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

Question

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

Surojit Ghosh · Answer

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

DSANJU · Answer

There has been an update in the program to specifically impel the users to create two different type of envelops- Service and Strength to cater two different aspect of design- deflection checking with Service Envelop and member design using Strength Envelop. This provides a clear vision on design aspect.

DSANJU · Answer

You need to create two different envelops- one for strength and another for service. Service load envelop is to be used for deflection check and Strength load envelops are to be used for member design where you will find the stress checking. 
 Please have a look into the following: 
 communities.bentley.com/.../92764 
 communities.bentley.com/.../23987.serviceability-and-strength-check-for-the-same-load-combination

Sye · Answer

I have attached a modified file with SERVICE and STRENGTH envelopes which has subsequently been used to do a CODE CHECK. 
 Here are some points which should be noted. 
 1. For both service and strength and checks to be carried out, you have to have 2 separate envelopes. In the attached model, you will find 2 separate envelopes namely service ( cases 101 to 107 ) and strength ( cases 201 to 207 ). 
 2. The LOAD LIST ENV 1 2 has been used just before the design so that the design accounts for both envelopes during design. 
 3. DFF has to be specified as part of the design parameters if deflection check is to be carried out. This is in addition to defining the service envelope. Since you specified DFF for members 3 10 and 13, the deflection check will be carried out for these members only. If you need to check other members for deflection, specify DFF for those too. 
 4. Since you need the same combos to be checked for service and strength (ASD), you need to add the combos 201 to 207 which are basically same load combos as 101 to 107 but still needed as STAAD.Pro cannot consider same load combos for both service and strength envelopes. 
 I hope this helps. 
 2330.Structure1_rev.std

DSANJU · Answer

You have created Service and Strength envelop with the same load case / combination. Please refer to the attached model. 
 
 2465.a1.std

Rajat · Answer

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.

DSANJU · Answer

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

Sye · Answer

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.

Sye · Answer

I think you are using an older version of STAAD.Pro. I vaguely remember that there was a discrepancy with reporting the critical load case for deflection in some earlier version. Try with the latest 20.07.11.70 version and you should not have this issue. I checked with 20.07.11.70 and the critical load case reporting seems consistent.

Sye · Answer

The following wiki should be a one stop shop for all verification documents related to the AISC 360 implementation in STAAD.Pro 
 
 communities.bentley.com/.../28192.staad-pro-verification-documents-related-to-aisc-360-specifications

Sye · Answer

We investigated the issue and found that deflection check as per AISC 360, IS 800, S16-14 codes are always reporting last load case in the serviceability envelope as critical load case for deflection check. The design however is correct and reports the correct critical ratio. It is just the reporting of the critical load case which is incorrect and that too when deflection governs. So for any design where deflection is not the governing criteria, this reporting error does not have any effect. This error is found to exist in version 20.07.11.70 and will affect versions 20.07.11.50 and 20.07.11.33 too. It will be addressed in STAAD.Pro SS6 SP3 version scheduled for release in Q2 of 2016. The issue is now reported with id# 438681 at 
 
 communities.bentley.com/.../22866.known-issues-in-staad-pro-ss6

Sye · Answer

Ok sure. Will do. Also just wanted to inform you that whenever we release a new version of STAAD.Pro, the news is published in the STAAD News section that you see when you start up STAAD.Pro as shown next

Sye · Answer

We investigated the issue and found a bug that is causing the incorrect deflection check in this case. This has been logged with id# 460624 and will be fixed in the release of STAAD.Pro SS6 SP3 coming out at the end of June 2016. 
 
As a temporary workaround, for the second set of design in your file dealing with serviceability, you may use the CODE AISC instead of the CODE AISC UNIFIED which would invoke the AISC 9th edition code for checking the deflection. As far as deflection checking is concerned, it should be the same for both codes. However we are getting the issue addressed in the AISC 360 UNIFIED code with top priority.