Áurea Silva de Holanda

Dynamic Viscoelastic Analysis of Asphalt Pavements using a Finite Element Formulation

ABSTRACT This paper studies the effect of time and load rate on the structural response of asphalt pavements when the surface layer is a linear viscoelastic material. A finite element incremental algorithm for dynamic analysis of viscoelastic solids is presented, where the stresses are computed using a hereditary integral in which the relaxation modulus is described by a Prony-Dirichlet series. The stresses are integrated in a semi-analytical form, whereas the dynamic equilibrium equations are integrated by the Trapezoidal Rule. Different pulse loads are considered and the viscoelastic responses of different asphalt layer thicknesses are compared. Several performance indicators typically utilized in pavement design are studied, particularly those at the surface layer, i.e., tensile stress and strain, shear strain, and surface deflection.

An Object-Oriented System for Finite Element Analysis of Pavements

The calculation of displacements, stresses and strains caused by vehicle loads in pavements is not a simple task even when considering all layers formed by linear elastic materials. In reality, surface and granular layers present a complex constitutive behavior, with nonlinear and time-dependent effects. Such effects should be considered in mechanistic pavement design methodologies which make use of the pavement structural response into specific distress models [1]. Today, there is a trend in the pavement academic community to substitute pavement analysis based on the Multilayer Elastic Theory by analysis based on the Finite Element Method — FEM [2].

Nonlinear analysis of steel scaffolds for shoring of concrete structures

Shoring systems are temporary structures that should resist external loads during the construction of concrete structures. Therefore, the shoring system should have sufficient strength and stiffness to ensure the safety of the concrete structure until it becomes self-supporting. Unfortunately, a large number of accidents occur during the construction of concrete structures due to the failure of the shoring system, showing the importance of improving the knowledge about these structures. This work aims to study the behavior of steel scaffolds used in the construction of high-clearance concrete structures using three-dimensional finite element models considering both geometrical and material nonlinearities. The obtained results are in good agreement with experimental results available in literature. The results showed that the boundary conditions have a significant influence on the failure loads of steel scaffolds.