Etabs Flowchart: A. Structural Analysis 1.0
Set the unit: click at the lower right, use KN-m
2.0Model Initialization: NO (to use the built-in Etabs Etabs Default) 1.1Grid Dimension (click Custom Grid Grid Spacing to edit) 1.2Story Dimension (click Custom Story Story Data to to edit) 3.0Define 3.1Material Property Name a. Click Conc – Modify/Show Material Particular Units Used Type of Material
Remarks KN-m Isotropic (usually used for RC and steel)
Concrete comp. strength, f’c Bending Reinf. Yield Stress, Fy Shear Reinf. Yield Stress, Fy Mass per Unit Volume Weight per Unit Volume Modulus of Elasticity
Example Value KN-m Isotropic 27579 413685
= 4730 x sqrt (f’c inMPa) x 1000
Poisson’s Ratio Coeff. of Thermal Expansion
275730 2.4007 23.5616 24821128 0.2 9.900E-0.6
*Conversion from concrete cube (fcu) to cylinder strength (f’c) using L’Hermite formula: f’c = 0.76 0.76 + 0.2 log (fcu / 2840) where: fcu fcu in psi exa example: ple:
fcu fcu = 40 40MP MPa a = 58 5801 01..51 51ps psii
therefore:
f’c = 0.822 * fcu = 32.88MPa
3.2Frame Section a. Click Add Rectangular (arrow down the second dialog box at the right ), then click Modify/Show Material b. Modify Concrete Reinforcement (There are two tabs in the reinforcement reinforcement data dialog box. They are labeled column and beam. Pick the tab that corresponds corresponds to the frame section you are defining.) For beams: input As (area of steel reinf.) at reinforcement overrides for ductile beams for investigation. investigation. Otherwise, leave it at default values, 0 c. Set Property Property Modifi Modifier: er: Input Input modifica modification tion factor factor for for moment moment of inertia (for crack section, usually 0.7 for columns & 0.5 for beams)
3.3Wall/Slab/Deck Section
Click Add Deck or Wall or Slab (arrow down the dialog box at the right ), then click Modify/Show Material b. Type thickness for membrane and bending (same thickness) c. Choose the type to be used: Click Shell Type Behavior (Out-plane stiffness is provided for • the section) – usually used for cantilever slabs and walls Click Membrane Type Behavior (Only in-plane membrane • stiffness is provided for the section) – usually used for slab Click Plate Type Behavior (Combination of Out-plane and in• plane stiffness is provided for the section) a.
4.0
For Dynamic Analysis: Define Response Spectrum Function – define UBC97 & add UBC97 Spectrum
5.0Define Static Load Case Name
Load
Type
Dead Live EQX EQY
Dead Live Quake Quake
Self Wt. Multiplier 1 0 0 0
Auto Lat. Load UBC97 UBC97
Choose EQX then click Modify Lateral Load 5.2 Direction & Eccentricity = X-dir. + Eccen Y 5.1
Particular
UBC Referen ce
Eccentricity Ratio Time Period
Seismic Coefficient: Soil Profile Seismic Zone Factor Near Source
Referenc e
0.05 1630.2.2
Story Range
Overstrength Factor, R
Constant
NSCP
16-N
Steel = 0.035 RC = 0.030 Other = 0.020 Top Most level to Ground Floor only SMRF for Steel & RC = 8.5 Per Code
Constant 0.05
208.5.2.2
208-11
Steel = 0.0853 RC = 0.0731 Other = 0.0488 Top Most level to Ground Floor only SMRF for Steel & RC = 8.5 Per Code
16-J 16-I
SC 0.4
208-2 208-3
SC 0.4
16-U
B
208-6
B
Factor Distance to Source (Km) Importance Factor, I
10 16-K
10
1
208-1
1
Choose EQY then click Modify Lateral Load 5.4 Direction & Eccentricity = Y-dir. + Eccen X 5.5Copy constant used for EQX 5.3
