Prestress

Prestress loads can be thought of either as prestress forces, tendon prestress applied to the element or an initial strain. The tendon prestress option allows for the prestress to be offset by a constant distance from the centre of the element in the thickness direction to induce bending.

The prestress or initial strain is applied in either the local x or y direction or in both directions.

An element with a positive prestress tends to contract, as in a prestressed slab.

Definition

Name

The name is only used as a convenient way of identifying a load. Optional.

2D Element List

This specifies a list of 2D elements to load using any one of the forms detailed in “Lists”. The list may be a single item.

In sculpt: The 2D element list is set to the 2D elements in the current selection set. The 2D element list cannot be edited in the dialog.

Load Case

The load case in which the load applies. The load case gives a way of grouping load effects together.

Type

The user has a choice of the type of loading applied to the elements.

• Prestress force – an in-plane force applied to the element
• Initial strain – an initial in-plane strain is specified in the element
• Tendon prestress – an in-plane force is applied to the element at an offset from the neutral axis. Only the latter option induces forces and moments in the element.

Direction

The direction in which the load applies in element local axes. This can be x, y or both x and y directions where x and y are element local directions.

Prestress Force

The prestress force (load per unit length) to apply to the element.

Initial Strain

The initial strain in the element.

Tendon Prestress, Offset

The prestress force (load per unit length) and offset (in the local z direction) to apply to the element. When the offset is specified the element is loaded by an in-plane force and a moment.