Computation of Loads on Buildings of Different Typologies

Computation of Loads on
Buildings of Different
Typologies
C. J. Ragunathan, Managing Director
Design Forum India Private Limited, Coimbatore

About this template
Contents
1. Learning
2. Importance
3. IS Codes
4. Computation of Various
Loads on Buildings
5. Computation of Loads on a
RCC Framed Structure
6. Computation of Loads on an
Industrial Roof
7. Few special structures
8. Conclusion
2

Few I S Codes
◉ IS 875- 1987 Loads except earthquake load
◉ IS 1893-2016 Seismic Loads
◉ IS 456-2000 Reinforced Concrete
◉ IS 800- 1984 Steel
◉ IS 3370- 2009 Liquid Retaining Structures
◉ IS 13920- 2016 Ductile Detailing
◉ National Building Code of India - NBC
6

IS 875- 1987- Design Loads
◉ Part 1 Dead
◉ Part 2 Imposed
◉ Part 3 Wind
◉ Part 4 Snow Loads
◉ Part 5 Special Loads and Load Combinations
7

4. Computation of Various Loads on Buildings
8

◉ Unit weight/mass of
materials.
◉ Parts or components
in a building
◉ Dead loads in the
design of buildings.
Weights of few commonly used
materials
◉ PCC 23 kn/cu.m
◉ RCC 25 Kn/cu.m
◉ Steel 78.5 Kn/cu.m
◉ Brickwork 20Kn/cum
◉ AAC Blockwork 6 to 8 Kn/cu.m
◉ AC Sheet 0.16kn/sq.m
◉ Galvalume Sheet 0.06 Kn/sq.m
IS 875 – 1987 Part 1 Dead Load
9

RCC framed structure
◉ Self weight of the structure
◉ Slab
◉ Beam
◉ Column
◉ Wall
◉ Flooring
You can also split your content
Industrial Building with sheet
roofing
◉ Sheet
◉ Purlin
◉ Truss
◉ Lattice
◉ Gantry
Girder
◉Wind Bracings
IS 875-1987 Part1 Dead Load ( Contd)
10

IS 875- 1987 Part2 Imposed Loads
11
Classification of buildings
◉ Residential
◉ Office
◉ Commercial
◉ Educational
◉ Industrial
◉ Institutional- Hospital
◉ Storage
◉ Special Buildings and Structures

◉ Human load,
Furniture, equipments
◉ Reduction of Imposed
Load on multi
storeyed buildings
◉ Loads to be
considered on
Parapets &
Balustrades- Normal
condn.
◉ Severe over loads or
abnormal loads – Not
covered
IS 875 -1987 Part 2 Imposed Load
12

IS 875-1987 Part 2 Imposed Loads
13
1. Residential
a) Dwelling UDL Conc. Load
Rooms& Kitchen 2.0 Kn / sq.m 1.8 Kn
Corridor & Stair 3.0 Kn/ sq.m 4.5 Kn
Balcony 3.0 Kn/ sq.m 1.5 Kn/m
b) Hotels, Hostels, Dorms.
Kitchen 3.0 Kn/ sq.m
Store 5.0 Kn/sq.m
Dining 4.0 Kn/sq.m
Balcony 4.0 Kn/sq.m 1.5 kn/m
c) Garages and ramps 2.5 to 6.0 Kn/ sq.m 9.0 Kn

2. Educational
Buildings
a) Class Room
b) Library
c) Balcony
3.Ins. Buildings
a) Plant Room
4. Assembly
a) Plant Room
UDL
3.0 Kn/Sq.m
6.0Kn/sq.m
4.0Kn/sq.m
5.0 Kn/sq.m
7.5 Kn/sq.m
Conc. Load
2.7 Kn
4.5 Kn
1.5 Kn/m
4.5 Kn
4.5 Kn
14

Industrial Buildings
◉ Loads on Roof
◉ Dead Load –Roofing Sheet,
Purlin, Truss/ Rafter
◉ Imposed Loads-human,
Insulation, False Ceiling ,
Ducting, fire fighting, lighting
◉ Loads on Floor- Light,
Medium and Heavy
15
• Loads on Wall - water, steam, chemical pipe lines
• Actual Load -Machinery

