Experimental Parametric Characterization of Bolted Angle Connection Behavior

This article describes an extensive experimental program that was conducted to characterize comprehensively the nonlinear sectional force-displacement response of bolted steel angle semirigid connections. A total of 139 tests were performed to investigate the influence of angle thickness, position of the column bolts, bolt grade, and bolt pretension. The effect of loading sequence was also examined by applying static and dynamic monotonic and cyclic loading. The observed behavior and failure modes are described. Key parameters defining the load-deformation response of the specimens are quantified, including yield strength, initial stiffness, sharpness of the transition between initial and yielding phases, postyielding stiffness properties, peak forces, and deformations at failure. Monotonic test results were used to define a four-parameter power model that reproduces the force-deformation response of the angles. The influence of each geometric parameter, the bolt type, and the loading protocols on the behavior of the bolted angles was also described. The tests showed that strength and stiffness increased when angle thickness increased, and decreased when the distance between the heel and the column bolt increased. The force-deformation response of monotonic tests can be used to predict the backbone of cyclic and seismic responses. The angles subjected to cyclic and seismic tests, however, developed stable hysteretic response characterized by gradual softening, strength degradation, and smaller ultimate deformations compared with those subjected to monotonic loading.