The document discusses seismic detailing requirements for earthquake-resistant construction in Bangladesh. It provides guidelines on structural systems, geometry requirements, reinforcement details, and transverse reinforcement for beams, columns, and beam-column joints. Specific deficiencies to avoid are also highlighted, such as poor anchorage, splices in critical regions, and inadequate shear reinforcement. The document emphasizes the importance of confinement through hoops and ties to prevent structural failure under seismic loads.

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Let’s adopt the Update Service

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The Pain ofThe Pain of
ChangeChange

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• The Composite Cement
• The High Strength Re-inforcement STEEL
• Use of CPVC Pipe & fittings for Plumbing
• Use of Admixture for Damp & Repair
• Painting
• Utility Equipments
• Outsource
Topic to be PresentedTopic to be Presented

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Severe Weather ConditionSevere Weather Condition

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Present Day LossPresent Day Loss

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Bhuj DisasterBhuj Disaster

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Bangladesh is among the most densely populated country inBangladesh is among the most densely populated country in
the world. Much of in active seismic zones making thethe world. Much of in active seismic zones making the
occurrence of deadly earth quakes a frighten scenario.occurrence of deadly earth quakes a frighten scenario.
Many of the earthquakes have occurred in the north-easternMany of the earthquakes have occurred in the north-eastern
part of the country and south-eastern area. The Madhupurpart of the country and south-eastern area. The Madhupur
Fault runs in Dhaka division. The border with the IndianFault runs in Dhaka division. The border with the Indian
state of Meghalaya is also a fault. Dhaka Division have bothstate of Meghalaya is also a fault. Dhaka Division have both
suffered severe earth quakes in the past. Tsunamis havesuffered severe earth quakes in the past. Tsunamis have
also effected many tiny nationsalso effected many tiny nations..

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Largest InstrumentedLargest Instrumented
Earthquakes inEarthquakes in
BangladeshBangladesh

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Largest Instrumented Earthquake in BangladeshLargest Instrumented Earthquake in Bangladesh
8 July 1918 – Near Kishorgaj (Dhaka Div.),8 July 1918 – Near Kishorgaj (Dhaka Div.),
Bangladesh, Mw 7.4Bangladesh, Mw 7.4
10:22:07 UTC, 24.50 N, 91.00 E10:22:07 UTC, 24.50 N, 91.00 E
Often referred to as the Srimangal earthquake, thisOften referred to as the Srimangal earthquake, this
massive quake was centered of Mymensingh, in themassive quake was centered of Mymensingh, in the
northern part of Dhaka Division near Kishorganj,northern part of Dhaka Division near Kishorganj,
Bangladesh has suffered some major EarthquakeBangladesh has suffered some major Earthquake
preceded by a series of light to moderatepreceded by a series of light to moderate
foreshocks.foreshocks.

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• 2 April 1762 – Near Chamble, (Sorthern Chittagong Division)
• 30 June 1868 – Near Sylhet, (Northern Chittagong Division)
• 14 July - 1885 – Near Dhaka, (Dhaka Division)
• 8 July - 1885 – Near Kishorganj, (Dhaka Division)
• 9 September 1923 – West of Durgapur, (Dhaka Division)
• 24 December 1944 – Near Sylhet, (Northern Chittagong Division)
• 19 May 1945 – Near Mohangonj, (Dhaka-Chittagong Division)
• 10 December 1949 – North of Saidpur, (Rajshahi Division)
• 24 December 1950 – Near Baniyachung, (Northern Chittagong Division)
• 12 June 1956 – Near Netrakona, (Northern Dhaka Division)
Continue………
Large Earthquakes in Bangladesh

