BASIC OF INDUSTRIAL COMPONENTS AND STRUCTURES

1. INDUSTRIAL BUILDING
BY TAUSIF KAUSWALA
ADIT COLLEGE
V.V. NAGAR, ANAND, GUJARAT, INDIA

2. Industrial building
• Any building structure used by the industry to store
raw materials or for manufacturing products of the
industry is known as an industrial building.
• Industrial buildings are generally used for steel
plants, automobile industries, utility and process
industries, thermal power stations, warehouse,
assembly plants, storage, garages, etc.

3. Factors considered while selecting site for industrial building
• Site should be located on an arterial road.
• Local availability of raw material.
• Facilities like water supply, electricity
• Topography of an area
• Soil conditions with respect to foundation design
• Waste disposal facilities
• Transportation facilities
• Sufficient space for storage of raw materials

4. Major Component of Industrial Unit:

6. • Roof Sheet: Material used to cover the shed is known
as roof shed.
• Roof trusses: A structure that is compound of a
number of line members pined connected at ends to
form a triangular form work is called truss.

7. Eave strut purlin
bracinggirt

8. • Purlin: A member supported on the panel points of
two consecutive roof truss is called purlin.
• Girts: Girts are the secondary structural member
which provide support to roof and wall covering and
also transferred wind load from wall material to
primary frame.
• Eave strut: The member located at the intersection of
roof and exterior wall is known as eave strut.

9. • Bracing: A member which transfer horizontal load
from the frame to the foundation is known as bracing.
• Wind Bracing: Two roof trusses are connected by
cross members to stabilize it against the action of
wind, such a members are called wind bracing.

10. Componentsof roof truss:

12. Points to be considered while planning and designing
of industrial building
1. Selection of roofing and wall materials

13. Roofing Material:
• Roofing material is used to cover the roof of truss.
• In India, corrugated galvanized iron (GI) sheets are
usually adopted as coverings for roofs and sides of
industrial buildings.
• Light gauge cold-formed ribbed steel or aluminium
decking can also be used.
• Sometimes asbestos cement (AC) sheets are also provided
as roof coverings owing top their superior insulating
properties.

14. • Galvanized Iron Sheet: Galvanized iron sheets are made by
black sheets rolled from good quality low carbon mild steel.
For corrugated G.I. sheets, the purlin space may vary from
1.5 to 1.75 m.
• End overlap of 150 mm is required.

15. • Asbestos Cement Sheets: Asbestos cement sheets do
not decay because of atmospheric action.
• These sheets are available in 1.75 m, 2.0 m and 3.0 m
lengths. These are manufactured in 6 mm and 7 mm
thickness.
• For asbestos cement sheet, the purlin space may be
vary from 1.4 m for 6 mm sheet and 1.6 m for 7 mm
sheet.

16. • In selection of wall system, the designer should
consider the following areas:
• Cost
• Interior surface requirements
• Aesthetic appearance
• Acoustic and dust control
• Maintenance
• Ease and speed of erection
• Insulating properties
• Fire resistance

17. 2. Selection of bay width
• A bay is defined as the space between two
adjacent bents. The roof truss along with
the columns constitutes a bent.
• An industrial building may have a single
span or multiple spans

21. • In most cases, the bay width may be dictated
by owner requirements. Gravity control
generally control the bay size
• For crane buildings (light or medium cranes),
bays are approximately 4-8 m may be
economical because of the cost of the crane
gantry girder

22. 3. Selection of structural framing system

23. • For the purpose of structural analysis and design,
industrial buildings are classified as:
• Braced Frames
• Unbraced frames
• In braced buildings, the trusses rest on columns with hinge
type of connections and the stability is provided by
bracings in three mutually perpendicular planes.
• Braced frames are efficient in resisting the loads and do
not sway.

24. • Unbraced frames: They are in the form of portal frames
and are used mostly, distinguished by its simplicity,
cleanliness and economy.
• The frames can provide large column free areas,
offering maximum adaptability of the space inside the
building. Such large span buildings require less
foundation and eliminate internal columns and
drainage.

25. • They are advantageous for more effective use of steel
then in simple beams, easy extension at any time and
ability to support heavy concentrated point loads.
• The disadvantages include really high material unit
cost and susceptibility to differential and temperature
stresses. In addition, these frames produce horizontal
reaction on the foundation, which may be resisted by
providing a long tie beam or by designing the
foundation for this horizontal reaction

27. 4. Roof trusses

28. CONFIGURATION OF TRUSSES
Pitched Roof Trusses :
• Most common types of roof trusses are pitched roof trusses
wherein the top chord is provided with a slope in order to
facilitate natural drainage of rainwater and clearance of
dust/snow accumulation.
• These trusses have a greater depth at the mid-span. Due to
this even though the overall bending effect is larger at mid-
span, the chord member and web member stresses are
smaller closer to the mid-span and larger closer to the
supports.

