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Isolated footing with axial load and moment

Isolated footing with axial load and moment . Design Input. Grade of concrete - 35 Grade of steel - 460 Allowable soil pressure – 200 KN/m 2 Column load – 1260 KN(D.L+L.L) Moment – 100 kN.m Condition about overburden of soil - No. By ACI 318. Design procedure. Checking the footing area.

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Isolated footing with axial load and moment

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  1. Isolated footing with axial load and moment Design Input • Grade of concrete - 35 • Grade of steel - 460 • Allowable soil pressure – 200 KN/m2 • Column load – 1260 KN(D.L+L.L) • Moment – 100 kN.m • Condition about overburden of soil - No L&T-GES

  2. By ACI 318 Design procedure Checking the footing area • Arrive footing size • Total load=wt of footing+column load • Average soil pressure q= total load / footing area • Allowable soil pressure > Average soil pressure • Then footing are is ok L&T-GES

  3. Finding factored loads • Factored column load=1.4xdead load+1.7xlive load • Average factored soil pressure qnet=Factored column load/footing area • Average dv=total thick – cover - bar dia • Eccentricity e = Mu/Pu • Solving two equations to get q1 and q2 • Service load equation • Vertical equilibrium L&T-GES

  4. Check for One way shear • Take the critical section as ‘d’ distance from the • face of the column (as per ACI 318 ) • 1.find pressure at critical section • 2.find Vu • 3.find Vu • If Vu>Vu Check for Two way shear • Take the critical section as ‘d/2’ distance all around • the face of the column (as per ACI 318 ) • find pressure at critical section • Find the value of bo • 2.find Vu • 3.find Vu is smallest of these L&T-GES

  5. Safe against two way shear Otherwise increase the depth L&T-GES

  6. Check for flexural reinforcement Max moment occurs at the face of the column • Find average pressure • Find required moment Mn=Mu/ • Find required Ast • Min Ast=0.0018bh • Max spacing=18 in Development length L&T-GES

  7. Isolated footing with axial load and moment • Word document (IS Method) • Word document (ACI method) • Spread sheet (ACI method) • STAAD output (ACI method) L&T-GES

  8. Final comparison L&T-GES

  9. Thank You L&T-GES

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