Estudio de los efectos estructurales del deterioro por corrosión de armaduras en estructuras hiperestáticas

Resumo

Reinforcement corrosion is one of the most frequent deterioration processes in reinforced concrete structures; it produces a reduction of the net area of structural steel and an increase of its overall volume which induces concrete cracking and further loss of cover, accelerating the steel corrosion process. Moreover, steel corrosion is also related to other local structural phenomena such as deterioration of the mechanical properties of concrete, steel and bond. Although initiation and propagation of steel corrosion processes have been studied by means of different durability models, studies about the direct evaluation of its effects in the overall structural security and functionality are analyzed. In the case of continuous structures, loss of reinforcement area produces, in addition to the reduction of strength and stiffness, redistribution of internal forces between the more damaged zones and the less damaged, this may play an important role in structural safety, delaying the overall structural failure. As internal forces redistribution implies stiffness reduction and, possibly, local yielding, interactions between the two processes can be expected which makes very difficult to assess the process. Therefore, theoretical models and experimental results on continuous structures with corroded reinforcement are needed to evaluate the phenomena, calibrate models and provide practical guidelines. Experimental campaign With the above objective, an experimental campaign was carried out on two-span continuous beams with span length of 2.4 m subjected to different degrees of corrosion. The beams had rectangular cross section of 0.12 m depth and 0.25 m width. A constant reinforcement of 2Ф12 in the bottom and 2Ф10 on top, in addition a 2 m top reinforcement of 2Ф10 was provided above inner support. Corrosion in bottom reinforcement was artificially generated by means of the impressed current method in which the time of exposure to the current is proportional to the desired degree of corrosion. In order to investigate the effects of an applied load during the corrosion process, three specimens with different loading were made for each degree of corrosion. A reference set of specimens with no corrosion was also tested. Once the desired degree of corrosion was reached, the specimens were tested to failure and reduction of structural performance and bearing capacity was evaluated and numerically studied.