Analysis, Design, and Dynamic Evaluation of a TL-2 Rough Stone Masonry Guardwall
Erin Johnson, Ronald Faller, John Reid, Dean Sicking, Bob Bielenberg, Karla Lechtenberg, Scott Rosenbaugh
This research study was performed to determine the minimum mounting height for the rough stone masonry guardwall to allow it to meet the Test Level 2 (TL-2) safety performance criteria found in NCHRP Report No. 350. A literature review was conducted to determine whether any relevant research had been performed on low-height, rigid parapets and rough stone masonry guardwalls. LS-DYNA computer simulations were performed on a rigid, vertical-faced barrier with varying heights to evaluate the propensity for vehicular instabilities and barrier override. Several design concepts were considered for providing shear transfer between the top capstones and the inner core wall. The new design utilized steel angle segments anchored to the core wall with the upper leg recessed into saw-cuts placed in the bottom of the capstones. Two TL-2 crash tests were performed on rough stone masonry guardwalls according to NCHRP Report No. 350. The first test was performed on a 22-in. (559-mm) tall, guardwall using a 2000P pickup truck impacting at a speed of 44.4 mph (71.4 km/h) and at an angle of 24.2 degrees. The second test was performed on a 20-in. (508-mm) tall, guardwall using another 2000P vehicle impacting at a speed of 43.6 mph (70.1 km/h) and at an angle of 24.4 degrees. Both crash tests provided acceptable safety performance according to NCHRP Report No. 350. Although the 20-in. (508-mm) tall, parapet adequately contained and redirected the pickup truck at the TL-2 conditions, barrier performance was slightly degraded over that observed in the 2000P testing of the 22-in. (559-mm) tall parapet. Based on the results of this study and for new construction, it is recommended that the rough stone masonry guardwall system be implemented using a nominal top mounting height of 22 in. (559 mm) relative to the traveled way. Finally, roadways that require resurfacing could be accommodated using a 2-in. (51-mm) pavement overlay placed adjacent to the barrier system as long as the rough stone masonry guardwall was originally installed using the 22-in. (559-mm) nominal mounting height relative to the traveled way.
Roadside Safety, Crash Test, Aesthetic Barrier, Concrete Barrier, Rough Stone Masonry, Guardwall, Vertical Banner, TL-2