1. CE 4251: Structure for Architecture

2. Course Content Fundamentals of Reinforced Concrete design. Design and analysis of reinforced beams I.Working Stress Design (WSD) Method II.Ultimate Strength Design (USD) Method Shear design of beams. Design of One way. Design of Two way. Analysis and design of RC column. Design and analysis of multistoried buildings for Gravity and Lateral loads. Analysis and design of pre-stressed concrete. Analysis and preliminary design of Folded plate, Arches, Domes, Shells.

3. Books Recommended: Nilson, Darwin & Dolan: Design of Concrete Structures (Thirteen edition) Nadim and Manaseer: Structural Concrete, Theory and Design T. Y. Lin and Ned H. Burns: Design of Prestressed Concrete Structures Levy & Salvadori: Structural Design in Architecture

4. Fig.: Behavior of concrete beam after loading Basics of RCC design Outward tension force at the bottom part Inward compression force at the top part Neutral Axis; where there is no tension or compression and passes through the center of the cross section of the beam Before Loading After Loading and consequent bending A A

5. Compression Neutral Axis A A Section: A-A Tension Zone Compression Zone N.A. Before Loading After Loading Stress Diagram Tension Compression Tension N.A. (No Tension or Compression) Basics of RCC design

6. Reaction of concrete with compression and tension? Very Strong in CompressionWeak in tension Compressive strength of concrete at 28 days is typically found from 3000 psi to 7000 psi. Tensile strength of concrete is typically found from 300 psi to 700 psi, almost 10% of compressive strength. We need a material in the concrete which is very good in Tension!!!

7. Available material that will take tension in concrete Mild Steel Rebar: Material with high tensile strength Yield tensile strength (fy) of Mild steel rebar is typically found from 40,000 psi to 75,000 psi. Therefore, we use steel reinforcement at the tension zone of the concrete and thus it is called Reinforced Concrete (RC) or Reinforced Cement Concrete (RCC).

8. Reinforced Cement Concrete (RCC) Concretesteel rebar  Concrete with the reinforcement of steel rebar is usually called as Reinforced Concrete (RC) or Reinforced Cement Concrete (RCC).  Reinforced Cement Concrete (RCC) = Concrete + Steel Rebar

9. Concrete Cement Fine Aggregate  Concrete is a mixture of cement, fine aggregate (sand), coarse aggregate (stone or brick chips) in a defined mixture ratio and after adding water it transforms into a strong mass due to the hydration of cement. Coarse Aggregate  Typical Mixture ratios by volume: Cement : FA : CA = 1 : 1.5 : 3 or 1 : 2 : 4 or by mix design method  Water Cement Ratio = 0.5 ~ 0.6

10. Cement  It is one of the most important constituents of concrete. The function of cement in concrete is to work as a binding and cohesive material. With the presence of water, it binds the fine and coarse aggregates and fills the void to form a compact mass.  Different ingredients of cement and their proportions are as follows: 1.Lime (CaO) – 60 to 65% 2.Silica (SiO 2 ) – 17 to 25% 3.Alumina (Al 2 O 3 ) – 3 to 8% 4.Calcium sulfate (CaSO 4 ) – 0.1 to 0.5% 5.Iron Oxide (Fe 2 O 3 ) – 0.5 to 6% 6.Magnesia (MgO) – 1 to 3%  Addition of gypsum in cement controls the setting time of cement. Setting time is essential for keeping cement in plastic phase to make it workable. If gypsum is not added, the cement will set immediately after mixing with water, leaving not enough time for concrete placement and finishing.

11. Cement  Common Cements used in construction - CEM I Portland cement - CEM II Portland-composite cement - CEM III Blast furnace cement - CEM IV Pozzolanic cement - CEM V Composite cement  In Bangladesh, usually two types of cement are produced known as CEM I and CEM II.  CEM I is Ordinary Portland cement (OPC) in which 5% minor amount of SCM (Supplementary Siliceous Materials such as fly ash, slag, silica fume etc.) is added to clinker.  CEM II is the Portland Composite Cement (PCC) where 15 to 35% SCM is added to the clinker.  Clinker is made from the four basic raw materials necessary for cement manufacturing such as lime, silica, alumina and iron oxide.  Most of the clinker used for cement production in Bangladesh is imported from other countries.

12. Cement Difference between OPC and PPC PropertiesCEM I (OPC)CEM II (PCC) Clinker percentage95%65 to 80% SCM5%20 to 35% Initial setting time30 minutes Final setting time280 minutes600 minutes Sulphate and weather resistance LowHigh CostMore costly, due to higher percentage of clinker Cheaper than OPC Strength gaining speedHigher than PCCGains strength with time. Environmental ImpactEmits more CO 2 Using of natural waste which makes it eco- friendly.

13. Steel Rebar (mild steel) Yield strength of steel rebar is considered as design tensile strength. Because, it represents the upper limit to forces that can be applied without causing permanent deformation. Due to ductility of MS rebar, large amount of plastic deformation precedes the fracture. Before fracture, it produces cracks in the concrete. This enables engineers to take necessary measures to prevent further concrete damages. Fig.: Stress strain curve of MS rebar of different grades

14. Steel Rebar details (rebar number, diameter, rebar area) Rebar number area

15. Some advantages of Reinforced Concrete  Availability of materials: Concrete ingredients such as cement, sand, coarse aggregates (stone chips, brick chips etc.) are widely available worldwide and inexpensive.  Durability: Reinforced Concrete structures are durable, if designed and constructed properly. The material is not affected by weather easily and can last up to 100 years. Fire resistance of concrete material is also high. Therefore, maintenance costs is low.  Ductile failure of structure: Ductility of steel rebar enables concrete to show sign of cracking and deflection if reinforced concrete member experience overloading. This enables engineers to take necessary measures to prevent further concrete damages.

16.  Easy to form in any shapes Concrete can be placed into various shapes of shuttering or formwork configurations to form desired shapes, surface and texture. This is because fresh concrete is flowable. Therefore, it is more suitable for architectural requirements. Fig.: Jubilee Church, Rome, Italy

17. Force acting on beams Here, N = Axial Force V = Shear Force M = Bending Moment Positive Shear Force: A shear force that tends to move the left of the section upward or the right side of the section downward will be regarded as positive shear force. Negative Shear Force: A shear force that tends to move the left of the section downward or the right side of the section upward will be regarded as negative shear force.

18. Positive Bending moment:  Downward bending of member  Causes sagging of the beam.  Tension in bottom fiber.  Compression in top fiber.  Clockwise moment – Positive (Conventional) Negative Bending moment:  Upward bending of member  Causes hogging of the beam.  Tension in top fiber.  Compression in bottom fiber.  Anti Clockwise moment – Negative (Conventional)

19. P kip AB L in feet  Draw SFD and BMD diagram

20. AB L ft W k/ft  Draw SFD and BMD diagram  Determine the maximum moment acting on the beam

21. W k/ft L ft  Draw SFD and BMD diagram  Determine the maximum moment acting on the beam

22. Thank You