In this paper, a computational approach is undertaken to determine the rotational stiffness and moment capacity provided by typical “pinned” column base-plate connections in low-rise metal buildings by analyzing a wide-range of connection parameters. The most influencing details of the connections on the overall behavior were identified. First, development and validation of high-fidelity computational models using experimental data are described. Then, the validated models were used to perform a parametric study to understand the effect of configurational details on the rotational stiffness and moment capacity of the column base-plate connections with anchor rods between the flanges. Anchor rod diameter, by itself, and in combination with base-plate thickness, was found to be the most influential parameter on the moment capacity of connections with smaller web depths. For larger web depths, the number of anchor rods was influential in the moment capacity, particularly, in one of the loading directions.

Low-rise metal buildings are used in all geographic locations, including high seismicity regions. In the design of low-rise metal building systems, column base connections are commonly modeled as pinned supports with no rotational stiffness or moment capacity. However, past studies have indicated that base connections, which are designed as pinned supports, exhibit a non-negligible level of rotational stiffness and strength. Neglecting the rotational stiffness of the base connection may result in a significant overestimation of the lateral displacement of the frames. This additional displacement is addressed by increasing the flexural stiffness of the frame members thereby increasing the cost of low-rise metal buildings. The moment capacity may similarly be exploited for strength design. However, there is a lack of design guidelines to support the use of rotational stiffness or moment capacity at the pinned column bases. This study evaluates the applicability of existing code-formulations to pinned colum base-plate connections. Both the rotational stiffness and the moment capacity from past experiments are compared with those calculated based on the provisions of the European and American design codes. It was found that the Eurocodes do not accurately estimate the rotational stiffness of the connections. A modification to the Eurocodes is recommended to capture the characteristics of pinned connections. It was also observed that the moment capacity of the connections was conservatively estimated by the existing codes.

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.