Beam Influence Effects

Beam Influence effects can be defined here for use in an influence analysis. The effect of a moving load will be found for any of the following situations:

• Displacement, rotation, force or moment in the specified direction at the specified position on any single beam element.

The total effect is the sum of the factored individual effects. Note that only the Effect columns in the Static Bridge Loads table will be affected in this way. The total effect is used to find the critical load pattern but the magnitude of the loads (and so of the moments and forces produced by analysing them) is independent of the effect factors.

Definition

Name

The name from the first line with a given effect number is used to identify the effect. Names from subsequent lines with the same effect number are ignored.

Effect

The effect number will normally be the same as the line number, unless the user chooses to combine effects (for example to maximise the sum of the bending moments from a series of elements across the width of a deck).

Beam

The beam number where the effect is to be calculated.

Position

The point on the element where the effect is to be calculated.

Factor

The effect to be calculated can be factored, but will normally be 1. Non-unity factors can be used to combine effects (e.g. to maximise the average moment either side of a node, two effects with factors of 0.5 could be used), but note, this is an advanced feature.

Type

• Displacement – element displacement will be optimized.
• Force – element force or moment will be optimized.

Direction

The direction, in the beam local axis, to be used for calculation.

Note: As the number of analysis cases in the bridge analysis task depends on the influence effects, the editing of influence effects will be disabled if there is a bridge analysis task.