Analysis Review

Even though the deformation patterns are similar for both linear and nonlinear analyses, the stress patterns differ. Though the horizontal loads are in opposing directions in the lug, the stress distribution in the web for the linear run are the same around both the lug holes which is not correct. This happens as all the gaps are in a closed condition for the linear analysis. Nonlinear gap analysis gives more accurate representation. The gap status, open or closed, depending on loading condition can also be observed from the .out file:

ITERATION   0
    NONLINEAR  ITERATION  SUMMARY        Subcase        1

LOAD FACTOR: 0.1000
--------------------------------------------------------------
            Nonlinear Error Measures          Gap Elem Status

ITER        EUI         EPI        EWI          Open   Closed
--------------------------------------------------------------
  1    9.9000E+01   1.1659E+00  1.1659E+00       23        25
  2    2.9097E-02   2.5218E+02  1.1274E+01       23        25
  3    8.4208E-05   1.9063E+01  1.9427E-02       22        26
  4    1.4632E-06   0.0000E+00  0.0000E+00       22        26