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Problem with DFF command not check in steel design with STAAD Pro SS6 built 20071150 (Latest built)

siwalak khamnurak
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Please see STAAD input command below. I try to change DFF parameter in any value (not 0) but the result still show all member pass all code check.

Please verify if I'm wrong...

Best regard.

STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 06-Feb-16
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KG
JOINT COORDINATES
1 0 5 0; 2 10 5 0; 3 0 4.91 1.7; 4 10 4.91 1.7; 5 0 4.93656 1.19832;
6 10 4.93656 1.19832; 7 0 3.8 0; 8 10 3.8 0; 9 0 4.99207 0.14979;
10 10 4.99207 0.14979; 11 0 4.9511 0.923706; 12 10 4.9511 0.923706;
MEMBER INCIDENCES
1 1 9; 2 2 10; 3 3 4; 4 5 3; 5 6 4; 6 7 5; 7 8 6; 8 9 11; 9 10 12; 10 9 10;
11 11 5; 12 12 6; 13 11 12;
START GROUP DEFINITION
FLOOR
_CP1 3 TO 5 8 TO 13
END GROUP DEFINITION
DEFINE MATERIAL START
ISOTROPIC STEEL
E 2.09042e+010
POISSON 0.3
DENSITY 7833.41
ALPHA 1.2e-005
DAMP 0.03
TYPE STEEL
STRENGTH FY 2.58192e+007 FU 4.1584e+007 RY 1.5 RT 1.2
END DEFINE MATERIAL
MEMBER PROPERTY JAPANESE
1 2 4 5 8 9 11 12 TABLE ST C150X75X9
3 10 13 TABLE ST RHS150X75X2.3
6 7 TABLE ST C100X50X5
CONSTANTS
BETA 180 MEMB 2 5 7 9 12
MATERIAL STEEL ALL
SUPPORTS
1 2 7 8 PINNED
LOAD 1 LOADTYPE None TITLE DL
SELFWEIGHT Y -1
FLOOR LOAD
_CP1 FLOAD -10 GY
LOAD 2 LOADTYPE None TITLE LR
FLOOR LOAD
_CP1 FLOAD -30 GY
LOAD 3 LOADTYPE None TITLE WX
FLOOR LOAD
_CP1 FLOAD 50 GY
LOAD 4 LOADTYPE None TITLE WZ
FLOOR LOAD
_CP1 FLOAD 70 GY
LOAD COMB 101 DL+LR
1 1.0 2 1.0
LOAD COMB 102 DL+0.75[LR+WX]
1 1.0 2 0.75 3 0.75
LOAD COMB 103 DL+0.75[LR+WZ]
1 1.0 2 0.75 4 0.75
LOAD COMB 104 DL+WX
1 1.0 3 1.0
LOAD COMB 105 DL+WZ
1 1.0 4 1.0
LOAD COMB 106 0.6DL+WX
1 0.6 3 1.0
LOAD COMB 107 0.6DL+WZ
1 0.6 4 1.0
PERFORM ANALYSIS
LOAD LIST 101 TO 107
PARAMETER 1
CODE AISC UNIFIED 2005
METHOD ASD
MAIN 1 MEMB 3 10 13
TMAIN 1 MEMB 3 10 13
*LY 5 MEMB 3 10 13
DFF 1000 MEMB 3 10 13
DJ1 9 MEMB 10
DJ2 12 MEMB 10
CHECK CODE ALL
FINISH

Parents
  • 0 Offline
    In your model, you have not specified any Serviceability load envelope. So program does not perform the deflection check for any member. In STAAD.Pro SS6 version, it is necessary to define a service load envelope with unfactored load combination cases and use that load envelope to check the deflection limits. for more information about this, you can go through the following posts--

    communities.bentley.com/.../23987.serviceability-and-strength-check-for-the-same-load-combination

    communities.bentley.com/.../20793.strengthserviceability-check-in-design

    In your model, create a Service load envelope (say ENVELOPE 1) and add the envelope in the load list command--

    LOAD LIST ENVELOPE 1
    PARAMETER 1
    CODE AISC UNIFIED 2005



  • 0 Offline in reply to Surojit Ghosh

    What different of command?.
    LOAD LIST 101 TO 107 and LOAD LIST ENVELOPE 1
    which Envelope 1 include load no. 101 to 107 ?
    I remember that I ever use this command in SS4 without define any envelope.
    STAAD can check code and check the deflection.

    Does it's mean in the SS6 we must define and evelope for check deflection limit

    and for steel design code check we must define envelope or not for the correct result ?.

    With most of my code only use LOAD LIST ... TO ... command.

    Regard.

  • 0 Offline in reply to vivekshine

    The load cases that are assigned to the serviceability load envelope happen to be the same as the ones that are assigned to the strength envelope. Thus, both envelopes have the same set of load cases. The AISC 360 design module in STAAD is current not set up to handle this situation currently. In other words, the load cases in those two envelopes need to be distinct and have no commonality. This limitation is expected to be removed in a future version.

