Semester

Spring

Date of Graduation

2014

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Hota V. S. GangaRao

Committee Co-Chair

Udaya B. Halabe

Committee Member

P. V. Vijay.

Abstract

Several advantages, such as high strength-to-weight ratio, high stiffness, superior corrosion resistance, and high fatigue and impact resistance, among others, make FRPs an attractive alternative to conventional construction materials for use in developing new structures as well as rehabilitating in-service infrastructure. As the number of infrastructure applications using FRPs grows, the need for the development of a uniform Load and Resistance Factor Design (LRFD) approach, including design procedures and examples, has become paramount.;Step-by-step design procedures and easy-to-use design formulas are necessary to assure the quality and safety of FRP structural systems by reducing the possibility of design and construction errors. Since 2008, the American Society of Civil Engineers (ASCE), in coordination with the American Composites Manufacturers Association (ACMA), has overseen the development of the Pre-Standard for Load and Resistance Factor Design (LRFD) of Pultruded Fiber Reinforced Polymer (FRP) Structures using probability-based limit states design. The fifth chapter of the pre-standard focuses on the design of members in flexure and shear under different failure modes, where the current failure load prediction models proposed within have been shown to be highly inaccurate based on experimental data and evaluation performed by researchers at the West Virginia University Constructed Facilities Center.;A new prediction model for determining the critical flexural load capacity of pultruded GFRP square and rectangular box beams is presented within. This model shows that the type of failure can be related to threshold values of the beam span-to-depth ratio (L/h) and total flange width-to-thickness ratio (bf /t), resulting in three governing modes of failure: local buckling failure in the compression flange (4 ≤ L/h < 6), combined strain failure at the web-flange junction (6 ≤ L/h ≤ 10), and bending failure in the tension flange (10 < L/h ≤ 42). Broadly, the proposed equations are predicting critical flexural load capacities within +/-22.3% of experimental data for all cases, with over 70% of all experimental data with within +/-10% error.;A second prediction model was developed for predicting the critical lateral-torsional buckling (LTB) load for pultruded GFRP open sections, including wide flange (WF) sections and channels. Multiple LTB equations from several sources were considered and applied but yielded inaccurate results, leading to the development of this new critical buckling load prediction model based on the well-established elastic LTB strength equation for steel. By making a series of modifications to equations for calculating the weak axis moment of inertia, torsional warping constant, and torsion constant for open sections, as well as recognizing the influence of the shear lag phenomenon, the critical LTB load is predicted within +/-15.2% of experimental data for all channel and WF specimens tested and evaluated in the study.

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