Pendulum Impact Tests on Steel W-Beam Guardrails

Abstract

The response of a G4(1S) strong post steel w-beam guardrail system to pendulum impacts has been investigated in a series of full-size physical tests and in simulated experiments using the explicit finite-element analysis code DYNA3D. The physical tests were conducted at the Federal Outdoor Impact Laboratory at the Turner Fairbank Highway Research Center of the Federal Highway Administration in McLean, Va. In the pendulum tests, an 880-kg mass was used to strike the rail perpendicular to its face. The rail section was attached to steel posts and blockouts and supported in a specially designed fixture. Initial velocities of the pendulum at impact were 9.25, 20, 30, and 35 km/h. Acceleration, force, velocity, and displacement histories of the impact event were obtained from accelerometer data taken during the testing. Data from the DYNA3D simulations of the impact tests compared well with the data obtained from the full-scale testing. Displacement plots of the deformed shapes of the rails at 25-ms intervals compared favorably with high-speed film images. Force versus displacement histories showed good agreement with those obtained from quasi-static experiments. The use of pendulum impact tests for screening and evaluation of alternative guardrail systems is recommended.