Structural design including disaster (wind & cyclone land slide_eq_ resistant design of structures

1. ‘Structural Design
including Disaster Resistant Design of Structures’

2. • Part 6 Structural Design
Structural Safety
– 7 Sections
– 438 pages
– almost half the NBC

3. Part 6 Structural Design
• Section 1 Loads, Forces and Effects
• Section 2 Soils and Foundations
• Section 3 Timber and Bamboo
3A Timber
3B Bamboo
• Section 4 Masonry

4. Part 6 Structural Design contd…
• Section 5 Concrete
5A Plain and Reinforced Concrete
5B Prestressed Concrete
• Section 6 Steel
• Section 7 Prefabrication, Systems Buildings
and Mixed/Composite Construction
7A Pre-fabricated concrete
7B Systems Buildings and
Mixed/Composite Construction

5. IS 875 Code
• IS 875 Code of practice for design loads
(other than earthquake) for
buildings and structures;
Part 2 : 1987 Imposed loads (second revision)
Part 3 : 1988 Wind loads (second revision)
Part 4 : 1987 Snow loads (second revision)
Part 5 : Special loads and load
combination (second revision)

6. IS 875 Code
• Also refer to SP 64 (S&T) :2001 ‘
Explanatory Handbook on Indian
Standard code of practice for design
loads (other than earthquake) for
buildings and structures : Part 3 Wind
Loads

7. Section 1 Loads, Forces and
Effects
• Revised Standard IS 1893 (Part 1) – 2002
‘Criteria for Earthquake resistant design
of structures: Part 1 General provisions
and Buildings (fifth revision)’

8. Imposed loads
• Residential Buildings
• Educational buildings
• Institutional Buildings
• Assembly Buildings
• Business and Office Buildings
• Mercantile buildings
• Industrial Buildings
• Storage Buildings

9. Imposed loads
• Label indicating Designed Imposed
Loading to be displayed at a conspicuous
place.
– Distributed Load kN/m2
– Concentrated Load kN

10. Wind Load
• Equivalent static load for steady wind load
is ok for short and heavy structures
• Gust factor method considering drag on
structures for flexible structures
• In case of tall structures with
unsymmetrical geometry designs are to be
checked for torsional effects

11. Wind Load
• Depends on
– risk level
– terrain roughness, height and size of structure
– local topography

12. Wind Load
• Basic wind speed Map( based on 50 year
return period from code

14. Wind &
Cyclone
Map
of India

15. TOO SMALL FOR
LIGHT WEIGHT
BUILDING, PULLED
COMPLETELY OUT OF
THE GROUND
FOUNDATIONS

16. Dramatic & Total Destruction Of Large, Steel, Portal
Frame Building
STEEL FRAMES

17. LOSS OF CORRUGATED, METAL, ROOF SHEETS
ROOF SHEETING

18. COLLAPSED LATTICE TOWERS
TELECOMMUNICATION TOWERS & MASTS

19. Wind Load
• Design wind speed
Vz = Vb k1 k2 k3
– Vz = design wind speed at any height z in m/s
– Vb = basic wind speed in m/s
– k1 = probability factor (risk coefficient) Table 4
– k2 = terrain, height and structure size factor
– k3 = topography factor

20. Wind Load
• Design wind pressure
pz = 0.6 Vz
2

21. Wind Load
• Pressure Coefficients
Cp code gives tables for various types
and shapes of buildings

22. Seismic load
• IS 1893 : 2002 ‘

27. Lack of shear connection
between floors and the
elevator shaft
5 storey R.C., collapse
of open plinth, water
tank at top dislocated
(Bhuj)

28. Identical 4 storeyed R.C.
buildings (Amdavad) two
out of four collapsed
Collapse of R.C.
frame railway station
building at Vondh

29. Soft ground storey
collapse (Amdavad)
Pancake collapse of a
R.C. Building
(Gandhidham)

30. Elevator shaft - weak
shear connections with
floors (Amdavad)
Infill wall damage

31. BIS Standards
• IS 1893-2002 : Criteria for earthquake
resistant design of structures
• IS4326-1993 : Earthquake Resistant Design
and construction for buildings – code of
practice (second revision)
• IS 13920-1993 : Ductile detailing of RC
structures subjected to seismic forces –
code of practice

32. VARIOUS PARTS OF
IS 1893:2002
• Part 1: General provisions and buildings
• Part 2: Liquid retaining tanks
- Elevated and ground supported
• Part 3: Bridges and retaining walls
• Part 4: Industrial structures including stack like
structures
• Part 5 : Dams and embankments

33. Important Modifications
• Design Basis Earthquake (DBE)
E/Q that can reasonably be expected to
occur once during the design life of the
structure
• Maximum Considered Earthquake (MCE)
The most severe earthquake effects
considered by this standard

