Mechanical Behavior Analysis And Experimental Study On Engineered Timber-Concrete Composite Beam

Engineered timber-concrete composite (TCC) structure is a new type construction, in which a timber beam is connected to an upper concrete flange using different types of connectors. The best properties of both materials can be exploited because tensile forces induced by load are resisted primarily by the timber and compressions by the concrete flange.Timber-concrete composite system appeared due to a shortage of steel in 1940s, and has widely been used for renovation and strengthening of existing timber structures in Europe. Until the end of last century, this technology has been used as a solution for new building and bridges in Europe, America, Australia? Japan and etc. The studies of timber-concrete composite structure mainly focus on the shear stiffness and shear capacity of connectors. In our country, however, the shortage of timber makes the study of it almost empty in last century. In 21st century, this composite structure has been used in large span and heavy structures, but the holistic resistant behavior, especially the basic theory research of design and application, are not perfect enough.In this paper, firstly, the mechanical behavior of angle steel connector, which is used as stiff connector in timber-concrete composite structure, has been researched. Push-out test and Finite Element Models are performed to obtain the shear capacity and stiffness of the angle steel connectors. Secondly, three simple-supported composite beams with different number of connectors are designed. The nonlinear finite element calculations of TCC beams are conducted by 3D FEM models with nonlinear constitutive relationship of different kinds of materials. Three modals are tested for the change of strain distribution, deflection and slip in typical section. Further more, the analysis of timber-concrete composite beams is conducted based on linear elastic theory of composite structure. Finally, followed conclusions can be obtained:1. The angle steel studied in this paper can be used as stiff connector in TCC beams, and the efffect of insert depth in mechanical behavior is considered, for different angle steels there should be a most reasonable arrangement mode.2. In order to explore the mechanical behavior of angle steel connectors and TCC beams, finite element models, experiments and analytical models and studied, and the results of which are agreed very well in elastic stage.3. Degree of shear connection in TCC beams has large influence on mechanical behavior of TCC beams, the greater the shear connection degree, the better the performance of TCC beams.Based on the theory analysis, finite element numerical calculation and experiment in this paper, it can be concluded that angle steel is a kind of stiff connector and it has potential of application in practical engineering.