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PROCEEDINGS OF THE ELEVENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING
Edited by: B.H.V. Topping
On the Influence of the Transition Slabs on the Dynamic Behaviour of Highway Bridge Decks
J.G.S. da Silva1, M.E. da N. Tavares2 and A.C.C.F. Sieira2
1Mechanical Engineering Department,
J.G.S. da Silva, M.E. da N. Tavares, A.C.C.F. Sieira, "On the Influence of the Transition Slabs on the Dynamic Behaviour of Highway Bridge Decks", in B.H.V. Topping, (Editor), "Proceedings of the Eleventh International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 193, 2007. doi:10.4203/ccp.86.193
Keywords: dynamic analysis, highway bridge decks, transition slabs, irregular pavement surface, computational modelling, finite element analysis.
In the design of reinforced concrete highway bridge decks with overhangs, in several situations, it is advisable that the transition slabs use among the access surface to the bridge and own structure. The main objective of the transition slabs is to eliminate the abrupt pavement level difference at the bridge extremities due to embankment settlement. Previous investigations [1, 2] have shown that the dynamic response values due to the load mobility, computed with the transition slabs used at the extremities of the reinforced concrete highway bridge decks with overhangs can lead to dynamical amplifications less than those obtained for the simply supported beam decks with overhangs (without transition slabs).
In this paper, the dynamic effects on bridge superstructures considering the two cases mentioned above (bridges with and without transition slabs) are investigated. A vehicle-structure mathematical model that includes the effect of the transition slabs is considered [1, 2]. Results for the evaluation of the dynamic response of the reinforced concrete highway bridge decks are presented.
The mathematical model assumes a finite element representation of the beam like deck and the vehicle simulation uses concentrated parameters of mass, stiffness and damping. The pavement roughness follows a non-deterministic strategy and is modelled by a weakly stationary, second order, and ergodic random process. This way, it can be obtained a direct relationship between the mean square values of the irregular profile and the roughness power spectrum density [1, 2]. The moving load is taken as an infinite series of vehicles, regularly spaced and moving at constant velocity. Only bridge steady-state response is considered. The representation of the soil is based on the Winkler's formulation [3, 4]. This theory assimilates the soil behaviour as a group of independent springs governed by a linear elastic model.
The influence of the transition slabs on the dynamical behaviour of highway bridge decks produces favourable effects directly proportional to its length. The transition slabs use at the extremities of the bridge decks with overhangs are a suitable solution for the decrease in the irregularities of the pavement response values at the overhang sections where the steady-state response can be a major concern as in the case of the bridge fatigue behaviour.
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