Download Design of Precast Prestressed Composite Beams Excel Sheet – The precast prestressed concrete units are erected first and can be used to support the formwork needed for the cast in situ slab without additional scaffolding (or shoring).
Design of Precast Prestressed Composite Beams Excel Sheet
In addition to its contribution to the strength and stiffness of the composite member, the cast in situ slab provides an effective means to distribute loads in the lateral direction. The cast in situ slab can be poured continuously over the supports of precast units placed in series, thus providing continuity to a simple span system.Pre-tensioning in plant is more cost-effective than post-tensioning on site.
Because the precast 4 prestressed concrete element is factory-produced and contains the bulk of reinforcement, rigorous quality control and higher mechanical properties can be achieved at relatively low cost. The cast in situ concrete slab does not need to have high mechanical properties and thus is suitable to field conditions. Design of Precast Prestressed Composite Beams Excel Sheet
What is Composite beam?
A structural member composed of two or more dissimilar materials joined together to act as a unit. An example in civil structures is the steel-concrete composite beam in which a steel wide-flange shape (I or W shape) is attached to a concrete floor slab (see illustration). The many other kinds of composite beam include steel-wood, wood-concrete, and plastic-concrete or advanced composite materials–concrete. Composite beams as defined here are different from beams made from fiber-reinforced polymeric materials.
There are two main benefits of composite action in structural members. First, by rigidly joining the two parts together, the resulting system is stronger than the sum of its parts. Second, composite action can better utilize the properties of each constituent material. In steel-concrete composite beams, for example, the concrete is assumed to take most or all of the compression while the steel takes all the tension. Design of Precast Prestressed Composite Beams Excel Sheet
Steel-concrete composite beams have long been recognized as one the most economical structural systems for both multistory steel buildings and steel bridges. Buildings and bridges require a floor slab to provide a surface for occupants and vehicles, respectively. Concrete is the material of choice for the slab because its mass and stiffness can be used to reduce deflections and vibrations of the floor system and to provide the required fire protection. The supporting system underneath the slab, however, is often steel because it offers superior strength-weight and stiffness-weight ratio, ease of handling, and rapid construction cycles. Since both the steel and concrete are already present in the structures, it is logical to connect them together to better utilize their strength and stiffness.