ADINA News Group

ADINA Substructuring in Dynamic Analyses with Local Nonlinearities

In the News of March 30, 2007, we demonstrated the solution efficiency of the ADINA substructuring capability in a static analysis when the analysis involves only local nonlinearities.

In this issue, we perform a dynamic analysis using ADINA 8.4.4(*) with substructuring of the building frame model with the local nonlinearity shown in the March 30 News.

As in the static analysis, the only nonlinearity in this large system is due to the frictional contact between the building and its foundation. A horizontal dynamic load is applied at the bottom of the foundation. Hence, as in the static analysis, most of the building structure can be modeled using a substructure.

The above movies show the response. On the left the complete structure is shown and on the right only the substructure is considered (with the displacement response magnified).

The solution statistics in the table below show that the savings in memory usage and solution time by use of substructuring are very significant. Almost one order of magnitude reduction in solution time is seen.


Substructuring No. of equations Memory used Memory usage reduction factor Solution time (40 steps) Solution time reduction factor
No

Yes
487,137

487,137
2,016 MB

370 MB
-

5.5
462 min

50 min
-

9.2


An important and unique feature of the ADINA substructuring in dynamics, as well as in statics, is that the same results as without substructuring are obtained in linear analysis and in a nonlinear analysis, like here. Differences in nonlinear analysis arise only due to convergence measures in the Newton-Raphson iterations.

In the following graph, the time history plot of the transverse displacement at the top of the building is given, obtained with and without substructuring.

Hence, it is seen that the ADINA substructuring capability is a simple, flexible and effective modeling option that is also useful for the analysis of nonlinear dynamic problems in which only local nonlinearities are present.


(*)
 
For our users, please request this latest version of ADINA if you want to use this capability.

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