Effect and evaluation of prying action for top- and seat-angle connections

Abstract

Nonlinear finite element (FE) static analyses of top-and seat-angle connections were performed using ABAQUS standard to investigate the influence of connection parameters and its properties on prying action developed due to the interaction between column flange and top angle's vertical leg. Contact phenomenon between two interfaces with finite sliding and bolt pretension in the initial step of analysis was considered in the FE model. FE analysis results were compared with the experimental ones to examine the applicability of the FE model. Then, the location of plastic hinges in connection assemblages was investigated at the ultimate state of the connection and a parametric study was performed varying connection parameters, material properties of connection assemblages, and magnitude of bolt pretension to visualize their effects on prying force and on the position of prying force on top angle's vertical leg. Current study shows that plastic hinges not only develop at top angle's heel and bolt hole region but also in the bolt shank that differs from some assumptions of power model (Kishi and Chen 1990): (1) top angle thickness and gage distance from angle heel to bolt hole center line have an distinct effect on prying action; and (2) distributed prying force developed near the region of the top edge of tension angle's leg adjacent to column flange can contribute to the failure of the connection. Finally, a mathematical formulation to identify the location of prying force action point is proposed.

Modified Three-Parameter Power Model to Predict Moment-Rotation Curve of Top- and Seat-Angle Connection

“…Due to that observation, the place of formation of the upper plastic hinge in the tension angle's vertical leg has been revised and an additional plastic hinge is supplied in the tension bolts according to the results of FE analyses for the proposed prediction model in determining the ultimate connection moment. FE analysis results [3,4,16] also demonstrated that the distance of the prying force acting point from the centerline of bolthole at the ultimate level of loading mostly depended on the thickness of the tension angle and gage distance from angle heel to the centerline of bolthole. Therefore, it was found that the distance b of the prying force acting point from the centerline of bolthole is a function of the angle thickness of tension angle, t t in combination with gage distance from angle heel to the centerline of bolt hole, g t ' and expressed as [16] …”

“…Advanced finite element analyses of top-and seat-angle connections were performed by the author and their geometrical and mechanical properties and analysis results were discussed elaborately in the literatures [3,4,15,16]. In those articles with the other's similar investigation [5,6,10], it was observed that plastic yielding of the connections initiated at the toe of the tension angle's fillet and then followed by yielding in the area under the tension bolt head for thinner angles (e.g., for the cases of ⅜" angle thickness), and in the areas of tension bolthole for the cases of thicker angles.…”

Prediction of moment–rotation characteristic of top- and seat-angle bolted connection incorporating prying action

“…In their threeparameter power model, Kishi and Chen (1990) considered bending and shear deformations of the angle, but disregarded deformation of bolts for deriving the ultimate moment capacity of angle type of connections. To establish a rational prediction model for representing the M-h r curves of the connections, this effect on connection behaviour needs to be considered (Ahmed and Hasan 2015). Thus, a formulation of determining the ultimate connection moment M u is proposed assuming three types of simple mechanisms of connection failure using the T-stub concept of Eurocode 3 (CEN 1997).…”

“…FE analysis results demonstrated that the distance of the prying force acting point from the centerline of bolthole at the ultimate level of loading mostly depended on the thickness of the top angle and gage distance from angle heel to the centerline of bolthole (Ahmed and Hasan 2015). Therefore, it is shown that the distance b of the prying force acting point from the centerline of bolthole is a function of the angle thickness of top angle, t t , in combination with gage distance from angle heel to the centerline of bolt hole, g 0 t (Fig.…”

“…Therefore, it is shown that the distance b of the prying force acting point from the centerline of bolthole is a function of the angle thickness of top angle, t t , in combination with gage distance from angle heel to the centerline of bolt hole, g 0 t (Fig. 4), and expressed as (Ahmed and Hasan 2015) If ð2:575t t À 0:05g 0 t Þ \a then b ¼ 2:575t t À 0:…”