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• 21 June 1963 – Near Netrakona, (Northern Dhaka Division)
• 12 May 1977 – Bangladesh-Myanmar border region
• 6 February 1988 – Near Sylhet, (Northern Chittagong Division)
• 12 June 1989 – Bay of Bengal, Off Khulna Division
• 8 May 1997 – Indo-Bangladesh border region
• 21 November 1997 – Southern Mizoram
• 22 July 1999 – Moheskhali Island, (Chittagong Division)
• 31 December 1999 – Off Kutubdia Island, (Chittagong Division)
• 19 December 2001 – Dhaka Area, (Dhaka Division)
• 26 July 2003 – Harina Bazar-Daluchari area, (Chittagong Division)

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Seismic DetailingSeismic Detailing
RequirementsRequirements

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Full Collapse of StructureFull Collapse of Structure

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The key objective of earthquake-resistant design is to make aThe key objective of earthquake-resistant design is to make a
structure with adequate strength and ductile to assure lifestructure with adequate strength and ductile to assure life
safety, specifically, to avoid collapse under the most intensesafety, specifically, to avoid collapse under the most intense
probable earthquake at a site during the whole life of structure.probable earthquake at a site during the whole life of structure.
Economy is one of the key objectives by allowing yielding inEconomy is one of the key objectives by allowing yielding in
some structural members subjected to moderate-to-strongsome structural members subjected to moderate-to-strong
earthquakes.earthquakes.
Traditionally, seismic risk levels have been classified as low,Traditionally, seismic risk levels have been classified as low,
moderate, and high. Similarly Bangladesh National Buildingmoderate, and high. Similarly Bangladesh National Building
code classifies three seismic zones; these are Zone 1, Zone 2code classifies three seismic zones; these are Zone 1, Zone 2
and Zone 3 with being the most severe.and Zone 3 with being the most severe.
Continue………..Continue………..
A. Introduction

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There are five basic structural systemsThere are five basic structural systems
for reinforced concrete buildings are :for reinforced concrete buildings are :
• Bearing wall system
• Building frame system
• Moment resisting frame system
• Dual system and
• Special structural systems.

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Load Bearing Brick StructureLoad Bearing Brick Structure

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Extreme Rescue DifficultyExtreme Rescue Difficulty

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Concerned moment resisting frameConcerned moment resisting frame
system is three typessystem is three types
which are as follows :which are as follows :
• Special Moment Resisting Frames (SMRF)
• Intermediate Moment Resisting Frame (IMRF)
• Ordinary Moment Resisting Frame (OMRF)
Continue……….

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For continued existence of buildings fromFor continued existence of buildings from
earthquake some configuration scarcityearthquake some configuration scarcity (Fig. I)(Fig. I) wewe
may avoid.may avoid.
These are:These are:
 Partial load paths
 Vertical and horizontal irregularities
 Weak column-strong beam
 soft story at any level

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Geometric ScarcityGeometric Scarcity

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Failure of Soft StoreyFailure of Soft Storey

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Also detailing be free from deficiencyAlso detailing be free from deficiency
Poor anchorage and splices of longitudinal rebar
in beams and columns
Inappropriate locations of splices of longitudinal
rebar
Inadequate shear reinforcement in beams and
columns
Inadequate reinforcement (ties) in beam-column
joint regions

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Result of DeficiencyResult of Deficiency

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B. General Requirements of Concrete and ReinforcementB. General Requirements of Concrete and Reinforcement
in Earthquake – Resisting Constructionin Earthquake – Resisting Construction
1. Compressive strength fc' of the concrete shall be
not less than 20 MPa.
2. Compressive strength of light weight aggregate
used in design shall not exceed 30 MPa.
3. Rebar shall confirm with ASTM A706, ASTM A6 1
5 and BDS 1 3 .3
4. No welded splices in the critical regions (twice
memberdepth from column or beam face) (Fig. 3
& Fig.7)
Continue ………….

