Study On Bending Mechanical Behavior Of Steel-timber Composite Beam

Owing to people's attention to environmental safety,the environment-friendly construction materials such as timber get more attention.In the past decade,timber composite construction has been found extensive application.Compared with reinforced concrete structure,the weight of timber composite structure is lower.The load-carrying capacity of timber composite structure is greater than that of reinforced concrete structure with the same quality.Timber composite beam is the most important part of timber composite structure.At present,the extensive experimental and theoretical research was focused on the structural behavior of timber-concrete composite beam,little attention has been paid to the possible applications and structural performance of steel-timber composite beam.Compared with steel-concrete composite beam,steel-timber composite beam is lighter.It also can improve the speed of construction and reduce the cost of construction.Furthermore,the steel-timber composite beam with bolt can immensely facilitate deconstruction and the further reuse and recycling of construction materials.The study is focused on bending mechanical behavior of steel-timber beam.The load-carrying capacity and bending stiffness was compared for two groups of timber-steel composite beam with different width of timber beam.In elastic stage,the strain over the section depth is linear distribution.Bernouilli's hypothesis is not applicable for the whole cross section.But the assumption that plane sections remain plane after deformation is still suitable for each component.There is slip between timber and steel in composite beam.At the pure bending section,the slip equal to zero,the slip is maximum at support.It can be found that the transverse stress of timber beam has close relationship with bending moment.A non-linear 3D finite element model is developed and validated by experimental results.The numerical result coincides well with the test result.The thesis summarizes four calculation theories of composite beam with partial composite action,which are ? method,reduced rigidity method,consistency factor method and elasto-plastic method.The theoretical bending stiffness and bending moment were compared with test results and other test results from literatures.The accuracy of the four calculation methods was analyzed and verified.