05/09/22 05/09/22 Let’s adopt the Update Service
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Let’s adopt the Update Service
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The Pain of The 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 Bangladesh is among the most densely populated country in the world. Much of in active seismic zones country in the world. Much of in active seismic zones making the occurrence of deadly earth quakes a making the occurrence of deadly earth quakes a frighten scenario. Many of the earthquakes have frighten scenario. Many of the earthquakes have occurred in the north-eastern part of the country and occurred in the north-eastern part of the country and south-eastern area. The Madhupur Fault runs in south-eastern area. The Madhupur Fault runs in Dhaka division. The border with the Indian state of Dhaka division. The border with the Indian state of Meghalaya is also a fault. Dhaka Division have both Meghalaya is also a fault. Dhaka Division have both suffered severe earth quakes in the past. Tsunamis suffered severe earth quakes in the past. Tsunamis have also effected many tiny nationshave also effected many tiny nations..
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Largest InstrumentedLargest Instrumented
Earthquakes in Earthquakes in
BangladeshBangladesh
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Largest Instrumented Earthquake in BangladeshLargest Instrumented Earthquake in Bangladesh8 July 1918 – Near Kishorgaj (Dhaka Div.), 8 July 1918 – Near Kishorgaj (Dhaka Div.), Bangladesh, Mw 7.4Bangladesh, Mw 7.410:22:07 UTC, 24.50 N, 91.00 E10:22:07 UTC, 24.50 N, 91.00 E
Often referred to as the Srimangal earthquake, this Often referred to as the Srimangal earthquake, this massive quake was centered of Mymensingh, in the massive 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 Earthquake Bangladesh has suffered some major Earthquake preceded by a series of light to moderate preceded 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 Detailing Seismic 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 The key objective of earthquake-resistant design is to
make a structure with adequate strength and ductile to make a structure with adequate strength and ductile to
assure life safety, specifically, to avoid collapse under assure life safety, specifically, to avoid collapse under
the most intense probable earthquake at a site during the most intense probable earthquake at a site during
the whole life of structure. Economy is one of the key the whole life of structure. Economy is one of the key
objectives by allowing yielding in some structural objectives by allowing yielding in some structural
members subjected to moderate-to-strong members subjected to moderate-to-strong
earthquakes.earthquakes.
Traditionally, seismic risk levels have been classified as Traditionally, seismic risk levels have been classified as
low, moderate, and high. Similarly Bangladesh National low, moderate, and high. Similarly Bangladesh National
Building code classifies three seismic zones; these are Building code classifies three seismic zones; these are
Zone 1, Zone 2 and Zone 3 with being the most severe.Zone 1, Zone 2 and Zone 3 with being the most severe.Continue………..Continue………..
A. Introduction
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There are five basic structural There are five basic structural systems for reinforced concrete systems for reinforced concrete
buildings are :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 Concerned moment resisting frame system is three types frame system 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 from For continued existence of buildings from earthquake some configuration scarcity earthquake some configuration scarcity (Fig. I) we may avoid. we 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 Also detailing be free from
deficiencydeficiency 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 B. General Requirements of Concrete and Reinforcement in Earthquake – Resisting Reinforcement in Earthquake – Resisting ConstructionConstruction
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 member\depth 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 C. Flexural Members of Frames (Beam) (Beam)
in Earthquake-resisting in Earthquake-resisting ConstructionConstruction
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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 Frame Members Subjected to Bending and Axial Axial
Load (Column) in Earthquake-resisting Load (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 quack\image\fig.8.gif) from each joint face where
l0 > hmax the 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:3Table-3
Development Length Id 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: 4Table-4
Development Length Id 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:5Table-5
Development Length Id for Straight embedment length not within the confined core
(Concrete weight 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:6Table-6
Development Length Id for Straight embedment length not within the confined core
(Light weight 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