Glue-laminated wood has nearly the same load-bearing capacity as steel, but is much lighter due to its charring properties and has excellent fire resistance. When used in heavy timber construction, glulam ensures high shock resistance and excellent resistance to corrosive substances. Many different "laminations" are possible, placing higher strength 2x laminations near the top and bottom of the most stressed beams to increase the beam's load-carrying capacity. Glulam allows for a high degree of prefabrication and, if necessary, longer structural spans - but is equally effective for shorter spans. Its thermal properties help prevent cold bridges.
- The glulam structure is divided into two types: the plywood structure and the orthogonal glulam structure. Laminated glulam structures are mainly suitable for single- or multi-storey wooden structures with large spans and large spaces. Orthogonal glulam structures are mainly suitable for floor and roof structures, or single- or multi-layer box-type wood structure buildings composed of orthogonal glulam.
- The fiber direction of each ply of the plywood component should be consistent with the length of the component. The number of laminate layers in the section of the laminated glulam component shall not be less than 4 layers.
- The directions of the fibers between the layers of the orthogonal glulam components should be stacked and orthogonal to each other. The number of layers of the cross-section should not be less than 3 layers, and it is not suitable for more than 9 layers, and the total thickness should not be greater than 500mm.
- When designing the laminated glulam components and orthogonal glulam components, the requirements for structural glue should be indicated according to the use environment, and the component manufacturers should strictly follow the design requirements for production.
- The design and construction requirements of the laminate-laminated timber structure should comply with the relevant requirements of the current national standard "Technical Specifications for Glued-Laminated Timber Structures" GB/T50708.
- The production requirements of the laminated wood structure should comply with the relevant provisions of the current national standard "Technical Specification for Glued Wood Structure" GB/T50708 and "Glulam for Structural Use" GB/T26899.
- The thickness t of the laminate is: 15mm≤t≤45mm; the size of the boards used for making cross-laminated wood should meet the following requirements: the width b of the laminate is: 80mm≤b≤250mm.
- Orthogonal glulam should be composed of boards of the same length and thickness of the same layer. The board can be lengthened with finger joints, and the strength of the finger joints should meet one of the following requirements: f t,j,k≥5+f tk m,j,k≥8+ f tk where; f t,j,k --Standard value of tensile strength of finger joints (N/mm2); f m,j,k--standard value of flexural strength in width direction of finger joints (N/mm2); f tk--standard of tensile strength of template value (N/mm2).
- Orthogonal glulam components can be used for floor panels, roof panels and wall panels, and the design of the components shall comply with the relevant provisions of Appendix G of this code.
- The length direction of the outer layer of orthogonal glulam should be arranged along the grain, and two layers of wood can be arranged along the grain as the outer layer. When required by the design, the cross-grain laminate can also be used in a two-ply plank configuration.
- Orthogonal glulam components can be connected by finger joints, and should meet the following requirements: when the components are finger-joined, the laminates of the cross-sections at both ends of the components at the finger joints should be arranged in the same way, and the grain direction of the components should be consistent accordingly; The finger joint length of the finger joint should not be less than 45mm.
- When the cross-laminated wood components are connected by finger joints, the strength of the finger joint joints shall be determined according to the following regulations: when the strength verification experiment at the finger joint joints of the components is carried out according to the relevant national experimental standards, the strength of the joints shall be determined. The standard value of flexural strength shall not be lower than the standard value of flexural strength of finger-jointed members required by the design; when the strength verification experiment at the finger-jointed joints of the members is not carried out, the design values of the flexural strength and tensile strength of the finger-jointed joints of the members shall be It can be taken as 67% of the value of the fingerless member, and the design value of the compressive strength is the same as that of the fingerless member.
- When the cross-laminated wood is glued, the surface of the board is smooth, free of dust, impurities, pollutants and other exuding substances that affect the bonding. After gluing, the laminate should be glued under pressure within the time specified by the adhesive used, and the glued surface should not be contaminated before gluing.
- The splicing surface between the outer parallel grain boards of the same layer with orthogonal glue is suitable for gluing with adhesive. Splicing can be adopted for the splicing surface between the inner side grain wood board of the same layer and the horizontal grain wood board of the same layer. However, the splicing gap should not be greater than 6mm.
- The adhesive used in cross-laminated wood should meet the requirements of strength and durability, and the type and performance requirements of the adhesive should comply with the relevant provisions of the current national standard "Technical Specifications for Glued Wood Structures" GB/T26899.