鋼管ぐいの座屈と端部補強

抄録

The authors carried out the axial compression test on short pipe piles which were easy to buckle in inelastic conditon. The results of these tests and many other previous similar investigations were discussed and those results were related with the decrease of strength of steel pipe piles under axial loading. For the thickness-radius ratio is 0.01 to 0.10, buckling occurred in the inelastic zone in terms of the stress-strain relationship. These results showed that buckling atress increased approximately in proportion to the thickness-radius ratio. Yield stresses and buckling stresses obtained in the tests were normalized on the basis of the yield stress of pipe pile materials in the tension lests. The experimental formula to estimate the decrease of the strength of pipe pile under inclastic buckling is presented as follows : [numerical formula] where σ_<sy>=the stress decreased by inelastic buckling, σ_y=the yield stress in tension test, t/r=thickness-radius ratio. The effect of the steel plate attached to the end of the pipe pile was tested by static axial compression tests. These test results showed a fairly good agreement with the results calculated by the finite element method. The finite element calculations on 12 types of the steel plate were carried out to investigate the deformations and the stress distributions at the end of steel pipe pile. The thickness and width of the steel plate to strengthen the end of steel pipe pile were proposed on the basbasis of these calculated results.