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Sandwich structures are widely used for the design and fabrication of lightweight structural systems, due to their capability to exhibit excellent structural and thermal performances at low material usage. Understanding the phenomena of propagation of macro-cracks in the core and delamination at the face-to-core interface are aspects of great computational interest. Linking sophisticated models with the actual characterisation of their mechanical properties is essential in view of real engineering applications. The elastic and fracture characterisation of the materials composing the core is particularly relevant because its cracking affects the capacity of the sandwich structures to carry out transverse loads. In this work, PVC foams typically used as the inner core in structural applications are investigated over a range of foam densities. Firstly, the elastic properties of foams under compressive uniaxial loading are measured using a full-field methodology. Subsequently, Semi-Circular specimens are tested in bending varying the position of supports to generate all range of mixed fracture modes. Suitable fracture criteria are also considered in order to assess their capability to evaluate fracture parameters in PVC foams. Finally, the parameters experimentally determined have been used to validate the response provided by a numerical model developed by the authors.
Marco Francesco Funari; Saverio Spadea; Paolo Lonetti; Paulo B. Lourenço. On the elastic and mixed-mode fracture properties of PVC foam. Theoretical and Applied Fracture Mechanics 2021, 112, 102924 .
AMA StyleMarco Francesco Funari, Saverio Spadea, Paolo Lonetti, Paulo B. Lourenço. On the elastic and mixed-mode fracture properties of PVC foam. Theoretical and Applied Fracture Mechanics. 2021; 112 ():102924.
Chicago/Turabian StyleMarco Francesco Funari; Saverio Spadea; Paolo Lonetti; Paulo B. Lourenço. 2021. "On the elastic and mixed-mode fracture properties of PVC foam." Theoretical and Applied Fracture Mechanics 112, no. : 102924.
A new methodology to predict interfacial debonding phenomena in fibre-reinforced polymer (FRP) concrete beams in the serviceability load condition is proposed. The numerical model, formulated in a bi-dimensional context, incorporates moving mesh modelling of cohesive interfaces in order to simulate crack initiation and propagation between concrete and FRP strengthening. Interface elements are used to predict debonding mechanisms. The concrete beams, as well as the FRP strengthening, follow a one-dimensional model based on Timoshenko beam kinematics theory, whereas the adhesive layer is simulated by using a 2D plane stress formulation. The implementation, which is developed in the framework of a finite element (FE) formulation, as well as the solution scheme and a numerical case study are presented.
Marco Francesco Funari; Saverio Spadea; Francesco Fabbrocino; Raimondo Luciano. A Moving Interface Finite Element Formulation to Predict Dynamic Edge Debonding in FRP-Strengthened Concrete Beams in Service Conditions. Fibers 2020, 8, 42 .
AMA StyleMarco Francesco Funari, Saverio Spadea, Francesco Fabbrocino, Raimondo Luciano. A Moving Interface Finite Element Formulation to Predict Dynamic Edge Debonding in FRP-Strengthened Concrete Beams in Service Conditions. Fibers. 2020; 8 (6):42.
Chicago/Turabian StyleMarco Francesco Funari; Saverio Spadea; Francesco Fabbrocino; Raimondo Luciano. 2020. "A Moving Interface Finite Element Formulation to Predict Dynamic Edge Debonding in FRP-Strengthened Concrete Beams in Service Conditions." Fibers 8, no. 6: 42.
A new adhesive beam-column connection is tested which possess the highest strength and stiffness compared to any other similar adhesive or bolted connection tested in the past. A square GFRP hollow section, acting as a column, was connected to a built-up beam made of two GFRP U-profiles by means of either epoxy or steel bolts. The beam-column assembly formed an L-shaped frame which was tested by applying a point load at the beam free end while the column was fixed at its base. Five bolted and five adhesive replicate connections were subjected to quasi-static loading up to failure. Another three adhesive connections were subjected to 400, 800 or 1200 cycles of loading and unloading with the maximum load being equal to 0.50 Pu,avg, where Pu,avg is the average static strength of the replicate adhesive specimens. At the end of the cyclic loading, the latter specimens were loaded quasi-statically to failure. Finally, another two adhesive connections were subjected to fatigue type loading. They were successively subjected to at least 196 cycles of loading and unloading with the load amplitude being 0.50 Pu,avg in the first 60 cycles, 0.75 Pu,avg in the next 60 cycles, 0.85 Pu,avg in the following 60 cycles and 0.95 Pu,avg after the 180th cycle. The test results show that the proposed adhesive connection can achieve on average 82% higher strength and 380% higher rotational stiffness than the companion bolted connection. Furthermore, the above cyclic loading has negligible effect on either the strength or the stiffness of the connection. Finally, the connection can sustain the foregoing fatigue load up to almost 180 cycles without significant damage but it will not be able to withstand the full 60 cycles of the load with 0.95 Pu,avg amplitude. The current results demonstrate the superior strength and stiffness of the new adhesive connection compared to a similar bolted connection.
