Civil and structural engineers know the limitations of the cost-per-pound mindset, but real innovation can start when we ask, “What if value-per-performance became our primary metric?” Titanium alloy bars (TiABs) notoriously command premium prices, yet their unparalleled structural performance, durability, and overall system cost render conventional material cost comparisons irrelevant.
Ti-6Al-4V (ASTM Grade 5), the workhorse alpha-beta titanium alloy in aerospace and medical fields, offers an exceptional combination of high specific strength, ductility, workability, and corrosion resistance, difficult to replicate in other retrofit materials. However, its high material price has long been a barrier to widespread adoption in civil and structural engineering applications. To determine whether this high cost was truly an obstacle, in 2012 we started doing research that would eventually transform smooth, commercially available TiABs into an economical and effective retrofit solution for reinforced concrete (RC) structures.
The Near-Surface Mounted (NSM) technique was advanced by embedding TiABs into precision-cut grooves, anchoring them with 90° hooks into the core concrete, and bonding the assembly with structural epoxy. Full-scale laboratory tests of RC bridge girders validated both flexural and shear capacity, even after exposure to combined high-cycle fatigue and repeated freezing-and–thawing conditions. These laboratory successes led to the first field deployment by the Oregon DOT in 2013, marking the technique’s real-world debut. Building on this foundation, the development of normative standards, AASHTO NSMT-1 Guide and ASTM B1009‑20, enabled the broader adoption of TiAB retrofits for bridge projects across Oregon, Texas, and New York’s Verrazzano Narrows Bridge.
Advancements now extend TiABs beyond simple strength applications. Our most recent innovations include seismic retrofits for bridge columns and coupling them with impressed-current cathodic protection systems to both reinforce and preserve corrosion-damaged elements. Globally, this work has spurred research into Titanium-Reinforced Ultra-High-Performance Concrete (TARUHPC) and conservation of heritage masonry structures.
This seminar describes the evolution of TiABs from concept to real-world impact, illuminating how engineering advancements can emerge when we challenge conventional thinking. It’s a call for engineers to pivot from material first-cost constraints and let system performance, endurance, and whole-cost guide our innovation.
Christopher Higgins is a professor of structural engineering in the School of Civil and Construction Engineering at Oregon State University. His field is structural engineering, and he created and directs the Structural Engineering Research Laboratory at OSU. He holds a B.S.C.E. from Marquette University, M.S. from The University of Texas at Austin, and Ph.D. from Lehigh University. He is a registered Professional Engineer.
At OSU, Prof. Higgins teaches graduate and undergraduate courses, mentors students, and conducts research in structural, bridge, and earthquake engineering. He has received numerous teaching as well as national and international research awards. Prof. Higgins’ research emphasis is on inspection, evaluation, and rehabilitation of civil infrastructure. He has conducted research on all traditional civil materials as well as titanium, aluminum, composite, hybrid, and polymer materials. His research findings have been implemented into practice and adopted into national design specifications.
Prof. Higgins’s research on load rating of aging reinforced concrete bridges for the Oregon Department of Transportation produced a documented savings of $500 million to state taxpayers by enabling more accurate assessments and cost-effective rehabilitation strategies, rather than unnecessary replacements.