Welded Connections Research Articles

Numerical Study on Seismic Behavior of Flexural Frames with Semi-Rigid Welded Steel Connections Considering Static and Reciprocating Loads: A Performance-Based Earthquake Approach

This paper aims to apply a performance-based earthquake engineering approach to assess the assurance of flexural frames whose members are jointed together by using new modified RBS connections, namely, semi-rigid welded steel connections, which obey a progressive failure mechanism. First, the structural members and connections are modeled and predesigned in ETABS software, and then, using OpenSees software, a series of nonlinear progressive failure analyses are performed on the built models extracted from ETABS. To this end, three types of multi-story structures with 3, 10, and 15 are modeled. The models are subjected to 15 earthquakes, such as Northridge (1994), Kobe (1995), Chichi (1999), Bam (2003), Tabas (1978), and so on. The connections are modeled by a series of rotational springs whose nonlinear behavior is estimated by a three-line curve that is established based on the modified Ibarra–Krawinkler deterioration model. Finally, obtaining the maximum ground acceleration versus the maximum relative drift of the floors, the fragility curves of the structures for a collapse level (CP) are determined, through which the seismic performances of the models are evaluated. The results show that by reducing the number of structural floors, the ductility of structures was reduced, and by increasing the ductility of structures, higher drifts in structures were achieved at the same seismic level. The average amount of ductility reduction coefficient in structures with RBS was 1.06 times those without RBS, which indicates that the energy dissipation capacity in structures without RBS connection is higher than in those with RBS. Local analysis of connections shows a 9% increase in the plastic rotation capacity if RBS connections are used. The ductility of all frames with RBS connection increased slightly compared to frames without RBS.

Investigation on the effect of process parameters on mechanical and microstructural properties of AA8011 similar FSW weld joints

Friction stir welding (FSW) factors significantly impact the welding characteristics of AA 8011 and similar alloys weld joints produced by FSW. The tool pin profiles influence joint characteristics, weld quality, and joint strength. This study used three tool pin profiles to create weld connections at three different tool rotation rates and various welding speeds. Design of experiments (DOE) was utilized to execute complete full factorial experiments. The welded joints’ mechanical characteristics were examined using hardness and tensile tests at room temperature. The average maximum hardness number was 38.28 HRB with the tapered tool at 1300 rpm spindle speed and welding speed of 20 mm/min at 5 kN unvarying axial force of the whole operation. The lowest hardness value was 30 HRB using a taper threaded pin profile tool, rotating at 1200 rpm and welding at 60 mm/min. When the taper pin profile tool was used at 1500 rpm, the highest tensile strength of the weld joint was achieved, which was the closest value of the parent material. At the same welding speed of 20 mm/min, the taper threaded pin tool at 1300 rpm produces the lowest tensile strength of 84.16 MPa, made utilizing a taper threaded pin tool.

Experimental Investigation of Steel Connections

Experimental results and comparative study has proven to be core for the foundation and development of structural and earthquake engineering. In the recent past, various research has been carried out from full scale to scaled model prototypes on the evaluation of weld and bolt steel connections. Reversal stresses that occur within milliseconds make beam-column connections most vulnerable to lateral loads when exposed. It would result in failure and catastrophe if not designed and erected correctly. The capability to transfer forces through the joint is the index to keep the structure safe and sound to avoid progressive collapse in the case of buildings. It is clear now that failure of beam-column joint will ultimately lead to structural damage, so the importance is self-evident.

Experimental observation of steel-concrete composite beamwith different shear connection degrees

The test program was carried out on two steel-concrete composite beams using perfobond shear connectors in order to investigate strains of steel-concrete composite beams with different shear connection degrees. The steel used for perfobond and steel girder with T inverse section was cut together from steel plate without using weld connection as applying to steel girder with I sec-tion. Some holes settled in beams were 10 holes and 22 holes to create the difference of shear connection degree. The study concentrated on evaluating the effect of shear connection degree on the steel-concrete composite strain. The observed strains included strain of concrete slabs, the strain of steel girders, and strain of perfobond shear connectors. The results showed that shear connection degree significantly affected strains of steel-concrete composite beams.