Other aspects
◉ Possible change of usage or occupancy
◉ Incidental Load during Construction
a) Excess stock of const. material
b) Const. equipment load
c) Crane or truck movement
◉ Sometimes Construction Load >
Design Load
16

◉ Wind forces
and their
effects for
designing
buildings,
structures and
components
thereof.
◉ Wind Load On the
structure
◉ Wind Map of India
◉ Basic Wind speed Vb
◉ Modification Factors
Probability of risk,
Terrain& ht of objects,
Topography and Size
◉ Design Wind Speed Vz
◉ Design Wind Pressure at
any height pZ
◉ Design Wind
Pressure pD
1. Wind Directionality
2. Area Averaging
3. Combination
◉ Pressure Co
Efficient Cpe &Cpi
◉ Wind Load
IS875-2015 Part 3 Wind Load
17
structure
Topography and Size
any height pZ
structure
Topography and Size
any height pZ

◉ Basic Wind Speed Vb
◉ Design Wind Speed Vz = Vb k1 k2
k3 k4
◉ Vz = Design wind speed
◉ K1 = Probability factor ( Risk co
efficient)
◉ k2 = Terrain roughness and height
factor
◉ k3= Topography factor
◉ k4= Importance factor for the
cyclonic region
◉ Design Wind Pressure Pz = 0.6 Vz2
at all heights
◉ Design Wind pressure Pd = Kd x
Ka x Kc x Pz , where
Kd = wind directionality factor
Ka = area averaging factor
Kc = combination factor
◉ Wind Load = ( Cpe- Cpi)A x P d
Cpe Pressure Co Efficient Ext
Cpi Pressure Co Efficient Int
IS 875-2015 Part 3 Wind Loads
18
k3 k4
efficient)
factor
cyclonic region
k3 k4
efficient)
factor
cyclonic region

Warehouse building
19
•24m High
•15 wide
• Storage
Racks

IS875 –1987 Part 5 Special Loads and Load
Combinations
◉ Loads and Load effects due to temperature changes
◉ Stresses due to Creep, shrinkage, differential
settlement
◉ Soil and hydrostatic pressure
◉ Accidental loads
◉ Guidance for load combinations
20

IS 875- Part 5 Special Load on Structures
21

Seismic Loads
◉ Earthquake hazard
assessment for earthquake
resistant design
◉ Buildings
◉ Liquid retaining structures
◉ Bridges
◉ Embankment & retaining walls
◉ Industrial & stack like structures
◉ Concrete masonry & earth dams
Part 1
◉ Earthquake resistant design
of buildings.
IS 1893- 2016 Earthquake Resistant Design of
Structures
22

IS1983- Part 1 Seismic Parameters
◉ Design horizontal seismic
coefficient Ah =[(Z/2)(Sa/g)] / [R/I]
• Z = Seismic zone factor I to V Zones
• I = Importance factor 1.0, 1.2 & 1.5
• R = Response reduction Factor (OMRF & SMRF)
• Sa/g = Design acceleration coefficient
Type I-Rock or Hard, Type II Medium of Stiff, Type III Soft
( soil types, ground acceleration,
natural time period T of structure).
23

IS1983- Part 1 Seismic Parameters
◉ Time Period
◉ h= Height of Building
d= Base dimension along X or Y dir.
◉ Ta < 0.4 sec Static Analysis
◉ Ta> 0.4 sec Dynamic analysis
◉ Sa/g
◉ Ah
24

IS1893-2016 Part 1
◉ Design Base Shear Vb= Ah xW
Ah – Design Horizontal Acceleration Co efficient
W- Seismic Weight of the structure/ Building
25

IS1893-2016 Part1
◉ Design Lateral Force Qi @ floor levels in each
direction
◉ Base Shear Vb
◉ Vertical Distribution of Base Shear to Different Floor Levels
◉ Lateral Force Qi
◉ Wi – seismic wt of the floor
◉ Hi- Height of the floor measured
from base
◉ n- number of storey in building
26

Let’s review some concepts
Dead Load Imposed Load. Wind Load .
Seismic Loads.
Loads to be considered on a Building
27

