Stress state of metal dome meridional ribs at different stages of overhang erection process

Research aim. The aim of the present research was an analysis of a metal ribbed ring-shaped dome metallic ribs stress state at different stages of a skeleton overhang erection process. The considered dome is hemispherical and is assembled bottom-up of individual elements. Due to a varying slope of meridional ribs elements at different relative elevations their stress state changes during mounting. The effect of the overhang erection process onto the stress state of the metal dome meridional ribs has been investigated. The relationship between the stress state of a meridional rib and mounting of each next dome skeleton tier has been established. Methods. A mathematical model of the metal ribbed ring-shaped dome assembled of steel H-shaped elements with rigid connections has been developed. Several extra models corresponding to different skeleton erection stages have been also generated to determine stresses in the meridional ribs at these stages. Response of each dome mathematical model under dead-weight load has been simulated. The obtained values of stresses in the meridional ribs within different models have been compared with corresponding design stresses values. Results. The dependence of the metal dome meridional rib stress state onto the stages of overhang erection process has been plotted. A degree of utilization of ribs steel strength at different erection stages has been represented by diagrams. An estimation of the dome skeleton stress state during overhang erection has been given. Imminence of assembly stresses during overhang erection and their influence onto dome structural reliability has been pointed out.

Bounding surface constitutive model for unsaturated soils considering microscopic pore structure and bonding effect

This article presents a bounding surface model for unsaturated soils by using skeleton stress and bonding variable based on microcosmic pore structure as constitutive variables. A Hydraulic hysteresis soil-water characteristic curve model considering deformation and hydraulic hysteresis is combined to achieve hydraulic coupling. The proposed model can capture the change of the inter-particles bonding effect in the deformation process of unsaturated soils and accurately predict the hydraulic mechanical behavior of unsaturated soils under complicated loading paths and wetting-drying cycles. The validity of the proposed model is confirmed by the results of unsaturated isotropic compression tests, wetting-drying cycles tests and unsaturated triaxial shear tests reported in the literature.

Composite Tangent-Exponent Model for Skeleton Stress-Strain Curve of Soft Soil under Dynamic Loading

Mathematical model for skeleton stress-strain curve under dynamic loading (SSSC) is one important issue to study the dynamic behavior of soft soil. Based on mechanism of developing process, primary mathematical behavior that SSSC model should meet is analyzed. Mathematical investigation on two conventional SSSC models, namely hyperbolic model and exponential model, is conducted. Dynamic stress index is proposed and employed to signalize the shortcomings of two conventional models. A composite tangent-exponent model for SSSC with three parameters is established, which is a monotone increasing and up limited function. The new model can overcome conventional shortcomings. Finally, good agreement between investigated and new model fitted data has been found out.