Experimental Study On The Wood Compression Properties For Ancient Buildings’ Protection

Different purposes emphasis on different wood properties test,ancient buildings’ protection and repairs focus on the mechanical and corrosion resistance properties under the influence of environment and humiture of wood.Woods in ancient buildings conclude the old and new timber,the key use of new timber are the members replacement and gap filling,despite usually small in number,the selection of wood and the recognize of its properties can directly influence the result of repair.Considering this aims,it is necessary to conduct targeted experiment and get conclusions.In ancient timber buildings, most of the members are under compression,during the repair of wooden structure,replacement member is mainly under compression.Thus,this paper aim at the compression properties test of five kinds of wood that used in the repair of ancient buildings.Considering the anisotropic properties of wood,this paper also studiedthe influence of grain direction to the wood compression properties.A self-made force sensor and dial gauge was used in this test by connecting with the computer via strain logger so that the data can be recorded automatically.Through the test of parallel-to-grain compression properties of the five kind of wood, the conclusion is that the wood density and hardness have great influence on the compression failure mode,and all failure are brittle;The compressive force-displacement curves show visible brittle characteristics as a sudden turning point could see;The parallel-to-grain compression strength and wood density has a significant liner relationship.A full-face compression properties in the transverse direction of the five kinds of wood test was conducted,and the species divided into radial, tangential and slant considering the impact of the grain direction.The results show that the failure mode of wood’s in radial and slant direction is mainly compression failure, while it is divided into stratification buckling failure and compression failure in tangential direction. The compressive force-displacement curves are three-stage curves in wood ’ s radial and slant direction while in tangential direction they are not three-stage curves since the difference between the failure modes. The equation of wood full-face compression strength and density can be fit out as a result of the obvious quadratic polynomial regression relationship.By the test of local compression properties in the transverse direction of the five kind of wood conclude that,the failure mode is mostly the compressive deformation in the compression zone along with the raise and crack in thenon-compression zone;The compressive force-displacement curves are three-stage curves in low density wood,while in high density wood the platform zone is not obvious;The equation of wood local compression strength and density can be fit out as a result of the obvious quadratic polynomial regression relationship.Through comparative analysis,the compression properties differences in the parallel-to-grain and transverse direction can be obtained,and so does the differences between the full-face and local compression in the transverse direction.