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DIRECT METHOD ANALYSIS - GENERAL

Giorgio Figari

I'm trying to crosscheck a AISC design example regarding the DIRECT METHOD ANALYSIS.

My problem is that, if I check the moments and the displacements obtained by the Staad Model, I cannot get the same results given in the example.

Could anybody have a look and let me know where in my mistake in the staad model?

Here below both the staad model, while the  the pdf reporting the AISC design example C.1A is given as attachment.

Many thanks in advance

Giorgio

STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 11-Dec-09
END JOB INFORMATION
INPUT WIDTH 79
UNIT FEET KIP
JOINT COORDINATES
1 0 0 0; 2 0 20 0; 3 0 4 0; 4 0 8 0; 5 0 12 0; 6 0 16 0; 7 30 0 0; 8 30 4 0;
9 30 8 0; 10 30 12 0; 11 30 16 0; 12 30 20 0; 13 45 0 0; 14 45 4 0; 15 45 8 0;
16 45 12 0; 17 45 16 0; 18 45 20 0; 19 7.5 20 0; 20 15 20 0; 21 22.5 20 0;
22 33.75 20 0; 23 37.5 20 0; 24 41.25 20 0;
MEMBER INCIDENCES
1 1 3; 2 3 4; 3 4 5; 4 5 6; 5 6 2; 6 7 8; 7 8 9; 8 9 10; 9 10 11; 10 11 12;
11 2 19; 12 13 14; 13 14 15; 14 15 16; 15 16 17; 16 17 18; 17 12 22; 18 19 20;
19 20 21; 20 21 12; 21 22 23; 22 23 24; 23 24 18;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 4.28151e+006
POISSON 0.3
DENSITY 0.489024
ALPHA 1.2e-005
DAMP 0.03
G 1.64674e+006
TYPE STEEL
STRENGTH FY 5288.19 FU 8517.08 RY 1.5 RT 1.2
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 TO 10 12 TO 16 TABLE ST W12X65
11 17 TO 23 TABLE ST W18X40
CONSTANTS
MATERIAL STEEL ALL
SUPPORTS
1 7 13 PINNED
MEMBER RELEASE
17 START MY MZ
23 END MY MZ
DEFINE DIRECT ANALYSIS
FLEX 1 ALL
*FYLD 6500 LIST ALL
AXIAL ALL
NOTIONAL LOAD FACTOR 0.002
END
LOAD 1
MEMBER LOAD
11 18 TO 20 UNI GY -2.4
JOINT LOAD
2 12 FY -36
18 FY -144
*
LOAD 2
NOTIONAL LOAD
1 X 0.002
LOAD 10
REPEAT LOAD
1 1.0 2 1.0
PERFORM ANALYSIS PRINT ALL
CHANGE
LOAD 20
REPEAT LOAD
1 1.0 2 1.0
PERFORM DIRECT ANALYSIS LRFD PRINT LOAD DATA
FINISH



  • Offline in reply to Grace Shen

    Here is the STAAD file that works perfectly. Please note that the FLEX parameter need to be given to all the members in the frame. Otherwise the results do not match with that is on AISC

