Date of Award

2018

Document Type

Open Access Dissertation

Department

Civil and Environmental Engineering

Sub-Department

Civil Engineering

First Advisor

Fabio Matta

Abstract

There is extensive experimental evidence of the decrease in the shear stress at failure at increasing effective depths in concrete beams reinforced with glass fiberreinforced polymer (GFRP) bars without shear reinforcement. An important practical implication is that extrapolating strength values from typical laboratory-scaled experiments to design larger members may be misleading. The complexity of the underlying mechanics is reflected in the difficulty of using commercially available numerical tools to accurately estimate shear strength irrespective of beam size. This dissertation presents research on a Lattice Discrete Particle Model (LDPM) based model to simulate the response of scaled slender GFRP reinforced concrete (RC) beams without stirrups. The numerical model includes: (1) a calibrated and validated concrete LDPM; (2) orthotropic GFRP bar elements; and (3) a nonlinear bond-slip law for the GFRP barconcrete interface. In the first study, LDPM-based numerical models are deployed to simulate the load-midspan displacement response, crack pattern, shear strength and associated size effect for GFRP RC beams without stirrups. Benchmark results were obtained from the literature based on physical tests on beams having effective depth in the range 146-883 mm, and similar maximum aggregate size. The numerical simulations yielded accurate predictions of load-deflection response, strength, and failure mode, irrespective of the size. The second study presents a calibration and validation procedure for the concrete LDPM based on typical information available from reports on physical experiments (i.e., cylinder compressive strength, and maximum aggregate size). Next, the concrete LDPM implemented in the beam model is validated by accurately simulating the shear behavior of GRFP RC beams without stirrups having maximum aggregate size different from the first study, and effective depth in the range 146-292 mm where the size effect becomes evident. In the third study, the influence of concrete fracture energy and maximum aggregate size are investigated numerically in two cases in which both the strength and failure mode of GFRP RC beams without stirrups are particularly difficult to predict. In fact. Based on the simulation results, it is recommended that fracture tests along with the compressive strength tests be performed on concrete specimens. The results of this research are significant since, for the first time, they demonstrate the successful use of numerical simulations to accurately describe the sizedependent shear behavior of GFRP RC beams without stirrups.

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