Plate Joints Research Articles

An innovative model to estimate the tension field inclination considering crack growth for steel plate shear wall

The Steel Plate Shear Walls (SPSWs) are known as a capable system to use in steel structures due to their significant advantages. Despite extensive studies concerning this system, few researchers have scrutinized thecrack effect on SPSW behavior. However, the crack dramatically affected the experimental results. In the currentpaper, the effect of central and edge cracks, therefore, has been studied in jointed plates at mid-height of SPSW.Results indicated that the central crack is more destructive than the edge crack. The central crack having a long initial length also makes a sudden wall fracture in the elastic zone and consequently cannot be used in high seismic regions. Due to the dependence of the wall on the diagonal tension field and its angle, an equationis proposed taking into account shear, axial, and moment actions in columns, axial and moment actions in beams, as well as shear and axial actions in the plate which conform to finite element results. Because of thecomplication of the stress intensity factor for mode I and mode II calculations, this confidence is derived and offered.

Experimental Study of Precast Beam Joints Using Steel Plates in Beam-Column Joints Due to Cyclic Loading

In seismic design, reinforced concrete structures must perform well under heavy load conditions. To withstand large lateral loads without severe damage, structures require strength and energy dissipation capacity. It is generally not economical to design reinforced concrete structures to the greatest possible ground motions without damage. Therefore, the need for ductility must be weighed against economic constraints. This research is focused on dry joints where the joints are on beams in the plastic hinge area and modeled using steel plates, this modeling will be compared with the hysteresis and ductility curves in three types of specimens namely BU-1 without using plate joints, BU-2 using plate joints measuring 300mm x 400mm, BU-3 plate joints measuring 200mm x 400mm, with the same thickness and quality, namely 8mm thick and Fu 370 MPa. To strengthen the use of the plate connection, A325 bolts with a diameter of 12 mm and Fu 620 MPa are used. The results show that the pinching effect is found in the hysteresis curve of the BU-2 and BU-3 specimens. Meanwhile, for the ductility test at peak load, namely the seventh ductility for BU-1, the value is still better than BU-2 and BU-3. These results can still be improved with several variations of plate thickness, for this reason, further studies are recommended to develop and increase recommendations for several variations of plate joints, because precast joints, especially dry joints, are still the focus of research, especially in Indonesia.

Partially sleeved joints between hollow sections using self‐drilling screws.

AbstractThe present piece of research studies partial sleeve joints between similar rectangular tubes, involving bolts under shear as joining means. These are connections between two rectangular hollow sections that can be fitted one in another just by adequately cutting some faces and then bolting. For these elements, the use of self‐drilling screws is evaluated here. These connections could be removable and reusable in some cases, providing more sustainability. They also present semi‐rigid behaviour, which leads to weight saving structures and makes them ideal in many situations for structures like greenhouses or other light portal frames.The structural joints following this typology can be planned as beam‐column, ridge, or even column‐base plate joints. This paper is focused on the initial experimental results of the first two cases under bending moments, comparing them with some simplified analytical assumptions for the strength and the stiffness. These calculations are based on eccentric bolted connections with in‐plane moments but considering some particularities of these joints and joining means (self‐drilling screws).

Strength Evaluation of Pipe‐Rack Connection Using Extended End Plate

AbstractPipe‐rack structure is generally designed as a steel structure, but size of each column and beam is small because vertical loads on the structure is relatively low. In addition, due to the surrounding environment, the end plate joint is mainly used as on‐site bolting rather than welding. In this paper, seismic performance evaluation of pipe‐rack structures was conducted for three types of extended type end plate connection using the panel zone reinforcement and end plate thickness as variables. Connection of the pipe‐rack structure which is commonly used is the type of panel zone yielding occurred before other members, and its ductility and energy dissipation capacity was calculated 24.2% and 19.5% higher than the type of reinforcing panel zone by plates. As a result of the test, it is judged that yielding of the panel zone in a steel structure such as a pipe‐rack structure can be beneficial in the seismic loads.

