Long-term analysis of bending moment resistance on pre-cast concrete beams

Koris, Kálmán; Bódi, István

doi:10.3311/pp.ci.2009-2.01

Cited by 1 publication

(1 citation statement)

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“…Recent studies on the behavior of RC beams refer, in general, to elements built with deformed bars. For example: i) Kovács and Farkas [29] conducted a series of tests in laboratory on a lightly reinforced concrete beam, aiming to study the continuous monitoring of concrete bridges during their design life; ii) Draskóczy [12] tested a series of 24 reinforced concrete beams with the main objective of developing the variable strut inclination method used for shear design of RC beams by Eurocode 2; iii) Koris and Bódis [18] presented a method for the calculation of flexural resistance of pre-cast RC beams as a function of time and relative ambient humidity, with the objective of determining the decrease of load carrying capacity in time due to slow deformations and aging of materials and calculating the probability of failure of the structure by means of varying the load carrying capacity and external loads. Among the very scarce number of existing work about the cyclic behavior of beams built with plain bars, a recent work by Marefat et al [22] can be referred as an example.…”

Section: Introductionmentioning

confidence: 99%

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

Fernandes

Melo²,

Varum³

et al. 2011

Per. Pol. Civil Eng.

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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,

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