Anchorage Design Solution for Attaching an Approved Traffic Barrier to Multivoid Aluminum Bridge Decks

Abstract

Bridge decks are the most stressed elements in a highway bridge due to direct loading from vehicular traffic and occasional overloading, combined with stresses induced by environmental effects and the use of deicing salts in cold wintery conditions. The use of structural aluminum alloys offers considerable promise for building modern bridges and for redecking aging and deficient bridges. Traffic barriers are mounted on bridge decks to provide a physical impassable limit to redirect errant vehicles safely onto the roadway. Current design standards require that the traffic barrier and anchorage system be physically tested under full-scale crash conditions to assure satisfactory interaction with impacting vehicles at the desired level of performance. Certain modifications to an already crash-tested and approved barrier may be permitted if it can be demonstrated by comprehensive analyses that they would not adversely affect the designed performance of the safety barrier. The present study seeks to develop and validate an anchorage design for attaching an already approved traffic barrier on bridge decks made from welded multivoid aluminum extrusions. The anchorage design facilitates installation and is able to absorb vehicular impact loads without compromising the structural integrity of the aluminum bridge deck. The study consists of two stages: (1) the capacity design and analysis of the attachment system based on equivalent static forces, and (2) a dynamic simulation of a full crash-test. This is followed by an approved procedure for verification and validation of the barrier-vehicle interaction, by comparing simulation results with observations from the original physical crash test.