Development of sandwich panels combining fibre reinforced concrete layers and fibre reinforced polymer connectors. Part I: Conception and pull-out tests

Abstract

a b s t r a c tIn this paper, an innovative and thermally efficient sandwich panel is proposed for the structural walls of a pre-fabricated modular housing system. Traditionally, sandwich concrete panels consist of reinforced concrete wythes as outer layers, polystyrene foam as core material and steel connectors. However, steel connectors are known to cause thermal bridges on the building envelope, with possible consequent occurrence of condensation and mould problems. Furthermore, the reduction/optimization of the thickness of conventionally reinforced concrete layers is frequently limited by minimum concrete cover requirements for the protection of the reinforcement from corrosion. To overcome these issues, the proposed sandwich panel comprises Glass Fibre Reinforced Polymer (GFRP) connectors and two thin layers of Steel Fibre Reinforced Self-Compacting Concrete (SFRSCC). This paper presents the material and structural concept of the proposed building system. Moreover, the feasibility of using the proposed connectors and SFRSCC on the outer wythes is experimentally investigated through a series of pull-out tests where failure modes and load capacity of the connections are analysed.

Development of sandwich panels combining fibre reinforced concrete layers and fibre reinforced polymer connectors. Part II: Evaluation of mechanical behaviour

“…1 from the first part of this paper [1]). The length of the panel was determined by transportation and handling constraints.…”

“…As connections between GFRP and SFRSCC were modelled as perfectly bonded, this modelling approach cannot simulate the failure of the connection itself. Considering this limitation and although the mechanisms occurring in the connection under bending are different from what happens in the pull-out tests, it is possible to perform a partial evaluation on the integrity of the connections, by comparing the principal tensile stresses obtained through the numerical simulations with the maximum tensile stresses in the free section of the GFRP in the pull-out tests performed in Lameiras et al [1]. Considering that the CSM laminate is a linear elastic material and that an uniform distribution of stresses is attained in the GFRP section during the pull-out tests, the minimum and maximum tensile stresses in the free section of GFRP corresponding to the connection failure were 18.4 MPa and 58.32 MPa, obtained respectively for the adhesively bonded (TAB) and T-profiled embedded connectors (TEM) (see [1]).…”

“…The SFRSCC and GFRP properties used in the panel simulations are the ones experimentally determined and presented in the first part of the paper [1]. The SFRSCC was characterised by a modulus of elasticity of 35.45 GPa.…”

“…It may be considered that the panel is casted in the horizontal position (see Fig. 3 from the first part of the paper [1]) and that the panel is stripped by the internal SFRSCC layer. Then, the load corresponding to the weight of the external SFRSCC layer is transferred to the internal SFRSCC layer through the GFRP connectors.…”

“…In the first part of this paper [1] the authors proposed an innovative insulated panel to be used as a load-bearing wall of modular buildings. This panel comprises Glass Fibre Reinforced Polymer (GFRP) connectors and two thin outer layers of Steel Fibre Reinforced Self-Compacting Concrete (SFRSCC).…”