    STAAD PLANE
    START JOB INFORMATION
    ENGINEER DATE 14-Mar-20
    JOB NAME Direct Analysis
    JOB NO AISC Design Example C.1A
    ENGINEER NAME Karthik
    END JOB INFORMATION
    INPUT WIDTH 79
    UNIT FEET KIP
    JOINT COORDINATES
    1 0 0 0; 2 0 20 0; 3 30 0 0; 4 30 20 0; 5 60 0 0; 6 60 20 0; 7 90 0 0;
    8 90 20 0; 9 120 0 0; 10 120 20 0;
    MEMBER INCIDENCES
    1 1 2; 2 3 4; 3 5 6; 4 7 8; 5 9 10; 6 2 4; 7 4 6; 8 6 8; 9 8 10;
    SUPPORTS
    1 3 5 7 9 PINNED
    MEMBER RELEASE
    6 START MY MZ
    6 END MY MZ
    8 START MY MZ
    8 END MY MZ
    9 START MY MZ
    9 END MY MZ
    DEFINE MATERIAL START
    ISOTROPIC STEEL
    E 4.176e+006
    POISSON 0.3
    DENSITY 0.489024
    ALPHA 1.2e-005
    DAMP 0.03
    TYPE STEEL
    STRENGTH FY 7200 FU 9630 RY 1.5 RT 1.2
    END DEFINE MATERIAL
    MEMBER PROPERTY AMERICAN
    1 TO 5 TABLE ST W12X65
    6 TO 9 TABLE ST W18X40
    CONSTANTS
    MATERIAL STEEL ALL
    DEFINE DIRECT ANALYSIS
    FLEX 1 LIST ALL
    FYLD 7200 LIST 2 3 7
    AXIAL LIST 1 TO 5
    NOTIONAL LOAD FACTOR 0.002
    END
    LOAD 1 LOADTYPE Live  TITLE LIVE LOAD
    MEMBER LOAD
    6 TO 9 UNI GY -1.2
    LOAD 2 LOADTYPE Dead  TITLE DEAD LOAD
    MEMBER LOAD
    6 TO 9 UNI GY -0.4
    LOAD 3 LOADTYPE None  TITLE 1.2DL+1.6LL+NL
    REPEAT LOAD
    1 1.6 2 1.2
    NOTIONAL LOAD
    1 X 0.0032 2 X 0.0024
    PERFORM DIRECT ANALYSIS LRFD ITERATION 15 TAUTOL 1 DISPTOL 0.0001
    *PERFORM ANALYSIS
    *PDELTA 10 ANALYSIS SMALLDELTA
    *DEFINE ENVELOPE
    *3 ENVELOPE 1 TYPE SERVICEABILITY
    *END DEFINE ENVELOPE
    *LOAD LIST ENV 1
    *PARAMETER 1
    *CODE AISC UNIFIED 2010
    *METHOD LRFD
    *DFF 360 ALL
    *FYLD 7200 ALL
    *CHECK CODE ALL
    FINISH

