Tubular structural member with non-uniform wall thickness

Abstract

A tubular structural member has substantially constant cross-sectional size and configuration along its length between its opposite ends. The member has a pair of parallel oppositely aligned flat areas in its exterior surface. The member has substantially uniform wall thickness except in a selected portion of each the opposing areas where the member's wall thickness is a selected amount greater than the uniform wall thickness. The increase wall thickness preferably is manifested in the interior of the tubular member. The cross-sectional area of the member can have orthogonal neutral axes, and the exterior dimension of the member along one of those axes can be greater than the exterior dimension of the member along the other of those axes which is normal to the exterior flat areas; the amount and distribution of the thickening of the member's walls over the uniform thickness can be defined to cause the section modular of the member about each of the neutral axes to be substantially equal.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a division under 35 U.S.C. § 120 of co-pending application Ser. No. 11 / 525,721 filed Sep. 22, 2006, and claims the priority of only that Application and not the priority of any application filed before application Ser. No. 11 / 525,721.FIELD OF INVENTION [0002] This invention pertains to tubular structural members. More particularly, it pertains to tubular structural members having non-uniform wall thickness having particular utility in pinned connections. BACKGROUND OF THE INVENTION [0003] A space frame is a network of structural framing members, such as tubes, interconnected at multi-member connection points (commonly called “nodes”) in such a way that the whole structure behaves as one structural element. By contrast, in the typical framing of beams and columns, as in buildings, structural elements often act independently of each other and can have completely separate force paths. [0004] Two broad classes of space fr...

AI Technical Summary

Benefits of technology

[0106] Many benefits and advantages are afforded by this invention and its aspects and features described above. The node connectors enable certain chords of a DLG space frame to extend continuously though them. The node connectors can be used with space frame framing members of substantially any cross-sectional configuration desired; they are not limited to use with members having round or rectangular cross-sections. Node connectors and framing members can be extruded for low cost and dimensional precision. Node connectors and framing members can be made of materials having uniform metallurgical properties so that, among other benefits, space frames incorporating them are little affected dimensionally by temperature changes. The node connectors enable framing members of differing numbers, size and cross-sectional configuration to be effectively interconnected at a given node in a space frame. The node connectors can be defined to enable good, even ideal, positioning and alignment of framing members at a space frame node so that there are minimal or no eccentricities of framing member axes relative to each other at a node. The node connectors enable convenient use of variable bay spacing in a space frame, enabling the overall frame to efficiently carry design loads. The node connectors can be defined to provide interconnections between framing members in a diverse range of positions and numbers, thus enabling the use of DLG design and construction principles in more complex structures including non-static (movable) structures for electro-magnetic radiation focusing applications such as movable mirror or reflector support armatures in solar power generation facilities and in radio and optical telescopes. Use-specific elements can be accommodated in space frames, such as mountings for solar reflectors, torque members, and other supports and accessories.

Problems solved by technology

The reason for the use of pinned connections in DLGs is the cost and difficulty of assembling such grids having moment connections of the framing members at or to the nodes.

Eccentricity at a DLG node causes the node to have moment loads or other undesired loads applied to it.

Clearances at pinned connections in a DLG also can cause the grid framing members to have effective lengths between nodes which deviate from design lengths, thereby affecting the magnitudes of the actual loads in the framing members as compared to design load magnitudes.

It is apparent, therefore, that existing structures and techniques for establishing connections of framing members to nodes in DLGs have deficiencies which adversely affect the load carrying capacities of an overall DLG and of the framing members present in it.

The principal factors effecting the cost of a given DLG are primarily the cost of the materials used to define the grid components and secondarily the cost of labor to assemble those components.

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