GB2541633A - Columns - Google Patents

Abstract

A tubular column (8, Figure 1) includes an inspection opening 10 formed in one of its sides and an internal expanded press fitted tube 14 positioned within the column in the vicinity of the inspection opening. The tube 14 is mechanically secured to the column at locations above and below the opening such as by shear pins, rivets or the like 16. The mechanical securing may be by equally spaced shear pins 16 above and below the opening. The column may be used to support lighting units, security cameras, traffic signals and signs.

Description

COLUMNS

This invention relates to tubular columns and more especially to columns for supporting such items as lighting units, security cameras, traffic signals and signs .

BACKGROUND TO THE INVENTION

Most columns which support such items as lighting units, security cameras, traffic signals, signs or the like include an inspection door in one side for inter alia monitoring the condition of such items as electrical wiring housed within the column. In order to strengthen a column at a door opening section of the column, it has been proposed in GB patent 1,413,334 to locate an expanded press fitted tube within the door opening section of the column to increase the bending capacity (but not the torsional capacity) of the combined section.

It has been found that whereas the pre stress reinforcement achieved by the presence of such internally located expanded press fitted reinforcement tubes generates some frictional resistance through which torsional loads can be transferred, the relevant standard (BS EN 40-3-3:2013 lighting columns part 3-3 : design and verification - verification by calculation) requires that any transfer at ultimate limit state is to be disregarded.

Columns in accordance with the invention have the advantage that they benefit from the full torsional capacity of a reinforced section and that this benefit can be included in the design of the column thereby increasing the structural capacity of a conventional lighting column by between 10 and 20%.

SUMMARY OF THE INVENTION

In one aspect, the Invention provides a tubular column which includes an inspection opening formed in one of its sides and an internal expanded press fitted tube positioned within the column in the vicinity of the inspection opening, the press fitted tube being mechanically secured to the column at locations above and below the opening.

The press fitted tube may be secured to the column by pins, rivets or the like.

In a preferred arrangement the press fitted tube is secured to the column above and below the inspection opening by a plurality of equally spaced shear pins. Typically, three equally spaced shear pins are positioned above and below the opening. For high torsion columns, the number of shear pins required may well be more than three .

BRIEF DESCRIPTION OF THE INVENTION

One embodiment of my invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which:-

Figure 1 is a side view of a lighting column In accordance with the invention in which that part of the column which includes an Inspection opening is shown in section;

Figure 2 is an enlarged view of that part of the column shown In Figure 1 which includes the inspection opening;

Figure 3 is a side view of a press fitted tube positioned within the column and shown in broken line in Figure 2; and

Figure 4 is a cross section taken along line "A-A" of Figure 2.

The tubular lighting column (8) illustrated in the drawings is typically produced from aluminium and includes an inspection opening (10) which is normally closed by a lockable door (not shown). Electrical cabling (12) which connects lighting units, security cameras, traffic signals, signs or the like supported by the column to a source of mains electricity is shown positioned within the column. Positioned also within the column in the vicinity of the inspection opening (10) is an aluminium press fitted tube (14) which engages tightly against the internal surface of the column. The function of the press fitted tube is to increase the bending capacity of the column in the vicinity of the inspection opening.

The press fitted tube (14) is physically secured to the column by shear pins (16) positioned above and below the door opening (10) . The shear pins act to transfer torsional loads between the column and the press fitted tube. Thus, the full torsional capacity of the column section reinforced by the press fitted tube can be included in the design of the column thereby significantly increasing the structural capacity of the column.

Trials of columns in accordance with the invention indicate that the structural capacity of such columns is increased by between 10 and 20% by the seemingly simple expedient of employing mechanical pins or rivets above and below the inspection opening which anchor the press fitted tube (14) to the column (8) and provide a physical connection between the column and the press fitted tube. This increase in structural capacity can be employed inter alia to reduce the size of the column base thereby providing a significant saving in material.

It will be appreciated that the foregoing is merely exemplary of columns in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention.

Claims (5)

1. A tubular column which includes an inspection opening formed in one of its sides and an internal expanded press fitted tube positioned within the column in the vicinity of the inspection opening, the press tube being mechanically secured to the column at locations above and below the opening.

2. A column as claimed in claim 1 wherein the press fitted tube is secured to the column by pins, rivets or the like.

3. A column as claimed in claim 1 wherein the press fitted tube is secured to the column above and below the inspection opening by a plurality of equally spaced shear pins .

4. A column as claimed in claim 3 wherein three equally spaced shear pins are positioned above and below the opening.

5. A tubular column substantially as herein described and as described herein with reference to the accompanying diagrammatic drawings.