6.0For Dynamic Analysis: Define Response Spectrum Case Data 6.1add new spectrum Mark x-direction y-direction Spectrum Case Name Specx Specy Damping 0.05 0.05 Modal Combination CQC CQC Directional Combination SRSS SRSS Input Response Spectra U1 = 1 (scale factor) U2 = 1 (scale factor) Excitation Angle 0 0 Override Eccentricity 0 0 7.0Load Combination (ultimate design due to earthquake based on NSCP) 7.1Based on NSCP: Comb1: 1.4DL Comb2: 1.4DL + 1.7LL Comb3: 1.3DL + 1.1LL + 1.1EQX Comb4: 1.3DL + 1.1LL - 1.1EQX Comb5: 1.3DL + 1.1LL + 1.1EQY Comb6: 1.3DL + 1.1LL - 1.1EQY Comb7: 1.42DL + 1.0LL + 1.0EQX Comb8: 1.42DL + 1.0LL - 1.0EQX Comb9: 1.42DL + 1.0LL + 1.0EQY Comb10: 1.42DL + 1.0LL - 1.0EQY 7.2Based on UBC’97: cas DL LL e 1 1.40 1.70 2 1.40 1.70 3 1.05 1.275 4 1.05 1.275 5 1.40 6 1.32 0.55 7 1.20 0.5 Where:
LLr 1.70 1.70 1.275 1.275 0.5
E
WL
1.30 1.10 1.30 DL = deadload LL = liveload LLr = roof liveload E = earthquake WL = windload
H
T
F
1.70 -
1.05 1.40 -
1.40 1.40 1.05 1.54 -
H = Earth pressure T = effects due to creep, shrinkage, thermal gradients and differential settlement F = fluid loads Where dead and live load are beneficial, the following shall apply: cas DL LL LLr E WL H T F e 2R 0.90 1.70 1.40 3R 0.90 1.30 6R 0.90 1.10 8.0Special Seismic Load Effect (check reliability /redundancy factor) 8.1 Rho Factor – reliability /redundancy factor – choose program calculated 8.2Omega factor – 2.8 9.0Define Mass Source 9.1From Loads – define mass multiplier (DL &SDL = 1) 9.2Uncheck – include lateral mass only 9.3Checked – Lump lateral mass at story levels 10.0 Draw & Assigned 10.1 Column – (elev. view - easier to draw) 10.2 Column – check column orientation in plan view If adjustment is needed – select columns at elev. view, click Assign, Frame/Line, Local Axes and type the desire angle 10.3 Wall– (elev. view - easier to draw) 10.4 Joint/Point – Restraint (support) – fixed (click joint at base level for footing Support – columns & walls) 10.5 Shell/Area – Pier Label (for design of walls) 10.6 Beams & Girders (plan view – easier to draw) 10.7 Frame line – Frame Releases/Partial Fixity – check Moment 2-2 & 3-3 for pin connection (intermediate beams) 10.8 Slab (plan view – easier to draw) - please ensure proper meshing, as much as possible use only 3 to 4 point nodes in modelling slabs element. 10.9 Assigned Diaphragm – Select all elements (plan view per floor) – Assign\Shell/Area\Rigid Diaphragm, select D1
11.0 Assigned Loads 11.1 Select area – assign shell/area loads - uniform 11.2 Select line – assign frame/line loads – point or uniform loads 11.3 Select point – assign joint/point load – joint forces 12.0 Analyze – set analysis option 12.1 Building Active Degrees of Freedom – checked full 3D 12.2 Check Dynamic Analysis if applicable 12.2.1Dynamic Parameters – used Eigenvectors 12.2.2No.of modes - check if structure is 90% participated for static 12.3 P-Delta effect - check if applicable 13.0 Analyze – check model – checked all boxes for checking 14.0 Run Analysis
Verify Analysis - File – Last Analysis Run Log – check for warnings messages 16.0 Check graph of storyshear, Display – Show Story Response Plots – choose Story Shears. Curve should be gradual curve 17.0 Check period, T: File – Print Tables – Summary Reports – scroll down – Modal Period and Frequencies, T for mode 1 should be
• • •
21.0 Check story drift File – Print Tables – Summary Reports – scroll down – Story Drift
B. Concrete Frame Design Design – Concrete Frame Design – Select Design Combo – choose the desire load combination to be used for design, used the add or remove icon to choose. 2.0 Design – Concrete Frame Design – Start Design/Check of Structure 3.0 Design – Concrete Frame Design – Display Design Info • Longitudinal Reinforcing – defined as As in mm 2: # rebars = As / As 1 where As1 = area of one reinf. bar in mm 2 • Shear Reinforcing – defined as As/meter in mm 2/m: Spacing, s = As 1/As where As1 = area of one reinf. bar in mm 2 Torsion Reinforcing 1.0
•
4.0
