Concrete contribution to initial shear strength of RC hollow bridge columns

Abstract

The primary objective of this study was to identify concrete contribution to the initial shear strength of reinforced concrete (RC) hollow columns under lateral loading. Seven large-scale RC rectangular hollow column specimens were tested under monotonic or cyclic lateral loads. The most important design parameter was column length-to-depth aspect ratio ranging between 1.5 and 3.0, and the other test variables included web area ratio, hollow section ratio, and loading history. The tests showed that the initial shear strength reduced in a linear pattern as the column aspect ratio increased, and one specimen tested under cyclic loading achieved approximately 83% of the shear strength of the companion specimen under monotonic loading. Also, several pioneering shear models proposed around the world, all of which were mainly based on tests for columns with solid sections, were reviewed and compared with the test results of this study, for their possible applications to columns with hollow sections. After all, an empirical equation was proposed for concrete contribution to the initial shear strength of RC hollow columns based on fundamental mechanics and the test results.

On the Assessment of the Shear Strength of Existing Hollow Circular Reinforced Concrete Members

“…For (μmax ≥ 7), a minimum value of concrete and transverse reinforcement contribution to shear strength is considered, reduced of 40% with respect to their not-degraded value. This value is in tune with the maximum degradation adopted in literature for similar approaches [3; 4], slightly higher, due to the presence of the void in the cross section, which limits the concrete-core resisting to shear stresses, in tune with research works by [9] and [42].…”

“…Conversely, the shear capacity of RC members with hollow-core cross section is still an open issue, particularly if cyclic loads are considered. No seismic code, in fact, provides specific formulations for this structural typology, despite several experimental studies showed significant differences with respect to solid sections, in terms of both resisting mechanisms and cyclic degradation phenomena [7,8,9,10,11].…”

Hollow bridge columns with triangular confining reinforcement

“…Traditional hollow reinforced concrete bridge columns are designed based on economic considerations of the cost saving associated with reduced material and design moments compared with increased construction complexity of hollow column crosssections, and hence increased labor costs (Zahn et al 1990;Yeh et al 2001;Delgado et al 2008;Kim et al 2012a).…”

Capacity Models for Shear-Critical Rc Bridge Piers With Hollow Cross-Section

“…Special attention has to be paid also to shear strength degradation with increasing flexural ductility demand, which may drastically reduce the energy dissipation capacity of the piers. On the other hand, past earthquakes around the world have highlighted the inadequate seismic performance of existing hollow rectangular piers, generally characterized by poor structural detailing and small web thickness [2]. 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.…”

“…Despite their widespread use, none of the current codes addresses specialized attention to shear strength of RC hollow core members, both for design and assessment [2]. The main existing code-based shear strength models have been calibrated on experimental results of members with solid crosssection, rectangular or circular ( [3]- [6]).…”