Ultimate strength of CFST-gusset plate joints with ring stiffener plates under tension

Tube-gusset plate joints are increasingly adopted in large lattice towers for wind power, due to the advantages of simple fabrication and clear force transmission path. To investigate the mechanical performance of CFST-gusset plate joints with ring stiffener plates, tensile bearing capacity tests of three tube-gusset plate joints were performed in this study. The test results showed that setting ring stiffener plates and filling concrete could effectively improve the stiffness and tensile bearing capacity of tube-gusset plate joints. In addition, the finite element (FE) models were established in this study, and the accuracy of the FE models was verified by comparing it with the test results. Parameter analysis showed that the increase of the width ratio (R/D) and thickness ratio (tr/t) of the ring stiffener plate and the width ratio (LGP/D) of the gusset plate was a significant method to improve the ultimate strength of tube-gusset plate joints under tension. But when the width ratio and thickness ratio of ring stiffener plates exceeded the limit relationship, the ultimate strength of joints would not be further improved, which was easy to cause waste of materials. Finally, to simplify the calculation of CFST-gusset plate joints with the ring stiffener plates, an equivalent interaction method (EIM) was proposed in this study, which could accurately predict the ultimate strength of CFST-gusset plate joints with ring stiffener plates under tension.

Fretting wear behaviour in 6061-T6 aluminium alloy

Abstract In this study, fretting wear in riveted lap joints of aluminium alloy plates was investigated. For the fretting test, 6061-T6 aluminium alloy plates, which are widely used in aircraft construction, and blind rivets were used. Experiments were carried out using a computer controlled Instron testing machine. Fretting surface roughness, microhardness was investigated by metallographic techniques and scanning electron microscopy. Tensile load cycles in the riveted lap joint were found to cause damage to all surfaces. Two contact surfaces where friction occurs were investigated. The contact surface of the lower plate with the upper plate, and the contact surface of the lower plate with the rivet head. As load and cycles increased, fretting scars and surface roughness increased. Consequently, it has been determined that fretting damages occur between the contact surface of the plates and between the plate and the rivet contact surface.

Realizing deep penetration and superior mechanical properties in a titanium alloy thick plate joint via vacuum laser beam welding

It is usually very difficult for achieving deep penetration in titanium alloy thick plates by conventional laser beam welding (LBW) under the atmospheric environment, since the laser beam energy is easily dissipated in air. In this study, LBW in a low vacuum environment (100 Pa) was proposed to realize the deep weld penetration of 16 mm of Ti–6Al–4V alloy thick plate, which was over 1 time deeper than that in the atmospheric joint (7 mm). In addition, the contents of the impurity gas elements (N, H and O) hardly changed after vacuum LBW (VLBW), ensuring the welding quality. The fusion zone mainly consisted of acicular α′ martensite, which enhanced the α′/α′ interface strengthening, resulting in the higher microhardness than that of the base material. The average tensile strength of the joint achieved 1010 MPa, with the strength efficiency 100%. Microstructure evolution mechanisms during VLBW were discussed. This study provides a reference for the engineering application of VLBW of titanium alloy thick plates.

Finite element analysis of butt joint of 316Ln steel thin plate welded by laser welding process

This study focuses on the FEM-based thermal analysis of laser welding for 1.5 mm thick austenitic stainless steel 316Ln, which is commonly used in high-temperature applications such as oil & gas industries and thermal power plants. The objective is to investigate the thermal behavior of the welding process and validate the FEM-based calculations with measured thermal cycles. The thermal cycles at a distance of 10 mm from the welding zone were measured using K-type thermocouples. To analyze the thermal behavior, a Finite Element Method (FEM) approach was employed using the SYSWELD software. The FEM-based calculated thermal distribution was then compared and validated against the measured thermal cycles. In order to accurately model the laser heat source distribution, two different heat source models were selected: a conical model and a combined double ellipsoidal plus conical model. The findings of this study provide valuable insights into the thermal characteristics of laser welding for austenitic stainless steel 316Ln. The validated FEM-based thermal analysis helps in understanding the temperature distribution and thermal effects during the welding process. Such knowledge is crucial for optimizing the welding parameters and ensuring the integrity and quality of the welded joints in high-temperature applications.

Hematomyelia associated with coronavirus disease 2019: A rare case report.

