Design Settings > Steel > Portal Frames
Note: Portal Frame design is currently only
available for Eurocode regional codes.
General
| Frame Defaults tab | |
|---|---|
|
Frame Loads |
The area loads specified here are used as initial defaults for the Dead, Service and Roof imposed loadcases when working in the 2D portal frame environment. |
| Base | The distance below the F.F.L at which the portal frame supports are created. |
|
Eaves Haunch |
The length and depth coefficients are applied to each portal frame span to determine the initial default sizes of eaves haunch in each span. |
|
Apex Haunch |
Select Generate in order to specify length and depth coefficients. These are applied to each portal frame span to determine the initial default sizes of apex haunch in each span. |
| Design Limits tab | |
| Eaves Deflection | When the portal frame is designed a
serviceability check is optionally performed at each eaves.
|
| Apex Deflection | When the portal frame is designed a
serviceability check is optionally performed at each apex.
|
| Cladding Stiffness | The percentage cladding stiffness is an allowance for the stiffening effects of the cladding that is taken into consideration in the sway checks when the design combination includes wind loads. |
| Tie (Elongation) | When a portal frame containing ties is
designed an elongation check is optionally performed at each
tie.
|
| Controls tab | |
| Axial load factor |
In certain stages of the analysis, reduced plastic moment capacity (Mpr) values are calculated allowing for the effect of axial load. The loads are taken from an initial elastic analysis of the frame and the Mpr values are then used in the elastic-plastic analysis. Plastic re-distribution will alter the member forces between those established for the elastic analysis and those for the elastic-plastic analysis. For this reason, a factor is applied to the initial axial loads prior to calculating the Mpr values. The default value is based on experience at Trimble. |
| Apply dimensional constraints |
If you want to limit the sections based on their physical size, then you can specify dimensional constraints the Limits tab, check that limit b |
| Run member stability checks at the end of design | Select this option to have member stability checks performed automatically at the end of each design run |
| Increment Sections in Design Frame Mode | When a design is run you can choose to
have section sizes incremented automatically to achieve a
pass for the following:
|
| Lamda crit limit |
The elastic critical buckling load factor, λcrit. is determined directly from an elastic buckling analysis of the frame for each design combination. If λcrit. is calculated to be less than the limiting value the design status for the design combination to set as invalid. |
Analysis
| Setting | Description |
|---|---|
| Maximum hinge rotation |
If the rotation of any hinge exceeds this limit, the analysis is halted. For further details, see:Maximum plastic hinge rotation |
| Plasticity (% of Mp) | The value entered here is used to control where plastic hinge locations are indicated on the bending moment diagram. For further details, see:Percentage of Mp for plasticity |
| Solve on open | When on, the check of all 2D portal frames is run when the model is first opened. This makes sure there are valid results for the frames without having to re-run the check. |
Fire Check
| Setting | Description |
|---|---|
| Include fire check | When included, you are then required the
boundaries (Left, and/or Right) to be checked. You also are required to specify the weight of purlins, and the combined weight of cladding and services remaining after the fire, as these are inputs for the check. |