Document details

Flexural strengthening by means of a arc overlay in the tension zone

Author(s): Rocha, Daphne Wojciechowski

Date: 2012

Persistent ID: http://hdl.handle.net/10362/8850

Origin: Repositório Institucional da UNL

Subject(s): Reinforced concrete; Structural strengthening; Interface; Adherence; Connectors


Description

Reinforced concrete structures may be flexurally strengthened in the tension zone by the addition of a new concrete layer with embedded steel reinforcement. However, the interface between the new and old concrete creates a weak area that may cause failure to occur for loads inferior to the designed. Therefore the success of this technique relies on the interface capacity to transmit stress. Surface treatments and cleanliness are the two main aspects that affect adhesion between different age concretes cast against each other. Nevertheless, the amount of steel reinforcement crossing the interface is a factor that may overcome adhesion and improve shear resistance. In the last years, several studies have been elaborated on this theme. In the present dissertation, an experimental study was conducted in order to evaluate the performance of this strengthening solution, characterize failure modes and shear resistance at the interface. Simply supported beams with a bonded concrete overlay in the tension zone were subjected to a three point bending test, and interfacial failure was forced. Three different solutions for stress transmission across the interface are analyzed. In the first solution, shear transmission relies solely on adherence, whereas the two remaining solutions were developed with the aim of evaluating the contribution of reinforcement crossing the interface. Regarding the strengthening solutions with reinforcement crossing the interface, the difference between the effect of reinforcement concentrated near the borders of the new concrete layer or equally distributed along the interface is studied. During the tests, ultimate load, deflections, steel strains, cracking and rupture modes were analyzed. The obtained values were compared among each other and with the provisions of EC2 and MC2010.

Dissertação para obtenção do Grau de Mestre em Engenharia Civil – Perfil de Estruturas

Document Type Master thesis
Language English
Advisor(s) Lúcio, Válter
Contributor(s) Rocha, Daphne Wojciechowski
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