Development of Canadian Design Standards for Traffic Barriers for Bridge Applications

This paper summarizes the research work done in Canada on steel- and GFRP-reinforced concrete barriers. AASHTO LRFD Bridge Design Specifications specify a triangular yield line failure pattern for steel-reinforced concrete barrier design. However, no evidence was found in the literature to support this failure shape. Recent experimental tests on steel-reinforced barriers showed a trapezoidal crack pattern within the barrier that led to the development of new equations for the barrier transverse flexural capacity using the yield line theory. These equations along with conditions for their use were included in the 2019 Canadian Highway Bridge Design Code (CSA-S6.19). Also, a new punching shear equation for the barrier transverse capacity was developed based on the experimental findings. Due to the use of de-icing salt in winter times, GFRP bars have been used in Canada as a cost-effective alternative to corroded steel reinforcement. Recent design work on a GFRP-reinforced barrier was qualified by conducting three vehicle crash tests using different types of GFRP bars. Then, static load tests to collapse were conducted on the constructed barriers to study their structural behaviour. Test results showed that their failure mode was punching shear at the transverse load location, with trapezoidal-shape flexural cracks appearing at the tapered faces of the barrier during loading. Experimental findings were incorporated in CSA-S6.19 in the form of GFRP bar size, and arrangement to satisfy the crash test acceptance criteria and equation for the punching shear capacity of GFRP-reinforced barrier subjected due to transverse vehicle impact loading.