Low-cycle fatigue behavior on the tensile region of Hollo-bolted angle connections

This paper presents the results of an experimental program to evaluate the low-cycle fatigue-related characteristics of the tensile region of Hollo-bolted angle connections. A summary of a total of 40 tension tests of equivalent T-stub connections is reported. The geometric parameters vary with the bolt gauge width, the column wall's thickness, the bolt type, and the angle's thickness. Based on the experimental test results, the typical failure mechanisms, the hysteretic load-deformation relationship, and the response characteristics such as degradations of strength and energy dissipation capacity of the connections are examined. It is shown that the bolt gauge width and the angle's thickness have significant influences on the failure mode. Energy-based model is proposed to overcome certain geometric limitations and five commonly used damage models are used to predict the damage behavior of connections. Moreover, the low-cycle fatigue life test results are compared with the codified S–N curves through a transformation of the displacement range into the effective stress range. Furthermore, the cumulative damage mechanism is analyzed and the fatigue life formula is obtained. Finally, the results are evaluated and verified by regression analysis. The 90% confidence level was used to test the availability of the regression equation, and the equivalent level of fatigue strength of the tensile region of angle connections is not less than Category 40 (ΔσC = 40 N/mm2). The EC3, BS7608, and AISC-LRFD-1999 specifications are used to evaluate the low-cycle equivalent fatigue strength, and it is found that there is a certain safety reserve when using Category 36. •Characterization of the low cycle fatigue response of the connection dominated by the tubular column in lexural bending and the Hollo-bolt in tension are necessary to the design of its constitutional semi-rigid joints under earthquake scenarios.•The general failure modes of test connections are featured depending on whether the column bolt yielded, two deformation modes under cyclic loading. The bolt gauge width and the the Aangle's thickness are the key parameters significantly influenced the tensile capacity and the failure mode of the connection.•The comparison of degradation curves of strength and energy dissipation capacity indicates that the connections in failure mode i have significant degradation mainly with the cycle ratio within the range of 0–0.2, while these in failure mode ii have remarkable de