A.G. Razaqpur; F. Ascione; M. Lamberti; S. Spadea; M. Malagic. GFRP hollow column to built-up beam adhesive connection: Mechanical behaviour under quasi-static, cyclic and fatigue loading. Composite Structures 2019, 224, 111069 .
AMA StyleA.G. Razaqpur, F. Ascione, M. Lamberti, S. Spadea, M. Malagic. GFRP hollow column to built-up beam adhesive connection: Mechanical behaviour under quasi-static, cyclic and fatigue loading. Composite Structures. 2019; 224 ():111069.
Chicago/Turabian StyleA.G. Razaqpur; F. Ascione; M. Lamberti; S. Spadea; M. Malagic. 2019. "GFRP hollow column to built-up beam adhesive connection: Mechanical behaviour under quasi-static, cyclic and fatigue loading." Composite Structures 224, no. : 111069.
Marco Francesco Funari; Fabrizio Greco; Paolo Lonetti; Saverio Spadea. A numerical model based on ALE formulation to predict crack propagation in sandwich structures. Frattura ed Integrità Strutturale 2018, 13, 277 -293.
AMA StyleMarco Francesco Funari, Fabrizio Greco, Paolo Lonetti, Saverio Spadea. A numerical model based on ALE formulation to predict crack propagation in sandwich structures. Frattura ed Integrità Strutturale. 2018; 13 (47):277-293.
Chicago/Turabian StyleMarco Francesco Funari; Fabrizio Greco; Paolo Lonetti; Saverio Spadea. 2018. "A numerical model based on ALE formulation to predict crack propagation in sandwich structures." Frattura ed Integrità Strutturale 13, no. 47: 277-293.
A novel shear reinforcing system, wound fiber–reinforced polymer (W-FRP), that capitalizes on the flexibility of carbon fiber to create durable reinforcement cages for geometrically optimized concrete structures, is proposed thereby unlocking new potential to minimize carbon emissions associated with new concrete structures. Fiber-reinforced polymer (FRP) shear design methods have been extensively validated against prismatic beam tests, but variations in geometry have not yet been considered. This paper proposes revised design methods, validated using tests of eight W-FRP–reinforced variable-depth concrete beams, to examine the contributing factors to shear capacity. The corner strength, orientation, and compression concrete confinement provided by W-FRP links, along with the contribution to shear of longitudinal bars, are shown to be key design parameters. Optimizing the W-FRP pattern is found to enhance shear capacity by as much as 50%. The variable-depth geometry tested in this paper uses 19% less concrete than an equivalent-strength prismatic beam. Both reinforcement and geometry optimizations are the key steps toward achieving minimal material use for concrete structures.
Yuanzhang Yang; John Orr; Saverio Spadea. Shear Behavior of Variable-Depth Concrete Beams with Wound Fiber–Reinforced Polymer Shear Reinforcement. Journal of Composites for Construction 2018, 22, 04018058 .
AMA StyleYuanzhang Yang, John Orr, Saverio Spadea. Shear Behavior of Variable-Depth Concrete Beams with Wound Fiber–Reinforced Polymer Shear Reinforcement. Journal of Composites for Construction. 2018; 22 (6):04018058.
Chicago/Turabian StyleYuanzhang Yang; John Orr; Saverio Spadea. 2018. "Shear Behavior of Variable-Depth Concrete Beams with Wound Fiber–Reinforced Polymer Shear Reinforcement." Journal of Composites for Construction 22, no. 6: 04018058.