Development of a Non-pinned Low-profile End Treatment

In the early 1990s, the Low-Profile Portable Concrete Barrier (PCB) system, including both the sloped Low-Profile PCB segment and Low-Profile PCB end treatment, were developed. The original Low-Profile PCB end treatment was designed with steel pins inserted along the barrier centerline, through precast holes, and anchored to the pavement or subgrade. The purpose of these pins was to reduce lateral deflection of the end treatment during an impact. For various reasons, users of the Low-Profile PCB system have stated that the system would be more easily deployed if the vertical pins were not used in situations where lateral deflections can be permitted. The primary objective of the research presented herein was to determine the feasibility of removing the vertical, steel pins from the Low-Profile PCB end treatment in certain applications and if necessary make modifications. The secondary objective of the research presented herein was to demonstrate the applicability of the finite element analysis (FEA) to unpinned barrier systems.

The research objectives were achieved through the use of sound engineering judgment, FEA, and a full-scale crash test. Based on sound engineering judgment and approximate strength analyses of the original Low-Profile PCB design, the author determined the system would most likely function acceptably but would have large lateral deflections. In order to increase connection rigidity and thus control lateral displacement, a plate washer was added to the barrier connection.

The modified non-pinned Low-Profile PCB system was tested for strength in a full-scale crash test under Manual for Assessing Safety Hardware (MASH) test 2-35. Additionally, the recommended system was analyzed under similar test conditions with LS-DYNA, a finite element code. The recommended system passed the MASH test 2-35, in both a full-scale crash test and FEA. While this does not replace the original barrier, it does provide another option for use of the Low-Profile PCB in situations where sufficient room for deflection outside of the length of need exists. If this room does not exist, the barrier must remain pinned.