Cyclic behavior of a two-span RC beam built with plain reinforcing bars

Abstract

Abstract1 Introduction A significant number of existing reinforced concrete (RC) structures in Europe prior to the enforcement of the modern seismic-oriented design philosophies. In fact, many were designed to withstand only gravity loads. Also, they are generally reinforced with plain bars that exhibit poor bond and need specific anchoring end details [14]. As a consequence of poor reinforcement details and absence of any capacity design principles, a significant lack of ductility at both the local and global levels is expected for these structures resulting in inadequate structural performance even under moderate seismic excitation [17,26]. Damages observed in recent severe earthquakes like, for example, the 2008 Sichuan-China, the 2009 L'Aquila-Italy, 2010 Port-au-Prince-Haiti and 2010 Chile earthquakes confirm the important source of risk that old RC structures represent the society, in both human and economic terms.The common causes of damage and collapse of RC structures due to earthquakes are usually associated to the following effects/mechanisms [30]: (i) stirrups/hoops, confinement and ductility; (ii) bond, anchorage and lap-splices and bond splitting; (iii) inadequate shear capacity and failure; (iv) inadequate flexural capacity and failure; (v) inadequate shear strength of the joints; (vi) influence of the infill masonry on the seismic response of structures; (vii) vertical and horizontal irregularities; (viii) effect of higher modes; (ix) strong-beam weak-column mechanism; and, (x) structural deficiencies due to architectural requirements.The sudden loss of concrete-steel bond is one of the sources of brittle failure in RC elements, and is reported to have been the cause of severe local damage and even collapse of many structures during earthquakes. Even if no anchorage failure occurs, the hysteretic behavior of RC structures, namely when subjected to alternate actions (like earthquakes), is highly dependent on the interaction between steel and concrete [6].Perfect bond between the steel reinforcing bars and the surrounding concrete is usually assumed in the analyses of RC structures, implying full compatibility between concrete and steel strains. However, this assumption is only valid for early loading stages and low strain levels. As the loads increases,

Hybrid simulation of a multi‐span RC viaduct with plain bars and sliding bearings

“…For example, steel reinforcement in old reinforced concrete (RC) bridges consists mainly of smooth steel bars. Thus, to investigate the influence of their bond–slip and anchorage efficiency on the member response, existing formulations have been updated , and specific experimental/numerical investigations were conducted on portal frame piers in an old RC viaduct .…”

Experimental cyclic behaviour of RC columns with plain bars and proposal for Eurocode 8 formula improvement

“…Recent experimental studies on RC columns with plain bars include those of Verderame et al [5,6] and Di Ludovico et al [7], described here. Some additional experimental studies can also be found in the literature for beam-column joints [2,[8][9][10] and beams [11,12], and are supplemented by data from pull-out tests [13].…”

Cyclic behaviour of interior beam–column joints reinforced with plain bars

“…In recent, much research has been carried out on the design of new RC structures and the improvement of design codes [7][8][9][10][11][12]. Many fewer studies have focussed on the assessment and retrofitting of old RC structures [4,5,[13][14][15][16][17][18][19], and knowledge on the cyclic behaviour of existing RC elements is still limited. Therefore, further research on the deformation and softening mechanisms of RC elements under cyclic loading are essential to better estimate the capacity and to develop retrofitting techniques for old RC structures.…”