34. Assumptions
• Generally designed for earthquake coming
from one direction at a time
• Resonance will not occur
• Earthquake will not occur with extreme
wind

35. Performance criteria
• Moderate Earthquake
– Without structural damage
– Could occur a number of times in the life span
– Code based design seismic coefficients
• Large earthquake
– Without collapse
– May occur once in the life of the structure
– Not catered by the codal design seismic co-
efficient
– Additional resistant by incorporating details for
ductility

36. Zoning Map
• Zone I and II of the contemporary map has been
merged and assigned the level of Zone II
• Khillari area has been included in Zone III
• The parts of eastern coast areas, the level of
Zone II has been enhanced to Zone III

38. Seismic Zone Factors
• Maximum Considered Earthquake(MCE)
– The most severe earthquake effects considered by
this standard
• Zone Factor (Z)
– It is a factor to obtain the design spectrum depending
on the perceived maximum seismic risk characterized
by MCE in the zone in which the structure is located.
– The basic zone factors included in this standard are
reasonable estimate of effective peak ground
acceleration
Seismic Zone II III IV V
Factor 0.1 0.16 0.24 0.36

39. DESIGN HORIZONTAL LOAD
• When lateral resisting elements are
orthogonal, consider e/q load in one
direction at a time.
• When non-orthogonal
– Combine full load in one direction with
30% of load in other direction
EL in load combination replaced by
ELx±0.3ELy or 0.3ELx±ELy

40. Response reduction factor (R)
• It is the factor by which the actual base shear
force, shall be reduced to obtain the design
lateral force.
– Actual base shear force - that would be generated if the
structure were to remain elastic during its response to the
Design Basis Earthquake (DBE) shaking.
– The values of ‘R’ depend upon seismic damage
performance of the structure, i.e. ductile/brittle.
• Design Basis Earthquake (DBE)
– It is the earthquake which can reasonably be expected to
occur at least once during the design life of the structure.
– Z / 2

41. Response Reduction Factor(R)
Ordinary RC moment-resisting frame(OMRF) 3.0
Special RC moment-resisting frame(SMRF) 5.0
Load bearing masonry wall buildings
a) Un-reinforced 1.5
b) Reinforced with horizontal RC bands 2.5
c) Reinforced with horizontal RC bands and vertical
bars at corners of rooms and jambs of openings 3.0
Ordinary reinforced concrete shear walls 3.0
Ductile shear walls 4.0
Ordinary shear wall with OMRF 3.0
Ordinary shear wall with SMRF 4.0
Ductile shear wall with OMRF 4.5
Ductile shear wall with SMRF 5.0
Lateral Load Resisting System R

42. Design Lateral Force Revised
• Design Seismic Base Shear (VB ) (Lower Bound)
VB = Ah W
Where,
Ah = Design horizontal acceleration spectrum using the
approximate fundamental natural period Ta (Clause 7.6)
in the considered direction of vibration; and
W = Seismic weight of the building

43. Design horizontal seismic coefficient Ah)
• Z = Zone factor given in Table 2, is for the MCE and
service life of structure in a zone.
The factor 2 in the denominator of Z is used so as to reduce
the MCE zone factor to the factor for DBE.
• I = Importance factor (Table 6)
• R = Response reduction factor (Table 7)
I/R shall not be greater than 1.0
• Sa / g = Average response acceleration coefficient.
gR
SIZ
A
a
h
2
=

44. Response Spectra
1. 0
3.0
2.0
1.0 2.0 3.0 4.0
Type III (Soft soil)
Type II (Medium soil)
Type I (Rock, or Hard soil)
Period
SpectralAccelerationCoefficient(Sa/g)

45. Fundamental Natural Period
RC frame building
• Moment-resisting frame building without brick
infill panels
Ta = 0.075 h0.75
[Old version, Ta = 0.1N(No. of storey) , No mention about the
brick infill panel]
• Moment-resisting frame buildings with brick
infill panel
where,
h = Height of building and
d = Base dimension of the building at the plinth level, in m,
along with considered direction of the lateral force.
d
h
aT 09.0=

46. Attributes to perform well in a
earthquake
• Simple and regular configuration
• Adequate lateral strength
• Adequate stiffness
• Adequate ductility

47. Regular and Irregular
Configuration
• Buildings having simple regular configuration
suffer less damage than buildings with
irregular configuration.
• Regular Configuration
– Simple regular geometry
– Uniformly distributed mass and stiffness in plan and
elevation
• Irregular configuration
– As defined in Table 4 and 5 of the code

48. Plan and Vertical Irregularities

49. Plan Irregularities
• Torsion Irregularity
• Re-entrant Corners
• Diaphragm Discontinuity
• Out-of-plane offsets
• Non-parallel systems

