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In Hollow Structural Section (HSS) column-beam-brace connections, offset between gusset plate and HSS column webs leads to large distortion and out-of-plane deformation in HSS column face. To alleviate such undesirable effect, this paper proposes a new connection which consists of concrete infill and gusset plate passing through HSS column, called...
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Context 1
... and Astaneh-Asl (2000), it can be concluded that the braced frames 135 possess reservation capacity after brace failure due to beam-column connections. In this research, Through-Plate (TP) moment connections between beam and column relatively similar to the proposed connection by Mirghaderi, Torabian, and Keshavarzi (2010), are used. As shown in Fig. 3, similar to the connection of TGP to HSS column, TP is connected to HSS column. In this connection, based on the required length for the connection, the beam web is trimmed and the beam flanges are 140 beveled. The connection of beam to TP is provided by the longitudinal connection of beam flanges to both sides of TP and two web ...
Context 2
... elements. The concrete-damaged plasticity model presumes a non-associated potential plastic flow rule and isotropic damage and this model is beneficial for cyclic loading conditions. The stress-280 strain relationships proposed by Velasco (2008) for the concrete in tension and compression were utilized in the numerical models of this study (Figs. 13 and ...
Citations
... It can be concluded from Eq. (1) that, in conventional gusset plate connections, distortion and out-of-plane deformation of HSS column flange in the vicinity of the gusset plate can lead to decrease the stiffness of the beam and column parts to the working points and consequently, reduce the stiffness and strength of the braced frame. The numerical studies conducted by Ebrahimi et al. [34,35] showed that the throughgusset plate connections can decrease or remove the out-of-plane deformation which occurs at HSS column face adjacent to the conventional gusset plate connections. ...
In Hollow Structural Section (HSS) column, webs are available at both ends of column flanges. Thus, there is an offset between webs and a gusset plate connected to the middle of this column flange. However, in H-shaped column, both the column web and the gusset plate are connected to the middle of the column flange. On the other hand, unlike H-shaped column, HSS column flange does not possess an appropriate support and this problem can induce distortion, out-of-plane deformation, and fracture in HSS column flange. To resolve this problem, this study proposes a new gusset plate connection passed through HSS column and called through-gusset plate. Also, force transfer mechanism and design procedure are presented for through-gusset plate. To evaluate the cyclic response of the proposed connection, an experimental study was conducted on two full-scale one-bay, two-story Special Concentrically Braced Frames (SCBFs). This study considered beam-to-column connection as moment transfer via a through-plate to mobilize the reservation capacity of SCBFs. Square-HSS and circular-HSS cross-sections were used for braces and columns. The experimental results demonstrated that the proposed connection is acceptable since through-gusset plate can eliminate distortion and out-of-plane deformation of HSS column flange at the gusset plate vicinity via providing a new load path. The cyclic response of specimens showed that beam-to-column moment connection by through-plate increased strength, ductility, and energy dissipation capacity for approximately 41%, 79%, and 110%, respectively. In addition, in the phase of reservation capacity, noticeable slip in bolts and sudden fracture in connection plates occurred. Consequently, an acceptable performance was not observed for beam-to-gusset plate connection proposed in AISC.
In Special Concentrically Braced Frames (SCBFs) with Concrete-Filled Tube (CFT) columns, brace force must be transferred through beam–brace–column joint and thereafter distributed between steel tube and concrete infill of column. In the common practice, gusset plates are directly welded to the steel tube of CFT columns where the majority of force is transferred to only a part of steel tube placed adjacent to the gusset plate resulting in distortion and fracture. Accordingly, Through–Gusset Plate (TGP) passing through CFT column is proposed for connecting brace to CFT column and distributing the brace force between steel tube and concrete infill. Moreover, the gusset plates in the braced frames may encounter pinching forces due to frame action. The current study resolves this problem through proposing a new method for connecting the beam to the gusset plate. In addition, beam–to–column connections in SCBFs tolerate large rotation demands due to frame action. Consequently, fracture and damage may occur at beam–to–column connections. This research considers moment connections between the beam and the column using a Through–Plate (TP) to evaluate their effects on the behavior of SCBFs. The cyclic performance of the proposed connections is experimentally assessed through full-scale tests conducted on two one-bay, two-story SCBFs with CFT columns and braces. The results showed desirable behavior of TGP connections that remained undamaged. The proposed method for beam-to-gusset plate connections eliminated the pinching force on the gusset plates. In addition, beam-to-column moment connections using TPs resulted in delaying brace fracture and strength degradation.
In multi-story Special Concentrically Braced Frames (SCBFs), there are bracing nodes where two braces associated with two sequential adjacent stories of a similar bay intersect each other at beam-to-column joints. In these bracing nodes, under loading, one of the braces is in tension and the other is in compression. Consequently, maximum vertical force is imposed on the column. Note that in these bracing nodes, force distribution at a gusset plate affects the force distribution at the other gusset plate. Generally, two separate gusset plates are considered for the bracing nodes with two braces at the beam-to-column joints and designed according to Uniform Force Method (UFM). While the UFM proposed for corner gusset plates with one brace does not consider the force distribution effects at both gusset plates. To resolve this problem, the current study proposes a one-piece gusset plate for the bracing nodes with two braces at the beam-to-column joints. The one-piece gusset plate involves the gusset plate of the tension brace, the gusset plate of the compression brace, a part of the beam web whose length is equal to the interface of the gusset plate to the beam, and finger stiffeners. The finger stiffeners are considered in the connection region on both sides of the one-piece gusset plate to simulate the presence of the beam flanges removed in this region. Note that in this connection, the beam is extended to near the one-piece gusset plate and thereafter is connected to it. The aims of this study are as follows: (1) considering the force distribution effects on both gusset plates, (2) calculating the force and bending moment demands of the gusset plates in the bracing nodes with two braces at the beam-to-column joints via proposing a new method, and (3) determining the gusset plate dimensions in the bracing nodes with two braces at the beam-to-column joints through presenting a new procedure. Five one-bay, two-story SCBFs with the brace angles of 37−37, 45−45, 59−59, 37−59 and 59−37° (the first number is the lower story brace angle and the second number is the upper story brace angle) were designed in accordance with the method and procedure proposed in this study. These specimens were simulated in ABAQUS and subjected to a monotonic loading. The accuracy of the proposed method was confirmed via comparing the results of ABAQUS and UFM with those of the proposed method.
