Semester

Fall

Date of Graduation

2024

Document Type

Problem/Project Report

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

GangaRao Hota

Committee Co-Chair

P.V Vijay

Committee Member

Chao zhang

Abstract

Glass fiber reinforced polymer (GFRP) composites have become an increasingly popular choice in construction industry due to their higher strength-to-weight ratio, ease of manufacture including lower Embodied Carbon Factor, and better durability in harsh environmental conditions than conventional structural construction materials. Currently, GFRP composite column design lacks well-established design standards due to the material's unique properties such as lower bending and shear stiffness than steel, differing compressive and tensile moduli, which leads to complexities in computing buckling capacities under local effects such as flange or web buckling and even torsional buckling under off-centered compression loading. Therefore, GFRP columns will behave differently under axial load than traditional steel and concrete materials. Therefore, AISC/ACI/ASCE’s effective length design guidelines and equations may not accurately predict failure modes and loads in GFRP members under compression.

This study consisted of testing 18-inch diameter GFRP piles through three testing methods to assess failure modes and loads. A lateral crush test was conducted on eight Samples to evaluate resistance to local transverse loading. A local compression washer test was conducted to assess the local crushing capacity. A pin test was performed on four Samples, two Samples tested in the longitudinal and two in the transverse direction, to analyze the bearing load capacity.

Additionally, 48 GFRP box columns were tested under axial compression with six replications for each column length. The columns were categorized by lengths in feet as follows: 1, 2, 4, 6, 8, 10, 15, and 20. All columns had the same cross-sectional dimensions of 3.5” x 3.5” x 0.36”. Half of these Samples were tested using fixed-fixed end conditions and the other half were tested with pin-pin end conditions. Furthermore, an effective length-dependent failure model was developed at the West Virginia University Constructed Facilities Center (WVU-CFC) to help develop standardized effective length recommendations for GFRP columns. In addition to the failure analyses, the degree of fixity provided by the end conditions was analyzed to assess its influence on column behavior by collecting strain gauge data near the support fixture and at the center of each test specimen. The experiments were conducted with due considerations to minimize crushing at the ends by providing column plugs and wraps at the ends and measuring column crookedness due to manufacturing anomalies. Also, extensive number of strain gages were mounted to measure stress concentration at corners of flanges, so that a draft testing procedure can be developed for ASTM standards.

Finally, the mathematical models and the corresponding failure load results were compared with both the prior and current experimental data to verify their accuracy and consistency

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