Coronavirus disease 2019 (COVID-19) can damage the central nervous system. Although there have been reports of cerebral hemorrhage and infarction caused by COVID-19, hematomyelia due to COVID-19 has never been reported. A 40-year-old male was admitted to the hospital with positive nucleic acid detection for COVID-19 after experiencing fever for 2 weeks, urinary retention, fecal retention, and pain in both lower extremities for a week. The patient diagnosis was established using thoracic and lumbar magnetic resonance imaging (MRI). Contrast-enhanced thoracic and lumbar MRI revealed subdural (dorsal predominant) short T1 and slightly long T2 bands in the T12-S2 infundibular canal in the scan field, and the subdural hematoma was yet to be distinguished from other diseases. Spinal cord edema was observed in the left vertebral plate and facet joint of the T11 vertebral body, indicative of inflammation. The cerebrospinal fluid (CSF) was positive for COVID-19 nucleic acid. Antiinfection, immunomodulation, correction of acid-base balance and electrolyte disorders, improvement of circulation, nerve nutrition, and other symptomatic supportive treatments were administered to the patient. The patient symptoms significantly improved after 4 weeks of anti-infection and immunomodulatory therapy. Repeat thoracolumbar MRI revealed absorption of the spinal cord hematoma, and the patient was discharged from the hospital. To date, COVID-19-related hematomyelia has not been reported and anti-infective and immunomodulatory therapies may be effective. COVID-19 not only easily leads to brain injury but can also cause spinal cord injury and even spinal cord hemorrhage. When patients with COVID-19 experience symptoms and signs of spinal cord injury, spinal cord injury and bleeding caused by COVID-19 should be considered, and MRI and lumbar puncture should be performed as soon as possible to make a clear diagnosis.

Influences of various parameters on shear stiffness of bolted joints subjected to shear load

Parameters which affect shear stiffness characteristics of bolted joints subjected to shear load should be elucidated in order to design mechanical structures for functionality focusing not only on their strength and self-loosening but also on their shear stiffness. In this study, we have both experimentally and analytically investigated the behaviors of a bolted joint subjected to shear load and primary parameters which determine the shear stiffness characteristics of bolted joints. The experiments have been conducted applying the shear load four times repeatedly on clamped plates of a bolt/nut assembly with washers. We measured the shear stiffness of bolted joints and the shear load at which the slippage started to occur between the clamped plates. Four types of washers were used in the experiments with different contact areas on the clamped plates in order to reveal the effect of contact area of washers. We also conducted FE analysis under the same conditions. As the results, it was seen that the shear stiffness slightly increased with an increase in the clamp force of bolted joint. The shear stiffness was not influenced by the number of loading cycles. It was also seen that the amount of rotational deformation in the bolted joint depended on the slippage between the clamped plates. Although the rotation deformation was very small until the slippage occurrence, the rotational deformation remarkably increased after the slippage occurred. In general, it is well-known that the joining portion of lap jointed plates by spot welding, for example, slightly and rotationally deformed, but it has never been elucidated that the inclination angle due to the rotational deformation depends on the slippage between the clamped plates in the bolted joint. It was also seen that the shear stiffness until the slippage occurrence increased with an increase in the contacting surface area between the clamped plates. Although we investigated the effect of surface roughness of the clamped plates only in the experiments, we cannot clearly reveal its effect on the shear stiffness. But it is seen from the FE analysis result that the friction coefficient between clamped plates had a slight influence on the shear stiffness. The result shows that the shear stiffness of bolted joint mainly depends not only on the slip resistance between the clamped plates but also on increase of the contact surface between the washers and clamped plates. The results can be applied in order to control the shear stiffness of lap-jointed plates by spot welding and so on.

