ABSTRACT
Abstract The experimental test results and analysis of eight (8) reinforced concrete slabs (1000 x 1000 x 50 mm) are discussed. Two-way reinforcing steel was used to reinforce six of the slabs, and one-way reinforcing was used to reinforced the remaining two. The 2-way slabs were simply supported on all four edges, and the 1-way slabs were simply supported on two parallel sides, perpendicular to the direction of the reinforcing steel. One 1-way and two 2-way slabs were tested as controls, and the remaining five were externally reinforced on their tension face with fibre-reinforced plastic (FRP) sheets. Glass FRP and carbon FRP unidirectional fibre sheets were used. The slabs were subjected to transverse patch loads, and the load versus displacement plots were obtained for key locations on the slabs. Strains were also recorded in the reinforcing steel and FRP materials. Both stiffness and strength were enhanced by the external FRP reinforcements. The ultimate loads supported by the slabs are compared to those predicted by Canadian code equations. Efficiency calculations are presented. Keywords: external reinforcement, FRP sheets, retrofitting, reinforced concrete slabs
1 Introduction
In Canada, as in many other parts of the world, the main activities in structural engineering are moving away from new construction and concentrating on the rehabilitation and strengthening of existing structures. Fibre-reinforced plastic (FRP) materials have been used to repair and strengthen reinforced concrete
510 Erki and Heffernan
structural members, especially beams and columns. Many reinforced concrete beams have been tested, demonstrating the feasibility and efficiency of this technology to improve flexural stiffness and strength. However, the efficiency of the FRP sheets compared to an equivalent amount of reinforcing steel improves significantly with decreasing thickness of flexural members. Therefore, the repair of slabs using FRP materials is very promising. Compared to reinforced concrete beams, such repairs for reinforced concrete slabs will require less FRP material to achieve equivalent increases in stiffness and strength.