50. Plan Irregularities (Table 4)
• Tortional Irregularity
– To be considered when floor diaphragms are rigid in
their own plan
– when the maximum storey drift, computed with design
eccentricity, at one end of the structure transverse to
an axis is more than 1.2 times the average of the
storey drifts at the two ends of the structure. { ∆2 =1.
2 (∆1 + ∆2) / 2}
∆ 1
∆ 2

51. Plan Irregularities (Table 4)
…Contd.
• Re-entrant Corners,
– where both projections of the structure beyond the re-entrant
corner are greater than 15 percent of its plan dimension in the
given direction.
A1<0.15L1, A2<0.15L2
Contd…
L1
L2
A1
A2

52. Plan Irregularities (Table 4)
…Contd.
• Diaphragm Discontinuity
– Diaphragms with abrupt discontinuities or
variations in stiffness:
• those having cut-out or open areas greater then 50
percent of the gross enclosed diaphragm area
• or changes in effective diaphragm stiffness of more
than 50 percent from one storey to the next.
Contd…

53. Plan Irregularities (Table 4)
…Contd.
• Out-of-Plan Offsets
– Discontinuities in a lateral force resistance path, such as
out-of plan offsets of vertical elements.
Position of shear wall
Ground Floor Plan First Floor Plan

54. Plan Irregularities (Table 4)
…Contd.
Non-Parallel Systems
– The vertical elements resisting the lateral force are not
parallel to or symmetric about the major orthogonal axes or
the lateral force resisting elements.
X
Y

55. Vertical Irregularities
• Stiffness irregularity – soft storey
• Mass irregularity
• Geometric irregularity
• In-plane discontinuity
• Discontinuity in capacity – weak storey

56. Vertical Irregularities (Table 5)
• Stiffness irregularity – Soft Storey
– A soft storey is one in which the lateral stiffness is less
than 70 percent of that in the storey
– or less than 80 percent of the average lateral stiffness of
the three storeys above.
• Stiffness irregularity – Extreme Soft Storey
– A extreme soft storey is one in which the lateral stiffness is
less than 60 percent of that in the storey above
– or less than 70 percent of the average stiffness of the three
storeys above, e.g., buildings on STILTS will fall under this
category.

57. Vertical Irregularities (Table 5)
…Contd.
• Mass Irregularity
– Mass irregularity shall be considered to exist where the
seismic weight of any storey is more than 200 percent of that
of its adjacent storeys.
– The irregularity need not be considered in case of roofs.
• Vertical Geometric Irregularity
– Vertical geometric irregularity shall be considered to exist
where the horizontal dimension of the lateral force resisting
system in any storey is more than 150 percent of that in its
adjacent storey.
Contd…

58. Vertical Irregularities (Table 5)
…Contd.
• In-Plane Discontinuity in Vertical Elements
Resisting Lateral Force
– A in-plane offset of the lateral force resisting
elements greater than the length of those elements.
• Discontinuity in Capacity – Weak Storey
– A weak storey is one in which the storey lateral
strength is less than 80 percent of that in the storey
above.
– The storey lateral strength is the total strength of all
seismic force resisting elements sharing the storey
shear in the considered direction.

59. Dynamic Analysis
• Regular Buildings
– Those greater than 40 m in height in Zones IV & V,
– Those greater than 90 m in height in Zones II and III.
– Modeling as per 7.8.4.5 can be used for response spectrum
method.
• Irregular Buildings
– All framed buildings higher than 12 m in Zones IV & V,
– Those greater than 40 m in height in Zones II and III.
– The analytical model for dynamic analysis of buildings with
unusual configuration should be such that it adequately models
the types of irregularities present in the building configuration.
– Buildings with plan irregularities, as defined in Table 4 (as per
7.1), cannot be modeled for dynamic analysis by the method
given in 7.8.4.5.
• At least 3 degree of freedom are to be considered for each floor

60. Buildings with Soft Storey
*Buildings with a flexible storey,
– such as the ground storey consisting of open spaces
for parking that is Stilt buildings,
– special arrangements needs to be made to increase
the lateral strength and stiffness of the soft/open
storey.
• Dynamic analysis of building is carried out
including
– the strength and stiffness effects of infill and
– inelastic deformations in the members particularly,
those in the soft storey,
and the members designed accordingly.
Contd….

61. Buildings with Soft Storey
…contd.
• Alternatively,
– Carrying out the earthquake analysis, neglecting the
effect of infill walls in other storeys.
– The columns and beams of the soft storey are to be
designed for 2.5 times the storey shears and moments
calculated under seismic loads specified in the other
relevant clauses; or
– Besides the columns designed and detailed for the
calculated storey shears and moments, shear walls
placed symmetrically in both directions of the building
as feasible; to be designed exclusively for 1.5 times
the lateral storey shear force calculated as before.