Influence of durability of waterproofing solutions terraces protecting against water and moisture

The article analyses the changes in the durability of waterproofing of terraces, with particular emphasis on the properties of waterproofing materials as a result of utility factors. It was analysed the influence of tensile properties of the above-mentioned materials on their resistance against fatigue resulting from movements of the substrates caused by temperature changes on the surface of the terraces coverings. The adopted range of horizontal plate movements was from 0 to 2 mm at variable temperatures: – 15°C and +70°C. The durability of waterproofing sheets, such as reinforced bitumen sheets and PVC sheets and rubber sheets, as well as coating products was assessed. Thermal deformations of the substrate plates occurring within the terrace covering are most effectively transferred by flexibility sheets with a high relative elongation value, that is: bitumen sheets with polyester reinforcement, PVC sheets and EPDM sheets. The correlation between the mechanical properties of the coatings and their resistance to fatigue cannot be determined but the most favourable properties are shown by two-component (polymer-cement) liquid applied water impermeable products reinforced on the entire surface or reinforced with special tapes over the thermal expansion joints of the substrate plates.

Structure Design Modification of DPW Nasdem Office Building using Steel Special Moment Resisting Frame

Manokwari is a District located at the junction of three main plates forming the earth's crust, namely the pacific plate. This makes Manokwari Regency prone to earthquakes. Therefore, building planning must be designed with the concept of earthquake-resistant buildings. Steel material is one type of material that is often used for planning earthquake-resistant building structures because it has high strength and lightweight properties that it is good for earthquake-resistant buildings. One of the methods often used in the planning of earthquake-resistant steel structures is the special moment resisting frame system (SMRF). This structural system is used because it has full ductility that it can survive in areas with a high earthquake risk. This planning modification was carried out at the DPW NasDem Office building by changing the main structure in the form of reinforced concrete using a steel structure with a special moment resisting frame system (SMRF). Based on the calculation and analysis, the results were obtained, namely: the dimensions of the secondary beam are IWF 300x150x6.5x9, the main beam 1 IWF 350x250x9x14, the main beam 2 IWF 300x200x9x14, the column dimensions KC 450x200x9x14 (floors 1-3), KC 400x200x8x13 (floors 4-5), and KC 350x175x7x11 (elevator columns). Floor slabs are 12 cm thick and 10 cm thick for roofing plates. The SRMF joint design uses a high-quality bolt (A325) with the quality of the BJ41 joint plate and the planning results meet the requirements.

Applicability Analysis of Nickel Steel Plate Friction Coefficient Model Based on Fractal Theory

In the field of aerospace, weapons and other complex assembly, there are more than 50 factors affecting the performance degradation of joint structures, among which the friction coefficient is the main factor. Nickel steel is widely used in large complex equipment due to its advantages of high strength. Therefore, this paper first establishes a theoretical model of friction coefficient based on fractal theory. Secondly, the friction coefficient experiment was carried out to measure the friction coefficient of nickel steel plates with different roughness under different normal loads. Finally, the experimental results are compared with the theoretical results, and the accuracy and error analysis of the model is carried out. The results show that the friction coefficient increases with the increase in roughness. When the normal load is greater than 50 kg, the friction coefficient gradually tends to be stable. The error of identification results of correction factor a was all within 5%. The error between theoretical model prediction and experimental data is 6%–15%, which indicates that the calculation of the friction coefficient has high accuracy. The results of this study can provide data and theoretical support for the friction coefficient evaluation of nickel steel plate joint structures, and contribute to the health detection and reliability evaluation of nickel steel plate joint structures.

Cyclic flexural performance of precast lightweight aggregate concrete insulation panels

AbstractThis study investigated the structural safety of the developed panel‐to‐base joint technique for full‐size precast lightweight aggregate concrete (PLC) insulation panels subjected to cyclic lateral loads. The main parameters were the compressive strength of insulating concrete and the safety factor of the joint reinforcing bar for connecting with the base or beam. The test results revealed that the PLC insulation panel specimens with a safety factor of 1.0 experienced severe pinching effect and low ductile performance. However, the PLC insulation panel specimens with a safety factor of 1.6 exhibited higher flexural moment capacity, displacement ductility ratio, and work damage index than those with a safety factor of 1.0. Consequently, the overall flexural behavior of the PLC insulation panel specimens with a safety factor of 1.6 can be developed stably, resulting in satisfactory seismic connection performance requirements specified in NEHRP. Meanwhile, the developed panel‐to‐base joint using the joint reinforcing bar and L‐shaped steel plates can be considered as a fixed end according to the analysis of the collapse mechanism, as with spliced sleeve or welding plate joints.

