Beam design is a wide subject that covers a vast area in structural engineering design. The beam is one of the primary elements of structures.
There are different types of beams and they and be categorized by different methods. The following categorization may also be used.
- Reinforced Concrete Beams
- Precast Concrete Beams
- Fiber-reinforced beams
- Steel beams
There are many other types as well.
We have discussed the design of the following type of beams on this website.
- Bridge Beam Design – Post Tension Beam Design
- Ground Beam Design
- Steel Beam Design – Desing guide and code requirement as per BS 5950
- Steel Beam Design – Worked Example; Universal Beam
- Singly Reinforced Beam Desing according to Eurocode 2
- Beam Design to BS 8110
- Double Reinforced Beam Design to BS 8110
- Concrete Beam (Desing and Detailing)
- Prestressed Composite Beam (Design Aspects)
- 6 Causes for Beam Failures (A Guide for Designers)
- Design of Singly Reinforced Beam; Desing aspects
- Shear Design of Beam
- Design of Deep Beam
- Beam Shear Design to Eurocode 2
In this article, we are concentrating on the different aspects of the design and code provisions.
Let’s discuss the design procedure.
- Load Calculation; The design load to be applied on the beam shall be calculated as per the relevant code of practices.
- Carrying out Analysis; Bending moments, shear forces, and torsional moments need to be evaluated. This could be done by manual calculation or with the use of computer software.
- Then proceed with reinforcement calculation.
Before starting the design, the first step is the initial design where we finalized the section dimensions.
Initial Design
This is the stage where we finalized the member sizes.
In most of the construction, with the limited time to complete the designs, designers finalized the foundation drawings initially to proceed with the construction and then issue the balance drawings.
With the initial design, we could do a load evaluation for the foundation after preparing the general arrangement.
The initial design is done as per the relevant standard practice and based on the judgment of the structural behavior.
Let’s see some of the methods available for the initial design of beams.
The following method is discussed as per the British standards (BS 8110).
- Firstly, we need to select to cover the reinforcement based on the durability requirements and fire resistance requirements.
- Then depending on the boundary condition of the element, we can calculate the effective depths a follows.
The following table may be used to evaluate the section.
The above table indicates the minimum section thickness/width and cover to the reinforcements according to the fire rating.
From the above table, we could select the appropriate span/effective depth creation. If we know the span, we can calculate the effective depth as per the restrained condition.
The member sizing done at the initial stage may not be matching with the final design if we are solely relying on the values obtained from this method.
We may use our experience and judgment also to select suitable member sizers.
Beam Analysis and Design
Once the initial member sizing of all the members is done, the structure could be model and design as per the loading requirements.
Structural analysis may be done manually or using a computer program. If it is a simple beam like a simply supported beam, the calculation is much easier and it can be done manually.
However, when it becomes more complex, the use of the software will save our time.
After find the bending moment and shear forces, the design of the beams can be done as per the work examples and explanation given in the relevant code.
You may refer to the detailed explanation and work examples given in above when designing a beam.
Special Note on Beam Design of Serviceability Limit State
All the designs shall satisfy the serviceability limit states.
The following type of serviceability limit stage checks is done.
- Limit the deflection of the beams
- Limit the crack with od the beams
- Attend on the durability aspect also can be considered as a servility requirement. Selecting suitable cover to reinforcement, concrete grade, etc.
We use the reinforcement detailing methods also to control the serviceability limit stage issues.
For example, adding reinforcement to avoid cracking.
Detailing of Beam Reinforcements
Reinforcement detailing is very important as the analysis and design.
Constructibility, idealization of design in the drawing is a must in the structural design of beams.
The considerations in the design shall represent in the construction. For example, if we consider a joint allowing the rotation, reinforcement detailing shall be done accordingly.
The following articles published on the website will guide you on the reinforcement detailing and dealing requirements. In addition, relevant detailing manuals could be referred to.
Let’s summarize the beam design process
The following sketch indicates the beam process.