The spandrel beam emerges as an important part of frame structures. This article focuses on defining and discussing different aspects of spandrel beams.
What is Spandrel Beam?
In steel or concrete structures, the spandrel beam is the exterior beam that stretches horizontally from one column to another column. These are also known as edge beam.
Spandrel beams are provided on each floor which helps distinguish floor levels in high-rise buildings. These are used to withstand the load of the peripheral walls, in some cases, also roof loads of a building because masonry walls generally can not carry self-weight and slab weight entirely.
Load Distribution Method
Spandrel beams are designed to transfer external wall load and slab load from slabs to the outer columns. Then the whole load is passed on to the footings through the columns. In RCC structures, these beams undergo axial compression, torsion, bending moment, and shear stresses simultaneously due to their interaction with the floor beams. Slab load is fundamentally transmitted by torsion from beam to columns. Hence, it creates a complex system of load distribution.
Features of Spandrel Beam
The properties of the Spandrel beam highly depend on the floor beam characteristics. Beams connected to flanged floor beams rather than rectangular floor beams produce enhanced capability of resisting torsional stresses. This consequently increases the ultimate load capacity of the high-rise building. Torsional behavior of the Spandrel beam is a significant feature as slab load is fundamentally transmitted from beam to column by torsion. Therefore, the beam requires additional attention to torsional failure while designing. The latest design code followed for this beam is ACI Committee 318, Building Code Requirements for Structural Concrete and Commentary (ACI 318-19).
Uses of Spandrel Beam
Spandrel beams are used in multi-story buildings at each floor level. These are attached to the outer perimeter of floor slabs as a belt to support the floor beams. It also strengthens the connection between the slab and outer columns. On the roofs, the parapets are placed above these beams.
Advantages of Spandrel Beam
- Spandrel beams impart extra strength to the outer sides of a multi-story building.
- These beams increase the lateral stiffness of steel and concrete structures. In wide beam-column connections, spandrel beams with both longitudinal and transverse reinforcements are preferred to use. This enhances the building’s seismic performance.
- Spandrel beams are used in coupled shear walls to produce sufficient stiffness and ductility against earthquake activities. These also provide support for the external side openings such as windows along with shear walls and lintel.
Disadvantages of Spandrel Beam
As Spandrel beams are located on the exterior of a building, these more often come in contact with moisture than floor beams which results in
- Deterioration or rusting of reinforcement steels.
- Cracking and spalling of concrete.
Therefore, a considerable amount of money is spent on the restoration.
- McGraw-Hill Dictionary of Scientific & Technical Terms
- Mogbo, N.C.I. (1968). “Torsional behavior of Spandrel beams”. Retrieved from Rice University Library
- Behnam, H., Kuang, J.S., Abdouka, K. (2016). “Behaviour of RC Spandrel beam in exterior wide beam-column connections” Australian Earthquake Engineering Society 2016 Conference, Nov 25-27, Melbourne, Vic
- Salman, R.M.S., Ali, A.A.M. (2015). “Reinforced Concrete Spandrel-Floor Beams Interaction” ISSN(Online): 2319-8753