While analysis the cantilever portion generates the warning message, " Instability Joint" , How does it can be rectified?
furthermore i want to have some metal structure as pergolas in RCC frame ( Cantilever) can it be analysed with staad?
The free end of the cantilever should not be pinned / hinged / released, otherwise the node at the tip can spin leading to your problem. See our wiki on instability for more:
communities.bentley.com/.../ram-instability-in-finite-element-analysis.aspx
hi cgai,
can you please
attach your model?
tnx
rekcah
Dear Rekcah,
here is the model.
4520.Canitlever.zip
Dear Seth
Thanks for the reply.
yes my model also generated instability, but i am not able to find the solution.
is there any way to avoid the instability ?
Hi,
I have modified members connectivity, inorder to avoid instability in your model.
Now there is no Instability warning in your model. Download the attached STD file or Try this code:
STAAD SPACE DXF IMPORT OF MANDAI ROOF STRU.DXFSTART JOB INFORMATIONENGINEER DATE 01-Jan-02END JOB INFORMATIONINPUT WIDTH 79UNIT INCHES POUNDJOINT COORDINATES3 21264.1 0 9002.8; 4 21264.1 0 9418.8; 21 21264.1 0 9168.8;22 20910.1 0 9168.8; 23 21264.1 0 9274.8; 24 20910.1 0 9274.8;25 20910.1 0 9418.8; 26 21088.1 0 9002.8; 27 21088.1 0 9418.8;40 21264.1 100 9062.8; 41 21396.6 100 9062.8; 42 21264.1 100 9002.8;43 21264.1 100 9418.8; 46 21264.1 100 9114.02; 47 21396.6 100 9114.02;48 21264.1 100 9163.73; 49 21396.6 100 9163.73; 50 21264.1 100 9213.44;51 21396.6 100 9213.44; 52 21264.1 100 9263.16; 53 21396.6 100 9263.16;54 21264.1 100 9312.87; 55 21396.6 100 9312.87; 56 21264.1 100 9362.59;57 21396.6 100 9362.59; 58 21264.1 100 9410.8; 59 21396.6 100 9410.8;60 21264.1 100 9168.8; 61 20910.1 100 9168.8; 62 21264.1 100 9274.8;63 20910.1 100 9274.8; 64 20910.1 100 9418.8; 65 21088.1 100 9002.8;66 21088.1 100 9418.8; 67 21229.6 100 9002.8; 68 21229.6 100 9070.78;69 21196.1 100 9002.8; 70 21196.1 100 9070.78; 71 21162.6 100 9002.8;72 21162.6 100 9070.78; 73 21129.1 100 9002.8; 74 21129.1 100 9070.78;75 21095.6 100 9002.8; 76 21095.6 100 9070.78; 77 21088.1 100 9070.78;78 21264.1 100 9070.78; 79 21088.1 0 9168.8; 80 21088.1 0 9274.8;81 21088.1 100 9274.8; 82 21088.1 100 9168.8;MEMBER INCIDENCES23 40 41; 27 46 47; 29 48 49; 31 50 51; 33 52 53; 35 54 55; 37 56 57; 39 58 59;41 60 82; 43 62 81; 44 43 66; 46 66 64; 50 67 68; 52 69 70; 54 71 72; 56 73 74;58 75 76; 65 3 42; 66 21 60; 67 22 61; 68 24 63; 69 25 64; 70 27 66; 75 81 63;76 81 66; 78 82 61; 79 82 81; 80 79 82; 81 80 81; 82 26 65; 83 4 43; 85 61 64;87 42 65; 91 23 62; 95 77 76; 96 76 74; 97 74 72; 98 72 70; 99 70 68;100 68 78; 101 65 77; 102 77 82; 103 43 58; 104 58 56; 105 56 54; 106 54 62;107 62 52; 108 52 50; 109 50 60; 110 60 48; 111 48 46; 112 46 78; 113 78 40;DEFINE MATERIAL STARTISOTROPIC CONCRETEE 3.15e+006POISSON 0.17DENSITY 0.0868ALPHA 5.5e-006DAMP 0.05END DEFINE MATERIALMEMBER PROPERTY AMERICAN41 43 44 46 65 TO 70 75 76 78 TO 83 85 87 91 95 TO 113 PRIS YD 12 ZD 923 27 29 31 33 35 37 39 50 52 54 56 58 PRIS YD 6 ZD 4CONSTANTSMATERIAL CONCRETE ALLSUPPORTS3 4 21 TO 27 79 80 FIXEDLOAD 1 LOADTYPE None TITLE DLSELFWEIGHT Y -1 LIST 23 27 29 31 33 35 37 39 41 43 44 46 50 52 54 56 58 65 -66 TO 70 75 76 78 TO 83 85 91PDELTA ANALYSIS PRINT ALLSTART CONCRETE DESIGNCODE INDIANDESIGN BEAM 23 27 29 31 33 35 37 39 41 43 44 46 50 52 54 56 58 75 76 78 79 -85 87 95 TO 113DESIGN COLUMN 65 TO 70 80 TO 83 91TRACK 1 ALLEND CONCRETE DESIGNFINISH
-Vivek