STUDY ON INTERFACE SLIP AND DEFORMATION OF BAMBOO-STEEL COMPOSITE I-BEAMS

On the basis of elementary beam deformation theory as well as the relationship between interface slip and strain difference, differential equations of interface slip in I-section bamboo-steel composite beams are established. Analytic expressions of bamboo-steel interface slip and strain difference which corresponds to three classical loads are derived, based on which the formula of additional mid-span deflection caused by interface slip is put forward according to the principle of virtual work, so as to deduce a calculation method of additional mid-span deflection considering slip effect. 6 specimens were prepared in the experiment, the strain difference, distribution of the interface slip and deformation of the composite beam were investigated, and the theoretical method was compared with the experimental results. Results show that theoretical calculations of bamboo-steel interface strain difference coincide with experimental results well, and distributions of strain differences in compression area and tensile area are basically the same; slop of interface slip curve increases in the pure bending area and decreases in the bending-shear area; maximum values of the slip are found on the beam ends, and the slip is larger in the whole bending-shear area, thus the arrangement of a number of connectors in the bending-shear area may effectively improve the working performance of the composite beams. Considering the slip effect or not, a comparison between the new method and the transformation-section method show that the new method is more closer to the experimental results, as the average error decreases from 11.5% to 1.64%, and advantages of the new method become more obvious when deformation increases.