Curved Members to SCI P281
Curved Members in MasterSeries - jump to 43min 30sec
Curved members, which are treated as a single structural entity within the system, undergo design checks in accordance with SCI Publication P281. Although the underlying analytical model uses a series of faceted strips or chords, the user interacts with the member as one entity.
The design process incorporates specific modifications necessary for curved sections:
- Strength Reduction: For members curved in elevation, a reduction in design strength is taken into account. This is necessary due to the additional out-of-plane flange banding as discussed in SCI P281.
- Effective Length: The system incorporates the effective length modifications specifically required for curved sections, aligning with P281.
- Lateral Torsional Buckling (LTB): The lateral torsional buckling of the curved member is addressed, with the calculation of the critical moment (M_cr) coming into play for the curved section.
- Torsion Design (Curved in Plan): The program handles the calculation of the curve for torsion even if the torsion diagram does not sum to zero. This is crucial because the SCI P281 approach for torsion design (for members curved in plan) uses a technique that differs from the normal torsion design methods derived from publications like SCI P57 (and the newer P385), which typically assume or require the torsion diagram to sum to zero for warping calculations.
Modeling Constraints
When defining curved members in the software, the following constraints apply, based on the scope of the available design guidance:
- Axis of Curvature: A curved member can be defined in elevation or on plan.
- Design Limitation: The member cannot be curved about both the major axis and the minor axis of the cross-section simultaneously, as the existing design guidance does not cover this scenario.
- Inclined Placement: Curved members can be created on an inclined plane.