62. Need for ductility
• Earthquake resistant design – costs money
• Cost increases geometrically for no damage
design
• Codes adopts lower coefficient
– reduction factor
• Provisions for durability for once in life
earthquake
• Design criteria is no-collapse design
• IS-13920 – 1993 detailing for ductility

63. Roof-top DisplacementRoof-top Displacement
V/W(Acceleration)V/W(Acceleration)
Low-Strength; Low-Stiffness; BrittleLow-Strength; Low-Stiffness; Brittle
Moderate Strength and Stiffness; DuctileModerate Strength and Stiffness; Ductile
High-Strength; High-Stiffness; BrittleHigh-Strength; High-Stiffness; Brittle

64. Principles of ductility
• Avoid shear failure
• Avoid compression failure
• Ensure continuity
• Confine the critical areas where hinge can form.

65. Snow load
• s = μ s0
s = design snow load in N/m2
μ = shape coefficient
s0 = Ground snow load

66. Special Loads
• Temperature Effects
• Hydrostatic & soil Pressure
• Fatigue
• Structural Safety during construction
• Accidental loads
• Vibrations

67. Load Combinations
• Various loads are to be combined to
evaluate the most unfavourable effect
• Simultaneous occurrence of maximum
values of wind, earthquake, imposed and
snow load is not likely

68. Multi – Hazard Risk
• Earthquake
• Cyclones
• Windstorm
• Floods
• Landslides
• Liquefaction of soils
• Extreme winds
• Cloud bursts
• Failure of slopes

69. DISASTER MANAGEMENT CYCLE
Emergency Response
Post-disaster: recovery
Preparedness
Prevention/
Mitigation
Reconstruction
Rehabilitation
Response/Relief
Pre-disaster: risk reduction
Disaster
Emergency Response
Post-disaster: recovery
Preparedness
Prevention/
Mitigation
Reconstruction
Rehabilitation
Response/Relief
Pre-disaster: risk reduction
Disaster

70. Multi – Hazard Risk
• Code gives criteria for identifying the multi-
hazard districts and a list of such districts
is at Ann: M

71. Vulnerability Atlas of India, 1987
• Seismic hazard map
• Cyclone and wind map
• Flood prone area map
• Housing stock vulnerability table

72. Vulnerability Atlas of India, 1987
• Landslide Hazard Zonation Atlas, 2003
BMTPC

73. Hazard Maps
The earthquake , wind storm and flood
hazard maps are drawn for each state and
Union Territory separately in which various
district boundaries are clearly shown for
easy identification of the hazard prone
areas.

74. The Vulnerability Atlas of India
The Vulnerability Atlas of India has
been structured to serve as a tool towards
natural disaster prevention , preparedness
and mitigation for housing and related
infrastructure at local as well as national
levels.

75. Hazard Maps
The earthquake , wind storm and flood
hazard maps are drawn for each state and
Union Territory separately in which various
district boundaries are clearly shown for
easy identification of the hazard prone
areas.

76. Flood
Hazard
Map
of
India

78. LANDSLIDE
HAZARD
MAP
OF
INDIA

81. EARTHQUAKE HAZARD MAP OF GUJARAT

82. FLOOD HAZARD MAP OF GUJARAT

83. WIND & CYCLONE HAZARD MAP OF
GUJARAT

84. TABLE 1 – BUILDING TYPES IN FIVE DISTRICTS OF
GUJARAT
Wall Type No. of Houses and percentage of Total in District
Kachchh
%
Jamnagar
%
Banaskanth
a (incl.
Patan)
%
Rajkot
%
Surendranagar
%
Category A 276,390 70.72 215,135 52.04 268,790 54.90 295,005 46.81 281,475 85.04
Category B 56,995 14.58 183,050 44.28 202,185 41.29 310,925 49.34 43,705 13.20
Category C 42,135 10.78 9,980 2.41 6,705 1.37 15,15 2.46 2,870 0.87
Category X 15,290 3.91 5,210 1.26 11,955 2.44 8,760 1.39 2,9 0.89
Total 390,810 100 413,375 100 489,635 100 630,205 100 330,995 100
Source: Vulnerability Atlas of India, 1997
Category A - Building in field-stone, rural structures, unburnt brick houses, clay houses
Category B - Ordinary brick buildings; buildings of the large block and prefabricated type,
half-timbered structures, buildings in natural hewn stone
Category C - Reinforced building, well built wooden structures
Category X - Other types not covered in A,B,C. as of biomass, metal sheets etc.
These are generally light.

