DIRECT METHOD ANALYSIS - GENERAL

RE: DIRECT METHOD ANALYSIS - GENERAL

Karthik M — Mon, 16 Mar 2020 01:23:00 GMT

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

RE: DIRECT METHOD ANALYSIS - GENERAL

jeevan hingne — Wed, 27 Mar 2019 13:57:13 GMT

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

RE: DIRECT METHOD ANALYSIS - GENERAL

jeevan hingne — Wed, 27 Mar 2019 13:57:03 GMT

PERFORM DIRECT ANALYSIS LRFD ITERATION 15 TAUTOL 1 DISPTOL 0.0001
FINISH

RE: DIRECT METHOD ANALYSIS - GENERAL

Carlos Aguera — Mon, 15 Aug 2016 13:23:05 GMT

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.

RE: DIRECT METHOD ANALYSIS - GENERAL

Grace Shen — Mon, 29 Jun 2015 19:29:09 GMT

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

Re: DIRECT METHOD ANALYSIS - GENERAL

eugene afable — Tue, 23 Jul 2013 11:43:16 GMT

What I did I follow directly according to the original example of AISC example C1.A

I got Mz=135.358 ft-kips. A very significant difference from AISC example.

STAAD PLANE

START JOB INFORMATION

ENGINEER DATE 22-Jul-13

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 2 4; 3 3 4; 4 4 6; 5 5 6; 6 6 8; 7 7 8; 8 8 10; 9 9 10;

MEMBER RELEASE

2 6 8 START MY MZ

2 6 8 END MY MZ

DEFINE MATERIAL START

ISOTROPIC STEEL

E 4.176e+006

POISSON 0.3

DENSITY 0.489024

ALPHA 6e-006

DAMP 0.03

TYPE STEEL

STRENGTH FY 5184 FU 8352 RY 1.5 RT 1.2

END DEFINE MATERIAL

MEMBER PROPERTY AMERICAN

1 3 5 7 9 TABLE ST W12X65

2 4 6 8 TABLE ST W18X40

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 3 5 7 9 PINNED

DEFINE REFERENCE LOADS

LOAD R1 LOADTYPE None TITLE REF LOAD CASE 1

*SELFWEIGHT Y -1

MEMBER LOAD

2 4 6 8 UNI GY -2.4

END DEFINE REFERENCE LOADS

DEFINE DIRECT ANALYSIS

FLEX 1 LIST 4

AXIAL LIST 3 5

NOTIONAL LOAD FACTOR 0.002

END

LOAD 1 LOADTYPE None TITLE LOAD CASE 1

REFERENCE LOAD

R1 1.0

NOTIONAL LOAD

R1 X 0.002

LOAD 2 LOADTYPE None TITLE LOAD CASE 2

REFERENCE LOAD

R1 1.0

NOTIONAL LOAD

R1 X -0.002

PERFORM DIRECT ANALYSIS LRFD ITERATION 10 TAUTOL 0.01 DISPTOL 0.001 -

PRINT LOAD DATA

FINISH

Re: DIRECT METHOD ANALYSIS - GENERAL

Giorgio Figari — Thu, 14 Mar 2013 14:04:05 GMT

Thank you very much RKillian for your post.

I was in doubt since it was the first time I was using Staad Direct Method, so I needed some confirmation.

Considering what you wrote, it seems that the procedure was correct, so I agree with you wedefinately need to get to the bottom of this because that's a significant difference.

I will wait for any other user that could help, in the meantime i will try to get in deep with this issue.

Re: DIRECT METHOD ANALYSIS - GENERAL

Tank — Tue, 12 Mar 2013 19:39:03 GMT

The only minor thing I found is you used a young's modulus a little higher than 29000 ksi. Probably because you've got STAAD set up to use metric and they don't use the exact same value for E between Imperial and metric. When I changed this I got 0.148 inches of first order deflection vs. 0.149" in the example. I stil didn't get AISC's values for bending, even in the first-order case. Very odd. There must be a difference in stiffness between the two models but AISC doesn't give us enough info to check what they actually used for the moment of inertia.

Does anybody have acces to another program this can be checked with?

One other minor thing, if you change this to a PLANE model instead of SPACE you will get rid of your warnings.

Anyway, where AISC is getting 149 k-ft moment, I'm getting 127 k-ft. About 17% less. We definately need to get to the bottom of this because that's a significant difference.