A truss girder is a steel-framed support system placed atop the truss plank between each run of the hollow block underlayment system for concrete slab floor formations. The triangular shape of the truss girder provides stability for the slab system between the block structures. It also provides a means of shift prevention throughout the slab design.
These girders are used mainly in suspended concrete floors because of their ability to provide a full span of support for the slab. They prevent any type of buckling in the slab due to the also disallowed shifting. Though there are many different components to these types of concrete flooring systems, the truss girder is one of the most important factors in the stability of the slab.
The construction of the truss girder is commonly comprised of three different deformed bars that run longitudinally across the span of the slab. These are held in shape by electro-welded support systems welded to each longitudinal bar within a foot (30 cm) of each other through the entire span of the truss girder. This shape and electro-welded construction allow the truss girder system to provide an ample amount of tensile strength and resistance to withstand force from any direction.
The concrete slab floor system is a basic design for a complex system. The risers the slab sits on provide vertical support for the beams that span the distance of the floor from exterior wall to exterior wall. The truss girder planks are run perpendicularly across the proprietary beams that support them. They are spaced according to the distance from exterior wall to exterior wall, with the truss girders built into the concrete girder planks.
In between the girder planks and suspended by the planks themselves sit hollow blocks. These blocks can be made from a number of different materials as long as they comply with building codes. The hollow blocks are beveled, which allows the truss girders to rise between the bevels to create a W formation into which wet concrete is poured to create a seamless junction between the planks, girders and blocks within the slab.
Once the girders have been incorporated into the block system, the surface is covered with a mesh covering. The covering is used as reinforcement for the slab to sit on. This mesh reinforcement is designed to allow the finished slab to sit stably on top of the block and girder support system.