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RAM | STAAD | ADINA Wiki Microstran Response Spectrum Analysis to NZS 4203
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    Microstran Response Spectrum Analysis to NZS 4203

       
      Applies To 
       
      Product(s): Microstran
      Version(s): V8i
      Environment:  N/A
      Area:  Analysis
      Original Author: Richard Collins
       

    An Excel spreadsheet, shown below, is available to assist in the use of Microstran Response Spectrum Analysis of structures to NZS 4203. The procedure is described briefly in notes at the top of the spreadsheet. The spreadsheet calculates scale factors that have to be entered in Microstran dialog boxes during the response spectrum analysis.

    February, 2000: The spreadsheet now interpolates for values of period and ductility factor that are not equal to values tabulated in the code.

    Values shown in the spreadsheet relate to this structure:

    Earthquake Example

    The spreadsheet is available at Microstran Excel Spreadhsheet Extensions.

    MICROSTRAN RESPONSE SPECTRUM ANALYSIS - NZS4203 PART 4        
             
    PROCEDURE:        
    1. Do dynamic analysis without RSA box checked.        
    2. File > List/Edit File command, then choose Dynamic Log.        
    3. Find fundamental period for direction of interest.        
    4. Enter values shown in red or orange. Do not change anything else.        
    5. Do static analysis with empty load case for RSA results.        
    6. Repeat dynamic analysis with…        
    a. RSA box checked.        
    b. Green value entered in Response Spectrum dialog.        
    c. Response spectrum curve A1, B1, or C1 selected.        
    7. Check dynamic log for 90% mass participation.        
    8. Analyse > Response Spectrum then:        
    In Dynamic Load Case Scale Factors dialog…        
    - transfer Reaction value to blue value below.        
    9. Repeat static analysis.        
    10. Repeat dynamic analysis with…        
    a. RSA box checked.        
    b. Magenta value entered in Response Spectrum dialog.        
    c. Response spectrum curve A1, B1, or C1 selected.        
    11. Analyse > Response Spectrum        
    12. Create Input/Analysis report and check base shear        
    for earthquake case.        
             
    Frequency of first mode, Hz = 2      
    Fundamental trans. period of vibration, T1 = 0.50 sec.    
    Site subsoil category = a     (Rock=a - Deep soil=c)
    Total seismic weight of structure, Wt = 5515 kN    
             
    Structural ductility factor, u        
    (Ratio: Max. displacement/Yield displacement) = 3.00     (1.00 to 10.00)
    Structural performance factor, Sp = 0.67     (Always 0.67 ?)
    Risk factor for structure = 1.0     (0.6 to 1.3)
    Zone factor, Z = 0.6     (0.6 to 1.2)
    Limit state factor, Ls = 0.1667      
    Limit state factor, Lu = 1.0      
             
    Equivalent Static Method: a b c  
    Serviceability limit state -        
    Serviceability - Ch(T1,1) = 0.63 0.77 1.00  
    Ch(T1,1)*Sp*R*Z*Ls = 0.0422 0.0516 0.0670  
    Lateral force coefficient, C = 0.0422      
    Horizontal seismic shear force, V = 233 kN    
    Ultimate limit state -        
    Ultimate - Ch(T1,u) = 0.26 0.32 0.37  
    Ch(T1,u)*Sp*R*Z*Lu = 0.1045 0.1286 0.1487  
    For site subsoil category, this = 0.1045      
    Lateral force coefficient, C = 0.1045     (Not less than 0.03)
    Horizontal seismic shear force, V = 576 kN    
             
    Modal Response Spectrum Method:        
    Serviceability limit state -        
    Sp*R*Z*Ls = 0.0670      
    Microstran RSA scale factor = 0.66      
    Ultimate limit state -        
    Sp*R*Z*Lu = 0.4020      
    Microstran RSA scale factor = 3.94     (Use this in first run with u=1 spectrum to obtain Vbase(1))
    Combined modal base shear, Vbase(1) = 1136     (Insert value from Microstran)
    Design spectrum scaling factor, Sm1 = 0.41      
    Modal analysis scaling factor, Km = 1.0     (0.8 or 1.0)
    4.6.2.7(b) C = 0.1045      
    Design spectrum scaling factor, Sm2 = 0.51      
    Sm = 0.51     (Max. of Sm1, Sm2)
    Sm*Sp*R*Z*Lu = 0.2040      
    Microstran RSA scale factor = 2.00     (Use this in final run with u=1 spectrum)

     

    • analysis
    • NZS 4203
    • Microstran
    • Dynamic Analysis
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    • Seth Guthrie Created by Bentley Colleague Seth Guthrie
    • When: Fri, Jan 30 2015 6:57 PM
    • Seth Guthrie Last revision by Bentley Colleague Seth Guthrie
    • When: Mon, Feb 2 2015 4:33 PM
    • Revisions: 2
    • Comments: 0
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