Paper presents assessment of bond behaviour between GFRP bars and concrete, investigated through set of centric and eccentric pull-out specimens. Main parameters under investigation are 1) bar external surface, 2) concrete mechanical properties and 3) concrete cover. Corresponding tests with steel reinforcement are performed for comparison in some cases. DIC technique was used for recording and evaluating of strain field on frontal side of eccentric specimens. Consequently, cracking patterns and local bond behaviour are described in details. Increasing of concrete mechanical properties always enhanced bond strength and delayed cracking of concrete cover. Ribbed GFRP bars showed excellent bonding performance when combined with low concrete cover. Their low splitting tendency and specific rib geometry developed better bond behaviour in case of eccentric tests, which showed the possibility of a proper prediction of the bonding behaviour of structural components

The thermo-mechanical behavior of sandwich panels was experimentally investigated. The panels featured two external concrete layers reinforced with glass fiber reinforced polymer rebars (GFRP) and an internal expanded polystyrene insulation layer. These are typical for low load bearing and thermally insulated panels in façade claddings. To assess the suitability of the internal GFRP reinforcement, the heating condition was such that rebars in one concrete layer were exposed to temperatures higher than the glass transition temperature of the resins. Such extreme condition allowed verifying the retention of the mechanical behavior, in terms of deformability and load-carrying capacity, with bending tests of unheated and heated panels. As main outcome, the elevated temperature produced significant modification of the insulation layer, considerable reduction of global stiffness and load-carrying capacity, while GFRP bars were not apparently modified.concrete, glass fiber bars, mechanical testing, sandwich panels, thermomechanical loading | INTRODUCTIONIn the last two decades, several investigations showed the advantages and disadvantages of replacing the steel reinforcement with FRP (fiber reinforced polymers) rebars in structural concrete components. 1 Many investigations and applications were focused on the GFRP (glass fiber reinforced polymer) rebars for their non-corrosive and nonconductive characteristics as well as their high strength, low weight, and durability. 2-4 One important field of application of GFRP reinforcement is slender concrete structures. The lack of corrosion allows to reduce the bar protection decreasing the concrete covers and, as consequence, the thickness of concrete members. Slender layers of reinforced concrete are frequently adopted as the load-carrying members of sandwich panels used, in the construction industry, as façade panels or slabs for pavements. External cladding sandwich panels made of pre-cast concrete usually consist of three layers: thin load-carrying concrete layer, the thermal insulation, and a thin facing concrete layer. Sandwich panels are frequently adopted in buildings to exploit their structural and thermal efficiency. Nowadays, they play an important role in the building industry that aims to improve the energy efficiency and increase the durability of building constructions.Several efforts were dedicated to the understanding and optimization of the mechanical behavior of sandwich panels with different reinforcements: steel rebars and connectors (see, e.g., Reference 5); steel rebars and GFRP connectors (see, e.g., Reference 6); steel fiber reinforced selfcompacting concrete and GFRP connectors (see, e.g., Reference 7). Some investigations were devoted to the mechanical response of steel-free sandwich panels having both reinforcement and connectors made of GFRP (see, e.g., Reference 8).In spite of the interest in constructions industry on steelfree sandwich panels, their durability and in particular their

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Precast concrete sandwich panels (PCSPs) are known for their good thermal, acoustic and structural properties. Severe environmental demands can be met by PCSPs due to their use of highly thermally insulating materials and non-metallic connectors. One of the main issues limiting the wider use of sandwich walls in construction is their unknown fire resistance. Furthermore, the actual behaviour of connectors and insulation in fire in terms of their mechanical performance and their impact on fire spread and the fire resistance of walls is not fully understood. This paper presents an experimental investigation on the structural and thermal behaviour of PCSPs with mineral-wool insulation and glass-fiber-reinforced polymeric bar connectors coupling two concrete wythes. Three full-size walls were tested following the REI certification test procedure for fire walls under fire and vertical eccentric and post-fire mechanical impact load. The three test configurations were adopted for the assessment of the connectors’ fire behaviour and its impact on the general fire resistance of the walls. All the specimens met the REI 120-M criteria. The connectors did not contribute to the fire’s spread and the integrity of the walls was maintained throughout the testing time. This was also confirmed in the most unfavourable test configuration, in which some of the connectors in the inner area of the wall were significantly damaged, and yet the structural connection of the concrete wythes was maintained. The walls experienced heavy heat-induced thermal bowing. The significant contribution of connectors to the stiffness of the wall during fire was observed and discussed.

<p>Precast concrete sandwich panels are known for their inherently good thermal, acoustic and structural properties. When using glass fibre reinforced polymeric (GFRP) connectors coupling the concrete layers, excellent thermal properties and high structural stiffness can be achieved. However lack of knowledge on fire resistance of sandwich panels and fire bahavior of GFRP connectors remain an important issue limiting their wider use in the construction. This paper presents results of fire tests performed on real size sandwich walls in terms of fire behavior of the GFRP connectors and its impact on fire resistance of the entire walls. All the three tested sandwich walls met the REI 120-M criteria for load-bearing fire walls. The connectors showed in general good fire resistance and did not contribute to fire spread. The tests delivered important information on structural behaviour of sandwich walls with GFRP connectors loaded with fire and vertical eccentric and impact load.</p>