DYNAMIC BEHAVIOR OF TIMBER FOOTBRIDGES WITH STOCHASTIC MECHANICAL PROPERTIES

Diego Garcia¹; Marta Rosales²; Rubens Sampaio³

¹ Department of Engineering, Universidad Nacional del Sur and CONICET, Argentina; ² Department of Engineering, Universidad Nacional del Sur and CONICET; ³ Department of Mechanical Engineering, Pontificia Universidade Catolica, Rio de Janeiro, Brazil

doi:10.20906/CPS/USM-2016-0028

Resumo

A dynamic study of timber footbridges with stochastic mechanical properties is presented in this paper. These structural systems made of timber are increasingly employed due to the high relation stiffness/weight that this material exhibits. More, the development and implementation of laminated beams permits larger spans. The sources of uncertainty of this structural model are the timber mechanical and physical properties. Also, the geometrical design of the laminates that compose the laminated timber beams supporting the floor involves variability in the distances between finger joints. Probability Density Functions (PDFs) of the timber properties are formulated from the Principle of Maximum Entropy (PME) and visual surveys of structural size $Eucalyptus$ $grandis$ laminated beams are used to obtain statistical parameters. The influence of these stochastic variables in the structural response is assessed in a forced vibration problem that includes a deterministic model of the load induced by the human walking. The Probability Density Functions (PDFs) of the natural frequencies of the structure, the mode shapes and the structural response are numerically obtained through the Finite Element Method (FEM) and Monte Carlo Simulations (MCS). In order to carry out this analysis plate elements and laminated beam elements formulated starting from the First Order Shear Deformation Theory (FSDT) are employed. The present stochastic model contributes to obtain a more realistic description of the response of this type of structures applicable for the study of the human comfort conditions.

Palavras-chave: timber structures; footbridge; uncertainty quantification; human walking