Seismic Performance of I-Shaped Beam-Column Joint with Cubical and Triangular Slit Dampers Based on Finite Element Analysis

Rzgar A. Mohammed 1,* , Hersh F. Mahmood Adnan L. Saifaddin, Nabard Habibi 1 Civil Engineering Department, University of Raparin, Sulaimani, 46012, Iraq 2 Civil Engineering Department, University of Halabja, Halabja, 46018, Iraq 3 Department of Mechanical Engineering Faculty of Engineering, University of Kurdistan, 6617715175, Sanandaj, Iran *Corresponding Author: Rzgar A. Mohammed, E-mail: rzgar.asad@uor.edu.krd


Introduction
Because of their excellent resistance to biaxial bending, I-formed columns are normally applied in locations with excessive seismic risk. Low and medium-upward push systems frequently use coldfashioned hole sections, even as excessive-upward push homes normally use built-up sections made from 4 plates welded together [1]. Since the 1994 Northridge earthquake, extensive studies have been undertaken, and numerous modern connection info was proposed to link I-beams to vast flange columns [2][3][4][5][6][7]. However, a minimum look has been carried out for the relationship of I-beams to the container-columns [8]. Kim et al. [9,10] built full-scale second connections to US container columns, using pre-Northridge connection facts and examining them. During a story flow perspective of much less than 1% rad, each specimen failed Journal of Studies in Science and Engineering. 2022, 2(1), 17-31. https://doi.org/10.53898/josse2022212 https://engiscience.com/index.php/josse because of brittle fracture of entire joint penetration JCPP) welds among the beam flange and the column, ensuing in no plastic rotation in the connections. Six huge-length specimens of metal beam-to-container column couplings had been examined with the aid of using Chen et al. [8]. The unreinforced link employing Northridge features was one of the test specimens, while the reinforced connections using rib plates or wing plates were another. During a 2.3 percent story drift angel cycle, the unreinforced link broke due to a fracture in the beam bottom flange's heat-affected zone (HAZ). While many structures in the United States were built to resist collapse, sparing lives [1,2], many steel buildings were severely damaged, with structural functions eliminated. Brittle fractures at welded beam-column joints looked to represent the most serious damage. While this was expected for older steel structures with no ductile connection features, it was also anticipated for some relatively recent buildings erected by existing seismic norms [3,4]. Following studies have convergences on determining the sources of steel structure damage, analyzing significant characteristics that affect the cyclic behavior of steel moment connections, and suggesting improvements to these connections. Following a chain of earthquakes in the United States, essential experimental applications on beamcolumn joints had been evolved in the United States and Japan, which include the decreased beam section (RBS) [5][6][7][8], the duvet plate or haunch [9,10], no weld get entry to the ole [6,11,12], we gain access to the hole [13][14][15]. Although those connections have established pleasant overall completion inside the laboratory, the seismic layout of that info is primarily based totally on the plastic rotation ability of primary participants in the frame, consisting of the beam and column, and broken homes can't be without difficulty subtle while that info is used. Because it's miles crucial to rebuilding systems and the features of the affected metropolitan location as quickly as possible after an earthquake, that welded connection info is useless in addressing the issues produced through the latest disasters. A damage-managed shape that consists of passive power dissipation gadgets has formerly been asserted to deal with those varieties of difficulties [16].
Passive power dissipation gadgets were proposed as a cost-powerful way to lessen the risk of earthquakes to systems. Since a chain of earthquakes in the United States, passive dampening techniques were broadly considered, and extra homes were equipped with dampers [17,18]. We currently utilize two distinct kinds of slit dampers of the flange at of which, wish are triangular and cubical shapes, as shown in the following pictures, which were evaluated using Abaqus software.

Figure 2. Cubical shapes of slit beam-column joint
Plastic deformation is contiguity to the slit dampersAthenaenoa foam, which is one of the key characteristics of these systems. This study discusses the suggested structural system's structural shape and mechanical characteristics. As the beam to column joint in the recommended structural configurations, a mechanical joint was used accordingly with various LLC damper shapes. These types of dampers were analyzed and designed by program Abacus.

