steps for seismic analysis

Steps for Seismic Analysis

1. Select SI units [kNm]2. Define the grid and story data3. Define materials (Ecd

cracked = 0.5*Ecd)Reinforced Concrete, with dense aggregate ... 2400 kg/m3Plain Concrete, with natural stone aggregate ... 2300 kg/m3Mass per unit volume = 2.4Weight per unit volume = 2.4* 9.80665 = 23.54Eurocode 2 :Ecm = 22 x (fcm/10)0,3 , fcm in MPafcm = fck + 8 , fck in MPaC12/15:fck = 12 MPa (cylinder, 15 on cube)fcm = 12 + 8 = 20 MPaEcm = 22 x (20/10)0,3 = 27.09 MPa => Ecm = 27 MPa (Table 3.1 SR EN 1992-1-1:2004)Ecd

cracked = 0.5*Ecd = 13.5 MPa = 13.5 N/mm2 = 13.500.000 N/m2

4. Define the cross-section for columns and beams5. Define (Draw) the columns 6. Define (Draw) the beams

ETABS: (Menu) Assign -> Frame/Line -> Frame Property Modifiers -> Mass = Weight = n

n = (A-Af)/A (~ 0.5)A = Af + AiAf = bf x hfAi = (hgr - hf) x bgrbf = 0.15*(L1 + L2) < Lmin/2 (1 m)

7. Define the sections for slabs (membrane)8. Define (Draw) the slabs 9-12. Define and Draw walls and coupling beams13. Assign the End (Lenght) Offsets for columns & beams

ETABS: Select -> by Frame Section (all columns & beams)Assign -> End (Lenght) Offsets... -> Automatic & Rigid-zone factor = 1

14. Assign Joint/Point Rigid Diaphragm (for slabs joints)ETABS: Select -> by Wall/Slab/Deck Section (all Slabs)

Assign -> Shell/Area -> Diaphragms -> New -> Rigid15-17. Mesh and pier for walls18. Define static load cases - gravity loads

19. Assign gravity uniform loads to slabs - current floor

20. Assign uniform loads to perimetrical beams - curtain walls21. Replicate story22. Assign gravity uniform loads to slabs - terrace

ETABS: Assign -> Shell/Area Loads -> Uniform

23. Assign uniform loads to perimetrical beams - attic

24. Define Mass Source

25. Check model & Set Analysis OptionsETABS: Analyze -> Check Model -> check all buttons

Analyze -> Set Analysis Options -> Set Dynamic Parameters -> Modes (6)26. Run Analysis27. Show Mode Shapes & Display “Modal Participating Mass Ratio”

ETABS: Display -> Show Tables -> Modal Inf/Building Modal Inf/Mass Ratios-> Building Output/Center Mass Rigidity

28. Define static load cases - eartquake loads

29. Run Analysis30. Verify the GF story shear (comparing with hand-calculated conventional seismic force Fb = c*Wt)31-32. Shear walls33. Show Deformed Shape for EQ load cases34. Visualize the joint displacement and Lateral Drifts

35. Check the amplified drifts fost SLS and SLU

36. Define LOAD COMBINATIONS

37. Show wall forces38. Show beam forces39. Show column forces for EQ on X and Y dir40. Print Diagrams41. Modify colors for print