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A tensioning method for internally prestressed glulam beams

A technology of prestressing and prestressing tendons, applied in the direction of joists, girders, trusses, etc., can solve the problems of section failure, damage, and little improvement in bending bearing capacity, and achieve the effect of improving bearing capacity.

Active Publication Date: 2020-02-18
SOUTHEAST UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In vivo prestressed glulam beams need to stretch the reinforcement, but the existing technology cannot determine the specific tension. When the tension is too small, the strength of the prestressed reinforcement will be small, and the fiber strength utilization rate in the compressed area of ​​the wood will be lower. The prestressed glulam beam is not high, and the flexural bearing capacity of the prestressed glulam beam is not much improved compared with the ordinary glulam beam, and the damage is sudden and brittle; when the tension is too large, the prestressed tendons are prone to premature failure under the load. It is very dangerous to yield or even break, resulting in failure of the section, and injury to people due to the ejection of the anchor clip

Method used

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  • A tensioning method for internally prestressed glulam beams
  • A tensioning method for internally prestressed glulam beams
  • A tensioning method for internally prestressed glulam beams

Examples

Experimental program
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Embodiment 1

[0061] The method for determining the upper and lower limits of the effective tensile force will be described in further detail below in conjunction with the accompanying drawings.

[0062] figure 1 The cross-sectional schematic diagram of the prestressed glulam beam in the body. Among them, b and h are the width and height of the prestressed glulam beam respectively; h at , H ac , Respectively, are the distances from the joint force point of the tension and compression ribs to the edge of the timber tension and compression zone; A rc Is the cross-sectional area of ​​the compression bar; A rt Is the cross-sectional area of ​​the tension prestressing tendons.

[0063] The method for determining the upper and lower limits of the effective tensile force proposed by the present invention includes the following steps:

[0064] Step 1: Make basic assumptions about the calculation, including:

[0065] (1) The average strain of the cross-section of the component is linearly distributed, tha...

Embodiment 2

[0117] The following is a detailed description of the use of the upper and lower limit formulas of the effective tension force in conjunction with a calculation example.

[0118] A simply supported beam is a linear internal pre-stressed glulam beam with a span of 4m. Reinforcement is only arranged in the tension zone. The cross-sectional size of the wooden beam is b×h=100×240mm. The glulam timber is made of Douglas fir and the prestressed reinforcement is 1860. Level φ s 15.24 Low relaxation steel strand. The relevant parameters of the material are as follows.

[0119] (1) Glulam (Douglas fir) related data (along the grain):

[0120] Modulus of elasticity: E w =11410MPa,

[0121] The ratio of the tangent modulus to the elastic modulus of the descending section of the compression zone: m=-0.1,

[0122] Compressive strain at yield: ε wcy = 0.321%,

[0123] Ultimate tensile strain: ε wtu =α m ·Ε wmu =1.3×0.298%=0.387%,

[0124] Ultimate compressive strain: ε wcu = 0.572%.

[0125] (2) R...

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Abstract

The invention discloses a tensioning method of an internal prestressed laminated wood beam. The tensioning method comprises the following steps that 1, the structural parameters of the internal prestressed laminated wood beam are obtained; 2, according to the structural parameters obtained in the step 1, the upper limit value and the lower limit value of effective tensioning force of the prestressed laminated wood beam are determined, wherein the lower limit value is effective tensioning force corresponding to the critical states of tension failure and compression failure, and the upper limitvalue is effective tensioning force corresponding to the situation that prestressed tendons are exactly yielded under the extremity state; and 3, according to the determined upper limit value and lower limit value of the effective tensioning force, the laminated wood beam is tensioned. According to the tensioning method of the internal prestressed laminated wood beam, the upper and lower limit values of the tensioning force can be directly, conveniently and accurately, so that the reasonable and effective tensioning force is determined to tension laminated wood, and the bearing capacity of thelaminated wood is improved under the premise that safety is ensured.

Description

Technical field [0001] The invention relates to a method and technology for determining the upper and lower limits of the effective tensile force of a prestressed glulam beam in the body, and belongs to the technical field of wood structure design. Background technique [0002] Glulam is a composite wood made of logs as the main raw material, using high-performance environmentally friendly adhesives and modern wood processing technology. Due to the advantages of energy saving and environmental protection, excellent structural performance, and size and shape that are not restricted by log diameter levels, as early as the 1940s and 1950s, the development of glulam structures has spread throughout Europe, America, Japan and other countries, and has been widely used in large-span, Space and bridge structure. The bending failure of traditional glulam beams is mostly the tensile failure caused by the tensile edge defects, and the wood strength, especially the compressive strength, can...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E04G21/12E04C3/18
CPCE04C3/18E04G21/12
Inventor 张晋沈浩王卫昌
Owner SOUTHEAST UNIV