Static structures (e.g. – buildings) – Frangible section or means
Patent
1984-12-04
1986-12-23
Pate, III, William F.
Static structures (e.g., buildings)
Frangible section or means
52 40, 404 10, E01F 901
Patent
active
046304134
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a post, primarily intended for traffic signs and lighting and the like and of such construction as to offer little resistance when struck by a vehicle.
It is previously known to manufacture posts for the above purpose, the construction of which is such that the posts under normal conditions, like a conventional tube pole, carry the sign and have resistivity to transient load, i.e. essentially wind load, but will yield when subjected to transverse load over a predetermined magnitude.
(b) Description of the Prior Art
A common type of prior art posts with reduced resistance to impacts has a fracture indication in the region where the post is anchored to the foundation. When such a post with sign is being run into it is forced into rotation about its centre of rotation without any translation velocity worth mentioning having been produced, with the consequence that there is a great risk that the post and sign will smash down the car wind-shield at a high relative velocity.
SUMMARY OF THE INVENTION
The essential characteristic of the post according to the invention is that the post consists of a polygonal hollow profile of metal in which each of the sides is relatively rigid in the transverse sense and joined with adjacent sides by portions which are weakened by attenuation of material.
An embodiment of a post in accordance with the invention will be described more fully below with reference to the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-section through a post according to the invention;
FIGS. 2 and 3 are cross-sections of a post along a plane on level with the point of impact in two successive moments;
FIG. 4 is a side view of a portion of the post having the cross-section indicated in FIG. 1;
FIGS. 5 and 6 show the same portions after they have been struck by a vehicle and been deformed as indicated in FIGS. 2 and 3.
In the preferred embodiment according to the invention the post consists of a hexagonal hollow profile of extruded metal, preferably light metal. Also other shapes than hexagonal ones may be used. The essential point is that two side portions on either side make such an angle with one another that they will buckle together when the post is run into.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the preferred embodiment there are two sides 1 and 2 which are localized at right angles to the direction of travel of any striking vehicle and these two sides are joined with one another by two pairs of outwardly inclined sides 3a, 4a and 3b, 4b respectively.
All the sides are joined with each other via weakened corner or edge portions formed of internal grooves 5 and 6.
When it is desired to have a more stable post for carrying a large sign it is possible, in order to permit interconnection of several posts in cooperation, to provide the two first-mentioned sides 1 and 2 with a notch 7 and a tenon 8 to guide posts which are joined together by wrapping bands, glueing or by some other appropriate means. An additional post is indicated by dashed lines in FIG. 4.
As long as the post is intact the interconnected sides coact in a normal manner.
When, on the contrary, the post is run into it will be deformed in the way shown in FIGS. 2-3 and 5-6 respectively.
When the side 1 is hit by the bumper of a car it will be pressed in towards the side 2 because the connections at the grooves 5 and 6 are weaker than the remaining material and this will lead to displacement and turning of the sides 3a, 4a and 3b, 4b while the material at the grooves 5 and 6 is subjected to a very strong relative tensional strain which rapidly results in a fracture which, in case the grooves have been made by cold rolling or pressing, is brittle and instantaneously progressive. As the cross-sectional extent of the post, as seen in the direction of travel, will rapidly diminish, the section modulus or bending resistance of the post will immediately be reduced. The section modulus of the post in intact c
REFERENCES:
patent: 4061435 (1977-12-01), Schmanski et al.
patent: 4196550 (1980-04-01), Svensson
patent: 4236843 (1980-12-01), Chisholm
patent: 4378175 (1983-03-01), Hasselqvist et al.
LaKemper Jean M.
Pate III William F.
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