wide range of anisotropic material parameters. Applications include reinforced‐earth and geotextile retaining walls, vertical slopes of horizontally jointed rock, and unsupported excavations of overconsolidated anisotropic clay. An additional contribution of the paper is the generalization of the solutions available for the corresponding half space problem to cover the case of complex roots of the “characteristic” equation.

A new cap‐type constitutive model is proposed to characterize stress‐strain responses of general pressure‐sensitive materials. The model is noble in the sense that both the failure surface and the yield cap are described by the same list of material constants. Thus the compatibility between the two is automatically satisfied. Besides, the model effectively describes the strength variations along various directions on the octahedral plane. There are 10 material constants associated with this model which can be determined using conventional test data.

An analytical solution, using the Trefftz‐Mikhlin method, is presented for seismic‐induced hydrodynamic pressures on dams with a nonvertical upstream face. The solution is constructed as a linear combination of functions that are the solution of the problem's governing equation. These functions satisfy all boundary conditions except the one at the upstream face of the dam. The unknown coefficients of the linear form are obtained from the continuous treatment of the remaining boundary condition in the least‐squares sense. Numerical results are presented for different geometries of the dam‐water interface, and comparisons with exact and experimental solutions are provided.

The magnitudes of response cumulants are investigated for linear systems excited by stochastic inputs. This extension of the classical study of mean and covariance (i.e., first and second cumulants), provides basic information regarding the non‐normality of a response process. The dependence of the response cumulants on the parameters of the linear system is emphasized, as are approximations and order‐of‐magnitude results which reveal the nature of this dependence without numerical computation of response values. New information is provided regarding the phenomenon of a linear system having a nearly normal response to a non‐normal excitation. Conditions are determined under which a complicated stochastic excitation may be adequately approximated by a process which is delta correlated and a numerical example is given to illustrate one particular situation. Conditions are also derived under which a stationary process may adequately approximate an excitation that is nonstationary.

Asphalt concrete is often used as a waterproofing membrane on the slopes of embankment dams, reservoirs, and other hydraulic structures. When used for this purpose, it needs to have sufficient resistance to deformation under gravity at the highest temperatures that will occur. Slope tests on layers of asphalt concrete have been carried out in the laboratory to investigate the effects of the following parameters: the thickness of the specimen, the angle of slope, and the test temperature. The results have been analyzed in the light of previous research on the creep properties of asphalt mixes, and this has led to proposals for a slope test procedure for mix design purposes and also a method of predicting the deformation of an asphalt lining for given conditions of time, temperature, and slope.

A comprehensive analysis is made of the dynamic response of vertically excited circular ring foundations with mass that are supported at the surface of a homogeneous, linear halfspace. The harmonic response of such foundations is evaluated over wide ranges of the parameters involved, and it is shown that both the harmonic and transient responses may, over a wide range of conditions, be computed with good accuracy by considering the foundation‐soil system to respond as a single‐degree‐of‐freedom system. Plots are included from which the natural frequency and damping of the equivalent simple oscillator may be determined readily.

The problems of torsion of a transversely isotropic nonhomogeneous and elastic half-space due to certain distributions of shearing forces prescribed over a circular area on the plane boundary is considered. The elastic properties of the material are continuous functions of position. The aim of this paper is to determine the torsional deformation and shear stresses in the half-space.