• Structural Engineering and Mechanics
• /
• v.18 no.1
• /
• pp.59-78
• /
• 2004

This paper is devoted to illustrate some numerical procedures to solve the boundary equilibrium problems of three-dimensional solids that are subjected to thermal strains. The constitutive equations take into account the bounded tensile strength of the material and they are presented in the framework of non-linear elasticity and small strains. The associated equilibrium problem is solved numerically by means of the finite element method and the numerical techniques, i.e. the Newton-Raphson method and the secant method, are revised in order to assure the solution convergence of the discretized problem. Some numerical examples are illustrated.

• Structural Engineering and Mechanics
• /
• v.15 no.4
• /
• pp.395-414
• /
• 2003

In this paper we recall briefly the constitutive equations for solids subjected to thermal strain taking in account the bounded tensile stress of the material. In view to solve the equilibrium problem via the finite element method using the Newton Raphson procedure, we show that the tangent elasticity tensor is semi-definite positive. Therefore, in order to obtain a convergent numerical method, the constitutive equation needs to be modified. Specifically, the dependency of the stress by the anelastic deformation is made explicit by means of a parameter ${\delta}$, varying from 0 to 1, that factorizes the elastic tensor. This parameterization, for ${\delta}$ near to 0, assures the positiveness of the tangent elasticity tensor and enforces the convergence of the numerical method. Some numerical examples are illustrated.

• Journal of the Korean Wood Science and Technology
• /
• v.51 no.4
• /
• pp.309-319
• /
• 2023

Bamboo culm is in the form of a tube/pipe, composed of internodes which are bounded by a partition/diaphragm (node). Anatomically, bamboo is composed of vascular bundles and parenchyma ground tissue. One of the constituents of vascular bundles is fibers that are grouped to form a fiber sheath. The anatomical structure of the nodes and internodes is thought to influence the strength of bamboo strips, including tensile strength. This study aimed to determine the characteristics of vascular bundles (distribution and fiber percentage) and their effects on the density and tensile strength of Gigantochloa apus bamboo strips with and without nodes. The bamboo culms were divided into three parts (outer, middle, and inner) along the radial direction. The results showed that the distribution of vascular bundles and percentage of fiber sheaths decreased significantly from the outer to the inner layer. This also had a significantly decreased density and tensile strength. Furthermore, the number of vascular bundles (in the transverse plane) was greater in the internodes than in the nodes. Anatomically, the orientation of the vascular bundles at irregular nodes is observed in the radial and tangential planes, where the direction is not only in the axial direction, but also in the radial and tangential directions. This caused the tensile strength of the G. apus bamboo strips to be lower at the nodes than at the internodes.

• Steel and Composite Structures
• /
• v.14 no.1
• /
• pp.41-55
• /
• 2013

Fiber reinforced polymers (FRP) materials are increasingly being used for strengthening and repair of steel structures. An issue that concerns engineers in steel members which are retrofitted with FRP is stress experienced due to temperature changes. The changing temperature affects the interface bond between the FRP and Steel. This research focused on the effects of cyclical thermal loadings on the interface properties of FRP bounded to steel members. Over fifty tests were conducted to investigate the thermal effects on bonding between FRP and steel, which were cycled from temperature of $-11^{\circ}C$ ($12^{\circ}F$) to $60^{\circ}C$ ($140^{\circ}F$) for 21-36 days. This investigation consisted of two test protocols, 1) the tensile test of epoxy resin, tack coat, FRP and FRP-steel plate, 2) tensile test of each FRP compound and FRP with steel after going through thermal cyclic loading. This investigation reveals an extensive reduction in the composite's strength.