Research On The Behavior Of Timber Structural Members Strengthened With CFRP

Timber structure is the main structural style of traditional ancient buildings in China. However, large numbers of exiting ancient timber buildings such as houses, bridges, temple, and towers have been being in service for lots of years, and their structures have been greatly damaged so that the seismic capacity is not enough to resistant the major earthquake. Using the technology of CFRP strengthening is an effective way to strengthen and rehabilitation timber structure. The perfect effect in strengthening and appearance can be obtained using the technology. However, there is not the technical specification for strengthening timber structures with carbon fiber reinforced polymer home and abroad, so that the design of strengthening timber structures accords to nothing. It is restrained heavily for the technology to be applied widely in engineering.On the basis of the study upon the present situation about CFRP strengthened wood member, this dissertation mainly focuses on the following items:1 Through the experiments on twelve timber beams of the rectangular section in bending, the effects on the flexural behavior of various parameters, such as the size of the test members, setup manner of CFRP sheets, are discussed. The failure pattern of the timber beams strengthened by CFRP is studied. The bearing capacity of the timber members in bending, the rule of the strain distributing in the mid-span section and the effect of CFRP on the flexural stiffness of timber beams are analyzed. The test results indicate that the ultimate load bearing capacity and the behavior of deformation of the timber beams is greatly enhanced after strengthened by CFRP, and the longitudinal strains of intact beams and strengthened beams are all consistent with the assumption of plane section.2 Based the experiments on twenty-four timber columns of the circular section subjected to axial compression, the effects on the compression behavior of various parameters, such as slenderness ratio, setup manner of CFRP sheets, are discussed. The failure pattern of the timber columns strengthened by CFRP is studied. The bearing capacity and the characteristic of volumetric deformation of the timber members subjected to axial compression and the effect of CFRP on the compression stiffness and lateral stiffness of timber columns are analyzed. Firstly, it is brought up for CFRP to be stuck along the longitudinal direction of timber members subjected to axial compression. The test results indicate that CFRP along the longitudinal direction of the columns canconspicuously improve lateral behavior of timber columns in order that the ultimate load bearing capacity and the ductility of the timber columns is greatly enhanced after strengthened by CFRP. The favorable strengthening effect is achieved.3 Based the formula about the bearing capacity in the current code for design of timber structures, and according to the test results in the dissertation and the research findings in foreign countries, a non-linear model about wood and the formulas about the bearing capacity of the timber structural members strengthened by CFRP are presented in this dissertation. The comparison of the results obtained using the proposed model and formulas and the experimental results indicate that the behavior of strengthened timber members can be predicted with reasonable accuracy. Finally, the design method and some suggestion for the CFRP strengthened timber structural members are presented, which provide references for its engineering application.