85. GUJARAT – EARTHQUAKE DAMAGE TO BUILDINGS
(100 YEARS RETURN PERIOD) (Number of Buildings)

86. ESTIMATED PROBABLE MAXIMUM SURGE AT
MEAN SEA LEVEL

87. MAH INSTALLATIONS - ALL CHEMICAL
HAZARDS

88. Section 2 Soils and Foundations
• 1080: 1985 Design and construction of
shallow foundations in soils ( other than
raft, ring and shell) (second revision)
• 1904: 1986 Design and construction
foundations in soils : General
requirements (third revision)

89. Section 2 Soils and Foundations
contd….
• 2911 (part 1/sec 1): 1979 Design and
construction of pile foundations: Part 1
Driven cast in situ concrete piles)
• 2911 (part 1/section 2): 1979 Bored cast in situ
concrete piles
• 2911 (Part 1/section 3): 1979 Driven precast
concrete piles
• 2911 (Part 1/section 4): 1984 Bored precast
concrete piles
• 2911 Part 3): 1980 Under-reamed piles (first
revision

90. Section 2 Soils and Foundations
contd
• 2950(Part 1): 1981 Raft foundations
• 9456: 1980 Conical hyperbolic
paraboloidal types of shell
foundations

91. Section 2 Soils and Foundations
contd
• Site Investigations
• Shallow foundations
• Allowable bearing Pressure
• Safe bearing capacity based on shear
strength
• Based on allowable
settlement
• Depth of foundations
• On soils min 500 mm

92. Section 3 Timber and Bamboo

93. Timber
Codes
• 399: 1963 Classification of commercial
timbers and their zonal
distribution (revised)
• 883: 1994 design of structural timber in
buildings
• 1150: 2000 Trade names and abbreviated
symbols foe timber species (third
revision)
• 2366: 1983 Nail-jointed timber construction
(first revision)

94. Timber
• 4891: 1988 specification for preferred cut
sizes of structural timber (first
revision)
• 4983: 1968 design and construction of
nailed laminated timber beams
• 11096: 1984 design and construction of bolt-
jointed timber construction
• 14616: 1999 specification for laminated
veneer lumber

95. Bamboo
Codes
• 6874: 1973 Method of test for round
bamboo
• 8242: 1976 Method of test for split
bamboo
• 9096: 1979 Preservation of bamboo for
structural purposes
• 13958: 1994 specification for bamboo
mat for general purposes

102. Masonry
Codes
• 1905: 1987 Structural use of
unreinforced masonry (third
revision)
• 4326: 1993 Earthquake resistant design and
construction of buildings
• Sp 20: 1991 Handbook on masonry design
and construction (first revision)

103. Masonry
Changes
• Special consideration for earthquakes brought
in line with IS 4326
• New clause on guidelines for improving
earthquake resistance of low strength masonry
buildings added
• Reference to design and of reinforced brick
concrete floors and roofs has been included

104. • I S 1905- 1987 : Code of Practice for
Structural Use of Un-reinforced Masonry
• SP 20: Handbook on
Masonry Design and Construction

105. IS 1905 Cl. 0.6
Assumes that :
Design is carried out by qualified Engineer

106. 1905 is applicable for
• Un-reinforced load bearing wall
•Non-load bearing wall Constructed with:
- Solid or perforated burnt clay bricks
IS 1077 (Common burnt clay) or
IS 2180 (Heavy duty burnt clay) or
IS 2222 (Burnt clay perforated)
- Sand lime bricks IS 4139-1976
- Stones IS 3316(Structural granite) or
IS 3620(Laterite block)

107. 1905 is applicable for
contd..
• Concrete blocks
IS 2185 Part 1 Hollow &Solid
IS 2185 Part 2 Hollow and solid ( light weight)
• Lime based blocks IS 3115
• Burnt clay hollow blocks IS 3952
• Gypsum partition blocks IS 2849
• Autoclaved cellular concrete blocks IS 2185 Part 3
• Walls constructed with mud mortars are not
included

108. Planning
• Eccentricity is kept minimum
Adequate stiffness of walls
Load to be uniformly distributed
• For load bearing buildings up to 4 stories,
height to width ratio of buildings should not
exceed 2
• For halls of length exceeding 8 m, safety and
adequacy of lateral supports shall be checked
by structural analysis

109. Mortar
Properties
Lime is added to improve workability,
water retention, and bonding properties
Plasticised cement sand mortar
Mortar for masonry shall conform to IS 2250

110. effect of joint thickness on
brickwork strength fig 3.2

111. Method of construction
• Stone masonry IS 1597 part 1
• Rubble stone masonry
• IS part 2 Ashlars
• Brickwork masonry IS 2212
• Hollow concrete block masonry IS 2572

112. Method of construction
contd..
• Autoclaved cellular concrete block
masonry: IS 6041
• Light weight concrete block masonry:
IS 6042
• Gypsum partition blocks: IS 2849

