Numerical Seismic Assessment of an Existing Bridge with Different Support Conditions

The assessment of existing infrastructures is a critical issue in the seismic protection of the modern societies. Field surveys in the aftermath of major seismic events have demonstrated the high vulnerability of highway bridges. This led to an increasing interest in the seismic performance assessment of existing bridges. The present paper deals with the seismic assessment of a bridge substructure reproducing typical existing Italian infrastructures. The reference structural system is a reinforced concrete (RC) 1:3 scale single span bridge that will be tested on the shaking table facilities at the University of Naples, Italy. The details of the numerical models adopted in the nonlinear dynamic analysis and the seismic performance prediction required for the test preparation are discussed in details. The record selection, the development of a step-by step validated numerical model are presented for the case study comprising an existing RC bridge designed primarily for gravity loads . The advanced numerical models and the assumptions made to account for the shear behavior of the piers are also illustrated. The preliminary results of the incremental dynamic analysis are presented and analyzed with reference to the effectiveness of the use of base isolation strategy commonly adopted for the seismic retrofit of the bridge deck