Feasibility Studies On Modified Fast-growing Wood Of Poplar For Timber Structure

The possibility of modified fast-growing poplar applied in timber structure was studied in the paper. According to methods of physical and mechanical tests of wood (GB/T 1928-37-1991), standard small samples without defects should be used, and five kinds of experiments were designed with more than 300 hundred test sample altogether, and physical and mechanical properties of modified fast-growing wood of poplar must be measured. Then ultimate strength and elastic modulus of modified fast-growing wood of poplar should be made sure through analyzing data by statistical methods.Experiments show: air-drying density was 0.614 g/cm3 , coefficient of cubage shrinkage was 0.516%, compression strength parallel to grain normal value was 29.74 N/mm2 , bending strength normal value was 68.10 N/mm2 ,modules of elasticity was 6289 N/mm2 . According to calculation methods of Timber Structure Design (GB50005-2003), the modified fast-growing poplar's allowable stress was obtained. So allowable stress of grain compressive strength was 8.59N/ N/mm2, the bending strength was 10.01 N/mm2.Through the contrast experiment, several kinds of primary factors affecting wood physical and mechanical properties differently should be analyzed. The paper showed that water content was one of the important factors of density and density increased with the water content augment in certain scope. It also indicated that its average of shrinkage rate was 4.894% and drying shrinkage coefficient was 0.516%, modified fast-growing poplar shrinkage rank belonged to medium. The experiment indicated that Compression strength parallel to grain increased with density and reduced with the water rate in certain scope from 8% to 15%. Similarly, bending strength increased with density and reduced with the water rate from 8% to 15%.At the same time, the relationship between bending strength and bending elasticity modulus was direct proportion. The modified fast-growing poplar's allowable stress of grain compressive strength and the bending strength was proved to satisfy the requirements of Timber Structure Design.Based on physical and mechanical properties of modified fast-growing wood of poplar, that the modified fast-growing poplar uses in the botanical garden project and the architectural engineering is feasible was indicated. Simultaneously, its economy and the social efficiency were proved to be obvious, and the related contents about the applicable scope, the application prospect and the thorough research should be explained.