Rigid Tie Rods Arrangement and Function in Portal Frame Structures

I. Mandatory Locations for Rigid Tie Rods

II. Coordination Between Rigid and Flexible Struts

Each temperature zone must form an independent stable system;

Braced bays must be equipped with rigid struts;

Intermediate unbraced bays may use flexible struts (tension-only members) to save steel weight.

III. Primary Function of Rigid Tie Rods (Load Path)

Load transfer path:

Gable wind load / Longitudinal seismic load / Crane longitudinal horizontal force

→ Rigid struts

→ Vertical bracing / Roof bracing

→ Foundation

In short: Rigid struts primarily carry and transmit all types of longitudinal horizontal loads (longitudinal forces).

IV. Mechanical Differences Between Rigid and Flexible Struts

V. Additional Design Notes and Practical Tips

1.Rigid struts often serve double duty as compression members in roof bracing systems. Their slenderness ratio must comply with code limits (typically λ ≤ 200 or stricter, depending on the design code version);

2.For long temperature zones, rigid struts should run continuously throughout the entire zone without interruption;

3.When steel rod flexible struts are used, turnbuckles should be provided for tensioning to ensure proper functionality;

4. In practice purlins may double as rigid struts, provided that:

The section satisfies compressive stability requirements;

Connections are capable of transmitting axial forces effectively;

Such purlins are treated as "strut-purlins" with reinforced connections;

5.Longitudinal load transfer between gable wind columns and frame column tops also relies on rigid struts;

6. In crane buildings,the longitudinal rigid struts at the crane beam top flange should be placed as close as possible to the crane beam top flange elevation for more direct transmission of crane longitudinal forces.

Rigid struts form the "structural backbone" for longitudinal force transfer in portal frames. They are mandatory in braced bays and at critical elevations, while flexible struts can be used economically in unbraced intermediate bays.

For more information needed or any inquiry,please feel free to contact Yumisteel team.