Elements of RCC Framed Structure (With Steel Detailing)

Aimed for the basic or foundation course in civil engineering. From introduction to detailing of steel. This will help you to get understanding of RCC framed structure.

1. RCC Framed building Elements of R.C.C. Structures

2. Introduction Concrete frame structures are the most common type of modern building . It usually consists of a frame or a skeleton of concrete . Horizontal members are beams and vertical ones are the columns. Concrete Buildings structures also contain slabs which are used as base, as well as roof / ceiling. Among these, the column is the most important as it carries the primary load of the building. 1/3

3. Reinforced concrete frame structure is actually a connected frame of members which are firmly connected to each other. These connections are called moment connections. There are also other types of connections which include the hinged connections that are mostly used in steel structures, but the concrete frame structures have moment connections in almost all of the cases. 2 /3

4. The concrete framed structure should resist various loads that act on the building during its life. These loads include Dead loads, live loads (imposed loads), wind loads, dynamic loads and earthquake loads. 3 /3

5. Typical elements of a RCC framed building - Major Parts : Foundation (Footing) Columns Beams Slab Staircase Minor Parts: Lintel beam Chhajja

6. Footing

7. Foundation / Footing

8. Footing Load is transferred to the soil through the isolated column footing Reinforcement of column is tied to reinforcement of footing Types of Isolated footings Rectangular footing Trapezoidal footing Stepped footing

9. Plan and section of footing (only footing reinforcement showed) 3D view footing

10. 1 2 3

11. Typical detailing of plain rectangular footing

12. Detailing of footing in a technical drawing

13. Beams

14. Beams

15. Beams Horizontal, sloping or curved rcc member used for support the slab and walls of the building Types of Beam: 1.Simply supported beam 2.Cantilever beams 3.Continuous beams 4.Flanged beams

16. Flanged beam (c/s is T-Shaped) Types of beams

17. Function of Beam is to transfer the load from slab to the column It is reinforced with main bars (main or Bent-up) (details on next slides) Consists of Anchor bar at top and stirrups (details on next slides) A uniform cover of 25 mm is provided on sides, top and bottom of beam. (Cover : Distance of steel bar from outer edge of beam)

18. These bars are called ‘main reinforcement bars’ or simply ‘main bars’ These rings of steel are called as ‘stirrups’ (and ‘lateral ties’ in column) Cross section of the beam (more on next slide) [Top bars sometimes called as ‘Anchor bars’]

19. These bars are called ‘main reinforcement bars’ or simply ‘main bars’ These rings of steel are called as ‘stirrups’ (and ‘lateral ties’ in column) This one is just the side view of the previous slide

20. Continuation of sections : There may be more ‘rings’ of steel depending on load on building <- Two legged stirrups Four legged stirrups ->

21. Now, spacing of these stirrups Notice the spacing of stirrup at middle and at end ? Stirrups are closer near end (due to high shear force) And wider at middle (due to low shear force)

22. Last one -- Bent-up bars Some of the bars are bent upwards at 45 ° near ends

23. It’s just the main bar, but bent-up !! (figure shows only one such main bar) [Note : Not all bars of bottom are bent-up, only few]

24. Okay, now we know all components of the beam. Let’s Put it together : Steel in RCC beam = Main reinforcement + stirrups + bent-up bars

25. Typical detailing of a RCC Beam

26. Typical detailing of a RCC Beam Contd.

27. Additionally, Typical details of beam-column joints

28. Columns

29. Columns

30. Columns It is a vertical member in a framed structure which is provided with footing Transfer load from beam to footing or another column It consists of main bars and transverse rings, called lateral ties (In beams, we called them stirrups) Minimum cover of 25 mm is provided to the reinforcement. Basically, columns are Beams but vertical. :D

31. Top View Front section Main bars (minimum 4) Lateral Ties

32. Typical detailing of a RCC Beam Image from IS 13920: Ductile detailing of RC Frames Here, column and beam connection are also shown Notice spacing of lateral ties at middle -- They are closer

33. Slabs

34. Slabs

35. Slabs R CC member used flat or sloping as roofs to cover the building Types of Slab : 1.Simply supported (one way and two way slab) 2.Continuous Slab 3.CantiliverSlab

36. One-way slab bends only in longer direction Two -way slab bends in both directions

37. One-way slab is supported by two beams on longer side Two -way slab is supported by all four sides

38. But how to know which slab is one-way or two-way ? Answer : If the ratio of longer side of slab to shorter side is greater than 2, it’s one-way slab. Otherwise, two-way. Mathematically, Ly / Lx > 2, for one-way slab. Ly / Lx <= 2, for Two-way slab.

39. Other type of slabs Continuous slabs Spans over multiple supports After bending

40. Cantilever slab Have you seen it somewhere? Yes, Balconies and chajjas Other type of slabs

41. Let’s talk about steel in slabs !

42. Types of steel bars in slab: Main bar (along shorter side of one-way slab and along both side in two-way slabs) + Distribution steel (bars along longer side - - only in one-way slab) = Steel Mesh

43. Steel Mesh

44. Sections from both sides are shown for additional details Some bars are bent-up just like in bema, here they are called as ‘cranked bars’

45. After placing all steel, Steel mesh will be formed as shown

46. Staircase

47. Components of staircase

48. Landing and support of staircase

49. Typical staircase steel detailing

50. Lintels and Chhajjas

51. Lintels and Chajjas (SUNSHADE) RCC lintels are fire proof, durable, strong, economical and easy to construct The plain concrete lintels can be used upto span of 800 mm but RCC lintels is necessary in some form as plain concrete lintels is weak in tension The amount of reinforcement depends on span of lintel , width of opening and the total load to be supported by the lintel.

52. Lintel beam Chhajja (Sunshade)

53. Typical steel detailing Lintel beam Chhajja (Sunshade)

54. References

55. All construction activities in sequence - https://www.youtube.com/watch?v=_A7_tfvt0UY

56. References https://www.slideshare.net/arunkurali/design-of-rcc-lintel?qid=bdf15646-c0fb-48ca-8657-bb50baba3fe1&v=&b=&from_search=2 http://www.understandconstruction.com/concrete-frame-structures.html https://civildigital.com/major-parts-reinforced-concrete-buildings-framed-structures/