Giving inputs in
STAAD /ETab
Computation of
loads on various
elements of the
building
Our process is easy
Structural Analysis and Design
Understanding
the Building
28

◉ Terrace Slab
◉ Roof Level Tie Beams
◉ Floor Slabs
◉ Floor Level Tie Beams
◉ Plinth Level Tie Beam
◉ Column
◉ Footing
◉ Location - Coimbatore
◉ Residential Apartment
◉ Stilt + 4 Floors
◉ Walls – Brick wall 230mm tk
and 115mm thick
◉ Terrace Finish – Clay tiles
over weathering course
◉ Floor Finish- Vitrified Tiles
Computation of Loads on a RCC Framed structure
29

Residential Apartment- Stilt Floor
30

Residential Apartment- Typical Floor
31

Want big
impact?
Use big
image.
33

Enlarged Portion of Ground Floor
34

Dead Load
◉ Thickness of Slab 125
◉ Size of beam 230 x 500
◉ Weathering Course
◉ Floor Finish
◉ Wall load 230 tk
◉ Partition walls
Terrace
◉ 0.15 x25 Kn/cu.m = 3.75
Kn/sq.m
◉ 0.23x 0.5 x 25 Kn/cu.m=
2.875 kn/m
◉ WC 2.5kn/sq.m
◉ Parapet Wall per m run for
1m height
0.23 x1.0 x 20kn/cu.m= 4.6 kn/m
Floor
◉ 0.15 x25 Kn/sq.m
=3.75Kn/sq.m
◉ 0.23x 0.5 x 25 Kn/sq.m-
2.875Kn/m
◉ Finishes 1.5 Kn/sq.m
◉ Brick wall 230 tk for 3.0 m
(3.5m-0.5)m
= 0.23x 3.0x20Kn/cu.m = 14 kn/m
◉ Partition walls 1.5 kn/sq.m
Computation of Load on a Residential Apartment
Building
36

Imposed (Live) Load
◉ Human load
◉ Furniture
◉ Solar Panels
◉ Any movable
equipments like
Refrigerator,
washing machine
etc
Terrace Floor
◉ IS 875-1987
◉ Roof with access
1.5 Kn per sq.m
Typical Floor
◉ IS 875- 1987
◉ Residential
Building
2 Kn/sq.m
Building
37

Wind Load
◉ Location : Coimbatore, Tamilnadu
◉ Vb: Basic Wind Speed 39m/sec
◉ K1 Probability Factor : 1 for General
Buildings
◉ K2 Terrain Roughness & height:
1.05 for Terrain category 2 and
Height 15m
◉ K3 Topography : 1 for Plain
Topography
◉ K4 Importance Factor : 1 for
General Building
◉ Vz = Vb x k1 xk2 xk3
Vz = 39 x 1x1.05x1 = 40.95 m/sec
◉ Basic Design Wind Pressure pz= 0.6 x Vz
2 = 0.6 x 40.952
= 1.0 kN/m2
◉ Design Wind Pressure pd = KdKa Kcpz> 0.7 pd
Kd = 0.9 for Buildings, Rectangular, Cl; 7.2.1
Ka = 0.8 for ≥100 m2 Tributary area, from Table 4
Kc = 0.9 for Frames, Cl; 7.3.3.13
pd = 0.9x 0.8 x 0.9(1.0) or 0.7 x 1.0 whichever is
higher
= 0.7 kN/m2
Computation of Loads acting on an RCC Framed
Structure
39

Building
40
Design wind pressure to the column of the building = 0.7kN/m2 x 3.26m( Column spacing)
= 2.3 Kn/m

Seismic Parameters
41
◉ Seismic Base Shear Vb = Ah x W
◉ Horizontal Seismic Co-efficient, Ah = Z/2 x I/R x Sa/g
Where, Z = Zone Factor = 0.16 for Zone III
I = Importance Factor = 1.0 for All General Buildings
R = Response reduction Factor = 5.0 (for Special Moment Resisting Frame-SMRF)
◉ Sa/g = Spectral Acceleration co-efficient = 2.5 for X Dir, 1.5 for Y Dir
(Based on Soil condition and Time Period Sa/g is arrived using relevant fig in IS 1893)
◉ Ahx = 0.16/2 x 1.0/5.0 x 2.5 = 0.025
◉ Ahy = 0.16/2 x 1.0/5.0 x 1.5 = 0.015