Study on New Prefabricated Reinforced Concrete Structure Technology Based on Fault-Tolerant Design

To reduce the impact of poor field connection on structural safety in prefabricated concrete structures, a new kind of prefabricated reinforced concrete structure—an FTPC (fault-tolerant prefabricated concrete) structure based on the fault-tolerant design concept—was proposed and studied in this paper. The horizontal load-bearing units of an FTPC structure are fully prefabricated or semi-prefabricated slabs. The vertical load-bearing units are formed by four types of prefabricated cantilever components. Prefabricated cantilever components are horizontally connected by welded connection and vertically connected by a specific connection method using steel tubes and cast-in-place concrete. A mathematical sampling method can be used to select several welded connection nodes as disconnected nodes to consider the actual weld quality. Enveloping design can be carried out to obtain the final design results of each cantilever component, which can realize the fault-tolerant design and better ensure the structure safety. Finite element analysis was carried out for a two-story villa as an example to verify the feasibility and rationality of an FTPC structure. Study results show that an FTPC structure can meet the requirements of safety and applicability. Moreover, it has the advantages of a flexible arrangement of load-bearing components, a clear force transmission mechanism, and a moderate component volume.

Research on Failure Diagnosis Method of a Rocket Borne Micro Electro-Mechanical Systems Recorder Based on Fault Tree

With the complexity and diversification of rocket launch tasks, more stringent requirements are put forward for MEMS electronic equipment, which is closely related to the stability and security of rocket. The key components of the rocket-borne electronic system are composed of discrete components, integrated components and corresponding connected fixed components. The selection, welding and board level connection of each electronic element determine the reliability of the MEMS component. In this paper, the fault tree analysis method is applied to the reliability analysis of the rocket-borne recorder, and the dynamic fault tree analysis method is introduced to compensate the deficiency of the traditional static fault tree analysis method, finally the simulation comparison with Monte-Carlo analysis method is carried out to verify the effectiveness and feasibility of the proposed method. The work of this paper is of great significance for establishing the reliability theory of the system and mastering the experience of quick failure diagnosis.

NILAI AMPERE PENGELASAN SMAW DENGAN MENGGUNAKAN ELEKTRODA 6013

ABSTRACT
 
 Technological developments in the increasingly advanced construction sector cannot be separated from welding. Welding has an important role in metal engineering. A good welding connection will greatly affect the welding of low, medium and high carbon materials in the SMAW (Shield Metal Arc Welding) welding process. The shipping industry in Indonesia uses a lot of 10 mm plate types, in reality welding using 10 mm plate materials is very difficult, especially in determining the number of amperes that must be used so that the welding results are said to be good. The purpose of this study was to determine a good amperage value for SMAW welding using a 10 mm A36 plate material with an E6013 electrode. By using a tensile test and a micro test by first using the experimental material in the form of a plate with type A36 which is welded using an E6013 electrode. With plate-shaped samples totaling 12 pieces using different amperes, namely 70, 110 and 160 amperes. From the results of the study it can be concluded that the best amperage and recommended for use in welding is 110 amperes. With an amperage value of this size, it will produce welding material that is not easily broken. So that in practice in the field, if this ampere value is used, it will produce a better product, more durable and have a better product selling value.
 
 Keywords: A36, E6013, Ampere, Welding.

Performance of steel metal prepared using different welding cooling methods

Different welding cooling methods used in steel manufacturing confer different mechanical properties to the produced material. The use of the electric arc-type welding connections generates extremely high temperatures that alter the mechanical properties of the steel and also the ability of the steel to resist applied loads. Therefore, in the present study, experiments were conducted to investigate the properties of 24 specimens of standard steel plates that were cooled using different methods after the welding process. The experimental results revealed that gradual cooling through the air after the welding process exerted a negative effect on the mechanical properties of the steel material. This was evident in the values of the yield stress, ultimate stress, and modulus of elasticity, which were reduced by a factor of 11.8%, 8.4%, and 7.0%, respectively, for the specimens with a thickness of 2 mm, and by 13.8%, 12.7%, and 5.2%, respectively, for the specimens with a thickness of 5 mm. On the contrary, the process of rapid cooling using water exerted a positive influence on the mechanical properties of the steel material, which manifested as enhanced values of all mechanical properties. Moreover, the welding efficiency achieved using different cooling processes decreased with the increase in the thickness of the steel plate. It is noteworthy that the negative impact of cooling in the air on the mechanical properties of the produced steel is not considered in the current design codes.