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Beam Splice DetailBeam Splice Detail

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• Column Tie Detail

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Joint FailureJoint Failure

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5. Welded splices and mechanical connection shall not
more than alternate bars in each layer of longitudinal
bar are spliced at a section and the center to center
distance between splices of adjacent bars is 600 mm
or more measured along the longitudinal axis of the
member (Fig. 7).
6. Welding of stirrups, ties or other similar elements to
longitudinal reinforcement required by design shall not
be permitted

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Column FailureColumn Failure

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C. Flexural Members of Frames (Beam)C. Flexural Members of Frames (Beam)
in Earthquake-resisting Constructionin Earthquake-resisting Construction

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Geometry General RequirementsGeometry General Requirements
1. Members shall be flexure dominated component i.e. lower axial load
2. Factored axial Compressive force on the member shall not exceed
Ag fc'/10
3. Clear span for the member shall not be less than four times is
effective depth i.e. if span is less, ln ≥ 4d (Fig. 9)
4. The width-to-depth ratio (b/d) shall not be less than 0.3 (Fig. 12)
5. The width of beam shall not be less than 250 mm (Fig. 13)
6 The width shall not be more than the width of the supporting
member (measured on a plane perpendicular to the longitudinal
axis of the flexural member) plus distances on each of the
supporting member not exceeding three-fourths of the depth of the
flexural member, i.e. b < bcol + 2(3/4 db)
Contd………..

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Beam Depth SpanBeam Depth Span

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Max Width/DepthMax Width/Depth

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Min Beam DimensionMin Beam Dimension

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7. Lap splices of flexural reinforcement shall be permitted only if hoop or
spiral reinforcement is provided over the lap length.
8. Welded splices and mechanical connections conforming to sec
8.2.12.3(a) through 8.2.I2.3(d) of BNBC/93 are allowed for splicing
provided not more than alternate bars in each layer of longitudinal
reinforcement are spliced at a section and the center to center distance
between splices of adjacent bard is 600 mm or more measured along the
longitudinal axis of the frame member.
9. Maximum spacing of the transverse reinforcement enclosing the lapped
bars shall not exceed d/4 or 100mm. (Fig. 2)
10. Lap splices shall not be used (Fig. 3}
• Within the joints
• Within a distance of twice the member depth from the face of the joint
• At locations where analysis indicates flexural yielding caused by
inelastic lateral displacements of the frame.
Main/Longitudinal Reinforcement RequirementMain/Longitudinal Reinforcement Requirement

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Beam Hoop DetailBeam Hoop Detail

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Beam Splice AreaBeam Splice Area

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11. At least two longitudinal bars shall be provided
continuously both top and bottom. (Fig. 2)
12. Lap splices only permitted outside yielding regions and
beam- column joints, i.e. Splices shall be in the middle
third must be enclosed by hoop or spiral reinforcement
(Fig. 2)
13. Mechanical splices or welded splices are preferred.

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Displacement FailureDisplacement Failure

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TRANAVERSE REINFORCEMENT GUIDELINETRANAVERSE REINFORCEMENT GUIDELINE
14. Hoops shall be provided in the following regions (Fig. 2)
* At both ends of the flexural member, over a length equal to twice
the member depth measured from the face of the supporting
member toward mid-span at both ends
* Locate the first hoop not more than 2 in. from the face of support
* The hoop spacing, Sh shall also fulfill the following
Sh ≤ d/4
≤ 8-times the diameter of the smallest longitudinal bars
≤ 24-times the diameter of hoop bars and
≤ 300 mm
15. Elsewhere through the span hoop spacing shall not more than d/2
(Fig.2)

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D.D. Frame Members Subjected to Bending and AxialFrame Members Subjected to Bending and Axial
Load (Column) in Earthquake-resistingLoad (Column) in Earthquake-resisting
ConstructionConstruction

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Geometry/General RequirementsGeometry/General Requirements
I. Factored axial compressive force on the member shall
not less than Pu ≥ Ag fc’/ 10
2. The shortest cross-sectional dimension bmin ≥ 300 mm
(Fig. 16)
3. The ratio of shortest cros-sectional dimension to the
perpendicular dimension to the perpendicular dimension
bmin / bmax ≥ 0.4 (Fig. 15)

