| Applies To | |||
| Product(s): | STAAD.Pro | ||
| Version(s): | 20.07.09.31 | ||
| Environment: | N/A | ||
| Area: | Modeling | ||
| Subarea: | Curved Beams | ||
| Original Author: | Modestas Turulis, Bentley Technical Support Group | ||
The following are some of the limitations or features not supported with curved members:
Tapered section properties
Composite decks
PRIS ROUND sections
Beta angle
Member releases, global or tangent
Member Springs
Member offsets
Member end springs
Physical members
Member Tension/compression
Any span loads except "Uniform load throughout the length in global directions", such as:
Member Loads - UMOM, CON, CMOM, LIN, TRAP
Area Load, One Way, Floor Load
Wind Load, Prestress, Poststress
Temperature load, Strain
Fixed End Load
Snow Load
Moving load
Imperfections
Geometric stiffness, Pdelta, buckling, Pdelta KG with/without dynamics
Mass for dynamics will not include the effect of the member cg being off the chord line
Intermediate section displacements, and hence the deflection diagram
Intermediate section forces, and hence the bending moment and other forces diagram
Steel or concrete design at any location other than nodes
Member selection
Weld design
*Limitations faced with curved beams in designing:
It is not advisable to perform steel design on curved members using STAAD. The reasons are :
1) The design codes are written for straight members, not curved ones. The rules in most standard design codes do not adequately address the peculiarities of curved members. LY and LZ for example in the KL/r checks are the straight line distances between the bracing points of a straight member. To use those rules on curved members without adjusting for the curvedness may not be correct. An out of plane load on a curved member causes major torsional moments, but most codes only discuss axial forces, bending and shear, not torsion.
2) STAAD can calculate the member forces only at the nodes of curved members. It cannot calculate them at intermediate span locations. Consequently, during steel design, these members will be designed for the forces at their ends only. Intermediate section points within the span cannot be designed.
3) STAAD can calculate the displacements at the nodes of curved members. It cannot calculate them at intermediate span locations. Consequently, deflection check cannot be performed for curved members.
Due to all these limitations, modeling the curved beams using a series of straight segments might be a better option.