113. Guidelines for Approximate
Design of Non-load Bearing Wall
• Panel walls
• Curtain walls
• Partition walls

114. construction of RB and RBC floors
and roofs
IS 10440 code of practice for construction of RB and RBC
floors and roofs

115. IS 13828: Improving earthquake resistance of low
strength masonry buildings guidelines
Earthquake Resistance

116. Earthquake Resistance
IS 4326: Code of Practice for
Earthquake Resistant Design and Construction
of Structures

117. Table: 2 BUILDING CATEGORIES FOR
EARTHQUAKE RESISTING
FEATURES (Clause 7.1.1)
Building Range of αh
Categories
A 0.04 to less than 0.05
B 0.05 to 0.06 (both inclusive)
C More than 0.06 and less than 0.08
D 0.06 to less than 0.12
E Equal to or more than 0.12

118. Table 3 Recommended Mortar Mixes
(Clauses 8 1.2.1 and 8.2.6)
*Category of Proportion of Cement
Construction Lime-Sand†
A M2 (Cement-sand 1:6) or M3 (Lime-
cinder‡ 1:3) or richer
B,C M2 (Cement-lime-sand) 1:2:9 or
Cement-Sand 1:6) or richer
D,E H2 (Cement-sand 1:4) or M1 (Cement-
lime-Sand 1:1:6) or richer

119. Table 4 SIZE AND POSITION OF
OPENINGS IN BEARING
WALLS (Clause 8.3.1 and Fig.7)
Sl. Position of Pening Details of Opening for Building
Category
No.
1. Distance b5 from the inside corner of A and B C
D and E
outside wall, Min Zero mm 230 mm 450
mm
2. For total length of openings, the ratio
(b1+b2+b3)/11 or (b6+b7)/12
shall not exceed:
a) one-storeyed building 0.60 0.55
0.50
b) two-storeyed building 0.50 0.46
0.42
c) 3 or 4-storeyed building 0.42 0.37
0.33
3. Pier width between consecutive open- 340 mm 450 mm 560 mm
ning b4, Min

120. Fig.7 Dimensions of Openings and Pipes
for Recommendations in Table 4

121. Table 5 STRENTHENING
ARRANGIEMENTS
RECOMMENDED FOR MASONARY
BUILDINGS (Rectangular Masonry Units)
Building Number of Strengthening
to
Category Storeyes be
Provided in all
Storeyes
A i) 1 to 3 a
ii) 4 a, b, c
B i) 1 to 3 a,b,c,f,g
ii) 4 a,b,c,d,f,g
C i) 1 and 2 a,b,c,f,g
ii) 3 and 4 a to g
D i) 1 and 2 a to g
ii) 3 and 4 a to h
E 1 to 3* a to h

122. Table 5 (Contd…)
Where
a Masonry mortar (See 8.1.2)
b Lintel band (see 8.4.2)
c Roof band and gable band where necessary
(see 8.4.3 and 8.4.4),
d Vertical steel at corners and junctions of walls (see
8.4.8)
e Vertical steel at jambs of openings (see 8.4.9)
f Bracing in plan at tie level of roofs (see 5.4.2.2)
g Plinth band where necessary (see 8,4,6), and
h Dowel bars (see 8.4.7)

125. Table 6 Recommended Longitudinal Steel
in Reinforced Concrete Bands
(Clause 8.4.5)
Span Building Building Building
Building
Category Category Category
Category
B C D E
No. Dia No. of Dia No. of Dia No. of Dia
of Bars Bars Bars Bars
(1) (2) (3) (4) (5) (6) (7) (8) (9)
m mm mm mm mm
5 or less 2 8 2 8 2 8 2 10
6 2 8 2 8 2 10 2 12
7 2 8 2 10 2 12 4 10
8 2 10 2 12 4 10 4 12

126. Cyclone Resistance
Guidelines for
Improving Cyclone Resistance of Houses/Buildings

128. Section 5 concrete

129. IS : 456
• 1st
Revision 1953 Working Stress
Method
• 2nd
Revision 1964 Ultimate Load
Method
• 3rd
Revision 1978 Limit State Method
• 4th
Revision 2000 Durability

130. 4th
Revision
Sampling and Acceptance Criteria
Types of Cements increased.
Mineral admixtures introduced
 Fly ash
 GGBS
 CSF
 Rice Husk Ash
 Metakaoline

131. 4th
Revision
 Higher strength concrete
 Exposure condition
 Minimum requirements for durability
 Quality Assurance, Inspection
 Fire Resistance
 Cover/Nominal Cover
 Lap Length

132. TYPES OF CEMENT
 33 Grade Ordinary Portland cement
conforming to IS 269
 43 Grade ordinary Portland cement
conforming to IS 8112
 53 Grade ordinary Portland cement
conforming to IS:12269
 Rapid hardening Portland cement
conforming to IS:8041
 Portland slag cement conforming to IS:455

133. TYPES OF CEMENT
Portland pozzolana cement (fly ash based)
conforming to IS:1489 (Part 1)
Portland pozzolana cement (calcined clay
based) conforming to IS:1489 (Part 2).
Hydrophobic cement conforming to IS:8043
Low heat Portland cement conforming to
IS:12600.
Sulphate resisting Portland cement
conforming to IS:12330.

