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Highlights • FRP bridge deck that incorporates PU foam was developed for ABC and repair. • Results of testing indicated that the deck significantly exceeded the AASHTO requirements. • The decks behaved linearly-elastically throughout the full range of loading. • The experimental results were used to evaluate the applicability of existing FRP design equations. Abstract A fiber-reinforced polymer (FRP) bridge deck panel that incorporates a polyurethane foam core was developed for accelerated bridge construction and repair. This low cost panel was tested under monotonic loading and compared to applicable FRP design equations. This new prototype system consisted of two stiff facesheets of stitch bonded plain-weave woven E-glass fabric with sloping webs of E-glass woven fabric that are separated by trapezoidal-shaped, low-density polyurethane foam. The polyurethane foam was used in an attempt to reduce initial costs. The panels used in this study were manufactured using a one-step, vacuum-assisted, resin transfer molding process (VARTM) using a newly formulated, two-part, thermoset, polyurethane resin developed by Bayer MaterialScience to facilitate the infusion process. The results of the flexural and shear testing indicated that the prototype panels significantly exceeded the AASHTO Design Code Strength requirements by nearly three times. Even more importantly, the panels behaved linearly-elastically throughout the full range of loading and possessed significant post-buckling strength. In addition, the results of these full-scale panels were used to evaluate the applicability of existing FRP design equations when used for the design of the VARTM- manufactured, prototype FRP bridge deck. Results showed that the existing FRP design equations correctly predicted a flexural failure due to local buckling of the compression flange and a bearing failure due local buckling of the webs beneath the concentrated load. [ABSTRACT FROM AUTHOR]

Concrete sandwich panels (CSPs) are oftentimes subjected to extreme exterior temperatures, causing thermal gradients between inner and outer surfaces, and eventually bowing. In addition, the composite degree (k p) of CSPs has been conventionally estimated using methods that require costly and time-consuming experimental tests or rigorous numerical models. The lack of research and understanding on the effects of k p and bowing oftentimes result in overly conservative and uneconomic design, particularly for partially composite (PC) panels. This study develops simple design equations for thermal bowing and k p in CSPs based on a comprehensive parametric study using a transient thermal-structural coupled finite element (FE) model developed earlier by the authors. Key parameters considered are span (L); connector configuration, material, and reinforcement ratio; wythe and insulation thicknesses; concrete strength and thermal differential (ΔT) on both sides. In panels with L larger than 13 m, particularly those featuring steel and CFRP truss connectors and subjected to temperature gradients (ΔT) higher than 30 °C, bowing was larger than the deflection serviceability limit of L /360. Cracking in concrete wythes and yielding of steel connectors were also observed and were mainly dependent on ΔT and k p. Two existing theoretical models were evaluated using results of the parametric analysis and were found to overestimate thermal bow, particularly for panels with low k p. A proposed bowing model is presented which incorporates the effects of composite degree and yields much better predictions than these from literature. • Evaluation of thermal bowing (Δ) and composite degree (k p) in concrete sandwich panels (CSPs). • Parametric study conducted using transient thermal-mechanical FE model. • Parameters are span; connector configuration, material, and reinforcement ratio, wythe and insulation thicknesses; concrete strength; and thermal differential (ΔT). • Temperature can cause cracking and serviceability issues for CSPs, mainly when ΔT ≥ 30o. • Two models were developed, for Δ and k p , from regression analysis and can be used for design purposes. [ABSTRACT FROM AUTHOR]

• Incorporation of novel solutions of hemp fabrics to the FRCM composites as wythes of sandwich panels. • Bending and compression behavior of full-scale sandwich panels with hemp-FRCM. • Development of ductile sandwich panel with effective composite action of hemp-FRCM. • Simplified analytical approach validated from experimental results. Sandwich panels composed of fabric-reinforced cementitious matrix (FRCM) and extruded polystyrene foam (EPS) represent a light and insulating solution compared with other types of enclosure walls, such as steel-reinforced concrete (RC) panels. To improve the sustainability and lightness of FRCM sandwich panels used for building enclosures, this study proposes the use of hemp fabrics in contrast to glass fabrics. Modal analysis and bending and compression tests were conducted on full-scale panels with hemp- and glass-FRCMs. The results obtained from these tests indicate that the use of hemp fabrics with greater equivalent thickness and deformation capacity than glass fabrics make the production of ductile and strength (35 % more than glass-FRCM) sandwich panels possible. Nevertheless, glass-FRCMs allow the production of more stiffened panels. In addition, this study presents a simplified analytical model of sandwich FRCM panels based on the definition of cracked section strength, which is useful in the case of full composite action in the sandwich solution. [ABSTRACT FROM AUTHOR]