Seismic Load Calculations
◉ Seismic weight of the building
◉ Floor area = 21m x 63m = 1323sq.m
◉ Dead load = 6.0kn/m2 (self. wt + finishes + partition)
◉ Live load = 0.5 Kn/sqm (25% of 2.0 kn/m2 LL alone is taken as per code
for < 3.0 Kn/sq.m)
◉ Additionally outer 9” brick wall weight
◉ Total weight per one floor = Wi= 11536 kN
◉ Total seismic Weight of Structure W = 11536 x5 floors =57680kN
42

Seismic Base Shear Calculations
◉ Seismic Base Shear in X dir Vb = Ah. W
= 0.025 x 57680Kn
= 1442 kN
◉ Seismic Base Shear in Ydir Vb = Ah. W
= 0.015 x 57680Kn
= 860 kN
43

Vertical Distribution of Base Shear
44

Seismic Load in X Directions
45

Seismic load in Y Direction
46

LOADs
◉ Dead Load ,DL
◉ Live Load ,LL
◉ EarthQuake Load in X direction,
EQ X
◉ EarthQuake Load in -X direction
EQ -X
◉ EarthQuake Load in Y direction,
EQ Y
◉ EarthQuake Load in -Y direction
EQ -Y
1. DL+LL
2. 1.5DL+1.5LL
3. 1.5DL+1.5EQ X
4. 1.5DL+1.5EQ-X
5. 1.5DL+1.5EQ Y
6. 1.5DL+1.5EQ –Y
7. 0.9DL+1.5EQ X
.
Load Combinations
47
8. 0.9DL+1.5EQ -X
9. 0.9DL+1.5EQ Y
10. 0.9DL+1.5EQ -Y
11. 1.2DL+1.2LL+1.2EQ X
12. 1.2DL+1.2LL+1.2EQ X
13. 1.2DL+1.2LL+1.2EQ Y
14. 1.2DL+1.2LL+1.2EQ-Y
Load Combinations
For Wind Load Substitute WL in the place of EQ

Computation of Load on an Industrial Roof
48

◉ Span of the roof is 90.6
m
◉ Spacing of the Truss is
8.1m
◉ Length 434m ,Width 90.6 m
◉ Span 90.6m
◉ Spacing of truss 8.13m
◉ Truss on RCC column and Lattice
◉ Lattice span 24.39 m supported on RCC columns
◉ Textile spinning Mill
Real Time Industrial Project - Plan
49

◉ Roof sheet material - Galvalume
◉ Under deck insulation – Bubble Wrap sheet
◉ False ceiling - calcium silicate boards
◉ Truss and lattice - HR sections
◉ Purlins - CRF section – C sections
◉ Collateral Loads- GI Ducts, False Ceiling
Sectional Elevation & Enlarged Plan
50

Dead Load
◉ Due to sheet = 0.06 kN/sqm
◉ Due to Purlin = 0.10kN/sqm
◉ Due to Truss = 0.15 kN/sqm
◉ Due to Insulation= 0.10kN/sqm
◉ Due to Duct + False Ceiling= 0.25
kN/sqm
◉ Total Dead Load = 0.66 kN/sqm
◉ Truss spacing =
8.13m
◉ Purlin Spacing = 1.6 m
◉ Load per node = 0.66 x 1.6 x 8.13
= 8.58 kN/Node
Computation of Loads acting on an Industrial Roof
51

Imposed Load
◉ On Roofing Sheet
= 0.75 kN/sqm
◉ Solar Panel =0.25 kN/sqm
◉ Truss Spacing 8.13 m
◉ Purlin Spacing 1.6 m
◉ Load per node =
0.75 x 1.6 x 8.13
= 9.76kN / Node
52