  • Offline in reply to eugene afable
    STAAD PLANE
    START JOB INFORMATION
    ENGINEER DATE 12-Feb-19
    END JOB INFORMATION
    INPUT WIDTH 79
    UNIT FEET KIP
    JOINT COORDINATES
    1 0 0 0; 2 30 0 0; 3 60 0 0; 4 90 0 0; 5 120 0 0; 6 0 20 0; 7 30 20 0;
    8 60 20 0; 9 90 20 0; 10 120 20 0;
    MEMBER INCIDENCES
    1 1 6; 2 2 7; 3 3 8; 4 4 9; 5 5 10; 6 6 7; 7 7 8; 8 8 9; 9 9 10;
    SUPPORTS
    1 TO 5 PINNED
    MEMBER RELEASE
    6 8 9 START MY MZ
    6 8 9 END MY MZ
    DEFINE MATERIAL START
    ISOTROPIC STEEL
    E 4.28151e+006
    POISSON 0.3
    DENSITY 0.489024
    ALPHA 1.2e-005
    DAMP 0.03
    TYPE STEEL
    STRENGTH FY 5288.19 FU 8517.08 RY 1.5 RT 1.2
    END DEFINE MATERIAL
    MEMBER PROPERTY AMERICAN
    1 TO 6 8 9 TABLE ST W12X65
    7 TABLE ST W18X40
    CONSTANTS
    MATERIAL STEEL ALL
    DEFINE DIRECT ANALYSIS
    FLEX 1 ALL
    FYLD 5288.19 ALL
    AXIAL ALL
    NOTIONAL LOAD FACTOR 0.002
    END
    LOAD 1 LOADTYPE Dead  TITLE DL
    MEMBER LOAD
    6 TO 9 UNI GY -0.4
    LOAD 2 LOADTYPE Live REDUCIBLE TITLE LL
    MEMBER LOAD
    6 TO 9 UNI GY -1.2
    LOAD 3 Generated AISC PUBLIC 1
    REPEAT LOAD
    1 1.4
    NOTIONAL LOAD
    1 X 0.0028
    LOAD 4 Generated AISC PUBLIC 2
    REPEAT LOAD
    1 1.4
    NOTIONAL LOAD
    1 X -0.0028
    LOAD 5 Generated AISC PUBLIC 3
    REPEAT LOAD
    1 1.4
    NOTIONAL LOAD
    1 Z 0.0028
    LOAD 6 Generated AISC PUBLIC 4
    REPEAT LOAD
    1 1.4
    NOTIONAL LOAD
    1 Z -0.0028
    LOAD 7 Generated AISC PUBLIC 5
    REPEAT LOAD
    1 1.2 2 1.6
    NOTIONAL LOAD
    1 X 0.0024 2 X 0.0032
    LOAD 8 Generated AISC PUBLIC 6
    REPEAT LOAD
    1 1.2 2 1.6
    NOTIONAL LOAD
    1 X -0.0024 2 X -0.0032
    LOAD 9 Generated AISC PUBLIC 7
    REPEAT LOAD
    1 1.2 2 1.6
    NOTIONAL LOAD
    1 Z 0.0024 2 Z 0.0032
    LOAD 10 Generated AISC PUBLIC 8
    REPEAT LOAD
    1 1.2 2 1.6
    NOTIONAL LOAD
    1 Z -0.0024 2 Z -0.0032
    LOAD 11 Generated AISC PUBLIC 9
    REPEAT LOAD
    1 1.2 2 0.5
    NOTIONAL LOAD
    1 X 0.0024 2 X 0.001
    LOAD 12 Generated AISC PUBLIC 10
    REPEAT LOAD
    1 1.2 2 0.5
    NOTIONAL LOAD
    1 X -0.0024 2 X -0.001
    LOAD 13 Generated AISC PUBLIC 11
    REPEAT LOAD
    1 1.2 2 0.5
    NOTIONAL LOAD
    1 Z 0.0024 2 Z 0.001
    LOAD 14 Generated AISC PUBLIC 12
    REPEAT LOAD
    1 1.2 2 0.5
    NOTIONAL LOAD
    1 Z -0.0024 2 Z -0.001
    LOAD 15 Generated AISC PUBLIC 13
    REPEAT LOAD
    1 1.2
    NOTIONAL LOAD
    1 X 0.0024
    LOAD 16 Generated AISC PUBLIC 14
    REPEAT LOAD
    1 1.2
    NOTIONAL LOAD
    1 X -0.0024
    LOAD 17 Generated AISC PUBLIC 15
    REPEAT LOAD
    1 1.2
    NOTIONAL LOAD
    1 Z 0.0024
    LOAD 18 Generated AISC PUBLIC 16
    REPEAT LOAD
    1 1.2
    NOTIONAL LOAD
    1 Z -0.0024
    LOAD 19 Generated AISC PUBLIC 17
    REPEAT LOAD
    1 0.9
    NOTIONAL LOAD
    1 X 0.0018
    LOAD 20 Generated AISC PUBLIC 18
    REPEAT LOAD
    1 0.9
    NOTIONAL LOAD
    1 X -0.0018
    LOAD 21 Generated AISC PUBLIC 19
    REPEAT LOAD
    1 0.9
    NOTIONAL LOAD
    1 Z 0.0018
    LOAD 22 Generated AISC PUBLIC 20
    REPEAT LOAD
    1 0.9
    NOTIONAL LOAD
    1 Z -0.0018
    PERFORM DIRECT ANALYSIS LRFD ITERATION 15 TAUTOL 1 DISPTOL 0.0001
    FINISH
  • Offline in reply to eugene afable
    STAAD PLANE
    START JOB INFORMATION
    ENGINEER DATE 12-Feb-19
    END JOB INFORMATION
    INPUT WIDTH 79
    UNIT FEET KIP
    JOINT COORDINATES
    1 0 0 0; 2 30 0 0; 3 60 0 0; 4 90 0 0; 5 120 0 0; 6 0 20 0; 7 30 20 0;
