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Description:
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Millions of square feet of mechanically stabilized earth retaining wall are constructed
annually in the United States . When used in highway fill applications in conjunction with
bridges , these MSE walls are typically constructed with a roadside barrier system supported
on the edge of the wall . This barrier system generally consists of a traffic barrier or bridge rail
placed on a continuous footing or structural slab . The footing is intended to reduce the
influence of barrier impact loads on the retaining wall system by distributing the load over a
wide area and to provide stability for the barrier against sliding or overturning . The proper
design of the roadside barrier , the structural slab , and the MSE wall system requires a good
understanding of relevant failure modes , how barrier impact loads are transferred into the wall
system , and the magnitude and distribution of these loads .
In this study , a procedure is developed that provides guidance for designing : 1 . the
barrier -moment slab , 2 . the wall reinforcement , and 3 . the wall panels . These design
guidelines are developed in terms of AASHTO LRFD procedures . The research approach
consisted of engineering analyses , finite element analyses , static load tests , full -scale dynamic
impact tests , and a full -scale vehicle crash test . It was concluded that a 44 .5 kN (10 kips )
equivalent static load is appropriate for the stability design of the barrier -moment slab system .
This will result in much more economical design than systems developed using the 240 kN
(54 kips ) load that some user agencies are using . Design loads for the wall reinforcement and
wall panels are also presented . |