Experiments And Analysis Of The Performance Of Nailed Connections For Timber Structures

Encouraged and guided by national policies,modern timber structures are booming.Nailed connection is one of the main connection types of modern timber structures.At present,the research on the load-carrying capacity of doweled connections in China is mainly focused on bolted connection,generally ignoring the influence of different material properties and driven methods between nails and bolts on the dowel-bearing strength and load-carrying capacity.In addition,the factored shear resistance of shearwall in the light wood frame construction can be directly checked out in China standard,which means that the diversity of modern timber structure cannot be satisfied.Above all,this paper conducts the tests on properties of nails,dowel-bearing strength and nailed connection,and explores the design and calculation methods of the shear resistance of shearwall using the load-carrying capacity of the nail connection.This paper includes the following aspects:The tensile tests on domestic round nails of 4 diameters were carried out,and the yield strength of each diameter nails was obtained,the results of which can be used for determining the material properties of the nails while calculating the load-carrying capacity of the nailed connection.The test results show that the elastoplastic strengthening coefficient of domestic round nails is reasonably taken as 1.0.At the same time,the density and moisture content of the wood used in the tests were tested.The tests of dowel-bearing strength on 380 specimens were produced,and the effects of factors including wood species,nail diameter and loading direction on dowel-bearing strength were investigated.The half-hole method was used for dowel-bearing strength and failure modes.The empirical equations of the parallel-to-grain dowel-bearing strength and perpendicular-to-grain dowel-bearing strength with respect to the oven-dry specific gravity and nail diameter are fitted.The calculation results of European codes and American codes,test results,and the calculation results of empirical equations were compared,and the correctness of the empirical equations proposed in this paper were verified.246 symmetrical single-shear nailed connection test specimens were produced,the tests were carried out and the effects of wood member thickness,nail diameter,and wood species on the load-carrying capacity of the nailed connection were explored.The corresponding nailed connection yield criterion of the calculation equations of the nailed connection load-carrying capacity in standard for design of timber structures was analyzed.The completely developed plasticity of nails should be considered in the calculation of nailed connection load-carrying capacity.Based on the load-carrying capacity of the nailed connection,a proposed equation for the resistance of shearwall was proposed,and the calculation results were compared with the results of the monotonic loading test of the shearwalls,which confirmed the accuracy and applicability of proposed equation.