LHV Precast, Inc. provides engineering design and complete product for box culverts, three-sided spans, bridge systems featuring Stone Strong® Retaining Wall abutments, precast concrete bridge beams spanning to 30’, and light-weight precast transverse slabs.
Using the Stone Strong® Retaining Wall System as a “Precast Concrete STAY IN PLACE FORM” saves you time in building your abutment and wing-walls. The assembly of the blocks is an easy process. Rebar is incorporated as per design into the voids that are afterward filled with class “A” concrete.
It is an engineered solution built in a controlled environment that is durable and eco-friendly; The benefits of using precast construction are that it is easy to assemble on-site saving time and money with end results that are aesthetically pleasing.
The wing walls, an integral part of bridge construction are important in retaining the soil below the approach to the bridge. The Stone Strong® Retaining Wall System, used for bridge abutments, can also be used as a wing-wall to support the roadway.
Bridge Seats are required as in any bridge. Anchor the bridge seat and backwall reinforcing into the block concrete. The choice of the combination of 24 SF blocks (36” high) in combination with 6 SF blocks (18”) to limit bridge seat concrete thickness (12”-18”) based on designer’s preference and bearing requirements.
The Stone Strong abutments can accept steel, timber or other Bridge Beam types.
*On Short Spans you can design direct span (longitudinal) concrete slab beams without pre-stressing, practically to about 27’ in length.
*For Longer Spans you need a different type of superstructure. For the purposes of this presentation we will focus on steel beams or girders with precast transverse slabs. Local municipalities have been using this system to be able to construct these bridges with their own forces quickly, and with limited resources, and with a short construction season.
For the design of the steel beams or girders, once you know the dead loads, everything else such as the live load, future wearing surface, etc. is prescribed by the municipality. Most municipalities are not designing for anything less than HS-20, or HL-93. For a coating system, some municipalities are using nothing but hot-dipped galvanizing once the beams and connections have been fabricated.
The advantages of steel beams with transverse bridge slabs include:
Design of pieces is done with standard AASHTO transverse reinforcing then prefabricated with: Lifting devices, pockets for stud shear connectors (connection not composite design) and Shear Keys Longitudinal ducts for post tensioning (if used).
Shear transfer between pieces; “Shear Keys”. The connection between the steel beams and the light-weight bridge slabs is accomplished with tapered pockets for stud-shear connections and stud-shear connections attached to the steel beams, these tapered pockets are in-filled with grout completing the connection from steel beam to light-weight concrete deck.