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Max Column RatioMax Column Ratio

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Min Column DimensionMin Column Dimension

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Main/Longitudinal Reinforcement NecessitiesMain/Longitudinal Reinforcement Necessities
4. The reinforcement ratio pg shall not be less than 0.01
and shall not exceed 0.06
5. Lap splices are permitted only within the center half of
the member length and shall be designed as tension
splices. (Fig. 7)
6. Welded splices and mechanical connections (conforming
to sec 8.2.12.3[a] through 8.2.12.3[d] of BNBC/93) are
allowed for splicing the reinforcement at any section
provided not more than alternate longitudinal bars are
spliced at a section and the center to center distance
between splices of adjacent bard is 600 mm or more
along the longitudinal axis of the reinforcement. (Fig. 7)

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Tranaverse Reinforcement GuidelineTranaverse Reinforcement Guideline
7. Transverse reinforcement shall be provided as specified below
(Unless a larger amount is required by see 8.3.8 of BNB/93)
* The Volumetric ratio of circular hoop reinforcement, ρs shall
not be less than that
and shall not be less that that required by Eq. (6.3.3)
* The total cross-sectional area of rectangular hoop reinforcement
shall not be less than given by the following equations-
Ash = 0.3 (Shcfc’ / fyh) [Ag/Ach)-1] ……………. (8.3.3)
Ash = 0.09 Shcfc’ / fyh ………………………….(8.3.4)
yhf
fc'.
Ps
120
=

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Importance of TieImportance of Tie

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TieTie

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* Transverse reinforcement shall be provided by either
single or overlapping hoops. Crossties of the same bar
size and spacing as the hoops shall be permitted to be
used, each end of crosstie shall engage a peripheral
longitudinal reinforcing bar. Consecutive crossties shall
be alternated end for end along the longitudinal
reinforcement.
* If the design strength of member core satisfies the
requirement of the specified loading combinations
including earthquake effect, Eq. (8.3.3) and (6.3.3) of
BNBC/93 need not be satisfied

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8 Transverse reinforcement spacing are as follows within 10
(Fig.8)
s ≤ 0.25 hmin
≤ 100 mm
9 Crossties or legs of overlapping hoops shall not be spaced more
than 350 mm on center in the direction perpendicular to the
longitudinal axis of the structure. [Fig. 11(a)]
10 Special transverse reinforcement required along length l0 (Fig.
8G:Presentatio on earth quackimagefig.8.gif) from each joint face
where
l0 > hmaxthe depth of the member at the joint face
> ln/6 the clear span of the member
> 500 mm

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Tie Detail in ColumnTie Detail in Column

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11 If the lower end of the column terminates on a wall,
transverse reinforcement as specified in D.7 to D.9 shall
extended into the wall for at least the development length of
the largest longitudinal reinforcement in the column at the
point of termination. (Table 1 to Table 6)
12 If the column terminates on a footing or mat, transverse
reinforcement as specified in D.7 to D.9 shall extend at least
300 mm, into the footing or mat. (Fig. 10)
13 Where transverse reinforcement, as specified in D.7 to D.9,
is not provided throughout the full length of the column, the
remainder of the column length shall contain spiral or hoop
reinforcement with the following spacing (Fig. 8)
S ≤ 6db
≤ 150 mm

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E. Joints Of Frame Structures

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Failure due to jointFailure due to joint

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1. Beam longitudinal reinforcement terminated in a column shall be
terminated in a column shall be extended to the far face of the
confined column core and anchored in tension according to S.3..7.4
of BNBC/93 (tension development length) and in compression
according to chapter-6 of BNBC/93 (compression development
length)
2. Where longitudinal beam reinforcement extends through a beam-
column joint, the column dimensions parallel to the beam
reinforcement shall not be less than 20 times (Fig. 5) the diameter of
the largest longitudinal bar for normal weight concrete. For lightweight
concrete, the dimension shall be not less than 26 times the bar
diameter.

