Impact Performance of Flexible Guardrail Systems using LS-DYNA

In Canada, different types of vehicle collisions are recorded every year, resulting in many injuries and fatalities (2,969 road users killed and 17,500 seriously injured during 1999, Road Safety Vision 2001). The severity of these collisions depends partly on the aggressiveness and incompatibility in vehicle-to-roadside hardware collisions. This paper evaluates, using LS-DYNA software, the vehicle impact performance of flexible barriers made of steel W-Beam guardrails supported over six different types of post configurations and material properties. These types include wood posts, steel I-shape posts, steel box-beam posts and steel Z-shape posts. The dynamic performance criteria considered in this paper include energy absorption for the guardrail, as well as the vehicle rails, were examined. Moreover, movements at the driver’s side rocker panel along the bottom of the A-pillar and beneath the front door as well as along the bottom of the B-pillar, and at the brake pedal were measured. In addition, the acceleration at the driver’s side rocker panel along the bottom of the B -pillar and beneath the front door was examined. Results show that The guardrail system with box-beam posts, sliding into a foundation tube that is driven into the ground with proper overlap, provided better safety performance than traditional wood and steel-I-beam posts. Results also showed that the danger of tire snagging was faced regardless of the type of the posts used. On contrast to the traditional concept of guardrail system design of absorbing impact energy and redirecting the vehicle on road, guardrail systems with Z -shape posts, connected to the guardrails along their flanges, showed quick post collapse and the vehicle continued moving off the road.