EVALUATION OF THE STIFFNESS AND DAMPING OF ABUTMENTS TO EXTEND DIRECT DISPLACEMENT-BASED DESIGN TO THE DESIGN OF INTEGRAL BRIDGES

Abstract eng:
There is an urgent need for maintenance-free transportation infrastructures worldwide. Integral Abutment Bridges (IABs) are robust structures, without bearings or expansion joints that require zero or minimum maintenance. The challenge to the assessment of existing and the application of IABs is the dynamic interaction between the bridge and the backfill soil. In many cases, this interaction is misinterpreted due to the inherent non-linear behavior of the soil during the so-called in-service interaction, which modifies drastically the stresses within the backfill soil under daily displacements of the abutment. A step towards the better understanding of the seismic response of IABs is the evaluation of the resistance of the abutment, which depends upon the geometry of the abutment, the properties of the soil and the successive interactions, i.e. quasi-static, under thermal expansion and contraction of the deck, or dynamic, when the bridge is subjected to seismic excitations and/or breaking loads. Towards this end, this paper attempts to: (a) interpret the condition of the abutment and the backfill soil at the onset of the dynamic excitation based upon the antecedent in-service interaction of the components and (b) to evaluate the stiffness and the damping properties of existing and/or representative integral abutments under dynamic loads to extend the Direct Displacement-Based Design (DDBD) to the design of integral bridges. A typical geometry of the integral abutment and typical backfill soil is investigated based on 2D fully coupled FE simulations adopting a visco-elasto-plastic stress model for the soil (coupled approach) under static and dynamic loads.

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