134. TABLE 1
PERMISSIBLE LIMIT FOR SOLIDS
(Clause 5.4)Tested as per Permissible Limit
Max.
Organic IS 3025 (Pt 18) 200 mg/1
Inorganic IS 3025 (Pt 18) 3 000 mg/1
Sulphates (as SO3) IS 3025 (Part 24) 400 mg/1
Chlorides (as C1) IS 3025 (Part 32) 2 000 mg/1 for concrete work
containing embedded steel and 500
mg/1 for reinforced concrete work
Suspended matter IS 3025 (Pt 17) 2 000 mg/1

135. TABLE 2 :
GRADES OF CONCRETE
(Clauses 6.1, 6.2.1, 9.2.1, 15.1.1 and 16.1
Group Grade
Designa-
tion
Specified Characteristic
Compressive Strength of
150 mm cube at 28 days
in N/mm2
1 2
M 10 10
M 15 15
Ordinary Concrete
M 20 20
M 25 25
M 30 30
Standard Concrete
M 35 35

136. GRADES OF CONCRETE
M 35 35
M 40 40
M 45 45
M 50 50
M 55 55
M 60 60
M 65 65
M 70 70
M 80 75
High Strength
Concrete
80

137. CONCRETE MIX
• Concrete of compressive strength less than M20
may be used for plain concrete constructions,
lean concrete, simple foundations, foundation for
masonry walls and other simple or temporary
construction.

138. MODULUS OF ELASTICITY
• Modulus of Elasticity of concrete
5 000 √fck

139. HOLISTIC APPROACH TO
DURABILITY
• Selection of Site
• Structural designs and detailing
• Concrete technology
• System of construction
• Drainage, cover, water proofing
• Inspection, maintenance & repair

140. FACTORS AFFECTING
DURABILITY
 the environment
 the cover to embedded steel
 the type and quality of constituent
material
 the cement content and water/cement
ratio of the concrete
 workmanship, to obtain full compaction
and efficient curing
 the shape and size of the member.

141. TABLE 3 : ENVIRONMENTAL
EXPOSURE CONDITIONS
(Clause 8.2.2.1)
Environment Exposure Conditions
Mild Concrete surfaces protected against weather or
aggressive conditions except those situated in coastal
area.
Moderate Concrete surfaces sheltered from seven rain or freezing
whilst wet
Concrete exposed to condensation and rain
Concrete continuously under water
Concrete in contact or buried under non-aggressive
soil/ground water

142. ENVIRONMENTAL EXPOSURE
CONDITIONS
Severe Concrete surfaces exposed to severe rain, alternate
wetting and drying or occasional freezing whilst wet or
severe condensation.
Concrete completely immersed in sea water
Very severe Concrete exposed to coastal environment
Concrete surfaces exposed to sea water spray, corrosive
fumes or severe freezing conditions whilst wet.
Concrete in contact with or buried under aggressive
subsoil/ground water.
Extreme Surface of members in tidal zone. Members in direct
contact with liquid/solid aggressive chemicals.

143. TABLE 5 :
MINIMUM CEMENT CONTENTS, MAXIMUM W/C RATION AND
MINIMUM GRADE OF CONCRETE FOR DIFFERENT EXPOSURE
WITH NORMAL WEIGHT AGGREGATES OF 20 MM NOMINAL
MAXIMUM SIZE.
Exposure Plain Concrete Reinforced Concrete Minimum Grade of
Concrete
Mini. Cement
content
Kg/m3
Max. Free
w/c
Mini.
Cement
content
Kg/m3
Max. Free
w/c
Plain
Concrete
Reinforced
Concrete
Mild 220 0.60 300 0.55 - M20
Moderate 250 0.60 300 0.50 M15 M25
Severe 260 0.50 350 0.45 M20 M30
Very Severe 280 0.45 375 0.45 M20 M35
Extreme 300 0.40 375 0.40 M25 M40

144. MAXIMUM CEMENT CONTENT
• Maximum Cement Content 450 Kg/m3

145. NOMINAL COVER TO MEET
DURABILITY REQUIREMENTS
Exposure Nominal Concrete Cover in mm
Not less than
Mild 20
Moderate 30
Severe 45
Very Severe 50
Extreme 75
Notes:
i. For main reinforcement up to 12 mm diameter bar for mild
exposure the nominal cover may be reduced by 5 mm
ii. Unless specified otherwise, actual concrete cover should not
deviate from the required nominal cover by +10 mm or 0mm.

