> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/openbrimfea/live-load-fea/influence-line-analysis-on-felines-fea.md).

# Influence Line Analysis on FELines \[FEA]

Runs an influence-line analysis by marching a unit load along a path of finite-element lines and recording the response at every placement. The resulting influence lines drive the live load envelopes used in design.

## Path

**Path Points:** Points defining the path the unit load travels along.

**FELines:** The finite-element lines the unit load is applied to as it moves along the path.

**Pier Locations (For two truck cases):** Pier stations used to position the second truck in the two-truck (negative moment) load cases.

**Alignment:** Alignment the path stations are measured against.

## Lanes

**Design Lane Option 1:** First design lane arrangement considered in the analysis.

**Design Lane Option 2:** Second design lane arrangement considered in the analysis.

**Design Lane Option 3:** Third design lane arrangement considered in the analysis.

**Design Lane Option 4:** Fourth design lane arrangement considered in the analysis.

## Unit Load

**Placement Increment:** Distance the unit load advances between successive placements along the path. Smaller increments give a smoother influence line and cost more solve time (default: 12).

**Unit Force X:** X component of the unit load (default: 0).

**Unit Force Y:** Y component of the unit load (default: 0).

**Unit Force Z:** Z component of the unit load. The default of -1 applies a downward unit force (default: -1).

**Unit Moment X:** Unit moment about the X axis (default: 0).

**Unit Moment Y:** Unit moment about the Y axis (default: 0).

**Unit Moment Z:** Unit moment about the Z axis (default: 0).

## Centrifugal

**Centrifugal Fact. for Radial Force::** Centrifugal factors applied to the radial force component, entered per path region.

**Centrifugal Fact for Left Wheel:** Centrifugal factors applied at the left wheel, entered per path region.

## Settings

**Run on Construction Stage\[NO=0/YES=1]:** When YES, the influence-line analysis is run on a specific construction stage rather than on the final structure (default: NO=0).

**Construction Stage:** The construction stage the analysis is run on. Applicable when Run on Construction Stage is YES.

**Group:** Finite-element group the analysis is restricted to.


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