analysis and design of a multi-storey reinforced concrete
DESCRIPTION
Multi StoryTRANSCRIPT
1Analysis and Design of a Multi-storey Reinforced Concrete
Building
United Arab Emirates University College of Engineering
Civil and Environmental Engineering DepartmentGraduation Project II
Second Semester 2007/2008
PreparedSultan Saif Saeed Alneyadi 200203903Sultan Khamis AL-shamsi 200101595Hasher Khamis AL-azizi 200106031Rashed Hamad AL-Neyadi 200204018Abdulrahman Abdulla Jarrah 200210915
Adviser Dr. Usama Ebead
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Outline
Objectives Summary General Approach Building Types Concrete Structural Elements
Slabs Flat Slab Design of Flat Slab
Columns Rectangular Columns Design of Rectangular Columns
Shear walls Design of Shear Walls
Foundations Pile Group Design of Pile Group
Economic Impact Enviromental Impact Conclusion
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Objectives
The Objectives of the Project are:-
Carrying out a complete analysis and design of the main structural elements of a multi-storey building including slabs, columns, shear walls and foundations
Getting familiar with structural softwares ( SAFE ,AutoCAD)
Getting real life experience with engineering practices
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Summary
Our graduation project is a residential building in Abu- Dhabi. This building consists of 12 repeated floors.
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General Approach
Obtaining an architectural design of a regular residential multi-storey building.
Al-Suwaidy residential building in Abu Dhabi.
Establishing the structural system for the ground, and repeated floors of the building.
The design of column, wind resisting system, and type of foundations will be determined taking into consideration the architectural drawings.
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Types of building
Buildings are be divided into: Apartment building
Apartment buildings are multi-story buildings where three or more residences are contained within one structure.
Office building The primary purpose of an office building is to provide a workplace and
working environment for administrative workers.
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Residential buildings
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Office buildings
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Concrete Mixtures
Concrete is a durable material which is ideal for many jobs.The concrete mix should be workable.It is important that the desired qualities of the hardened concrete
are met.Economy is also an important factor.
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Structural Elements
Any reinforced concrete structure consists of : Slabs Columns Shear walls Foundations
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Flat Slab Structural System
Flat slab is a concrete slab which is reinforced in two directions
Advantages
Disadvantages
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Types of Flat slab
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Defining properties
Slab thickness = 23 cmConcrete compressive strength = 30 MPaModules of elasticity of concrete = 200 GPaYielding strength of steel = 420 MPaCombination of loads (1.4Dead Load + 1.6 Live Load)
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ACI 318-02
ACI 318-02 contains the current code requirements for concrete building design and construction.
The design load combinations are the various combinations of the prescribed load cases for which the structure needs to be checked.
1.2 DL + 1.6 LL
1515
Flat Slab Analysis and Design
Analyzing of flat slab mainly is done to find
1. Shear forces.
2. Bending moment.
3. Deflected shape.
4. Reactions at supports.
1616
Results and Discussion
Deflection
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Results and DiscussionReactions at supports must be checked by a simple method.
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Flat Slab Reinforcement
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Columns
It is a vertical structural member supporting axial compressive loads, with or with-out moments.
Support vertical loads from the floors and roof and transmit these loads to the foundation.
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Types of column
Spiral columnSpiral column Rectangular Rectangular columncolumn
• Tied ColumnsOver 95% of all columns in building in non-seismic regions are tied columns• Spiral ColumnsSpiral columns are generally circular. It makes the column more ductile.
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Steel Reinforcement in Columns
The limiting steel ratio ranges between 1 % to 8 %.
The concrete strength is between 25 MPa to 45 Mpa.
Reinforcing steel strength is between 400 MPa to 500 Mpa.
