Title: Evaluation of structural effects of deterioration, repair and retrofit by jeans of evolutionary non-linear analytical models

Author(s): Marí Bernat, A.; Bairán García, J.M.

Publication: ACHE

Volume: 60

Issue: 254

Appears on pages(s): 51 - 63

Keywords: Reinforced concrete, prestressed concrete, non-linear analysis, structural assessment, damage, deterioration, corrosion, durability, strengthening, service life.

DOI:

Date: 1/8/2009

Abstract:
Structures are subjected to damage and deterioration along their service life, which may affect their durability, functionality and safety. In order to realistically obtain the structural response at any instant of its service life, to evaluate the need for an intervention and, in such a case, its efficiency, analytical methods which take into account the most important aspects governing the non-linear and time dependent behaviour of concrete structures are needed. In this paper, an evolutionary step by step non-linear and time dependent analysis model, capable to take into account the structural effects of the deterioration process due to environmental causes as well as the structural changes due to any intervention is presented. For this purpose, the model can handle changes in the longitudinal and transverse geometry, in the structural scheme, in the supports, in the materials properties and in the loads at any time, in combination with material and geometric non-linearities and time-dependency. A verification example is presented in which a series of beams previously pre-cracked under several load cycles are strengthened and subsequently loaded up to failure. The analytical results obtained compare very well with the experimental ones. In addition, a theoretical example is also presented, in which a continuous reinforced concrete pedestrian bridge is subjected to loss of the upper concrete cover and to corrosion of the upper reinforcement due to the use of de-icing salts. Time dependent redistribution of forces and stresses, the evolution of deflections and crack widths and that of the ultimate flexural capacity are obtained. A retrofit system is applied and their effects on the functionality and safety of the structure are discussed and practical conclusions drawn.