Compression behavior of nonslender cylindrical steel members with small and large-scale geometric imperfections

The compression behavior of cylindrical steel members is affected by geometric imperfections resulting from manufacturing, handling, and damage during installation and service. This paper summarizes the full-scale laboratory tests and the finite element simulations to quantify the effects of both small-scale global and large-scale local geometric imperfections on the compression behavior of nonslender cylindrical steel members. Systematic measurements of the small- and large-scale imperfections on 300-mm internal diameter pipe specimens with 6.17-mm wall thickness were used to characterize the imperfections for nonlinear finite element simulations of axial compression. Excellent agreement is shown between the analytical results and the detailed force, deformation, and strain measurements on the test specimens loaded well beyond their peak loads. The analytical and experimental results are summarized for the load reduction effects of the global imperfections as a function of the amplitude, expressed as a percentage of the wall thickness, and the various patterns of the local surface imperfections. Recommendations are made with respect to the imperfection effects on the compression load capacity, methods of modeling the imperfections, and the implications with respect to the design, inspection, and the serviceability decisions in the field.