Design and Analysis of RC beam
- 1. Design of Concrete Structures-1 CE-2105
- 2. Presentation of design and analysis of RC beam(as per ACI code) Dr.Md. Rezaul Karim Associate Professor Department of Civil Engineering (CE) Dhaka University of Engineering & Technology Advisor
- 3. Our Group Member’s Kazi Abu Monjur Std Id: 121042 Md. Rabiul Islam Std Id: 121044 Md. Irafanul Kabir Std Id: 121045 Md. Shorab Hossain Pavel Std Id. 121058 Mohammad Anis Std Id. 121050
- 4. Contents of Presentation Objectives Singly Beam Design & Analysis Doubly Beam Design & Analysis T-Beam Design & Analysis
- 5. Objectives • Gain the concept about USD method • Gain the analysis concept of Singly, Doubly and T-Beam • Gain the Design procedure of Singly, Doubly and T-Beam • “In what sitution what Types of beam we should consider
- 6. As a Civil Engineer What should I have to consider ??? For Structures Design? Design Strength Serviceability Durability Implacability Economy
- 7. Design Parameter ß1=0.85-0.05(f’c-4000)/1000 and 0.65 ≤ß1 ≤0.85 Strength factor Φ should be adjust by ACI code provision
- 8. Analysis Over Reinforced as Doubly Analysis of Beam ρ < ρ max Analysis Under Reinforced as Singly Mn=Asfy(d-a/2) a=Asfy/.85f’cb Mn=ΦMn Adjust Φ by ϵt or c/dt Assume b Generally b=d/2 No Yes
- 9. Design Calculating the factored loads Mu=It’s depends on beam support Wu=1.2DL+1.6LL Adjust Φ by ϵt or c/dtMu=Φ ρfybd2(1-0.59ρfy/f’c) Determine b and d As= ρb𝑑2 Design complete
- 10. For Economy Design should be revised As=Mu/ Φfy(d-a/2)Assume a Check a Alternate solution use lower ρ as ρ=0.6 ρmax or ρ=0.75 ρmax etc
- 11. When a beam design as a Doubly reinforced beam ?
- 12. Step :1 Checking the Beam (Singly nor Doubly) ρ> ρ max ρ N×As ρmax= .85 βḟc/fy× Ԑ𝑐𝑢 Ԑ𝑐𝑢+0.004 0.003 This condition is satisfy thus the beam is doubly reinforced beam Step :2 Check the Limits on reinforced ratio If ρ>ῤ cy Compression bar yield But ρ<ῤ cy Compression steel below yield stress ῤcy= .85 βḟc/fy× ď 𝑑 × Ԑ𝑐𝑢 Ԑ𝑐𝑢+0.004 + ῤ 𝐴ś 𝑏𝑑
- 13. Step : 3 Determination the moment capacity ρ>ῤcy Where n s y s s s s 2 a M A f A f d A f d d OR ρ<ῤcy n s y s s s s 2 a M A f A f d A f d d
- 14. Design step of Doubly reinforced beam Step 1: Load Calculation This condition is satisfy compression steel’s will be needed i.e doubly reinforced beam Wu=1.2 DL+1.6LL Mu= Its defends on beam supports characteristics Step 2 : Check the Capacity of the Section Mn>Mu Wu=1.2 DL+1.6LL ΦMn=Asfy(d-a/2) ρ max × bd ρmax= .85 βḟc/fy× Ԑ𝑐𝑢 Ԑ𝑐𝑢+0.05 b=width of beam d= Effective depth
- 15. Step 3: Determine the area of steel Excess Moment M1=Mu-Mmax Aś= 𝑴𝟏 Φḟ 𝒔(𝒅−ď) ḟ𝒔=ἑsEs Ԑu (𝒄−ď) 𝒄 𝒄 = 𝒂 β𝟏 ď=2.5 “ (assume) If ď < 21.5 then Compression reinforced yield stress ,so using lower compression stress ḟ𝒔 As=Aś+As(max)
- 16. Checking Design Design of beam is OK Φ must be adjust Φ= 0.65+(Ԑt-0.002) 250 3 Ԑt=Ԑu(𝒅𝒕−𝒄) 𝒄 Now Mu=ΦMn=Φasfy(d- 𝑎 2 ) >Design Moment Hence Ok If (As-Aś ḟ 𝒔 𝒇𝒚 )<As Wrong True
- 17. - Beam When and why A T-section consider as a T-beam or a rectangular Beam ?? hf<a consider as T-Beam hf>a consider as Rectangular-Beam
- 18. • b≤ • b ≤ • 𝐿 4 where L= Span of beam 𝐶𝑙𝑒𝑎𝑟 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑜𝑓 𝑏𝑒𝑎𝑚 2 𝑏−𝑏𝑤 2 ≤ 8hf • • b ≤ • 𝑏 − 𝑏𝑤≤ 𝐿 2 where L= Span of beam 𝐶𝑙𝑒𝑎𝑟 𝑆𝑝𝑒𝑎𝑐𝑖𝑛𝑔 𝑜𝑓 𝑏𝑒𝑎𝑚 2 b-bw≤ 6hf • b≤ 4bw bw≤ 2hf For Symmetrical For having a Slab on side For Isolated
- 19. Analysis of - Beam Check is it symmetric or Isolated or hanging one slab?? hf>a ??? No Yes Analysis consider as rectangular beam Analysis consider as T- beam
- 20. Mn1=Asf fy(d-hf/2) Asw=As-AsfAsf=.85f’c/fy(b-bw)hf Mn2=Aswfy(d-a/2) Mn=Mn1+Mn2 Mu=ΦMn Adjust Φ by Ԑt or c/dt
- 21. Design of - Beam Established the hf generally slab thickness Determine b according to ACI code Choose bw & d
- 22. Calculate a trial As but not exceed hf For check the a trial As Check Ԑ or c/d Ensure that ρw≥ ρw min hf<a No Yes
- 23. Thanks to All
- 24. Any Query ??