Web-Flange Behavior of Pultruded GFRP I-beams: A Lattice Model for the Interpretation of Experimental Results

Significance Statement

Pultruded glass fiber reinforced polymer (GFRP) beams have been generally applied in the world of civil engineering due to their desired properties, among which the remarkable strength-to-weight ratio and resistance to environmental effects. However, deformability often represents a severe limitation to the design of GFRP structures. Fractures which occur at the web-flange joint when such elements are subjected to compressive loads remain a bane to technologists, which as a result led to implementation of various research based on experimental and numerical analysis.

Dr. Alessandro Fascetti and Professor Nicola Nisticò from ‘Sapienza’ University of Rome in collaboration with Professor Luciano Feo and Dr. Rosa Penna from University of Salerno in Italy have shown a non-negligible dispersion in strength and stiffness values in the web-flange junction of GFRP I-beams. This phenomenon is due to the non-symmetric distribution of stresses in the member, resulting from the accumulation of micro-cracks affecting the local strength of the material. They presented a recently developed random discrete lattice approach to investigate the fracturing behavior of GFRP systems. The approach is of interest because it overcomes limitations of other methods previously used to investigate the damage in fiber reinforced polymers, such as the fracture energy regularization and mesh-induced crack path bias. The research work is now published in peer-reviewed journal, Composites Part B.

The authors’ numerical model was first validated by comparison with a classical three-dimensional elastic Finite Element simulation. Subsequently, the nonlinear mesoscale lattice model provided a detailed description of crack propagation and explanation of the experimental results.

With the fundamentals that the stiffness of the material at the mesoscopic level (i.e. the level of the lattice network) is higher than the macroscopic one, the strength values (in both tension and compression) of the lattice model were also found to be significantly higher than the corresponding macroscopic ones, which conforms well to previous theories and findings.

A good agreement was realized in this study between numerical and experimental results in terms of both force-displacement curves and crack paths at failure.

The developed numerical model in this study is capable of predicting the accurate features of pultruded glass fiber reinforced polymer (GFRP) I-beams.

About the author

Alessandro Fascetti received his Ph.D. in Structural and Geotechnical Engineering from the “Sapienza” University of Rome. He currently serves as a Post-Doctoral Research Scholar at Vanderbilt University (Nashville, TN).

He conducts research on the multiscale modeling of different kinds of composite materials used in structure and infrastructure systems. His work focuses on failure mechanics as well as durability aspects, combining multiscale experimental information for the validation of the numerical models. Particular attention is devoted to the use of random lattice models for the solution of civil engineering related problems.

About the author

Luciano Feo is Full Professor of Structural Mechanics in the Department of Civil Engineering at the University of Salerno, Italy. He received a Ph.D. in Structural Engineering from the University of Napoli “Federico II”, in 1997.

He is currently the Editor for Europe of Composites Part B: Engineering journal (Elsevier) and the Director of the Structural Engineering Test Hall of the Department of Civil Engineering of the University of Salerno.

His main research interests include computational mechanics; multiscale numerical modeling and simulation of materials and structures; computational design and engineering of innovative materials, such as highly nonlinear phononic crystals, environmentally compatible composite materials, nanomaterials and biomaterials.

About the author

Nicola Nisticò is Associate Professor of structural engineering at the University of Rome “La Sapienza”. He is a member of the board of the PhD program in Structural and Geotechnical Engineering as well as of the Master in “Euorocodes based design”.
He received his Ph.D. in Structural Engineering at the University of Florence, defending a thesis oriented to 1) the validation of the Discrete Element Method for the seismic assessment of Block Masonry Structures 2) the formulation and implementation of an analytical-numerical model for contact-impact problems.

His scientific activity is focused on 1) structural and material modeling 2) structural monitoring 3) assessment and retrofitting of existing reinforced concrete structures 4) composite materials 5) structural glass 5) TMD systems for buildings.

About the author

Rosa Penna is a researcher in Structural Mechanics in the Department of Civil Engineering of the University of Salerno, Italy. She received a Ph.D. in Structural Engineering from the University of Salerno, Italy in 2014. She currently serves as an Editorial Board member for Composites Part B: Engineering Journal (Elsevier).

Her main research interests include numerical and experimental analysis of materials and structures; structural strengthening of existing structures with FRP composite materials; FRP composites bonded and bolted joints; NanoMaterials and NanoTechnology.

Journal Reference

A. Fascetti1, L. Feo2, N. Nisticò1, R. Penna2, Web-flange behavior of pultruded GFRP I-beams: A lattice model for the interpretation of experimental results, Composites Part B 100 (2016) 257-269.

Show Affiliations
  1. Sapienza Università di Roma, Dipartimento di Ingegneria Strutturale e Geotecnica, Via Eudossiana, 18, 00184 Roma, Italy
  2. Università degli Studi di Salerno, Dipartimento di Ingegneria Civile, Via Giovanni Paolo II, 132, 84084 Fisciano, SA, Italy


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