Definition of composite beams

Composite beams are to be defined as standard plate ribs. They may also be created using a ribbed plate 2D member, which includes the definition of the ribs. A few properties will then specify the beam as composite.

Type of connection

this property is visible only when the CAM is enabled. There are 4 possible values:

with standard composite action applies a composite cross-section to the plate rib without eccentricity on the 1D member; this has the advantage that it does not create parasite axial forces in the model; for details "Composite Analysis Model - Theoretical background"

with advanced composite action uses a standard eccentric plate rib, without adjustment of the cross-section; the composite effect is taken into account directly through the real eccentricity of the 1D member in the finite element model; this will, however, generate axial forces in both the beam and the deck

without composite action assumes that there is no longitudinal shear connection between the beam and the deck; it is taken into account by means of a plate rib without eccentricity using the selected beam cross-section without adjustment

user-defined eccentricity corresponds to a standard plate rib; it will not allow using composite functionalities on that beam; additionally, any plate rib linked to a non-composite deck will use this setting

Connection

this property is visible only for a type of connection with standard composite action; it allows to define the degree of shear connection between the beam and the deck. The possible values are:

default: the actual connection type is defined in the composite setup

full: this assumes a perfect shear connection between the beam and the deck

partial: this assumes a partial connection between the beam and the deck

Degree of connection

this property is visible only for a type of connection with standard composite action; it defines the actual degree of connection between the beam and the deck.

Only in case of a partial connection, the degree of connection may be defined here. Otherwise, this property is read-only. The default value of the degree of connection is defined in the composite setup.

Alignment

For all composite types of connection, the alignment is read-only and configured automatically according to the selected type of connection. It is centreed for standard and without composite action; it is bottom for advanced composite action.

For user-defined eccentricity, the alignment is defined by the user.

Effective Width

Effective width is a standard property of plate ribs in SCIA Engineer. It is used for several purposes in a usual analysis model. There are two sets of values defining the effective width of a plate rib:

It is important to note, that none of the above affects the stiffness of the system. Modifying the effective width does not modify the properties of the cross-sections in the analysis model.

 

There is however an important difference when using the Composite Analysis Model, which uses the effective width in a third way:

Important: unlike in all other cases, in a plate rib with standard composite action, the effective width affects the stiffness of the beam

 

The effective width of a plate rib may be defined manually or automatically. Available properties can be found in " Rib in the slab".

Detailed information about the automatic calculation of effective width can be found in "Automatic calculation of the effective width of plate ribs"