The use of advanced composites for building rehabilitation presents several advantages when compared with traditional construction materials. When degraded building floors need to be replaced, composite sandwich panels are a potentially interesting solution, namely for buildings with load-bearing rubble masonry walls. In this paper, connection systems between composite sandwich floors and load-bearing walls are proposed, and their behaviour under vertical loading is investigated. The systems comprise steel angles anchored to the walls, serving as main supports of the sandwich panels, which are then adhesively bonded and/or bolted to the angles. These connection systems are experimentally assessed using sandwich panels made of glass-fibre reinforced polymer (GFRP) face sheets and cores of either polyurethane (PUR) foam or balsa wood, by means of flexural tests on cantilevers, which are also simulated using non-linear finite element models. The structural response of the connection systems is determined, including the rotational stiffness conferred to the floors, the strength and the failure modes. Moment–rotation relationships are obtained for the connection systems and sandwich panel types considered, which provide a wide range of rotational stiffness values, from 60 to 10,856 kNm/rad per unit width (m). These are then used to analytically estimate the short-term mid-span deflections of floors with semi-rigid connections and spans ranging between 2 m and 5 m. It is shown that some of the proposed connections allow significant floor stiffness increases compared with simply supported conditions, with reductions in total mid-span deflection of up to 65% being achieved for a span of 4 m. The results obtained for the proposed connections highlight (i) their potential benefits for fulfilling serviceability limit states and (ii) the importance of considering an adequate structural model when designing sandwich floor panels. [ABSTRACT FROM AUTHOR]

• Research deals with experimental activity and related theoretical modelling. • The wall is made of monolithically casted shotcreted concrete and inner lightweight EPS. • The experimental program deals with a real scale perforated wall tested under cyclic loads. • A mechanically based formulation is suggested to include the deformability of bonded starter bars. • Different modelling approaches to include deformability of starter bars at foundations are compared. Fast construction of structural walls made of reinforced concrete for buildings or industrial warehouses in single panel is a cost-effective system in terms of both the quality of construction and the economy. Anti-seismic constructions can be built with additional reduction of heat dispersion and noise attenuation. In this study the structural system is composed of a factory produced corrugated panel of polystyrene covered on both sides by an electro-welded zinc coated mesh of galvanized steel and shotcreted concrete poured to build the vertical structural walls. This system allows economic savings compared to the traditional systems; however, deformability of the base connections can alter significantly the structural behaviour and seismic response. This study deals with both experimental tests on a real scale structure and numerical simulations, with the goal to provide an efficient formulation to model the deformability of base connections in such sandwich concrete structures, while the materials are modelled either linear elastic or nonlinear. [ABSTRACT FROM AUTHOR]

This paper presents the theoretical development that defines the small displacement behavior of foam insulated concrete sandwich panels. Composite theories presented by other researchers are first thoroughly reviewed and scrutinized in the context of their use for precast concrete beams. A more rigorous Discrete Model that incorporates the complex shear deformation behaviors and independent flexural resistance of the concrete wythes is then derived. Experimental data from full-scale precast sandwich panel tests are used to validate the developed methodology. Finally, it is demonstrated that this study provides a rigorous analysis methodology for foam insulated concrete sandwich structures. [ABSTRACT FROM AUTHOR]

Highlights: [•] Performance of sandwich panels under blast load is evaluated using nonlinear finite element analysis. [•] Effect of topological parameters and boundary conditions is studied. [•] Effectiveness of orthotropic topologies is shown. [•] Capacity analysis is carried out and energy dissipation is studied. [•] Recommendations are made on the use of sandwich panels for blast mitigation. [Copyright &y& Elsevier]

Abstract: This paper presents the first part of an experimental investigation carried out on a construction system based on completed in situ sandwich panels with non-shear connectors, concerning the study of vertical panels used as structural walls. Compression tests with axial and eccentric loads were carried out on several full scale panel specimens with different slenderness ratios in order to study the behaviour of panels under vertical in-plane forces. Additionally, diagonal compression tests were performed on square specimens in different configurations in order to study the behaviour of panels under horizontal in-plane forces. The most significant load–displacement diagrams for increasing load are illustrated and the failure modalities are discussed. The semi-composite behaviour of the panels, guaranteed by the internal layer of polystyrene and the reinforced concrete beams at the panel ends, is highlighted. Finally, some numerical simulations are performed with non-linear finite element models and some useful design indications are given. [Copyright &y& Elsevier]

