General Information

Tube Struts are an anti sag component available in various types depending on the end connection. They are fitted between ProSigma+ or Cee members as shown in the image above and help resist the compressive forces exerted by the cold-rolled sections.

The range of possible applications within a structure is vast however all use the connection details, or variations thereof, outlined in the Applications and connection configurations later on this page. For recommendations on the appropriate use of Tube Struts and guidance on the selection of suitable anti sag systems in general please refer to Anti Sag Systems.

Types of Tube Strut

There are 3 distinct types as shown in the diagram below. They are distinguished by the type of end connector. The most commonly used is the DP-TS which may be used with either ProSigma+ or Cee sections and with all section depths except the 145  ProSigma+. For this section the DP-TS145 is exclusively used in conjunction with the Tube Strut spacer. The standard DP-TS will not fit this section due to the narrow central web. The final type is the DP-TSFF which is designed to provide a Tube Strut connection to counterformed members allowing the provision of a flush finish on the outer surface of counterformed Cee sections.

Tube Struts are a bespoke component made to suit conditions on site and as such are fabricated to whatever length is required. Attention is drawn to the “LENGTH” dimension for each type as indicated above. This is normally 2mm less than the cold-rolled centres however for the DP-TS145 this is increased to 12mm to accommodate the Tube Strut spacer. In physical terms Tube Struts may be supplied in lengths limited only by the available length of tubing however it must be stressed that buckling capacity reduces considerably as length increases. Users should refer to the section on Load Data before specifying this product. This contains data verified by testing and in accordance with EN1993-1-3.

The DP-TS is the most commonly used Tube Strut and is shown in the diagram above. The male end passes through a 14mm hole in the cold-rolled member and screws into the adjoining Strut. It is orientated so the male end is at the bottom which allows easier connection with Tie Ropes. The Connection detail at Bottom of Run illustrates the use of Tie Ropes as part of a Tube Strut connection.  

The DP-TS145 has an extended spigot to accommodate the Tube Strut Spacer (DP-SP145) (shown in red in the image above). This arrangement is necessary due to the narrow web width. The strut is orientated so the male end is at the bottom to allow easier connection with Tie Ropes. (Refer to the Connection detail at bottom of run (DP-TS145 only) for further detail). Care should be taken to make allowance for the width of the spacer (10mm) when itemising lengths for order. 

The top end of a run of Tube Struts is secured with an M12 bolt and washer. This arrangement is the same irrespective of the type of Tube Strut used. Note: Countersunk head bolts may be used in certain circumstances where a flush finish is required. Details are outlined in the sections Tube Strut connection to counterformed members and DP-TSFF Connection detail.  

Clamp Plates are used at the bottom of a run to help counter the effects of any concentration of load that might occur where Tube Struts are applied. An example is shown in red in the image above and one is recommended at the bottom end of every run. Clamp Plates cannot be used with the 145 ProSigma+ as the web is too narrow. The Connection detail at bottom of run (DP-TS145 only) outlines an appropriate detail for this case.

Each run of Tube Struts for the 145 ProSigma+ section should be finished using a Tube Strut Spacer (DP-SP145) as shown. Clamp Plates are too wide to fit into the web of this section. A nut and washer secures the joint.

It may be desirable in certain circumstances to use Tube Struts with counterformed Cee sections. The image above illustrates such a case. The female end of any Tube Strut has a machined recess to allow it fit over a counterform. The "LENGTH" as indicated in the diagram above need not be amended. More details on the process of counterforming are available by referring to the Counterforming section of the ProSigma+ Customisation page.

The DP-TSFF Tube Strut may be used in circumstances where a flush finish is required at both ends of a run of Tube Struts. An example of a typical application is shown in the image above. The DP-TSFF has female type inserts either end and these fit over counterformed holes in the cold-rolled member as described in the section Tube Strut connection to counterformed members. In the example shown a single strut only is used however this type could equally be used as the last member in a run of standard Tube Struts (DP-TS) where flush ends are required.  

Load data

Duggan Profiles Tube Struts have been tested to EN1993-1-3 to determine their range of use. Tube Struts resist axially applied compressive loadings and are therefore prone to buckling if the critical buckling load is reached. The load which may be safely applied varies with length and the table below outlines safe working loads for a variety of lengths. The same values apply irrespective of the type of Tube Strut used. The lengths indicated correspond to the “LENGTH” dimension indicated in the diagram in the Types of Tube Strut section above.  

How to order

Product codes are used to uniquely identify all products and these should be used when ordering. The code for each type of strut along with a drawing and CAD file are included in the table below. The quantity required along with the length as indicated on the drawing must also be provided. Clamp Plates and Tube Strut Spacers if required must also be ordered as none are supplied automatically.

Note: If using ProSigma+ 145 sections the DP-TS145 must exclusively be used as other types will NOT fit this section. The required length is the Cold-rolled centres – 12mm and 1 Tube Strut Spacer per strut is required.