Experimental Study And Finite Element Analysis Of Mechanical Properties Of Timber-steel Dowel-type Connections

Wood is a historic building material.In China,wooden structures have a long history,and developed ingenious architectural skills,have good seismic performance.To this day,we can still see ancient buildings that have survived to this day.As a building material,wood has many advantages.Wood has the characteristics of light weight and high strength,easy to process,has a certain thermal insulation and sound insulation.And wood is a renewable material.Therefore,wood is still widely used in modern buildings.In modern wooden architecture,dowel type connection is a widely used connection method,has the characteristics of easy installation and good mechanical properties.It is of great significance to study the mechanical properties of dowel type connections.At present,there are more and more wooden structures in our country.However,in China’s current timber structure design code,the relevant regulations on the connection have not met the actual needs.Therefore,this paper studies the mechanical properties of dowel type connections,carried out the following research work:(1)This article considers two factors: the diameter of the dowel and the direction of the wood grain and designed 7 embedment strength test pieces.The influence of the above factors and the Applicability of the formula has been studed.And on this basis,further consider the dowel diameter and dowel slenderness ratio,designed 6 timber-steel dowel type connection test pieces.The effects of the above factors on the mechanical properties of dowel type connections were studied.And according to the European Code,the American Code and the Chinese timber structure design code,the bearing capacity,stiffness,ductility and other relevant provisions were calculated,and compared with the test results.The research shows that compared with test specimens loaded perpendicular to the grain,the embedment strength test specimens loaded parallel to the grain have higher load-carrying capacity,but have lower ductility.For timber-steel dowel type connection test pieces,the dowel diameter and slenderness ratio have a greater impact on the strength and stiffness of the test piece.The larger the dowel diameter,the higher the specimen’s bearing capacity and the greater the stiffness.The larger the slenderness ratio of the test piece,the greater the load-carrying capacity of the test piece.The slenderness ratio also has a greater impact on stiffness.(2)The test specimen model was analyzed using ABAQUS finite element analysis software,and compare the results of the finite element analysis with the experimental results,The deformation,stress distribution and load-displacement curve obtained by the finite element simulation are consistent with the experimental results,verified the accuracy of the finite element analysis.On the basis of analysis,consider the number of dowels,dowel spacing,number of dowel rows,dowel row spacing,etc,analyzed these parameters.And the effects of the above factors on mechanical properties were studied.The number of effective dowel rows in the dowel connection and the formula of the number of effective dowels were given.(3)Based on experimental research,based on the theory of beam on elastic foundation and related research,dowel type connection stiffness formula is proposed.In order to consider the influence of dowel assembly error and failure mode on the stiffness of the dowel type connection,according to the test results,the coefficient of influence is obtained by fitting.The calculated results are compared with the experimental results to verify the accuracy of the formula.Based on the test results?finite element analysis results and theoretical research,this paper puts forward design recommendations for timber-steel dowel type connections.