Types of beam

Types of beams

1. Types of Beams Subject: Strength of Materials By: Engr. Ajeet Kumar Kaka [email protected] [phone]

2. BEAM Beam is the horizontal member of a structure, carrying transverse loads. Members that are slender and support loadings that are applied perpendicular to their longitudinal axes are called beam. Beam is a structural element that is capable of withstanding load primarily by resisting bending. A beam is a structural member which spans horizontally between supports and carries loads which act at right angles to the length of the beam.

3. Generally a beam is subjected to two sets of external forces and two types of internal forces .   The external loads are the loads applied to the beam and reactions to the loads from the supports. The two types of internal force are bending moments and shear forces .

4. figure: A typical beam with internal and external forces acting on it.

5. Types of Beams in Construction There are different types of beams which are classified based on the following conditions: 1. Based on support conditions 2. Based on construction materials 3. Based on cross-section shapes 4. Based on geometry 5. Based on Equilibrium Conditions 6. Based on method of construction .

6. 1. Based on Support Conditions Simply supported beam Fixed beam Continuous beam Cantilever beam Overhanging beam Truss beam

7. 1. Simply supported beam It is a beam supported freely at the two ends on walls or columns.

8. 2. Fixed beam A beam whose both ends are fixed is known as a fixed beam. Fixed beam is also called as Built-in or en -caster beam. Incase of fixed beam both its ends are rigidly fixed and the slope and Deflection at the fixed ends are zero.

9. Advantages of fixed beam (i) For the same loading, the maximum deflection of a fixed beam is less than that of a simply supported beam. (ii) For the same loading, the fixed beam is subjected to lesser maximum bending moment. (iii) The slope at both ends of a fixed beam is zero. (iv) The beam is more stable and stronger

10. Disadvantages of a fixed beam (i) Large stresses are set up by temperature changes. (ii) Special care has to be taken in aligning supports accurately at the same level. (iii) Large stresses are set if a little sinking of one support takes place. (iv) Frequent fluctuations in loading render the degree of fixity at the ends very uncertain

11. 3. Continuous Beam A continuous beam has more than two supports distributed along its entire length. This beam is more economical for any span lengths.

12. Advantages of Continuous Beam Over Simply Supported Beam 1. The maximum bending moment in case of continuous beam is much less than in case of simply supported beam of same span carrying same loads. 2. In case of continuous beam, the average bending moment is lesser and hence lighter materials of construction can be used to resist the bending moment.

13. 4. Cantilever beam It is fixed in a wall or column at one end and the other end is free, it is called cantilever beam. It has tension zone in the top side and compression zone in the bottom side. Cantilever beams allow the creation of a bay window, balconies, and some bridges.

14. 5. Over hanging beam In overhanging beam, its end extends beyond the wall or column support. Overhanging of the beam is the unsupported portion of the beam. It may be one side or both the sides of the support.

15. 6. Truss beam A beam reinforced by a truss rod or formed of straight or cambered pieces joined by trussing. A truss is a network of bars that only experience tension or compression. This is made possible because the bars are connected to each other using only pin joints, which let the bars pivot.

16. 2. Based on Construction Materials 1. Reinforced Concrete Beams 2. Steel Beams 3. Timber Beams  4. Composite Beams

17. 1. Reinforced Concrete Beams It is constructed from concrete and reinforcement.

18. 2. Steel Beams It is constructed from steels and used in several applications.

19. 3. Timber beams This type of beam is constructed from timber and used in the past, but its application is significantly declined now.

20. 4. Composite Beams Composite beams are constructed from two or more different types of materials such as steel and concrete, and various valid cross sections have been utilized.

21. 3. Based on Cross-Section Shapes Several cross sectional shapes of beams are available and used in different parts of structures. These beams can be constructed from reinforced concrete, steel, or composite materials:

22. Reinforced concrete cross sectional shapes include : Rectangular beam This type of beam is widely used in the construction of reinforced concrete buildings and other structures.

23. T- section beam This type of beam is mostly constructed monolithically with reinforced concrete slab. Sometimes, Isolated T-beam are constructed to increase the compression strength of concrete. Added to that, inverted T-beam can also be constructed according to the requirements of loading imposed.

24. L-section beam This type of beam is constructed monolithically with reinforced concrete slab at the perimeter of the structure.

25. Steel Cross Sectional Shapes Include : There are various steel beam cross sectional shapes. Each cross sectional shape offer superior advantages in a given conditions compare with other shapes. Square, rectangular, circular, I-shaped, T-shaped, H-shaped, C-shaped, and tubular are examples of beam cross sectional shapes constructed from steel.

26. 4. Based on Geometry 1. STRAIGHT BEAM Beam with straight profile and majority of beams in structures are straight beams.

27. 2 . Curved beam Beam with curved profile, such as in the case of circular buildings

28. 3. Tapered beam Beam with tapered cross section.

29. 5 . Based on Equilibrium Conditions 1. STATICALLY DETERMINATE BEAM For a statically determinate beam, equilibrium conditions alone can be used to solve reactions, i.e the number of unknown reactions are equal to the number of equations

30. 2. S tatically indeterminate beam For a statically indeterminate beam, equilibrium conditions are not enough to solve reactions. So, the analysis of this type of beam is more complicated than that of statically determinate beams.

31. Difference between Statically determinate structures and statically indeterminate structures

32. 6. Based on Method of Construction 1. CAST IN-SITU CONCRETE BEAM This type of beam is constructed on project site. so, forms are initially fixed then fresh concrete is poured and allowed to be hardened. Then, loads will be imposed.

33. 2. Precast Concrete Beam This type of beam is manufactured in factories. So, the construction condition is more controllable compare with on-site construction. Consequently, the quality of concrete of the beam will be greater. Various cross-sectional shapes can be manufactures such as T- beam, Double T-beam, Inverted T-beam and many more.

34. 3 . Prestressed Concrete Beam This type of beam constructed by stressing strands prior to applying loads on the beam. Pre-tensioned Concrete beam and post-tensioned Concrete Beam are variations of pre-stressed concrete beam.

35. Thank you for your Kind Attention