Small Strain Characteristics Research Articles

Small strain deformation characteristics of two chalks subjected to varying stress conditions

Abstract The paper presents an attempt to consider the small strain characteristics of two high-porosity chalks from the northern Negev desert in Israel. Special attention was given to anisotropy, nonlinearity and stress regime; compression or tension. A theoretical and experimental framework for considering these aspects is presented and employed. The experimental programme included testing of air-dried hollow cylinder specimens under conditions of uniaxial compression, radial compression and radial tension. Results of the laboratory testing indicate that the chalks tested display a high degree of anisotropy in the modulus of deformation measured parallel and perpendicular to the direction of sedimentation. The stiffness of the chalks was found to be significantly higher perpendicular to the direction of sedimentation, despite the apparent massive uniform appearance of the intact rock. The chalks displayed significant non-linear stress-strain behaviour, with a strong tendency for the stiffness to decrease as deviator stress is increased. The ratio between material stiffness when subjected to compressive deviatoric stresses in comparison to tensile deviatoric stress was found to be very close to unity.

Numerical Study of Tall Masonry Cavity Walls Subjected to Eccentric Loads

This paper presents the results of the second phase of an ongoing investigation into the behavior of tall cavity masonry walls constructed with partially grouted and reinforced concrete block wythe and a burnt brick wythe tied together with semirigid shear connectors. In the first phase, a test program has been conducted on tall cavity walls under eccentric axial forces. In this phase a nonlinear finite-element analysis model is developed to simulate the database of existing test results. The model represents all components of the cavity wall, the reinforced concrete block backup wythe, the brick wythe, and the shear connectors. It accounts for the nonlinear material behavior of all components as well as the large displacement, small strain characteristics of the deformation. The numerical analysis results are successfully compared with a number of test results. The simulation offers insight into the mode of failure, in particular for walls with high eccentricity ratios. That same model is then used to numerically generate an extensive database to examine the effect of various wall parameters on wall stiffness and ultimate strength.