Integration of knowledge on FRP retrofitted structures

X. MARTINEZ; S. OLLER; A. BARBAT; P. MATA

Guidelines for seismic vulnerability reduction in the urban environment: LESSLOSS

IUSS Press

Año: 2007; p. 47 - 72

The use of carbon fibre reinforced polymers (CFRP) for retrofitting a damaged structure is first reported for the strengthening of the Ibach bridge in 1991, Lucern, Switzerland [Meier, 1995]. Since this first application, the use of this technology has increased exponentially, becoming one of the main applications of composite materials in building and civil engineering. In the case of seismic loads, the improvement provided by CFRP reinforcements in the structural capacity makes them a good solution to increase the ductility of the structure, preventing structural damage in an earthquake situation. Most of the existing knowledge about structural reinforcement and/or retrofitting of reinforced concrete (RC) structures with fibre reinforced polymers (FRP) is based on experimental simulations, supported and complemented by analytical calculations; and, when the problem is treated using a numerical approach, material nonlinearities are usually linearized and the FRP composite is considered as a single material (i.e. [Rabinovitch and Frostig, 2001]). On the other hand, the study of composite materials has been one of the major objectives of computational mechanics in the last decade. The numerical simulation of composite materials has been done, traditionally, using orthotropic materials with average properties of their constituents. With this approximation, no model has been found able to work beyond the constituents elastic limit state. Thus, these procedures limit the numerical computation to elastic cases. Different theories have been proposed to solve this problem, taking into account the internal configuration of the composite to predict its behaviour. The two most commonly used are herein remarked. i) Homogenization theory, and ii) Mixing theory.