Local structural effects in fiber-reinforced polymer web-core sandwich structures

Glass fiber-reinforced polymer (GFRP) pultruded decks and sandwich panels currently represent two of the most extensive applications of FRP materials for load-bearing structural components in the bridge and building domains. Based on the state of the art, the global structural behavior of both systems has been fairly well investigated. Nonetheless, local effects governing in most cases the global behavior have been barely addressed. Selected local structural effects relevant to the global structural performance of pultruded GFRP bridge decks and GFRP-foam web-core sandwich structures are therefore investigated in this research. The effect of the core geometry of pultruded GFRP decks on the systemâs behavior in its transverse-to-pultrusion direction was experimentally investigated. The experimental work conducted on two deck designs with trapezoidal- and triangular-cell cross sections showed that the transverse structural performance depends on the cell geometry. Furthermore, the systemsâ transverse bending and in-plane shear stiffness were evaluated and the results indicated that a triangular core causes a more pronounced bi-directional behavior of the deck when it is subjected to concentrated loads. The local behavior of the web-flange junctions (WFJs) of the pultruded deck with trapezoidal cells was experimentally investigated regarding energy dissipation capacity and recovery subsequent to unloading. The experimental responses reported for two junction types with similar geometry and fiber architecture but different initial imperfections demonstrated that dissimilar imperfections could significantly affect WFJ behavior and change it from brittle to ductile. The time-dependent recovery and energy dissipation mechanisms of the WFJs exhibiting a ductile response were evaluated; the viscoelastic effects were found to be small in both cases. The rotational behavior of all WFJ types present in the trapezoidal-core deck was characterized. An experimental procedure based on three-point bending and cantilever experiments conducted on the web elements was developed and used for this purpose. The rotational stiffness, strength and failure modes of the WFJs differed depending on the web type, location of the WFJ within the deck profile, existing initial imperfections and direction of the applied bending moment. Numerical simulations of the full-scale deck were performed to demonstrate the validity of the experimental moment-rotation (M-Ï) relationships and simplified M-Ï curves provided. The effects of creep on the load-bearing behavior of GFRP-foam web-core sandwich structures were investigated. A study of the creep behavior of polyurethane (PUR) foams was conducted and showed that in order to assess the long-term structural performance of the sandwich system, the foam anisotropy, density and loading type should be considered. The creep behavior of web-core sandwich panels, and specifically the structural aspects affected by the web-core interaction, were analyzed using the GFRP-PUR sandwich roof of the Novartis Campus Main Gate Building as case study and currently available design guidelines. The resulting sandwich designs depended on the applied design recommendations. Finally, provisions for the cross-sectional design of the hybrid web-core were proposed

Characterization of rotational behavior of web-flange junctions of pultruded GFRP bridge decks

The rotational behavior of the web-flange junctions (WFJs) of a pultruded GFRP bridge deck system was investigated. The rotational response of three WFJ types was characterized. An experimental procedure based on three-point bending and cantilever experiments conducted on the web elements and simple analytical models was used. The WFJs generally exhibited non-rigid and nonlinear behavior. The overall moment-rotation relationships, rotational stiffness, strength and failure modes differed depending on the web type, the location of the WFJ within the deck profile, the initial imperfections and the direction of the bending moment applied. Simplified expressions to model the WFJ rotational behavior were derived. The validity of the experimental and idealized rotational responses was assessed by means of numerical simulations of full-scale experiments conducted on the GFRP deck

Performance in Transverse Direction of Fiber‐Reinforced Polymer Bridge Decks

Pultruded glass fiber‐reinforced polymer (GFRP) bridge decks distribute punctual vehicular loads to the underlying superstructure and can also act as the upper chord of hybrid main girders. The deck’s structural performance in both cases is influenced by its transverse behavior. The static bending behavior in the transverse‐to‐pultrusion direction of two GFRP bridge deck systems with trapezoidal (DS) and triangular (AS) cell cross‐sectional geometry was experimentally studied. Different load transfer mechanisms were found in DS (frame‐dominated) and AS (truss‐governed) depending on the cell geometry. The DS deck exhibited a lower apparent bending stiffness and degree of composite action between the face sheets than the AS deck, which was attributed to the lower transverse in‐plane shear stiffness provided by the trapezoidal core than by the triangular core. The system in‐plane shear moduli were estimated from the experimental deflection results

Escuela de teatro en Almagro

Escuela de teatro en Almagro. Convocatoria Marzo. Plan 1996. Proyecto fin de carrera. Universidad Politécnica de Madrid. Escuela Técnica Superior de Arquitectur