Stress amplification effect and fatigue strength evaluation of marine thin plate welded structure considering welding deformation: Theoretical and experimental analysis

Due to the low bending stiffness of thin plate welded joints, welding deformations such as welding dislocation, welding angle deformation and initial welding deformation are easy to occur in the welding process. The existence of these deformations will cause additional stress concentration effect and reduce the fatigue performance of thin-plate welded structures. Therefore, the influence of various welding deformations should be considered when evaluating the fatigue strength of the welded joints of thin plates. Combined with the test data, the calculation formula of stress amplification factor considering various welding deformations proposed by this paper is compared with the calculation formula in the existing literature and finite element calculation results. Moreover, the analytical formula is applied to the fatigue assessment of 5059 aluminum alloy welded joints. According to the evaluation results, it is found that the structural stress method and equivalent structural stress method based on the proposed bending stress amplification coefficient formula have good evaluation results for aluminum alloy thin plate specimens with welding deformations. Fatigue strength class curves suitable for thin plate aluminum alloy welded joints corresponding to different fatigue evaluation methods are further suggested.

Study on Tensile Performance of Double-Bolted Joints between Carbon Fiber Reinforced Polymer Plate and Aluminum Plate

Carbon fiber reinforced polymer (CFRP) with high specific strength, specific modulus, and other outstanding properties, which could be used in aerospace, shipbuilding, and railway. The joint of carbon fiber composite material plate and metal material plate plays an important role in the overall performance of the structure. In this paper, a carbon fiber reinforced polymer (CFRP) progressive damage model is developed based on composite laminate theory and 3D Hashian theory. The model of the double bolt single lap joint shear connection is established for the CFRP plate and the finite element method is used to carry out the stress analysis and failure prediction of the lap structure. The effect on structural performance under tensile conditions was studied through the change of double bolt spacing. The results show that the decrease in bolt row spacing can lead to the interference effect between holes. In addition, the progressive damage of the composite plate is located near the center line of the bolt hole.

An investigation on the influence of torque and R-ratio on the fatigue life of double-lap bolted joint using FEM

In this investigation, the implications of bolt-clamping forces, stress ratio and their interaction effects on the fatigue life of double-lap bolted joints were examined with the aid of numerical analysis. The part models of double-lap joints were modelled and subjected to three sets of clamping forces on the bolt's shank and three sets of longitudinal loads corresponding to three different stress ratios (R = −1, 0 & 0.5) with a constant mean cyclic stress. The stress dispersion in the joint plates resulting from the clamping force and longitudinal applied loads was evaluated using finite element simulations. These were used in turn to evaluate the fatigue lives of the bolted joints using the Crossland and Smith-Watson-Topper multi-axial fatigue criterion. The simulation results revealed that the bolt clamping forces have a positive influence on the fatigue life of the joint owing to the compressive stresses around the bolt-hole. The results also revealed that increasing the stress ratio adversely affected the life of the joint.