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Design procedure
1. Calculate factored axial load Pu
2. Select reinforcement ratio
3. Concrete strength = 30 MPa, steel yield strength = 420 MPa
4. Calculate gross area
5. Calculate area of column reinforcement, As, and select rebar number and size.
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Columns to be designed
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Guidelines for Column Reinforcement
Long Reinforcement Min. bar diameter Ø12 Min. concrete covers 40 mm Min. 4 bars in case of tied rectangular or circular Maximum distance between bars = 250 mm
Short Reinforcement ( Stirrups) Least of:
(16)×diameter of long bars least dimension of column (48)×diameter of ties
dc
S
Asp
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Column Design
cs AA 01.0 8- # of bars =
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Reinforcement of Columns
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Shear walls
A shear wall is a wall that resists lateral wind loads which acts parallel to the plane of the wall.
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Shear walls
Wind results in a pressure on the surface of the buildingPressure increases with height
Positive Pressure, acts towards the surface of the building Negative Pressure, acts away from the surface of the building
(suction)
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Wind pressure
q = Velocity pressure(Wind speed, height and exposure condition)G = Gust factor that depends on the building stiffnessCp = External pressure coefficient
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Gust G Factor & External pressure Cp coefficient
for Stiff Structures take G =0.85 Windward Wall, Cp = +0.8Leeward Wall, Cp = varies between -0.2 & -0.5 Depending on the L/B Ratio L/B = 18.84 m /26.18 m = 0.719 < 1 then , Cp = -0.5
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Velocity Pressure
V = 160 km/hKz = To be determined from the equationsKzt = 1 (level terrain adjacent to the building – not on hill)Kd = 0.85 (rectangular building)I = 1 (use group II)
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Important factor32
3333
Velocity Exposure Coefficient ( Kz)
3434
Design of the wind force
North south direction
3535
Shear wall axial reactions
3636
Calculating Velocity Pressure
145 km/h
0.85 11V
(km/hr)145
α 9.5Zg 274.32Kzt 1Kd 0.85I 1
G 0.85Cp
(windward)0.8
Cp (leeward) -0.5B (m) 26.18
LevelHeight
(z)
Tributary Height
(ht )Kz qz (kn/m2)
12 43 1.75 1.36 1.15022511 39.5 3.5 1.34 1.12984910 36 3.5 1.31 1.1079949 32.5 3.5 1.28 1.0843918 29 3.5 1.25 1.0586887 25.5 3.5 1.22 1.0304066 22 3.5 1.18 0.9988735 18.5 3.5 1.14 0.9630924 15 3.5 1.09 0.9214953 11.5 3.5 1.03 0.8713642 8 3.5 0.95 0.8072701 4.5 4 0.85 0.715176
3737
Design of the wind pressure
G 0.85
Cp (windward) 0.8
Cp (leeward) -0.5
B (m) 26.18
qb = qz (at the top of the building)
LevelHeight(z) m
Tributary Height(ht ) m
Kz qz (kn/m2)
Design Wind Pressure(KN/m^2) Design Wind Force (KN)
wind ward(qz G CP)
lee ward(qb G CP)
wind ward(qz G CP)(B)
(ht )
lee ward(qb G CP)(B)
(ht )
Total(floor level)
Moment(KN.m)
12 43 1.75 1.36 1.150225 0.782153 -0.488846 35.834345 -22.396465 58.230810 2503.924826
11 39.5 3.5 1.34 1.129849 0.768297 -0.488846 70.399094 -44.792931 115.192025 4550.084972
10 36 3.5 1.31 1.107994 0.753436 -0.488846 69.037332 -44.792931 113.830262 4097.889443
9 32.5 3.5 1.28 1.084391 0.737386 -0.488846 67.566683 -44.792931 112.359614 3651.687445
8 29 3.5 1.25 1.058688 0.719908 -0.488846 65.965161 -44.792931 110.758092 3211.984664
7 25.5 3.5 1.22 1.030406 0.700676 -0.488846 64.202965 -44.792931 108.995896 2779.395349
6 22 3.5 1.18 0.998873 0.679233 -0.488846 62.238149 -44.792931 107.031079 2354.683748
5 18.5 3.5 1.14 0.963092 0.654903 -0.488846 60.008720 -44.792931 104.801650 1938.830531
4 15 3.5 1.09 0.921495 0.626617 -0.488846 57.416871 -44.792931 102.209802 1533.147032
3 11.5 3.5 1.03 0.871364 0.592527 -0.488846 54.293292 -44.792931 99.086222 1139.491559
2 8 3.5 0.95 0.807270 0.548944 -0.488846 50.299721 -44.792931 95.092651 760.7412106
1 4.5 4 0.85 0.715176 0.486320 -0.488846 50.927427 -51.191921 102.119348 459.5370657
sum 1229.707452 28981.39785
3838
Computing total moment acting toward N-S Direction
M = total floor level *height (z)
3939
W-E Direction Computation
L= 26.18
B=
18.
