Flexural strengthening of RC beams using Hybrid Composite Plate (HCP): Experimental and analytical study

Abstract

a b s t r a c tHybrid Composite Plate (HCP) is a reliable recently proposed retrofitting solution for concrete structures, which is composed of a strain hardening cementitious composite (SHCC) plate reinforced with Carbon Fibre Reinforced Polymer (CFRP). This system benefits from the synergetic advantages of these two composites, namely the high ductility of SHCC and the high tensile strength of CFRPs. In the materialstructural of HCP, the ultra-ductile SHCC plate acts as a suitable medium for stress transfer between CFRP laminates (bonded into the pre-sawn grooves executed on the SHCC plate) and the concrete substrate by means of a connection system made by either chemical anchors, adhesive, or a combination thereof. In comparison with traditional applications of FRP systems, HCP is a retrofitting solution that (i) is less susceptible to the detrimental effect of the lack of strength and soundness of the concrete cover in the strengthening effectiveness; (ii) assures higher durability for the strengthened elements and higher protection to the FRP component in terms of high temperatures and vandalism; and (iii) delays, or even, prevents detachment of concrete substrate. This paper describes the experimental program carried out, and presents and discusses the relevant results obtained on the assessment of the performance of HCP strengthened reinforced concrete (RC) beams subjected to flexural loading. Moreover, an analytical approach to estimate the ultimate flexural capacity of these beams is presented, which was complemented with a numerical strategy for predicting their load-deflection behaviour. By attaching HCP to the beams' soffit, a significant increase in the flexural capacity at service, at yield initiation of the tension steel bars and at failure of the beams can be achieved, while satisfactory deflection ductility is assured and a high tensile capacity of the CFRP laminates is mobilized. Both analytical and numerical approaches have predicted with satisfactory agreement, the load-deflection response of the reference beam and the strengthened ones tested experimentally.

Simulating concrete cover separation in RC beams strengthened with near-surface mounted reinforcements

“…In most cases, the material selected to strengthen these structures is usually fibre reinforced polymer (FRP) due to its high strength-to-weight ratio and ease of placement. FRP applied using external bonding with epoxy adhesive [1][2][3][4] had been applied in many real-world strengthening cases and were proven effective. Apart from externally bonded FRP, there is another type of FRP application called the near surface mounted (NSM) method which is gaining attention of late.…”

Phase-field modelling of failure in hybrid laminates

“…So, high performance composites that are characterised by a ductile or pseudo-ductile behaviour with predictable failsafe mechanisms similar to metals', where non-linear plastic strain hardening effects occur, are gaining popularity. In fact, research has focused attention to reach this peculiarity by the use of ductile [20] or tapered fibres [72], woven or braided fabrics [37,40,59] and more generically the use of hybrid materials [1,60,26,28,70].…”

Flexural strengthening of reinforced concrete beams with prestressed and unprestressed fabric-reinforced cementitious plates

“…To improve fabric utilization and achieve desired reinforcement targets, traditional FRCM strengthening must be improved. Esmaeeli and Barros (2015) tested RC beams strengthened by bending with a hybrid composite plate system composed of a strain-hardening cementitious composite plate and carbon fibre-reinforced polymer (CFRP). The researchers found that anchorage measures, such as sand blasting and chemical anchors, are useful in enhancing the bond strength at the interface of the strengthening system and the concrete substrate of the beams.…”