    So, here is what you can do presently. For each of the cases 1 and 3 to 6, create load combinations that are simply 1.0 times the respectives cases (Load combination 11 = 1 * LC1, Load combination 13 = 1 + LC3 and so on). Then, assign those combination cases to one of those envelopes.

    RAJAT

  • 0 Offline in reply to Rajat
    OK thanks.
    Dont know why such a limitations.

    Either STAAD has to remove the limitation or should trigger proper warning (**WARNING- Deflection check of member # 4 will not be performed as service and service envelope has same load combinations)

    Current warning "service envelope not provided" will confuse the users.

    Currently I copied the load combination and just changed the load combination numbers used in stress envelope.


    STAAD SPACE
    START JOB INFORMATION
    ENGINEER DATE 07-Apr-16
    END JOB INFORMATION
    INPUT WIDTH 79
    UNIT METER KN
    JOINT COORDINATES
    1 0 0 0; 2 5 0 0; 3 0 3 0; 4 5 3 0; 5 0 0 3; 6 5 0 3; 7 0 3 3; 8 5 3 3;
    MEMBER INCIDENCES
    1 1 3; 2 2 4; 3 3 4; 4 3 7; 5 4 8; 6 5 7; 7 6 8; 8 7 8;
    DEFINE MATERIAL START
    ISOTROPIC STEEL
    E 2.05e+008
    POISSON 0.3
    DENSITY 76.8195
    ALPHA 1.2e-005
    DAMP 0.03
    TYPE STEEL
    STRENGTH FY 253200 FU 407800 RY 1.5 RT 1.2
    END DEFINE MATERIAL
    MEMBER PROPERTY EUROPEAN
    1 TO 8 TABLE ST IPE500
    CONSTANTS
    MATERIAL STEEL ALL
    *
    SUPPORTS
    1 2 5 6 PINNED
    *
    LOAD 1 LOADTYPE Dead TITLE LOAD CASE 1
    SELFWEIGHT Y -1
    LOAD 2 LOADTYPE Live TITLE LOAD CASE 2
    MEMBER LOAD
    3 TO 5 8 CON GY -50
    LOAD COMB 3 GENERATED AISC GENERAL 1
    1 1.0
    LOAD COMB 4 GENERATED AISC GENERAL 2
    1 1.0 2 1.0
    LOAD COMB 5 GENERATED AISC GENERAL 3
    1 1.0 2 0.75
    LOAD COMB 6 GENERATED AISC GENERAL 4
    1 0.6
    *
    LOAD COMB 11 GENERATED AISC GENERAL 1
    1 1.0
    LOAD COMB 12 GENERATED AISC GENERAL 2
    1 1.0 2 1.0
    LOAD COMB 13 GENERATED AISC GENERAL 3
    1 1.0 2 0.75
    LOAD COMB 14 GENERATED AISC GENERAL 4
    1 0.6
    PERFORM ANALYSIS
    *
    DEFINE ENVELOPE
    1 3 TO 6 ENVELOPE 1 TYPE SERVICEABILITY
    1 11 to 14 ENVELOPE 2 TYPE STRESS
    END DEFINE ENVELOPE
    *
    LOAD LIST ENV 1 2
    *
    PARAMETER 1
    CODE AISC UNIFIED 2010
    DFF 500 MEMB 3 TO 5 8
    FYLD 248213 MEMB 3 TO 5 8
    FU 413688 MEMB 3 TO 5 8
    TRACK 2 ALL
    CHECK CODE MEMB 3 TO 5 8

    FINISH

    -Vivek

  • 0 Offline in reply to vivekshine

    I can answer the part on why the limitation has been set - In general the codes have distinct load combinations for Serviceability and Strength Limit States - this is true for all the codes I can think of - Indian, Eurocode or BS. Refer to clause 2.5 of BS 5950-1:2000 for an example.

    For the part of the said inappropriate message, we will advise the developers to put in a more reasonable one.

    Sudip Narayan Choudhury

  • 0 Offline in reply to vivekshine

    You can try the following:

    DEFINE ENVELOPE

    1 3 TO 6 ENVELOPE 1 TYPE STRESS
    1 3 TO 6 ENVELOPE 2 TYPE SERVICEABILITY
    END DEFINE ENVELOPE
    *
    LOAD LIST ENV 1 2
    *
    PARAMETER 1
    CODE AISC UNIFIED 2010
    DFF 500 MEMB 3 TO 5 8
    FYLD 248213 MEMB 3 TO 5 8
    FU 413688 MEMB 3 TO 5 8
    TRACK 2 ALL
    CHECK CODE MEMB 3 TO 5 8

    a1t.zip



  • 0 Offline in reply to vivekshine
    We do understand where you are coming from and the fact that with the way it is currently implemented, it could result in a significant amount of extra work in scenarios where the same load combinations need to be checked both for serviceability and strength. An enhancement request ( Id # 334336) has been filed asking for this to be modified.



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