Reversed Cyclic Behavior of Column-to-Foundation Connections in Low-Rise Metal Buildings

Low-rise metal buildings constitute a large portion of the nonresidential construction in the United States. These buildings are, in most cases, characterized by a pinned column-to-foundation connection. Although previous research has been conducted on other components of metal buildings (e.g., knee joints, tapered rafters), there is a lack of available data on the performance, particularly in terms of elastic stiffness, deformation capacity and energy absorption characteristics, of the pinned base-plate connections. The objective of this research is to evaluate the performance of the commonly used column base-plate pin connections in low-rise metal building systems. An experimental program is presented in which 11 column stubs were tested on concrete foundations and a systematic investigation was performed to study the influence of various parameters, including base-plate dimensions, number of anchor rods, anchor rod diameter and gage distance, on the connection behavior. The tests were performed on full-scale specimens subjected to horizontal cyclic displacements with an increasing amplitude and a constant axial load. All of the tested specimens showed high deformation capacity, and moderate strength and energy absorption. This paper presents the observed hysteretic behavior, elastic stiffness, moment and deformation capacity, and damage patterns of the tested specimens.