What is a Transfer Beam? | Transfer Structures | Transfer Girder Design
What is a Transfer Beam? | Transfer Beam Vs an Ordinary Beam |Transfer Girder Design
Transfer beam is a type of structural member that transfers load from one support to another. The most common use for this design in construction is as floor beams that transfer the weight loads on upper floors to columns at lower levels.
The primary purpose of a transfer beam, or T-beam, is to provide an uninterrupted flow of the load across supports and prevent it from being concentrated on any single point.
This helps reduce both downward pressure and uplift stress on individual supports which can lead to buckling or collapse.
Transfer beams are typically made out of steel with varying thicknesses depending on their function and size but are usually less than 4 inches thick so they can be lifted by crane, when necessary, without compromising their structural integrity.
Transfer structures have become popular, and in some cases, unavoidable, for both low-rise and high-rise buildings across the world, to give flexibility in varied architectural configurations above and below the transfer structures.
Transfer structures are flexural or shear structures that carry large loads from columns or walls operating on its top and redistribute them to supporting columns or walls.
Lower zones of buildings are often used for parking, shopping malls, assembly halls, podium gardens, or open areas for function requirements, whereas higher zones are typically used for housing or offices.
The transfer structure is an important connection point between the upper and lower floors of the structure system and plays an important function in the overall structural system of a high-rise building.
In both high- and low-rise buildings, various types of transfer structures are used. Transfer plates and transfer girders are used in high-rise residential and commercial buildings, whereas transfer beams are used in low-rise residential and commercial buildings.
Deep beam structures are typically idealized for transfer beam structures. Normally, the flexural stiffness and strength of transfer structures are substantially greater than those of the superstructure’s column supports or shear walls.
Transfer Girder Design
A Transfer Girder is used to transfer point load of column from the above storeys and transfer them to the supporting column. Transfer Girders are the main horizontal supports of a structure, and support smaller beams.
Behavior and design of transfer girder is very unconventional compare to normal beam, so it is necessary to study the behavior and design of the transfer girder in detail.
Bending moment and shear force in transfer girder are higher in construction stage analysis, which must be considered in the design phase to minimize beam and column cracking owing to sequence effect.
Transfer girder give good architectural aesthetic view to the tall structure.
Types of Girders
A box girder is made up of two vertical webs, short top flanges on top of each web, and a wide bottom flange that connects the webs. A box girder bridge is, as the name suggests, box-shaped.
A box girder has a high torsion resistance and is typically used when the bridge is susceptible to torsion or toppling impacts.
Rolled Steel Girder
Rolled Steel Girder is made by rolling a blank cylinder of steel through a succession of dies to form the necessary shape. This is done to produce a standardized I-beam and broad flange beam with lengths of up to 100 feet.
A plate girder is made by welding together plates to form the appropriate shape. Large steel plates of the necessary thickness are typically cut into flanges and webs from the plates in the desired length and shape.
The plate girder has a high degree of adaptability in terms of height and shape. The span of a plate girder bridge can range between 10 and 100 meters.
Transfer Beam Designs
Transfer beams transfer heavy and concentrated loads through shear. To avoid progressive collapse, the transfer beam should be cast monolithically and continuously while stretching across multiple supports.
For load path redundancy, the structural system should also provide an alternate load path. Furthermore, deflection controls are available for transfer beams. If the transfer beam deflects, all of the floors above it will deflect as well.
The design of a transfer beam differs from that of a main or secondary reinforced concrete beam. This is due to the nonlinear stress distribution of transfer beams induced by large concentrated point loads from the column loads of the stories above.
Because of the concentrated loads, this will result in a discontinuity region. Linear elastic theory cannot be applied to conventional beam design.
Depending on the design assumptions, you can use either the deep beam method or the strut and tie model method for transfer beam design.
Transfer Beam Vs an Ordinary Beam
What is the design and construction difference between a transfer beam and an ordinary beam?
There are numerous distinctions between the design and construction of a transfer beam and an ordinary beam. They may appear to be the same from the outside, but they are not.
A transfer beam is used to transfer the column’s loads to the columns around it. In a 40-story construction, for example, you do not want a certain column at one location below level 2. You utilize a transfer beam to sustain this column while transferring the load to the adjacent column.
So, what is the basis of this transfer beam’s depth? Deflection.
If your transfer beam deflects by one inch, all of the floors above it will deflect by at least one inch at that place, and these types of inconsistencies are undesirable.
When building a transfer beam, you must also consider the vertical component of the earthquake loads since the column loads are so enormous that even a modest vertical earthquake wave can create a significant demand in the beam.
In the case of a standard beam, you don’t have to be concerned about deflection to this amount. Once you’ve met the code’s deflection conditions, you’re set to go.
Shear in a regular beam is also less effective than shear in a transfer beam. Because a beam is carrying the load of a column several times, shear in the beam exceeds the nominal shear strength of the concrete, which can result in critical failures.
Because of the reasons I just discussed, a transfer beam in a building may become a more vital part than a column, and you will be planning and constructing it with greater care.