Reinforced Concrete.ppt
- 1. 1 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
- 2. 2 Summary Our graduation project is a residential building in Abu- Dhabi. This building consists of 12 repeated floors.
- 3. 3 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.
- 4. 4 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.
- 7. 7 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.
- 8. 8 Structural Elements Any reinforced concrete structure consists of : Slabs Columns Shear walls Foundations
- 9. 9 Flat Slab Structural System Flat slab is a concrete slab which is reinforced in two directions Advantages Disadvantages
- 10. 10 Types of Flat slab
- 11. 11 Defining properties Slab thickness = 23 cm Concrete compressive strength = 30 MPa Modules of elasticity of concrete = 200 GPa Yielding strength of steel = 420 MPa Combination of loads (1.4Dead Load + 1.6 Live Load)
- 12. 12 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
- 13. 13 13 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.
- 14. 14 14 Results and Discussion Deflection
- 15. 15 Results and Discussion Reactions at supports must be checked by a simple method.
- 16. 16 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.
- 17. 17 Types of column Spiral column Rectangular column • Tied Columns Over 95% of all columns in building in non-seismic regions are tied columns • Spiral Columns Spiral columns are generally circular. It makes the column more ductile.
- 18. 18 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.
- 19. 19 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.
- 20. 20 Columns to be designed
- 21. 21 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
- 22. 22 Column Design c s A A 01 . 0 8- # of bars =
- 24. 24 Shear walls A shear wall is a wall that resists lateral wind loads which acts parallel to the plane of the wall.
- 25. 25 Shear walls Wind results in a pressure on the surface of the building Pressure increases with height Positive Pressure, acts towards the surface of the building Negative Pressure, acts away from the surface of the building (suction)
- 26. 26 Wind pressure q = Velocity pressure (Wind speed, height and exposure condition) G = Gust factor that depends on the building stiffness Cp = External pressure coefficient
- 27. 27 Gust G Factor & External pressure Cp coefficient for Stiff Structures take G =0.85 Windward Wall, Cp = +0.8 Leeward 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
- 28. 28 Velocity Pressure V = 160 km/h Kz = To be determined from the equations Kzt = 1 (level terrain adjacent to the building – not on hill) Kd = 0.85 (rectangular building) I = 1 (use group II)
- 30. 30 30 Velocity Exposure Coefficient ( Kz)
- 31. 31 31 Design of the wind force North south direction
- 32. 32 32 Shear wall axial reactions
- 33. 33 33 Calculating Velocity Pressure 145 km/h 0.85 1 1 V (km/hr) 145 α 9.5 Zg 274.32 Kzt 1 Kd 0.85 I 1 G 0.85 Cp (windward) 0.8 Cp (leeward) -0.5 B (m) 26.18 Level Height (z) Tributary Height (ht ) Kz qz (kn/m2) 12 43 1.75 1.36 1.150225 11 39.5 3.5 1.34 1.129849 10 36 3.5 1.31 1.107994 9 32.5 3.5 1.28 1.084391 8 29 3.5 1.25 1.058688 7 25.5 3.5 1.22 1.030406 6 22 3.5 1.18 0.998873 5 18.5 3.5 1.14 0.963092 4 15 3.5 1.09 0.921495 3 11.5 3.5 1.03 0.871364 2 8 3.5 0.95 0.807270 1 4.5 4 0.85 0.715176
- 34. 34 34 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) Level Height (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
- 35. 35 35 Computing total moment acting toward N-S Direction M = total floor level *height (z)
- 36. 36 36 W-E Direction Computation L= 26.18 B= 18.84 Level Height (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
- 37. 37 37 Design of Shear Wall East west direction North south direction
- 40. 40 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
- 41. 41 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 Piles Weak soil Bearing stratum
- 42. 42 Pile foundation Piles are structural members that are made of steel, concrete or timber.
- 43. 43 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
- 44. 44 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
- 45. 45 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.
- 46. 46 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
- 47. 47 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
- 48. 48 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 cap n is the number of piles used to support the pile cap n Q P i i
- 49. 49 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 n i Q i P
- 50. 50 Second type Second type This 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 2 r r M n Q P i i i
- 51. 51 Design of pile cap (Vertical Load & moment) Shear wall # (1): M = 14072.11561 Q = 12285.6 Assume 8 piles KN P So P KN P So P r r M n Q P Pile of Capacity Pile of Capacity 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
- 52. 52 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.
- 53. 53 Environmental impact Although the cement production is environmentally challenging, the final product of a reinforced concrete building is environmentally friendly.
- 54. 54 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 practices This GP enables us to go into the market with an excellent background regarding design of RC At this point, we would like to thank all instructors, engineers, and Al Ain Consultant Office for their grateful effort.