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3. The nominal shear strength of the joint shall not be taken
greater than the forces specified below for normal weight
aggregate concrete.
For joints confined on all four faces …
For joints confined on all three faces
or two opposite faces……………………
For others ………………………………..
jAfc'7.1
jAfc'25.1
jAfc'0.1

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F. Development and splices of
Reinforcement

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1. The development length Idh for a bar (sizes No. 10 through
No. 36) with a standard 90-deg hook in normal weight
aggregate concrete shall not be less than 8db, 150mm and
length required by the following equation
Calculated values are in Table–1 (based on 21 Mpa
concrete and 414 Mpa steel)
2. For lightweight aggregate concrete the development length
for a bar with a standard 90-deg hook shall not be less than
10, 190mm and 1 .25 times that required by (Eq. 8.3.5 of
BNBC/93) Calculated values are in Table - 2 (based on 21
Mpa concrete and 414 Mpa steel)
)5.3.8(..........).........'4.5/( fcdfl bydh =

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3. For bar sizes No. 10 through No. 36 (normal weight aggregate
concrete), the development length Id for a straight bar shall not
be less than
3.1 Two and a half (2.5) times the length required by (Eq. 8.3.5 of
BNBC/93) if the depth of the concrete cast in one lift beneath
the bar does not exceed 300 mm. Calculated values are in
Table 3 (based on 21 Mpa concrete and 414 Mpa steel)
3.2 Three and a half (3.5) times the length required by (Eq. 8.3.5 of
BNBC/93) if the depth of the concrete cast in one lift beneath
the bar exceeds 300 mm. Calculated values are in Table – 4
(based on 21 Mpa concrete and 414 Mpa steel)
4 Straight bars terminated at a joint shall pass through the
confined core of a column or of a boundary element. Any
portion of the straight embedment length not within the
confined core shall be increased by a factor of 1.6. Table - 5 &
Table - 6 (based on 21 Mpa concrete and 414 Mpa steel)

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Table:3Table:3
Table-3
Development Length I d for Straight bar concrete cast in one lift
beneath the bar does not exeed 300 mm
BAR DIA Idh
8 335
10 418
12 502
16 669
20 837
22 920
25 1046
28 1171
32 1338
* All Calculations are based on 21 Mpa concrete and 414 Mpa reinforcement

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Table: 4Table: 4
Table-4
Development Length I d for Straight bar concrete cast in one lift
beneath the bar exceed 300 mm
BAR DIA Idh
8 468
10 586
12 703
16 937
20 1171
22 1288
25 1464
28 1640
32 1874
* All Calculations are based on 21 Mpa concrete and 414 Mpa reinforcement

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Table:5Table:5
Table-5
Development Length I d for Straight embedment length
not w ithin the confined core
(Concrete w eight concrete)
BAR DIA Idh
8 535
10 669
12 803
16 1071
20 1338
22 1472
25 1673
28 1874
32 2141
* All Calculations are based on 21 Mpa concrete and 414 Mpa reinforcement

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Table:6Table:6
Table-6
Development Length I d for Straight embedment length
not w ithin the confined core
(Light w eight concrete)
BAR DIA Idh
8 750
10 937
12 1124
16 1499
20 1874
22 2061
25 2342
28 2623
32 2998
* All Calculations are based on 21 Mpa concrete and 414 Mpa reinforcement

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Post Disaster is SeverePost Disaster is Severe

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Loss of Life & PropertyLoss of Life & Property

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Long Term Loss of NationLong Term Loss of Nation

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Rescue LogisticRescue Logistic

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Rescue ManagementRescue Management

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No Definte RescueNo Definte Rescue

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Future is uncertainFuture is uncertain

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Thank You