Abstract: This paper presents the second part of an experimental investigation carried out on a construction system based on completed in-situ sandwich panels with non-shear connectors, concerning the study of floor sandwich panels. Four-point flexural tests were carried out on several full-scale panel specimens with different slenderness ratios in order to study the behaviour of panels under vertical loads. Additionally, wall–floor nodes with different connection details were tested to analyze the effective degree of the rotational restraint of different realistic nodes. Furthermore, a loading test on the floor of a full scale 3D mock-up entirely built with sandwich panels was carried out to investigate the service and ultimate behaviour of a real floor. The most significant load-displacement diagrams for increasing load are illustrated and the failure modalities are discussed. The semi-composite behaviour of the panels, guaranteed by the internal layer of polystyrene and the reinforced concrete beams at the panel ends, is highlighted. The effects of the wall–floor connection and the bi-dimensional behaviour of the floor are also evaluated. Finally, some numerical simulations are performed with non-linear finite element models and some useful design indications are given. [Copyright &y& Elsevier]

Abstract: The response of composite sandwich structures to blast loading has received little attention from researchers when compared to the research performed on their metallic counterparts, despite the fact that composite sandwich panels are becoming more generally used in practice. This paper reports on a preliminary experimental investigation into the response of sandwich panels comprising E-glass fibre reinforced vinyl ester facesheets and closed cell PVC foam cores to localised blast loading. The loading is generated by detonating discs of plastic explosive in close proximity to the panel. Multiple failure modes were exhibited by the panels. A failure progression pattern was identified, with increasing impulse: front facesheet delamination, core compression, back facesheet delamination, fibre fracture, core fragmentation, plastic deformation and debonding of the back facesheet following by complete core penetration. No back facesheet rupture was observed, but this was anticipated as the next failure mode to occur at higher impulse levels. The panels with denser cores exhibited lower levels of damage. Theoretical estimates of midpoint displacement were calculated using an analytical beam model. Simple estimates of the delamination, core compression and fibre fracture energies were also made. The energy partition showed that delamination, core compression and fibre fracture were significant energy absorption modes, and that fibre fracture energies exceeded the core compression and delamination energies at higher impulses. This was particularly evident for the lower density core which provided lower resistance to front facesheet deflection. [Copyright &y& Elsevier]

Abstract: In this study the authors investigated experimentally the behaviour of prefabricated reinforced concrete sandwich panels (RCSPs) under simulated seismic loading through a large experimental campaign. Tests were carried out on single full-scale panels with or without openings, simulating the behaviour of lateral resisting cantilever and fixed-end walls. Tests were also carried out on a 2-storey full-scale H-shaped structure constructed by individual panels which were properly joined together. The performance and failure mode of all panels tested revealed strong coupling between flexure and shear due to the squat-type geometry of the panels. However due to their well-detailed reinforcement, all panels exhibited only a relatively gradual strength and stiffness degradation and in no case did any panel suffer from sudden shear failure. The prefabricated walls of the structural system investigated herein seem to meet all the requirements of Eurocode 8 for walls to be designed as “large lightly reinforced walls”; however this assumption should be supported with further experimental and analytical studies. [Copyright &y& Elsevier]

• Numerical study on thermal bowing of concrete sandwich panels. • A transient thermal–mechanical FE model is developed and validated with thermal and structural tests. • Studied effects of composite degree (k p), cold temperatures, and combined thermal and wind loads. • Increasing k p from 0 to 85% resulted in increasing bowing by 129%. • Up to 50% increase in bowing was observed when adding wind effects to thermal bowing. Thermal bowing in concrete sandwich panels (CSPs), which is an undesirable deflection due to temperature differentials between inner and outer surfaces, has not been studied sufficiently and its effects are still not well understood. In this study, a transient thermal-mechanical finite element technique in ANSYS software, featuring two separate but interrelated time-domain simulations, a heat transfer and a non-linear structural, has been developed to study the bowing phenomenon in CSPs. The model predictions were validated by comparing with experimental data from full-scale panels in the literature subjected to heating on one wythe that produced an increasing temperature differential up to 30 °C. Validation included thermal bowing, slip and temperatures gradient. The structural component of the model was also validated by comparing with panels tested under flexural loads. The coupled model was then used to study the effects of several key variables that were not examined in the experiments, including cooling load, degree of composite action (k p), and wind loading combined with thermal loading. Results showed that very cold temperatures can result in bowing that exceeds serviceability limits and can cause compression failure in connectors. Bowing increased by 129% when k p increased from zero to 85%. Up to 50% increase in bowing was observed when adding wind effects to thermally determined bowing for the thermal range investigated in the parametric study. [ABSTRACT FROM AUTHOR]

