STABILITY BEHAVIOR OF PULTRUDED GLASS-FIBER REINFORCED POLYMER I-SECTIONS SUBJECT TO FLEXURE by Tianqiao Liu Bachelor of Science, Chang’an University, 2012 Master of Science, Carnegie Mellon University, 2013 Submitted to the Graduate Faculty of Swanson School of Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Civil Engineering University of Pittsburgh 2017