THE INFLUENCE OF WELDING TYPE ON THE STRENGTH CHARACTERISTICS OF CONNECTIONS OF REINFORCING BARS WITH A METAL PLATE

Introduction. In reinforced concrete structures, the ends of reinforcing bars are anchored in the concrete by launching the reinforcement beyond the considered section for the length of the force transfer zone from the reinforcement to the concrete as well as by using anchoring devices. If the required design length of the reinforcement cannot be ensured, special measures to anchor the reinforcement bars are applied [1, p. 5.36]. One of these measures is to install special anchoring devices in the form of plates at the ends of the longitudinal bars. When anchoring devices in the form of plates, special attention is paid to the welding type of the plate with the bar, which should prevent the bar from being pulled out when longitudinal forces from external load are applied. Materials and methodology. The material to be investigated was reinforcing bars of class A500C with diameters of 25 and 32 mm, connected at the ends to metal plates by means of contact welding. Holes with a diameter equal to the diameter of the reinforcement were drilled in the metal plates. The bars were inserted into the holes flush with the surface of the plates and welded to the plates by one and double sided welding. A total of two bars were used per welded joint. The strength of welded connection of reinforcing bars with plates was determined on the tensile testing machine HMS-100 by applying maximum tensile force to reinforcing bars. The fracture pattern of each reinforcing bar to plate joint was noted. The results of the experiment. As a result of the experiment, it was found that the destruction of the connection between the two reinforcing bars of 25 mm and 32 mm diameter and the metal plate during one-sided welding occurred by destroying the welding connection and pulling the bars out of the plate. When the bars were joined on both sides, there was no pulling out of the plate. In this case, one 25-mm-diameter bar joint is out of service due to bar breakage in the area of contact with the weld and the other is due to the exhaustion of its physical yield strength. The destruction of the 32mm diameter bars and metal plate joint in the two-sided welding process was due to the rupture of one bar in the area of its contact with the weld and the cracking of the other bar's contact with the weld. Conclusions. As a result of the experiment, it was found that the strength values of the welded connection between reinforcing bars 25 mm and 32 mm in diameter and a metal plate at bilateral welding were 1,33−1,36 times higher than those at one-sided welding.

Study on Load–Slip Curve of a PBL Shear Key at a Steel–Concrete Composite Joint

The steel–concrete composite truss adopts a new type of steel-concrete composite joint with high rigidity and load-carrying capacity. In order to more conveniently and clearly grasp the working mechanism of Perfobond Leiste (PBL) shear keys in the core area of new composite structures such as steel–concrete composite trusses, the lack of strong theoretical support for the theoretical formula of load–slip relationships in the entire loading process of single PBL shear keys is solved. By proposing a straight–curved–straight three-stage simplified load–slip curve with respect to the PBL shear key, the stress process of the PBL shear key is divided into three stages—the elastic stage, plastic stage, and strengthening stage—based on the compressive yield and failure critical point of tenon concrete in the shear key. With reference to the calculation method of the bearing capacity of the order pile under horizontal loads and by calculating the shear stiffness of the shear key, a theoretical formula suitable for separating the load–slip relationship of a single PBL shear key in the entire loading process of the ear plate composite joint is proposed. The results show that, in the elastic section, the slope of the curve is related to the concrete reaction coefficient and the material parameters of the penetrating steel bar; moreover, in the strengthened section, the coefficient is related to the shear modulus of the penetrating steel bar, and a more uniform length distribution of the penetrating steel bar between the two joint plates will improve the initial stiffness of the PBL shear key to a certain extent. The results of the proposed method are in good agreement with the finite element results and experimental values. This research study’s results can provide a convenient design method for the design of the internal PBL shear keys of new composite structure joints, promoting the promotion and application of new composite structures and advancing the development of the engineering field.

Numerical Analysis of Fracture Behaviour for Cracked Joints in Corrugated Plate Girders Repaired by Stop-Holes.

The efficient crack eliminated stop-hole measure was proposed to repair and reduce the stress concentration associated fracture risk of the corrugated plate girders by setting it at the critical joint of flange plate with tightened bolts and gaskets under preloading. To investigate the fracture behaviour of these repaired girders, parametric finite element analysis was conducted, focusing on the mechanical feature and stress intensity factor of crack stop-hole in this paper. The numerical model was verified against experimental results first, and then the stress characteristics due to the presence of crack open-hole were analysed. It was found that the moderate-sized open-hole was more effective than the over-sized open-hole in the reduction of stress concentration. For the model with prestressed crack stop-hole through bolt preloading, the stress concentration was nearly 50% with the prestress around open-hole increased to 46 MPa, but such a reduction is inconspicuous for even higher prestress. Relatively high circumferential stress gradients and the crack open angle of oversized crack stop-holes were decreased owing to additional prestress effects from the gasket. Finally, the shift from the original tensile area around the edge of the crack open-hole that was prone to fatigue cracking to a compression-oriented area is beneficial for the reduction of stress intensity factor of the prestressed crack stop-holes. It was also demonstrated that the enlargement of crack open-hole has limited influence on the reduction of stress intensity factor and crack propagation. In contrast, higher bolt prestress was more beneficial in consistently reducing the stress intensity factor of the model with the crack open-hole, even containing long crack.