84
LevelHeight(z) m
Tributary Height(ht ) m
Kz qz (kn/m2)
Design Wind Pressure(KN/m^2) Design Wind Force (KN)
wind ward(qz G CP)
lee ward(qb G CP)
wind ward(qz G CP)(B)(ht )
lee ward(qb G CP)(B)(ht )
Total(floor level)
Moment(KN.m)
12 43 1.75 1.36 1.150225 0.7821531 -0.48885 25.7875879 -16.1172424 41.9048304 1801.907705
11 39.5 3.5 1.34 1.129849 0.7682974 -0.48885 50.6615328 -32.2344849 82.8960177 3274.392699
10 36 3.5 1.31 1.107994 0.7534359 -0.48885 49.6815633 -32.2344849 81.9160482 2948.977735
9 32.5 3.5 1.28 1.084391 0.7373860 -0.48885 48.6232356 -32.2344849 80.8577205 2627.875916
8 29 3.5 1.25 1.058688 0.7199079 -0.48885 47.4707271 -32.2344849 79.7052120 2311.451149
7 25.5 3.5 1.22 1.030406 0.7006763 -0.48885 46.2025923 -32.2344849 78.4370772 2000.145469
6 22 3.5 1.18 0.998873 0.6792333 -0.48885 44.7886449 -32.2344849 77.0231298 1694.508855
5 18.5 3.5 1.14 0.963092 0.6549025 -0.48885 43.1842734 -32.2344849 75.4187583 1395.247028
4 15 3.5 1.09 0.921495 0.6266165 -0.48885 41.3190931 -32.2344849 73.5535780 1103.30367
3 11.5 3.5 1.03 0.871364 0.5925275 -0.48885 39.0712612 -32.2344849 71.3057461 820.0160796
2 8 3.5 0.95 0.807270 0.5489438 -0.48885 36.1973543 -32.2344849 68.4318392 547.4547138
1 4.5 4 0.85 0.715176 0.4863200 -0.48885 36.6490728 -36.8394113 73.4884841 330.6981787
sum 884.9384415 20855.9791983
4040
Design of Shear Wall
East west direction
North south direction
4141
Interaction Diagram
4242
Shear Wall Reinforcement
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Foundations
Foundations are structural components used to support columns and transfer loads to the underlying Soil.
Foundations
Isolated Combined Strap wall Raft
Shallow
footing footing footing footing footing
Caissons Piles
Deep
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Pile foundation
Our building is rested on a weak soil formation which can’t resist the loads coming from our proposed building, so we have to choose pile foundation.
Pile cap
PilesWeak soil
Bearing stratum
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Pile foundation
Piles are structural members that are made of steel, concrete or timber.
