Optimizing Design For Glulam Beam Made Of Modified Wood Of Fast-growing Poplar

This research is focused on fast-growing poplar used in wood structure. Modified wood of fast-growing poplar is used for making glulam beam, the most important part of wood structure. Besides, a mathematic model is founded with material mechanics and composite mechanics. The model can not only calculate the rigidity and strength of glulam beam whose configuration of materials by layer is given in advance but also optimize the configuration of materials by layer of the beam on the premise of exceeding certain rigidity and strength. It helps avoid the redundancy of rigidity and strength and save the production cost of glulam beam.The research contains three parts:â… Research on properties of raw wood and modified wood of fast-growing poplar and bonding strength between materials glued by poly-urethane resinâ…¡Model for calculating rigidity and strength of glulam beam made of modified poplarSo long as properties of elements and joint form between each other are given, the properties of composites are able to be calculated according to theories in mechanics of composite materials. In the research a mathematic model for calculating modulus of elasticity and bending strength of glulam beam(rectangular form) is built by analyzing axial stress and shear stress of glulam beam in accordance with principle of laminates and theories in mechanics of materials.Thus, when mechanical properties of different kinds of modified poplar and bonding strength between each other are definite and form of the load to the beam is determined, modulus of elasticity and bending strength of the glulam beam made up with kinds of modified poplar in any configuration can be calculated by the model.â…¢Model for optimizing the configuration of materials by layer of glulam beam made of modified poplarThe optimizing model is founded in the base of the calculating model by VB program. How the model works is following:1,Find out the largest number of layers in accordance with the largest height of the beam allowed in the wood structure and the thickness of layer.2,List all of the projects of configuration by combining the largest of layers and the kinds of materials.3,Calculate the rigidity, strength and cost of the beam project by project using the calculating model in VB program.4,Find out the configuration of lowest cost and of rigidity and strength meeting the command by comparison.