Wind Load
◉ Location : near Coimbatore, Tamilnadu
◉ Vb: Basic Wind Speed 39m/sec
◉ K1 Probability Factor : 1 for General Buildings
◉ K2 Terrain Roughness & height: 1 for Terrain
category 2 and Height 10m
◉ K3 Topography : 1 for Plain Topography
◉ K4 Importance Factor : 1.15 for Industrial
Building
◉ Vz = Vb x k1 xk2 xk3
Vz = 39 x 1x1x1.15 = 44.85 m/sec
◉ Basic Design Wind Pressure pz= 0.6 x Vz
2 = 0.6 x 44.852
= 1.21 kN/m2
◉ Design Wind Pressure pd = KdKa Kcpz> 0.7 pd
Kd = 0.9 for Buildings, Rectangular, Cl; 7.2.1
Ka = 0.8 for ≥100 m2 Tributary area, from Table 4
Kc = 0.9 for Frames, Cl; 7.3.3.13
pd = 0.9x 0.8 x 0.9(1.21) 0.7 x 1.21
= 0.847 kN/m2
53

◉ Wind Co efficient External Cpe
◉ For walls, h/w = 7.5 / 90.66 =
0.083 < 1/2, Refer Table.5 First Row of values
l/w = 434 / 90.66 =
4.77 > 4, Refer First Row, Second sub-division
◉ For Roofs, h/w = 0.083, Roof Angle
7, the following are the Co-efficient
◉ Wind Co efficient Internal Cpi
◉ % of Opening - Cpi
< 5% - ±0.2
5% to 20% ±0.5
> 20% - ±0.7
54
Windward Leeward

Computation of Loads due to wind
55
Windward Leeward
Combined Co efficient
Actual Wind load on Nodes

Seismic Parameters
SEISMIC LOAD
◉ Seismic Base Shear Vb = Ah. W
◉ Horizontal Seismic Co-efficient, Ah = Z/2 x I/R x Sa/g
Where, Z = Zone Factor = 0.16 for Zone III
I = Importance Factor= 1.0 for All General Buildings
R = Response reduction Factor = 3.0 (for OMRF)
OMRF-Ordinary Moment Resisting Frame
◉ Sa/g= Spectral Acceleration co-efficient = 1.9 for X Dir and 1.45 for Y Dir
(Based on Soil condition and Time Period Sa/g is arrived using fig in IS 1893)
◉ Ahx = 0.16/2 x 1.0/3.0 x 1.9 = 0.051
◉ Ahy = 0.16/2 x 1.0/3.0 x 1.45 = 0.039
56

Seismic Parameters
W = Seismic weight = 100 % of Dead Load + 25% For LL < 3 kn/sq.m
(or 50% of Live Load for > 3 kn/sq.m)
57

Seismic Base Shear Calculations
◉ Seismic Base Shear in X dir Vb = Ah. W
= 0.051 x (75+125+125+190+50) x 2
= 0.051 x 1130
= 57.63kN
◉ Seismic Base Shear in Ydir Vb = Ah. W
= 0.039 x (75+125+125+190+50) x 2
= 0.039 x 1130
= 44.10kN
58

Seismic Load on the structure
◉ Base Shear in X Direction and Y direction to be arrived at various levels based on height and
weight.
59

62
• Purlin
• Truss
• Lattice

63
• Ducts
• False ceiling
• Under Deck
Insulation

64
• Galvalume
Sheet
• Insulation

Few Buildings or structures
65

66
Conveyor Bridge at 35m height, spanning for 40m in a Poultry Feed Mill Plant

67
• Height of the
Statue182 m
• Total height of the
structure is 240 m with a
base of 58 m
• Basic Wind Speed
• Seismic Zone
• Concrete 210,000
Cu.m
• Steel 25000 MT
• Bronze 3550 MT

69
Structural
Engineering as a
Responsible
Career!!

71
• Tanjore Big Temple
• Cultural Unesco World Heritage
• 1010 year old
• 216’ ( 66m) Tall incl. 80 MT Granite Cap
• Axial & Symmetrical Geometry

Few Innovative buildings of today. 72

Thanks!
ANY QUESTIONS?
You can find me at:
cjr@dfindia.com
cjragu@gmail.com
73

Computation of Loads on Buildings of Different Typologies

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Computation of Loads on Buildings of Different Typologies

Similar to Computation of Loads on Buildings of Different Typologies (20)

More from Ajit Sabnis

More from Ajit Sabnis (20)

Recently uploaded

Recently uploaded (20)

Computation of Loads on Buildings of Different Typologies