A new simple shear apparatus which is capable of applying monotonic and cyclic load on soil specimens is fabricated. Cylindrical specimens are placed in a special triaxial type cell where confining pressure, pore air and pore water pressures can be controlled. The apparatus consists of an inner part and an outer portion. The inner portion that is inside the triaxial cell consists of a pedestal attached to a movable base. The movable base is mounted on a pair of horizontal rolling tables, which makes the inner portion capable of moving back and forth, horizontally. The outer portion consists of a cylindrical frame that holds the top cap and prevents its lateral movement. A high air entry ceramic disk is sealed into the pedestal using an epoxy resin. The specimen is sheared in a simple shear mode. The horizontal load required to shear the specimen, divided by the nominal area of the specimen gives the shear stress. Soil suction can be measured using the so-called axis-translation technique [1] by increasing the pore air pressure through the top low air entry disk and recording the pore water pressure through the high air entry ceramic disk. Using the fabricated apparatus it is possible to measure and control the vertical normal stress as well as the all-around confining pressure applied to the soil specimen. Hence, testing the soil under initial isotropic or anisotropic confining pressure could be easily achieved. In this paper, the main features of the apparatus are discussed via some test results carried out on unsaturated soil specimens.

In this paper, results of a series of static and dynamic tests performed on Shiraz silty clay, are presented. Using these test results, the effect of dynamic loading in reducing the stiffness and consequent degradation of the soil is illustrated. Different factors affecting the rate of reduction of soil stiffness are investigated. Among these factors the effects of reconsolidation pressure, cyclic strain amplitude and number of load cycles on the soil behavior are studied and empirical relationships correlating the soil stiffness to these factors are derived. Variation of soil damping ratio during cyclic loading is also highlighted. The normalized behavior of Shiraz silty clay, under both static and dynamic loading is investigated.

In this paper, a displacement-based, variationally consistent, two variable refined theory for shear deformable beams is presented. The beam is assumed to be of linearly elastic, homogeneous, isotropic material and has a uniform rectangular cross-section. In this theory, the beam axial displacement and beam transverse displacement consist of bending components and shearing components. The assumed displacement field of this theory is such that, bending components do not take part in the cross-sectional shearing force, and shearing components do not take part in the cross-sectional bending moment. This theory utilizes linear strain-displacement relations. The displacement functions give rise to the beam transverse shear strain (and hence to the beam transverse shear stress) which varies quadratically through the beam thickness and maintains transverse shear stress-free beam surface conditions. Hence the shear correction factor is not required. Hamilton’ s principle is utilized to derive governing differential equations and variationally consistent boundary conditions. This theory involves only two governing differential equations of fourth-order. These governing equations are only inertially coupled for the case of dynamics and are decoupled for the case of statics. This theory is simple and has a strong resemblance with the Bernoulli-Euler beam theory. To demonstrate the efficacy of the present theory, illustrative examples pertain to the static bending and free vibrations of shear deformable isotropic rectangular beams are presented.