FE Composites [FEA]

FE composites are utilized to merge the forces from multiple finite elements at the section's center of gravity. For example, if a Steel I Girder comprises 5 elements (2 shell elements for the deck, 1 shell element for the web, and 2 beam elements for flanges), the forces extracted from these 5 elements must be combined at the section's C.O.G for design purposes.

In influence surface-based live load analysis results for FEComposite, OpenBrIM identifies the critical vehicle position that produces the maximum force effect at the section's center of gravity (C.O.G.). Rather than employing multiple critical vehicle positions for each element and then combining the outcomes at the C.O.G., which produces overly conservative but inaccurate results, OpenBrIM utilizes only one critical vehicle position for the entire section.

Path: The starting and ending points of each result extraction location are determined using a path, which is then divided into a specified number of segments. At every result extraction station, OpenBrIM generates imaginary planes perpendicular to the path to locate the relevant finite elements.

Alignment: If the path follows an alignment, it should be selected here.

FE Group to Filter Elements & Equation to Filter Elements: There are two ways to filter the elements at a specific location. If not selected, OpenBrIM will utilize nearly every element that intersects with the imaginary plane, resulting in the entire superstructure being selected instead of a single girder. Thus, users must carefully define fegroups that specify their single non-composite or composite girder. Another method of selecting these girders is by utilizing their properties as “Filter” equation. For instance, if users desire to select all elements between Node 1 Y coordinates 10 and 20, they can input the following filter equation: (x.Node1.Y .LT. 20 .AND. x.Node1.Y .GT. 10).

# of Segments: The starting and ending points of each result extraction location are determined using a path, which is then divided into a specified number of segments.

Additional Result Extraction Stations: Additional result extraction stations can be utilized if there are other locations of interest in addition to the ones obtained by simply dividing the path's start and end locations into a specified number of segments.

Orientation: The orientation can be used to rotate the local axis of the FE composite definition.