Bollard Energy Dissipation in Moving Barrier and Passenger Vehicle Impacts 2015-01-1424
Bollard systems are often used to separate errant vehicular travel from pedestrian and bicycle traffic. Various bollard systems are available for this function, including different installations, functional design, and protection levels. The security-type bollards are used primarily at high-security locations (e.g., military bases and other government installations) around the world. While a protocol exists for testing and rating security bollards, no such protocol or recommended practice or standard currently exists for non-security-type bollards. Non-security, concrete-filled bollards are commonly used by cities/states, local government organizations, and the private sector as “perceived impediments to access” to protect against slow-moving vehicles. There is a general lack of publically available test data to evaluate these non-security bollards and conventional installation procedures. Crash testing of this type of bollard system provides a better understanding of the dynamic strength of the bollards and allows for quantifying the energy dissipated during vehicular impacts.
Seven full-scale crash tests were performed on thirteen concrete-filled steel bollards, with outer diameters ranging from 4.5 to 8.5 inches, at Exponent's Test and Engineering Center in Phoenix, Arizona. Four tests were conducted with a non-deforming moving barrier, and three other tests used a full-size pickup or a mid-sized SUV. The tests included bollards of different diameters, varying wall thickness, and different installation configurations for the support footings. Additionally, two quasi-static tests were performed in an effort to compare and contrast bollard fracture energy between the dynamic and quasi-static responses. The energy dissipation of a single 4.5-inch steel bollard installation was determined to be approximately 15,000 ft-lbs, increasing to about 168,000 ft-lbs for an 8.5-inch steel bollard.