What Is Raker Beam Construction?
What Is Raker Beam Construction?
Raker beams are angled, notched beams that are used to support stadium riser units. They are commonly found in structures such as pedestrian bridges, ramps, staircases, and stadiums. Raker beams are usually subjected to bending moment, shear force, and axial force.
The analysis and design of these elements is typically done using Eurocode 2. During construction, raker beams must be supported by weights and crane access.
Formwork assembly is also necessary due to the different slopes of the raker beams. Raker beams can also be supplied with design certificates for building regulations purposes.
Raker Beam Advantages
Raker beams are angled, notched beams that are used to support stadium riser units. They are typically made as single, double or triple risers with heights cast to satisfy site lines in the venue.
Raker beams can be made from precast concrete and typically have a thickness of 6 to 10 inches. Abrasive nosing pieces are often cast into the treads of the raker beam to create a non-slip surface.
The advantages of using raker beam construction include increased stability and strength for stadium risers, as well as improved safety due to the abrasive nosing pieces providing a non-slip surface. Additionally, raker beams can be designed with mild reinforcement and do not necessarily require prestress or post-tensioning for large stadiums. This can help reduce costs associated with construction.
Disadvantages Of Raker Beam Construction
The main disadvantage of raker beam construction is that it requires rugged steel forms. This makes the construction process more difficult and time-consuming, as workers must be careful to ensure that the beams are properly aligned and secured.
Additionally, steel beams are heavier than wooden beams, making them difficult to work with. This can also lead to safety concerns, as it is difficult to manoeuvre steel beam structures.
Finally, flying rakers take the least amount of material to build but have several disadvantages such as being recommended for use only to initially stabilize a wall or roof.
Rake Beam Construction Safety
The safety of raker beam construction depends on the proper use of shoring techniques and materials. Shoring techniques such as diagonal or raker shore concrete walls, shoring hazardous roof/floor beams, and pulling down leaning walls after dealing with roof support can help ensure the safety of raker beam construction.
Self-spanning steel formwork is often used in raker-beam construction to create reinforced concrete rakers. This formwork must be rigid enough to ensure negligible deflection and should be equipped with bolsters to maintain the shape of the beam.
Additionally, the formwork should be set over a rebar cage and bolted in place before lifting it into place.
Raker support structures for underground pre-scaffolding systems should also be designed with safety in mind.
The wale should be installed in a lower part of a post pile driven into an underground excavation surface, and the raker beam should be connected to the radar beam via a raker end that has a vertical face plate closely contacting the flange of the belt face and a supporting face plate supporting the lower side of the strip length.
Measures and controls should also be taken to ensure that when earth pressure increases beyond the load capacity of the raker beam, additional reinforcement is performed to prevent dangerous situations such as walls being pushed out.