Escuela de teatro en Almagro

Escuela de teatro en Almagro. Convocatoria Marzo. Plan 1996. Proyecto fin de carrera. Universidad Politécnica de Madrid. Escuela Técnica Superior de Arquitectur

Energy dissipation in adhesive and bolted pultruded GFRP double-lap joints under cyclic loading

Fiber-reinforced polymer (FRP) structures, due to their low mass, are valuable alternatives to traditional steel or concrete structures in seismic areas. However, to resist seismic actions, FRP structures must be able to dissipate a significant amount of inelastic energy. Since FRP materials are brittle, this dissipation must occur in the joints. Monotonic tension and cyclic tension-compression experiments were thus performed on adhesive and bolted double-lap joints composed of pultruded glass fiber-reinforced polymer (GFRP) profiles; a flexible adhesive was used in the adhesive joints. A significant amount of energy was dissipated in the adhesive joints at lower and medium displacement rates through viscoelastic friction and damage in the adhesive, while almost no energy dissipation occurred at the highest rate. The energy in the bolted joints was dissipated by progressive crushing and shear-out failures in the inner laminates. Although the dimensions and monotonic strength of the adhesive and the bolted joints were similar, the former dissipated significantly more energy at the two lower applied displacement rates. The obtained results can contribute to the seismic design of inelastic joints in FRP structures. (c) 2020 The Authors. Published by Elsevier Ltd

Long-term design of FRP-PUR web-core sandwich structures in building construction

The structural behavior of GFRP-polyurethane (PUR) web-core sandwich structures subjected to sustained loading was investigated. As a basis, a study of the mechanical behavior of rigid PUR foams used as core materials was conducted, with emphasis on creep. The study showed that the foam anisotropy, its density and the loading type applied must be considered to assess the structural performance of the GFRP-PUR web-core sandwich. The influence of creep on the web-core interaction, i.e. on the shear load distribution and local instability phenomena were then analyzed. The effects of applying particular design recommendations on the design were assessed based on the example of a real GFRP-PUR sandwich roof. The design shear resistance of the GFRP webs, their dimensions and governing failure mode significantly depended on the applied recommendation. A design procedure to evaluate the overall shear resistance of the GFRP-PUR core over time, taking into account creep effects, was presented. (C) 2017 Elsevier Ltd. All rights reserved

Rotational stiffness of web-flange junctions of pultruded GFRP decks

The rotational behavior of the web-flange junctions (WFJs) of a pultruded glass fiber-reinforced polymer (GFRP) bridge deck system with trapezoidal cell cross-sectional geometry was investigated. The rotational response of three WFJ types, in two bending moment directions each, was characterized. An experimental procedure based on three-point bending and cantilever experiments conducted on the web elements and simple analytical models was used. The WFJs generally exhibited non-rigid and nonlinear behavior. The overall moment-rotation relationships, rotational stiffness, strength and failure modes differed depending on the web type, the location of the WFJ within the deck profile, the existing initial imperfections and the direction of the bending moment applied. This evidenced the relevance of separately characterizing the response of all WFJ types in the two possible bending directions. Simplified expressions to model the WFJ rotational behavior were derived. The validity of the experimental and idealized rotational responses was assessed by means of numerical simulations of full-scale experiments conducted on the GFRP deck. (C) 2017 Elsevier Ltd. All rights reserved

Energy dissipation and recovery in web-flange junctions of pultruded GFRP decks

The energy dissipation capacity resulting from progressive cracking and the recovery after unloading of the web-flange junctions (WFJs) of a pultruded GFRP deck were experimentally investigated. Web-cantilever bending experiments up to failure were performed on two WFJ types (If-o, Ic-o) with similar geometry and fiber architecture but different initial imperfections (deviations from the fiber architecture design, wrinkling of fabrics, resin pockets, pre-cracks). Dissimilar imperfections changed the WFJ behavior from brittle (If-o) to ductile (Ic-o): different crack sequences were observed, which resulted in an abrupt failure in If-o WFJs and a progressive failure in Ic-o WFJs, in addition to a higher load-bearing capacity of the latter. The Ic-o WFJs exhibited significant recovery; a small influence of the FRP viscoelastic properties on recovery and a constant damage rate were observed. The total and dissipated energies of the Ic-o WFJs and their ductility index, defined as the ratio of the dissipated to total energy, were modeled. The main energy dissipation mechanism of the Ic-o WFJs was related to crack development; dissipation through viscoelastic losses was significant only at low deflection levels. (C) 2016 Elsevier Ltd. All rights reserved