Example Description

This example tests this model non-prismatic frame section property. In this model the axial (A), torsion (J), weight, and mass properties can vary linearly, and the bending property (I) variation can be linear, parabolic or cubic. The variation of the moment of inertia is defined in this model as follows:

where, n = 1 for linear variation,

n = 2 for parabolic variation

n = 3 for cubic variation

The example model consists of a complex, non-prismatic frame section that is made up of four segments, assigned to a cantilever beam, and subjected to seven load cases, each with a different type of loading. An applicable deformation component at the free end of the cantilever is compared with independent hand calculated results for each load case.
Important Note: Only bending and axial deformations are considered in the analysis. Shear deformations are ignored. In this model is achieved by setting the property modification factor for shear area to 0.
This example also tests the frame automatic subdivide feature of this model. The automatic frame subdivide option internally divides the frame object into a userspecified number of elements for the analysis. The analysis results are combined and reported for the entire frame object, not the subdivided elements.
In this example two models are run. Model A has no automatic subdivision. Model B has automatic subdivision that divides the frame object up into 10 equal length elements. The results are compared for each model.

Tested Features

Structural behavior of a non-prismatic frame section

Self weight calculations

Linear variation of section area

Linear, parabolic and cubic variation of moment of inertia

Linear variation of section torsional constant

Automatic frame subdivision

Results Comparision

App Link:

https://openbrim.org/objid8dej8tlyngqy3jh490hn0r.project

LibraryLink:

https://openbrim.org/objidx2lkhjbet400hk02x2y7hwa.libobj

Load Case	Output Parameter	OpenBrIM	SAP2000	Independent	Percent Difference (SAP2000 vs Independent)	Percent Difference (OpenBrIM vs Independent)
1	My (fixed end)k-in	-185.00399	-184.95	-184.95	0%	0.02918%
2	Ux (free end) in	0.09081	0.0909	0.0909	0%	0.10179%
3	Uy (free end) in	0.43227	0.4312	0.4312	0%	0.24809%
4	Uz (free end) in	-0.14734	-0.1434	-0.1434	0%	2.6734%
5	Rx (free end) rad	0.08038	0.0799	0.0799	0%	0.59758%
6	Ry (free end) rad	0.03763	0.0374	0.0374	0%	0.60609%
7	Rz (free end) rad	0.07567	0.0763	0.0763	0%	0.82189%

Browser not supported