Flexural strengthening of RC slabs with prestressed CFRP strips: serviceability and ultimate load state behavior

Abstract

O presente trabalho pretende contribuir para o conhecimento da técnica EBR (Externally Bonded Reinforcement) usando laminados de CFRP (Carbon Fiber-Reinforced Polymer) pré-esforçados no reforço à flexão de estruturas de betão, sob condições de serviço (SLS) e estado limite último (ULS). Para tal, foi desenvolvido um programa experimental composto por 8 lajes ensaiadas até à rotura. Duas lajes foram usadas como de referência; 5 reforçadas com laminados de EBR/CFRP pré-esforçados; finalmente, 1 laje reforçada com um laminado EBR/CFRP. Dois sistemas distintos de ancoragem foram estudados: MA (Mechanical Anchorage) e GA (Gradient Anchorage). O efeito da largura e espessura do laminado foi também estudado. A performance dos protótipos é criticamente analisada ao nível dos SLS e ULS.

The present work intends to contribute to the knowledge of Externally Bonded Reinforcement (EBR) technique using prestressed Carbon Fiber-Reinforced Polymer laminates (CFRP) to strengthen concrete structures in flexure, at both serviceability (SLS) and ultimate load levels (ULS). For that purpose, an experimental program was carried out with 8 slabs monotonically tested under displacement control up to failure. Two slabs were used as reference specimens (unstrengthened); 5 slabs were strengthened with prestressed EBR CFRP laminates; finally, 1 slab was strengthened EBR CFRP laminates without being prestressed. To fix the ends of the prestressed CFRP laminates two different anchorage systems were used: Mechanical Anchorage (MA) and Gradient Anchorage (GA). The effect of the width and thickness of the CFRP laminate were also studied. The observed performance of the tested slabs is critically analyzed in terms of SLS and ULS aspects.