Experimental Research On Mechanical Properties Of Glued Laminated Arches

Modern timber structure have the advantages of light weight, high bearing capacity, environmental protection, convenient construction, good seismic performance and appealing shape.Since 1980s,modern timber structure buildings have been introduced to our country.In view of the problem of the construction technology of wood engineering components and structure,in our country,there is necessity to carry out the research on the mechanical properties of the laminated arch,which provides technical support and application our country to construct large span heavy duty engineering wood structure.This thesis chooses the Douglas fir timber and resorcinol resin adhesive to processing production of Glulam arch. On account of two bending load(cross in single point loading and 1/4 span single point loading),this paper presents a study of performance tests and finite element analysis of in-plane stability of Douglas fir glulam circular arch,which provides a better understanding of the whole process of stress instability in the plane of glued laminated timber and the ultimate bearing capacity and failure mode and mechanism in the plane of the test piece.The influence of vector span ratio on the stability of the test piece is analyzed by using the test data.At the same time, the influence of nonlinear factors and initial imperfections on the bearing capacity of arch rib is analyzed by using the finite element software.Specific content as follows:(1) Wood properties test of Douglas firIn order to reveal constitutive relation of Douglas fir Glulam in the direction of parallel to grain under different stress and provide basis for the subsequent laminated wood arch test and theory analysis,the Douglas fir wood longitudinal compressive, tensile and flexural mechanical properties were studied,which presents the stress constitutive relation of Douglas fir wood direction.(2) Results of the in-plane stability experimentIn the engineering, the more common form of glued arch is circular arch.This paper conducted 4 Douglas fir Glulam circular arch in-plane stability bearing capacity test.The main test parameters for designing are the rise span ratio (1/6 and 1/5) and the load type(cross in single point loading and 1/4 span single point loading).Article studied the entire testing experimental phenomena and failure form,and obtained the load displacement curve and the load-strain curve of the specimen,and analyzed the influence of the rise span ratio on the stability bearing capacity of the arch plane of the larch plywood. Meanwhile, referring to the design formula of bending wood components in "Timber Structure Code",the ultimate axial force of the equivalent column is obtained. According to the relationship between internal force and external load of arch,the ultimate bearing capacity is obtained and the theoretical calculation results are in good agreement with the experimental results.(3) Finite element model analysis based on the experiment3D finite element model of glued laminated wood is established by using ABAQUS finite element analysis software.Compared the finite element analysis results with the experimental results analysis results, the two were in good agreement.On the basis of the finite element software, the influence of the nonlinear factors and initial imperfections on the stability of the plane of the glued laminated timber is analyzed.