Experimental Seismic Assessment of the Effectiveness of Isolation Techniques for the Seismic Protection of Existing RC Bridges

The seismic vulnerability assessment of existing and new lifeline systems, especially transportation systems, is becoming of paramount importance in resilient social communities. Unfortunately, the transportation systems, especially in Italy, were mainly built in the late 60’s and early 70’s and were designed primarily for gravity loads. As a result, most of the reinforced concrete (RC) bridges do not employ seismic details and their structural performance has often been found to be inadequate under earthquake strong motions. In addition, existing seismic codes of practice, especially in Europe, do not contain specific guidelines for the reliable assessment of existing RC bridges. The present chapter illustrates the outcomes of two recent experimental seismic performance assessment carried out on typical portal frames and single columns existing reinforced concrete (RC) bridge designed for gravity loads only. The experimental response has been assessed by means of pseudo-dynamic and shake table testing. Intervention schemes employing innovative materials and technologies have also been considered as retrofitting measures to mitigate the onset of damage. The comprehensive experimental investigations prove the effectiveness of the isolation systems in preventing damage in the RC piers, especially limiting the maximum shear at the base of the piers, lowering the lateral drifts, preventing the onset of plastification in the frame sections and inhibiting the occurrence of the shear failure in the transverse beams of the RC portal frames of the piers.