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Function of piles
As with other types of foundation, the purpose of a pile foundation is: To transmit a foundation load to a solid ground To resist vertical, lateral and uplift load
Piles can be Timber Concrete Steel Composite
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Concrete piles
General facts Usual length: 10m-20m Usual load: 300kN-3000kN
Advantages Corrosion resistance Can be easily combined with a concrete superstructure
Disadvantages Difficult to achieve proper cutoff Difficult to transport
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Pile foundation
Piles can be divided in to two major categories:1. End Bearing Piles
If the soil-boring records presence
of bedrock at the site within a reasonable depth,
piles can be extended to the
rock surface
2. Friction Piles
When no layer of rock is present depth at a site, point bearing piles become very long and uneconomical. In this type of subsoil, piles are driven through the softer material to specified depths.
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Pile Cap Reinforcement
Pile caps carrying very heavy point loads tend to produce high tensile stresses at the pile cap.
Reinforcement is thus designed to provide: Resistance to tensile bending forces in the bottom of the cap Resistance to vertical shear
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Design of the pile cap
bearing capacity of one pile:
Rs = α Cu As .L⋅ ⋅ Length of pile penetration L = 18
meters Adhesion factor of soil (clay) α = 0.8 Untrained shear strength Cu = 50 Diameter = 0.9 m For piles with diameter 0.9 m
Rs = 2035.75 KN
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First type
This section shows how pile caps are designed to carry only vertical load, and the equation used to determine the resistance of cap is
Where P is the strength of the pile cap per one pile
Q is the total force acting on the pile capn is the number of piles used to support the pile cap
n
QP i
i
52
Columns layout & Reactions ( Vertical Load )
Column Reaction Total Reaction
kN kN
1 129.63 1555.56
2 246.85 2962.2
8 382.66 4591.92
10 393.38 4720.56
21 458.35 5500.2
23 400.85 4810.2
24 627.74 7532.88
25 384.14 4609.68
30 158.3 1899.6
32 355.26 4263.12
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Design of pile cap (Vertical Load only)
Pile Cap 2 Reaction = 4610.4 kN Pile diameter = 0.9 m Capacity for one pile = 0.8 * 50 * 18 * π * 0.9 = 2035.75 KN Need 3 piles Length between piles = (2*0.3) + (3*0.9) + (2*0.9)*2 =6.9 m Width = 1.5 meters Actual forces on each pile = = 1536.8 kN
niQ
iP
54
Second type
Second typeThis section shows how pile caps are designed to carry
vertical load and lateral loads ( Bending Moment), and the equation used to determine the resistance of cap is
2r
rM
n
QP ii
i
55
Shear walls layout & reactions
wall M (KN.m) N (KN)
W1 14072.12 12285.6
W2 366.048 3596.76
W3 366.048 3026.88
W4 5719.5 3605.04
W5 30.65295 4128
W6 301.6143 1899.6
W10 10141.2 32.80882
W11 2402.52 32.80882
W13 20978.4 6700.246
W14 3297.6 6700.246
W15 2040 262.4706
W16 5470.2 262.4706
W17 7262.76 7903.641
W18 8571.48 7086.706
56
Design of pile cap (Vertical Load & moment)
Shear wall # (1): M = 14072.11561 Q = 12285.6 Assume 8 piles
KNPSoP
KNPSoP
r
rM
n
QP
PileofCapacity
PileofCapacity
75.2035,676.24
)26.4(*11561.14072
8
6.12285
75.2035,676.24
)909.1(*11561.14072
8
6.12285
2
2
2
57
Economical impact
Reinforced concrete is proven to be a very economical solution in the UAE.
the most affordable solution for multistory building such as the one we are making the analysis and design for.
58
Environmental impact
Although the cement production is environmentally challenging, the final product of a reinforced concrete building is environmentally friendly.
59
Gantt Chart
60
Conclusion
We have applied our gained knowledge during our graduation project
We are able to use structural software ( SAFE )We have practiced real life engineering practicesThis GP enables us to go into the market with an excellent
background regarding design of RCAt this point, we would like to thank all instructors, engineers,
and Al Ain Consultant Office for their grateful effort.
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