146. DETAILING
• Corner of a section and the minimum cover to
either face is less than twice the diameter of
the lapped bar or where the clear distance
between adjacent laps is less than 75 mm or
6 times the diameter of lapped bar, whichever
is greater, the lap length should be increased
by a factor of 1.4.
• Where both condition (i) and (ii) apply, the lap
length should be increased by a factor of 2.0.

147. BATCHING
Ready mix concrete supplied by RMC
plant shall be preferred.
Accuracy of equipment

2% for cement

3% for aggregate, admixture, water.

148. 5b Prestressed concrete
• IS 1343: 1980 code of Practice for
Prestressed concrete (first revision)
•
• Under revision to be
incorporated when ready..

149. CONCRETE CORBELS
NEW CLAUSE
28.1 General
• A corbel is a short cantilever projection
which supports a load bearing member
and where:
a) the distance a between the line of the
reaction to the supported load and the
root of the corbel is less than d (the
effective depth of the root of the
corbel); and

150. CONCRETE CORBELS
NEW CLAUSE
b) the depth at the outer edge of the
contact area of the supported load is
not less than one-half of the depth at
the root of the corbel.
The depth of the corbel at the face of
the support is determined from shear
consideration in accordance with
40.5.2 but using the modified definition
of av given in (a).

151. WALLS
• Steel to be provided on both faces
• Min. thickness shall be 100mm
• Clause 32.2 method for vertical load only
• Clause 32.3 method for combined Vertical
& Horizontal forces.

152. 21. FIRE RESISTANCE
Durability removed ( & made into a new
Chapter.)
IS:1641 for fire resistance in hrs.
– Member size
– Detailing
– Cover
– Types of aggregate
IS:1642 for Fire Protection

153. MIN. REQUIREMENTS
• Min requirement – Fig.1 & Table of Fig.1
• Special provision when cover exceeds
40mm
• Clause 26.4.3. cover for fire resistance.
Table 16.

154. FIRE RESISTANCE
Nominal cover
Beams Floors Ribs Column
Fire
resist-
tance
hrs.
Simply
supported
Continuous Simply
supported
continuous Simply
supported
Continuous
0.5 20 20 20 20 20 20 40
1 20 20 20 20 20 20 40
1.5 20 20 25 20 35 20 40
2 40 30 35 25 45 35 40
3 60 40 45 35 55 45 40
4 70 50 55 45 65 55 40

155. FIRE RESISTANCE

156. FIRE RESISTANCE
Column dimension (b or
D)
Minimum wall thicknessFire
resista
nce
h
Min.
beam
width
b
Rib
width
bw
Min.
thickne
ss of
floors
D
Fully
expose
d
50%
expose
d
One
face
expose
d
P<0.4
%
0.4%<
p
<1%
>1%
Hrs. mm mm mm mm mm mm mm mm mm
0.5 200 125 75 150 125 100 150 100 100
1 200 125 95 200 160 120 150 120 100
1.5 200 125 110 250 200 140 175 140 100
2 200 125 125 300 200 160 - 160 100
3 240 150 150 400 300 200 - 200 150
4 280 175 170 450 350 240 - 240 180

157. Section 6 Steel
• IS 800 : 1984 Code of practice for general
construction in steel (second revision)
• IS 806: 1968 code of practice for use of
steel tubes in general building
construction (first revision)

158. • IS 800 is undergoing revision
• Introduction of limit state design
• Plastic range of material for design of
structural members
• Ultimate limit state and serviceability
limit state
• Incorporatea load factors
• Tension and compression have
different performance factors
• Critical buckling stress considering
local buckling of members classified as slender, semi-
compact, compact and Plastic.

159. • Section 7
• Prefabrication systems Buildings
• And mixed /composite
Construction
• 7A Prefabricated Concrete

160. 7A Prefabricated Concrete
• Importance aesthetics highlighted
• Clauses on materials added
• Clauses on prefabrication systems and
structural elements elaborated
• Clauses on testing of components revised
• Manufacture of cellular concrete added

161. 7A Prefabricated Concrete
• Modular coordination and modular
dimension of components revised bring
about more flexibility in planning
• Provisions for tolerance revised to include
different types of prefabricated
components
• Detailed clause on safety requirements
against progressive collapse added

162. Systems Buildings and
Mixed/composite Construction
• Prescribes general requirements
applicable to all valid existing systems and
mixed/composite constructions
• Flexibility to accommodate new systems
introduced in future is also incorporated

163. Jose Kurian
Chief Engineer, DTTDC