    8 60 20 0; 9 90 20 0; 10 120 20 0;
    MEMBER INCIDENCES
    1 1 6; 2 2 7; 3 3 8; 4 4 9; 5 5 10; 6 6 7; 7 7 8; 8 8 9; 9 9 10;
    SUPPORTS
    1 TO 5 PINNED
    MEMBER RELEASE
    6 8 9 START MY MZ
    6 8 9 END MY MZ
    DEFINE MATERIAL START
    ISOTROPIC STEEL
    E 4.28151e+006
    POISSON 0.3
    DENSITY 0.489024
    ALPHA 1.2e-005
    DAMP 0.03
    TYPE STEEL
    STRENGTH FY 5288.19 FU 8517.08 RY 1.5 RT 1.2
    END DEFINE MATERIAL
    MEMBER PROPERTY AMERICAN
    1 TO 6 8 9 TABLE ST W12X65
    7 TABLE ST W18X40
    CONSTANTS
    MATERIAL STEEL ALL
    DEFINE DIRECT ANALYSIS
    FLEX 1 ALL
    FYLD 5288.19 ALL
    AXIAL ALL
    NOTIONAL LOAD FACTOR 0.002
    END
    LOAD 1 LOADTYPE Dead  TITLE DL
    MEMBER LOAD
    6 TO 9 UNI GY -0.4
    LOAD 2 LOADTYPE Live REDUCIBLE TITLE LL
    MEMBER LOAD
    6 TO 9 UNI GY -1.2
    LOAD 3 Generated AISC PUBLIC 1
    REPEAT LOAD
    1 1.4
    NOTIONAL LOAD
    1 X 0.0028
    LOAD 4 Generated AISC PUBLIC 2
    REPEAT LOAD
    1 1.4
    NOTIONAL LOAD
    1 X -0.0028
    LOAD 5 Generated AISC PUBLIC 3
    REPEAT LOAD
    1 1.4
    NOTIONAL LOAD
    1 Z 0.0028
    LOAD 6 Generated AISC PUBLIC 4
    REPEAT LOAD
    1 1.4
    NOTIONAL LOAD
    1 Z -0.0028
    LOAD 7 Generated AISC PUBLIC 5
    REPEAT LOAD
    1 1.2 2 1.6
    NOTIONAL LOAD
    1 X 0.0024 2 X 0.0032
    LOAD 8 Generated AISC PUBLIC 6
    REPEAT LOAD
    1 1.2 2 1.6
    NOTIONAL LOAD
    1 X -0.0024 2 X -0.0032
    LOAD 9 Generated AISC PUBLIC 7
    REPEAT LOAD
    1 1.2 2 1.6
    NOTIONAL LOAD
    1 Z 0.0024 2 Z 0.0032
    LOAD 10 Generated AISC PUBLIC 8
    REPEAT LOAD
    1 1.2 2 1.6
    NOTIONAL LOAD
    1 Z -0.0024 2 Z -0.0032
    LOAD 11 Generated AISC PUBLIC 9
    REPEAT LOAD
    1 1.2 2 0.5
    NOTIONAL LOAD
    1 X 0.0024 2 X 0.001
    LOAD 12 Generated AISC PUBLIC 10
    REPEAT LOAD
    1 1.2 2 0.5
    NOTIONAL LOAD
    1 X -0.0024 2 X -0.001
    LOAD 13 Generated AISC PUBLIC 11
    REPEAT LOAD
    1 1.2 2 0.5
    NOTIONAL LOAD
    1 Z 0.0024 2 Z 0.001
    LOAD 14 Generated AISC PUBLIC 12
    REPEAT LOAD
    1 1.2 2 0.5
    NOTIONAL LOAD
    1 Z -0.0024 2 Z -0.001
    LOAD 15 Generated AISC PUBLIC 13
    REPEAT LOAD
    1 1.2
    NOTIONAL LOAD
    1 X 0.0024
    LOAD 16 Generated AISC PUBLIC 14
    REPEAT LOAD
    1 1.2
    NOTIONAL LOAD
    1 X -0.0024
    LOAD 17 Generated AISC PUBLIC 15
    REPEAT LOAD
    1 1.2
    NOTIONAL LOAD
    1 Z 0.0024
    LOAD 18 Generated AISC PUBLIC 16
    REPEAT LOAD
    1 1.2
    NOTIONAL LOAD
    1 Z -0.0024
    LOAD 19 Generated AISC PUBLIC 17
    REPEAT LOAD
    1 0.9
    NOTIONAL LOAD
    1 X 0.0018
    LOAD 20 Generated AISC PUBLIC 18
    REPEAT LOAD
    1 0.9
    NOTIONAL LOAD
    1 X -0.0018
    LOAD 21 Generated AISC PUBLIC 19
    REPEAT LOAD
    1 0.9
    NOTIONAL LOAD
    1 Z 0.0018
    LOAD 22 Generated AISC PUBLIC 20
    REPEAT LOAD
    1 0.9
    NOTIONAL LOAD
    1 Z -0.0018
    PERFORM DIRECT ANALYSIS LRFD ITERATION 15 TAUTOL 1 DISPTOL 0.0001
    FINISH
  • Offline in reply to Grace Shen
    Please note the calculations in V14.0 Design Examples had errors and the AISC have published updates. The current version of the publication is 14.2 (avaialble from the AISC site) and you will see that there have been corrections in the forces reported.



  • Offline
    Is there any more recent resolution to this issue? I would also like to see the solution. Thank you.
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