29. • The typical span to maximum depth ratios of
pitched roof trusses are in the range of 4 to 8,
the larger ratio being economical in longer
spans. Pitched roof trusses may have different
configurations.

30. • In Pratt trusses web members are arranged in such a way
that under gravity load the longer diagonal members are
under tension and the shorter vertical members
experience compression. This allows for efficient
design, since the short members are under compression.

33. • However, the wind uplift may cause reversal of
stresses in these members and nullify this benefit.
The converse of the Pratt is the Howe truss, This
is commonly used in light roofing so that the
longer diagonals experience tension under
reversal of stresses due to wind load.

35. Fink trusses are used for longer spans having high
pitch roof, since the web members in such truss are
sub-divided to obtain shorter members.

36. Fan trusses are used when the rafter members of the roof
trusses have to be sub-divided into odd number of panels

37. A combination of fink and fan can also be used to some
advantage in some specific situations requiring appropriate
number of panels.
Mansard trusses are variation of fink trusses, which have
shorter leading diagonals even in very long span trusses,
unlike the fink and fan type trusses.

38. • The economical span lengths of the pitched roof
trusses, excluding the Mansard trusses, range from 6
m to 12 m. The Mansard trusses can be used in the
span ranges of 12 m to 30 m.

40. Types of truss Span used
Pitched fink truss Upto 9 m (economical)
Pratt truss 6 to 15 m
Compound fink truss Longer span upto 28 m
Simple fan truss 12 m
Compound fan truss Upto 24 m

41. 5. Purlins, girts and sag rod

42. • Purlin support roof sheeting, and loads from the
sheeting are transferred to the purlins.
• The loads acting on the purlins are weight of roof
covering and fixtures self-weight of purlin, live load
from sheeting, snow load, and wind load

43. Sections used as purlins:
1.Angle Purlins: It is used in small shops when
spacing of roof truss is between 3 to 5 m.

45. •Channel Purlins: It is used for medium shops, when
spacing of roof truss is between 4 to 6 m.

46. • Beam Purlin: It is used for heavy shops, when
spacing of roof truss is between 6 to 8m.

47. Spacing of Purlin:
• The spacing of purlin depends largely on the maximum safe
span of the roof covering and glazing sheets. Hence they
should be less than or equal to their safe span when they are
directly placed on purlins.
• Thus for corrugated GI sheet, the purlin spacing may vary
from 1.5 to 1.75 m, and for corrugated AC sheets, it is
limited to 1.4 m, for 6 mm thick sheets, and 1.6 m, for 7 mm
thick sheets.

48. • For larger spans, if the configuration of the truss is such that
it is not feasible to place purlin at the nodes of upper chords,
the purlin are placed between the nodes, thus introducing
bending moment in the upper chords, in addition to the
compressive force due to truss action.
• Hence in this case, the weight of the truss may be increased
by about 10-15 %. Therefore, it is preferable to place purlin
at the nodal point of the truss, so that the upper chord
member are subjected to only direct compression

50. 6.Bracing system to resist lateral loads

51. 7. Gantry girders, columns, base plates
and foundation

52. Loads on trusses
• The main loads on trusses are dead, imposed and
wind loads.
• The dead loads is due to sheeting or decking and their
fixtures, insulation, false ceiling, weight of purlins
and self weight. This load may range from 0.3 to 1.0
kN/m2
Page no 30, table 1 IS 875-1

53. • The weights of purlins are known in advance as they
are designed prior to the trusses. Since the weight of
truss is small compared to total DL,LL, considerable
assumptions is taken in account for weight of truss
and it will not have a great impact on the stresses in
the various members.

54. • For Live load upto 2 kN/m2, following formula is
used to get the approximate value of weight of truss
• W =20 + 6.6L (w=wt of truss in N/mm2, L=span in
m)
• For welded trusses, the self wt of truss is
w=53.7 + 0.53A (A= area of one bay).
• For LL > 2 kN/m2, the value of w may be multiplied
by the ratio of actual live load in kN/m2/2

55. Load calculations for design
• The following load combinations of loads are
considered when there is no crane load
• DL + LL
• DL + Snow load
• DL + WL (normal to ridge or parallel to ridge
whichever is severe)
• DL + LL + WL(most critical)

56. • The weight of bracings may be assumed to be 12-15
N/m2 of the plan area.
• The imposed load on roofs will be as per IS-875-II.
Page no 15, table 2 IS 875-2

58. • The wind load should be calculated as per IS -
875-III
• Since EQ load depends on the mass of the
building, earthquake load do not govern the
design of light industrial buildings. Thus wind
load governs the design of normal trussed
roofs

59. Thank you…