US 4,275,537 A · Tension members

Abstract

Prestressed composite tension members comprise an assembly which includes compression and tension portions which are loaded longitudinally along or symmetrical with the center of gravity of the compression portion and prestressed causing both the tension and compression portions to cooperate in resisting lengthening of the assembly rather than the tension portion alone, thus lessening such elongations. In one embodiment, the tension member forms a tension member in a truss, having an upper chord and vertical webs acting in compression, and the tension member comprises a tensioned cable mounted within a series of abutting, slotted and glued wood members under compression. In another embodiment, the tension member comprises a tensioned cable centered in a plurality of tubes in compression, forming the truss lower chord. In another truss, the lower chord consists of the tension member comprised of a tensioned cable centered in a slotted wood member under compression with the end cable grips bearing on a bearing plate at the end of the compression member. In another truss lower chord, the tension member consists of a tensioned cable centered in a slotted wood member under compression with the end cable grips bearing on a plate at the end of the truss heel assembly. In another truss embodiment, the tension member comprises a tensioned, high strength, steel strap encircling the sides and ends of the wood compression member. In another embodiment, the tension member comprises tensioned cables centered in a slotted, glued-laminated compression member, such tension member forming the main structural elements of the roof system. In another, a plurality of tension members having tensioned cable cores and tubes in compression and connecting a central ring to an outer ring create a tension structure. In another embodiment, a tension-compression structure is created and comprises a tensioned cable centered in a slotted, glued-laminated, compression portion. In another embodiment, a mechanism, capable of supporting a substantial load at its end, comprises metal tubes abutting a high friction material abutting spherical balls allowing mobility and the ability to assume many different positions.

Claims9

Dependent claims

In an improved composite tension member,

a plurality of end-to-end segments having a longitudinal center of gravity, each segment including a pair of wood beams fastened together in face-to-face engagement, said segments comprising an elongated compression portion, said segments meeting at included angles to each other of less than 180.degree., said segments providing a longitudinal passageway extending therethrough;
elongated tension means disposed in said passageway, said tension means paralleling and being symmetrical relative to said longitudinal center of gravity and engaging the ends of said compression portion,
said tension means being normally under a preloading predetermined tension in sufficient magnitude to press against the ends of said compression portion to place and maintain said compression portion under compressive stress throughout the application of all contemplated external tension loading conditions on said tension member, thereby causing both said tension means and said compression portion to cooperate in resisting lengthening of the assembly rather than said tension means alone, thus lessening such elongation,
said tension means including a pair of abutment members engaging the extreme outer ends of said compression portion, said tension means also including anchoring devices abutting said abutment members;
and at least one connecting means engaging the tension means and the end portions of the compression segments to prevent crushing of the compression portion by the tension means.

2 more elements

Dependencies are inferred from the claim text.

Tension members

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Tension members

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Abstract

Claims9