Abstract: Bridges with FRP decks are gaining popularity, and there is a growing need to understand the behavior of FRP deck bridges. The characteristics of bridges with FRP decks (such as mass, stiffness, and damping) are significantly different from those of bridges with traditional concrete decks. For this reason, detailed finite element analyses are used in the present study to investigate the load distribution and the dynamic response of FRP deck bridges. The bridge–vehicle interaction based on a three dimensional vehicle–bridge coupled model is carried out on both steel and concrete multi-girder bridges. The dynamic response of bridges is obtained in the time domain considering the road roughness of the deck as a vertical excitation to the vehicles. The load distribution and the dynamic response of bridges are compared between the FRP deck and concrete deck bridges. In addition, there are some arguments whether a composite action between the deck and girders should be pursued or if a simple non-composite design should be used for FRP deck bridges. Discussions on this aspect have been made by modeling both the fully composite and partially composite FRP deck bridges. [Copyright &y& Elsevier]

Abstract: This paper focuses on the seismic design of moment resisting steel frames endowed with structural lightweight cladding panels. The aim is to investigate the possibility to profit from their contributing effect on both the serviceability and the ultimate limit states of the structure. An original design procedure is proposed, where the stiffening action provided by cladding panels is taken into account in order to increase the lateral stiffness of the bare frame, which is designed according to the strength only. In order to assess the reliability of the proposed solution a number of non-linear dynamic time-history analyses are presented and discussed. With this aim, accurate mathematical models interpreting the cyclic response of both screwed and welded lightweight steel panels have been set up and implemented into a general purpose computer program. The main parameters affecting the seismic performance of the system, namely the frame configuration, the mechanical and hysteretic characteristics of cladding panels and their distribution throughout the frame, are investigated. On the one hand, the obtained results show that the proposed design procedure leads to more rational and economic solutions, allowing for an important reduction of the sizes of the main structural members. Also, it is shown that the requirements for cladding panels in terms of both strength and stiffness are not excessive. On the other hand, it is apparent that the cladding panels provide an improvement on the global seismic performance at the conventional ultimate limit state also, even though such an effect is largely dependent on the above influential parameters. A simplified procedure to account for such an effect is also proposed. [Copyright &y& Elsevier]

• A new composite element for timber-concrete sandwich panels is proposed. • The model uses notably less computational efforts compared to FE models with conventional elements. • The model was validated against FE and experimental results of sandwich panels. Timber-concrete composite panels are commonly used as a sustainable alternative for reinforced concrete floor construction systems. Their performance also continues to advance with new approaches to interfacial shear connection and layer composition, for example as three-layer sandwich panels with a concrete compressive face layer, timber tensile face layer, and a cellular core. Due to significant difference in stiffness of the layers, such sandwich panels demonstrate large transverse shear deformations when subjected to bending. Existing finite element modelling techniques, relying on traditional shell or solid elements, can become computationally expensive when simulating the behaviour of sandwich panels. This paper presents a new composite element for simplified numerical modelling of sandwich panels, greatly reducing the computational effort. The proposed element comprises two face layers connected by an interlayer, with face layers considered as beams and the interlayer considered as springs. A numerical model was developed using the proposed element and was validated against finite element results of linear sandwich beams and experimental results of nonlinear, cellular-cored timber-concrete sandwich panels. [ABSTRACT FROM AUTHOR]

• Large experimental study analyses the shear performance of precast sandwich panels with steel plate connectors. • Connectors of varied thickness and depth give rise to different load capacities, stiffnesses and failure modes. • The insulation layer plays a significant role in preventing rotation in response to a shear load. • Finite element analysis is undertaken and identifies significant nonlinear behavior in the panel response. Precast concrete sandwich panels are an increasingly popular means of building cladding. They can be designed with high thermal resistance by embedding abundant insulation between two concrete wythes. Steel, in the form of thin plate connectors, remains one of the most common tie materials to support the outer wythe of concrete vertically, and transmit lateral forces from the external rain-screen to the internal structural wythe. The optimum design of steel shear connectors must satisfy thermal and strength capacity constraints. An extensive experimental study analyses the structural shear performance of precast concrete sandwich panels with steel plate connectors of various dimensions that give rise to different load capacities, stiffnesses and failure modes. [ABSTRACT FROM AUTHOR]