Behavior of strengthened concrete slab under eccentric compressive load

Abstract

Purpose The purpose of this study is experimental research of the mechanical behavior of slab reinforced by cork composite patch submitted to an eccentric progressive compressive load applied to on impact rectangle of dimensions 28 × 23 cm2. An analytical model and numerical modeling by finite elements are performed. This study is motivated by the evaluation of the effectiveness of this type of partial reinforcement to improve strength and ductility. The results are given by load-displacement curves, tensile damages cartography and ultimate strength histogram. Design/methodology/approach In experimental protocol, the following two parameters have been considered: the dimensions of the patch and the eccentricity of the load. The sections of the patches are calculated so that the ratio (XP/YP) patch is proportional to the ratio (LD/lD), with a step of 6 cm longitudinally and 4 cm transversely. Several dimensions patches are considered: (6 × 4) cm2, (12 × 8) cm2 and (18 × 12) cm2. The eccentric punching loading test was performed with an eccentricity of the load (1/3) L’ and (2/3) L’ compared to the center of gravity of the slab. Taking into account the eccentricity of the load in estimating the rupture strength, the equations are developed. Thus, numerical simulations are carried, to extract tensile damages cartography. Findings The results show that the rupture begins with the appearance of cracks in the unreinforced area. For an eccentricity of 1/3L’, the best strength/section ratio is obtained for patch (12 × 8) cm2, whereas for an eccentricity de 2/3L’, the patch (6 × 4) cm2 gives a better resistance. The results highlight the influence of the composite on the ultimate load. The force-displacement relations are little modified in the elastic phase. The experimental results have been compared with the theoretical models showing a good correlation. Originality/value The strength and ductility are depended on the dimensions of the patch and the eccentricity of the load. The use of a patch to cover the most stressed area, in the event of an eccentric axial load is a very economical solution compared to the total reinforcement. The damage field shows that the evolution of cracks depends on dimensions and the position of the patch. Indeed, the eccentricity of the vertical load induces an additional bending moment that will influence the fracture surface. The rupture load and ultimate displacement increase with the surface of the patch.