Study On Bending Behavior Of Timber Beam With Split Strengthened With FRP

The timber structure is one of the main structural styles of traditional ancient buildingsin China, Japan and countries in North American, and because of easy cracking of wood,many timber structural elements have cracks, even with through cracks along thelongitudinal direction. In order to protect the existing wooden structure, rehabilitationsand reinforcements need to be carried out. Compared to the traditional methods ofrehabilitation and reinforcement of wood structures, strengthening technology with fiberreinforced polymer (FRP) has more advantages and a wider range of applications.Therefore, and it is worthy of further study. The dissertation is focused on research ontheoretical modeling, analytic solution and parameter studies of rectangular cross-sectiontimber beams with longitudinal through split strengthened by bonding FRP sheets, and someresults are obtained. The main contents of the thesis are as follows:1. For rectangular cross-section timber beam with through split along longitudinaldirection strengthened with FRP sheets around its periphery, considering the bi-modulus fortension and compression of FRP sheets, the governing equations for bending deformation ofthe split timber beam strengthened with FRP sheet is established firstly under theassumption of the infinitesimal deformation of composite beam. It is revealed that, whenthe shear modulus of the FRP sheet approaches to infinite or zero, the governing equationscan be degenerated into those of timber beam without longitudinal split and combinationtimber beams(timber stoplog) which are strengthened with FRP sheets, respectively. Then,the bending behavior of the simply supported split timber beam strengthened with FRPsheets subjected to the uniform load is investigated, and the analytical expression of thebeam’s deflection is obtained. The influences of the material and geometry parameters andreinforcement method on the strengthened timber beam’s bending are examined.2. Based on the governing equation for bending deformation of the the split timberbeam strengthened with FRP sheets, the bending of the simply supported split timber strengthened with FRP sheets subjected to two concentrated loads is investigated, and theanalytical expression of the beam’s deflection is obtained using piecewise functions andcontinuity and boundary conditions. Then, the parameter study is conducted on the basisof that the reliability and applicability of the analytical solution are verified.3. The compressive and bending behavior of a simply supported FRP-strengthenedtimber column with longitudinal through split is investigated, and the governing equationsfor combined deformation of compression and bending of the split timber beamstrengthened with FRP sheets is established. The deformation of the simply supportedsplit timber column strengthened with FRP sheets subjected to an eccentric compressiveload at its one end is studied, and the analytical expressions of the FRP-strengthenedcolumn’s axial displacement and deflection are obtained. The influences of the material,geometry parameters, reinforcement method and the eccentricity of compression load on thestrengthened timber beam’s bending are examined.4. The bending of the simply supported intact timber column strengthened with FRPsheets subjected to an eccentric compressive load is studied, and the analytical solution ofthe problem is obtained. Then, the influences of elastic modulus of the FRP Sheet,reinforcement method, and slenderness ratio of timber column on the deflection of theFRP-strengthened intact timber column are examined.