Study On The Mechanical Properties Of Glued Timber-Concrete Composite Beams

With the development in economy and the progress in society,the ecology and sustainable structures are paid more and more attentions.Timber as a kind of environmental natural resources,once again gets attention.The timber-concrete composite structures are developed from timber structure and concrete structure.It has vast potential as a sustainable new composite structure.The advantages of both materials can be exploited because bending and tensile forces are resisted primarily by the timber and compression by the concrete.To sufficiently use load-bearing capacity of timber-concrete composite structures,it is important to ensure both materials act efficiently.However,the research and application of timber-concrete composite bridges are in the early stage around the world.For this,combined with the existing research work,mechanical properties of timber-concrete composite beams are studied,and the main conclusions are as follows:(1)The static load test of the wood-concrete composite beams was carried out to test the relevant parameters such as strain,deflection and slip of the typical section.The strain distribution law and the law of slip and deflection was obtained.(2)In light of the damage mechanism of connection failure caused by concrete shearing failure and the bending deformations of connectors,the formula to calculate the shear bearing capacity of the notched connectors was established,and the calculation results were compared with the test results.It turns out that the calculation results agree well with the testing results,which is conformed a better method to calculate the shear bearing capacity of notched connectors when the bars of the connectors have undergone bending damage.(3)Based on the idea of reduction stiffness method,the modified stiffness reduction method was established for the timber-concrete composite beams,which was verified by the test results,and compared with the converted section method and the y method.The calculation results show that the modified reduction stiffness method is suitable for the calculation of the deflection of the timber-concrete composite beams in the elastic phase.(4)The ANSYS finite element software was used to simulate the timber-concrete composite beams,and its results compared with the experimental results.It conforms that the load-deflection curves obtained from finite element numerical simulation are in good agreement with the experimental results in the early stage of experiment.(5)The first three orders flexural mode frequencies of the test beams were calculated by the theoretical methods,and the first three orders flexural modal shapes and the corresponding frequencies of the test beams were obtained by using the Midas finite element software.The results show that the bending mode fundamental frequencies calculated by the the y method and the modified reduction stiffness method are close to the ones on the whole by numerical simulation due to considering the slip effect.