Construction stages for composite analysis
The construction stages of a composite structure are taken into account for the entire structure at once. There are three stages in the CAM:
- construction stage: only the steel structure carries the loads; the concrete is soft, its self-weight acts on the structure, but has no stiffness
- final stage, long term: the composite structure carries the applied long term loads; the effect of creep is taken into account via a reduced apparent stiffness of the concrete
- final stage, short term: the composite structure carries the applied short term loads; there is no creep effect and the full stiffness of concrete is used
To account for those stages, only the stiffness of concrete is modified from one stage to the next one. Each load case is assigned to one of those three stages. By default, when creating the load cases:
- self-weight load cases are assigned to the construction stage
- permanent load cases are assigned to the final stage, long term
- variable load cases are assigned to the final stage, short term
| Composite stage | Description | Load cases assigned by default |
| construction stage | only the steel structure carries the loads; the concrete is soft, its self-weight acts on the structure, but has no stiffness | self-weight load cases |
| final stage, long term | the composite structure carries the applied long term loads; the effect of creep is taken into account via a reduced apparent stiffness of the concrete | permanent load cases |
| final stage short term | the composite structure carries the applied short term loads; there is no creep effect and the full stiffness of concrete is used | variable load cases |
The allocation of load cases to stages can be seen and edited in the properties of each load case:
It is also possible to see an overview of the load cases allocation via the Load cases & stages manager in the composite service:
Load cases can be moved from one stage to the other. The Automatic button resets all assignments to default, as described above.
The explanation above applies to static linear analysis. See also Nonlinear & Stability analysis of composite structures for more details.