Structural Configuration
It is desirable to develop easily repairable structures and modify replacement after the earthquake by limiting damage to the energy absorption devices to identify the best damage control design of the frame structures (slit dampers). It is possible to restrict damper damage by designing dampers that are weaker than the beam and column. While the simple construction and better stiffness of this connection are positives, the compression force might induce local buckling on the beam flange. During an earthquake, it is preferred for damage to be limited to energy absorption elements with good hysteretic properties rather than being transmitted to the mainframe, such as the beam and column. Figure 2 depicts the new form of slit damper presented in this study, a cubical shape connection system with an energy absorption element.
Before the main structural members, the slit damper on the bottom flange of the beam is actively plasticized.  utilizing these systems with a triangular and cubical shape. When considering the plastic hinge of beamends, the proposed structural system can be characterized as a "strong column weak beam" since the plastic deformation is concentrated on the dampers in the beam-ends.   as well as having a high stiffness compared to other shapes, and is thought fit to use as a connection element in the system offered in this study [25]. The struts of the dampers were idealized, as shown in

Test Results and Discussion
The ABAQUS symmetric boundary circumstance approximately the aircraft 2-3 constrains displacement alongside the 1 axis in addition to rotations` first derivative! The 2 and 3 axes have to be zero. The ABAQUS uneven boundary circumstance approximately the 1-2 aircraft constraints displacements alongside the 1 and a pair of axes to zero, in addition to rotations across the three-axis. The length of the finitedetail mesh modified relies on the period and peak of the specimen, as proven in Figure 8. and Figure 9.

Prediction of The Moment Versus Rotation Curve
The skeleton curves have been anticipated primarily based totally on the theoretical formulation  Were placed side by side those got from the experimental data. Furthermore, the predicted skeleton curve for the slit damper was obtained from preceding research, which was idealized with trilinear models, the predicted initial slope of the moment relationship virtually aligns with the experimental curve and the curves obtained by finite element analysis (FEA) for the proposed specimens. The accuracy of the expected connection strength is also significant. Referring to Table 2, the discrepancy between the predicted yield point result and the test yield point result is approximately ± 10%. Wherepayy = anticipated yield moment. Any P and eMyN = experimental yield moments of positive and negative deflection, respectively. This result shows that a theoretical model comparing the relationship between moment and rotation properly describes the behavior of the sample. In addition, we compared the FEA results of the proposed support system. A non-linear FEM was performed, and the pretend connection was represented by a slotted damper and bolt volume element and a beam and column shell element, the results of which were compared to the experimental skeleton curve. The elastic and plastic properties of the material were obtained directly from the coupon test. Figure 10 shows the von Mises stress contour of sample D2, the FEA model provided a very accurate prediction of the elastoplastic response.

Plastic deformation and energy
In a damage-restricted structure, most of the seismic input energy is absorbed by specific bars.
Therefore, the damage is limited to specific members. Figure 12 shows the relationship between the shear force of the proposed sample and the displacement of the damper and beam. Where "shift" indicates.   The columns were H400x400x21x21, and the beams were H582x302x12x17. According to the planned connection between the beam and the column, a split connector was used at the top of the beam, and D2, the maximum ratio of beam bending moment to plastic moment is 0.41 and 0.56, respectively.D1 or D2. The column was supported with pins on both ends, and the distance between the column center and the loading point was 3500 mm. The points were separated by 3000 mm. Lateral supports were added to the beam to avoid out-of-plane distortion during loading. A quasistatic cyclic pattern defined in terms of connection rotation was specified in the loading protocol.

Conclusion
This research proposes a new structural structure with good deformation capability and ease of repair after an earthquake. The suggested connection is a beam-to-column joint system in which three types of slit dampers are used to link the slit damper to the bottom flange of the beam (slender, triangular, and cubical shape). Three full-scale specimens with slit dampers and three specimens were subjected to quasi-static cycle testing to evaluate the proposed system's performance. The most important conclusions are:Under substantial tale drift, the suggested structural system demonstrates stable hysteretic behavior. Given that the results are greater than the welded test specimen, the proposed connection can be considered a rigid connection at first. And plastic moment of the beam section in the suggested structural systems was not less than the maximum beam moment. Furthermore, the plastic deformation was limited to the slit dampers, while the beams and columns remained elastic. varieties of slit dampers (cubical, triangular, and thin) have distinct theoretical solutions, proving that the cubical shape is the best moment resist and deformation capacity. And Test results revealed that specimens D1(cubical) had stronger plastic deformation capacities than specimens D2 (triangular). Even though the two specimens exhibited different plastic rotations, this finding shows that the impacts of the composite beam should be addressed while developing the suggested connections.So the energy absorption is thought to be centered only at the slit dampers and not at the beams.
After an earthquake, the slit dampers can be replaced., structural system's load-carrying mechanism is governed by bending moment rather than shear force, unlike the bracing system. This mechanism demonstrates that the recommended approach is well suited to tall structures when moment-resisting structures outperform brace frames.

Declaration of Competing Interest:
The authors declare that they have no conflict of interest.