Experimental study on bond strength failure of GFRP lap joints

Bonding has many advantages such as high adhesive strength, peel resistance, good toughness, shrinkage and corrosion-resistance, compared with bolting, welding and other connection patterns, which is the basic connection of the composite materials. The mechanical properties of the bond depend on the type and geometric parameters of the bond. In this paper, experiments were conducted to study the bond strength failure of GFRP single and double lap joints and explore related influencing factors. The variable factors of test specimens include bond type, length and thickness. The quasi-static tensile test was carried out at room temperature to analyze multiple influencing factors of lap joints and characteristic of GFRP bond failure strength. The results showed that the failure of the bond usually occurred at the interface of bond, and bond types, length and thickness have significant effects on the failure of bond. Failure strength increased firstly and then decreased with the increase of adhesive thickness. With the increase of bonding length, the failure mode of the double-lap joint become complex failure mode, which is accompanied by GFRP delamination near the surface of fiber of the bonding.

Thermoelastic state during electrofusion welding of polyethylene pipes at different ambient temperatures

The problem of welding polyethylene pipes used in the mining industry at low ambient temperatures is considered The numerical solution of a thermoelastic problem revealed the distinctive features of thermal and stress-strain states of weld connections of polyethylene pipes using embedded heater couplings at different ambient temperatures. It is found that in low-temperature conditions, the size of the melted zone is considerably smaller than during welding at permissible temperatures. In this regard, the pressure insufficient for high-quality welding is created between the coupling and the pipe. It is also shown that at the time of melt crystallization, the maximum values of stresses and strains during welding at low temperatures are higher than during welding in the permissible temperature range, which causes high values of residual stresses. The results obtained can be used in the development of low temperature welding technology.

Optimization of wire type and current welding on the strength of welding connection in two types of material testing via response surface methodology

The number of types of wire welding that circulate on the market and the development of welding technology, especially related to current welding, create a lack of information related to the quality of welding results for several types of materials. This can cause the strength of the welding connection to not be maximized. Therefore, this study aims to optimize the use of three types of wire welding and three current welding on the strength of the welding connection in two types of material testing using the response surface methodology. Box-Behnken, coupled with the RSM and the desirability function, was used to optimize the strength of the welding connection of the wire types (RD-46, LB-52, and RB-26), and current welding (100, 130, and 160 A) against two types of material testing (IWF-150 and ASTM-A517-G70). The strength of the welding connection observed in response included the tensile strength, Charpy impact-absorbed energy, hardness values in the welding metal and the hardness values in the main metal. Optimization of the strength of the welding connection in this study recommends the application of wire types RB-26, current welding of 100 A, and ASTM-A517-G70 material testing with the highest desirability value of 71.6%. Optimization of tensile strength, Charpy impact-absorbed energy, hardness values in welding metal, and hardness values in main metal by applying this parameter are 575.64 MPa, 110.69 J, 216.75 (HV10) and 126.6 (HV10), respectively. The results proved that an appropriate welding connection strength could be achieved using wire welding types and current welding in material testing.

Multivariate parametric study on laser beam welding of copper lap joints using adjustable intensity profiles

With increasing demand for pure copper welds in the production of electronic connections, various approaches were pursued to reduce the challenging spatter and melt ejection susceptibility of laser beam welding processes in copper materials. One is the use of adjustable intensity profiles of infrared laser beam sources with a combination of a core and ring beam, which enables a wider and more stable keyhole in deep penetration welding and makes a reduction of spattering and melt ejections possible. In order to research the influence of different power distributions with ring powers up to 4000 W and core powers up to 2000 W on the process spattering, welding experiments were evaluated with a stereo camera system for spatter detection using Cu-OF. In addition, the effects of different power distributions, focal positions and welding speeds on the weld metal dimensions and connection widths as well as the corresponding variance were investigated with a multivariate design of experiments based approach.

Friction stir welding of cast aluminum alloy (A319): Effect of process parameters

Due to their light weight and cast ability, cast aluminium alloys are gradually being used in aerospace and automotive applications. Welding aluminium castings together for variety of applications is very critical. Due to the existence of hot cracking, porosity and distortion, these alloys are difficult to fuse using conventional fusion welding techniques. Friction Stir Welding (FSW) is a revolutionary joining technology in solid state that does not require welded and melting the material, without the required for bulk melting, FSW forms the weld connection. Additionally, during dynamic recovery, the thermomechanical deformation refines the structure of the stir zone. As a result, FSW welds exhibit much superior mechanical properties compared to comparable fusion welds. As a result, the current inquiry will examine the outcome of FSW practice factors on the mechanical properties and metallurgical of cast aluminum–silicon alloys in a systematic manner. The effects of welding speed, rotation speed of tool, and axial force on the tensile strength, hardness, and microstructure of friction stir welding joints made of aluminum alloy are presented and discussed in this paper.

