Capacity models for shear-critical RC bridge piers with hollow cross-section

The assessment of seismic performance of existing bridge structures that have been constructed without appropriate details to support seismic loadings is a primary issue for seismic prone areas. Hollow section piers represent a very common structural solution for reinforced concrete (RC) bridge structures, due to the economical convenience and the higher structural efficiency with respect to solid sections. Nevertheless, a quite limited number of experimental tests are present in literature. Moreover, despite their widespread use, none of the current codes addresses specific attention to define proper capacity models for RC hollow core members, both for design and assessment. In addition, proposals from literature are generally calibrated on columns with solid cross-section or on a very small amount of experimental data. An experimental program of cyclic tests on four 1:4-scale models of typical RC existing bridge piers with hollow rectangular cross-section, poor structural detailing and small web thickness, has been carried out at the Department of Structures for Engineering and Architecture of the University of Naples Federico II. Different failure modes have been observed: flexure and flexure-shear failure, basically depending on the specimens' slenderness. On the basis of the major experimental results carried out by this experimental campaign, in this work, a database of similar tests from literature has been collected and presented. All tests exhibited a shear failure, with or without yielding of longitudinal bars. Collected experimental results are compared with capacity models existing in literature or codes, in terms of strength and displacement. Their predictive capability is analyzed and commented, and alternative proposals to improve their reliability are carried out.