MAG shield gas influence study on impact strength of Al-5052 joint

Metal Active Gas Welding is a technique for efficiently combining many materials. Al-5052 was chosen for its non-corrosive, wear-resistant, anti-static, light weight, and formability qualities. Aluminium alloys are important in engineering and metallurgy because of their superior corrosion characteristics, ease of manufacturing, and high specific strength paired with the ideal balance of toughness and formability. The shape of the weld bead, mechanical properties, and distortion can all be utilised to assess the quality of a weld connection. Through solutioning and ageing, post-weld heat treatment improves weld quality, resulting in grain size refinement and better mechanical characteristics. MAG process utilized in ship, aerospace & marine construction. Determine the gas flow rate influence on impact strength of 5052 AL-Alloy joints size as 45x10x4 in mm. In this, 17.3 Joule impact strength obtained maximum at shielding gas flow of 7 Lt/min with constant current 235 amp.

Effects of fillet weld to large-size stud shear connector in full-depth precast bridge deck panel

Resistance of large size headed stud shear connectors 31.8 mm (1¼″) diameter for full-depth precast concrete bridge deck panel with steel girders depends on various factors. One important factor is the weld connection between studs and a steel girder. This research presents two main welding effects: (1) beveling shape of the base stud and (2) layers of fillet weld, which could result to effective composite actions. Three groups of specimens were tested varying among three different beveling sizes, and 2 or 3-layer of fillet weld. The first group (S1-N0) contains studs without beveling, the second (S2-N5) and third (S3-N10) groups consist of studs with 5 mm and 10 mm bevel cut widths in 45-degree, respectively. Each was subjected to shear force from the hydraulic jack until failure or bending limit. The studs in S2-N5, both 2 and 3-layer of fillet weld, could obtain maximum shear resistance up to 56.8 kN (5.8 Ton-force). The large relative displacement (up to 56 mm) was carried on the studs in S1-N0 in both 2 and 3-layer of fillet weld. The stiffness (Load/displacement ratio) of the S3-N10 group were about 5% higher than those without beveling in the S1-N0 and S2-N5 group, which were about 3.56 kN/mm (0.4 Ton-force/mm). In terms of failure mode, tearing out at the bottom of the shank studs was appeared in some samples in the S2-N5 and S3-N10 groups, but in the S1-N0 group.

Residual shearing strength of fillet weld connections after exposure to elevated temperature

Experimental and analytical studies are carried out to investigate the residual shearing strength of fillet welded connections after exposure to elevated temperatures. Transverse fillet welds and longitudinal fillet welds were designed in the test, and four weld leg heights were considered. Fourteen specimens were manufactured for each weld leg height, including seven heating temperatures and two cooling methods, obtaining a total of 112 specimens, along with 8 unheated specimens for comparison. The load-displacement curves and stress-load ratio curves were obtained to evaluate the shearing strength, residual deformation, stress development, stiffness and ductility of the fillet welds. Test results exhibit the transverse fillet welds are mainly integral fracture, while longitudinal fillet welds occur obvious local and global cracks. The weld leg height has the greatest influence on the shearing resistance of fillet welds, followed by the elevated temperature and cooling method. When the heating temperature is between 400 °C-600 °C, an increasement in residual shearing strength can be noticed. Meanwhile, the residual deformation is positively correlated with the weld leg height. Additionally, water-cooling fillet welds are superior to room-temperature-cooled fillet welds in terms of stiffness and ductility. Moreover, the formulae for predicting the residual shearing strength of the fillet welds after exposure to elevated temperatures are proposed.

Effects of Steel Braces on Robustness of Steel Frames against Progressive Collapse

External installation of steel braces is an effective approach to increase the lateral load resistance of steel moment-resisting frames. However, the effects of existence of steel braces on the robustness of steel moment-resisting frames to resist progressive collapse is still not clear because little study has been carried out. To fill this gap, in this paper, six multistory steel moment-resisting subframes (three bare frames and three braced frames) were fabricated and tested. Test results indicated that the specimen with reduced beam section in the connection zone performed best among three types of connections due to the guaranteed formation of plastic hinges at the location of reduced section and avoiding brittle fracture of weld at the connection. Experimental results proved that steel braces could increase the load-resisting capacity by 45.1% and 83.9% of the frame with weld connection and end plate connection, respectively. The gusset plate restricted the rotation of the plastic hinges in the second story of the braced frames with V-shaped bracing, which decreased its deformation capacity and degraded its catenary action capacity. Actually, the ultimate load of the braced frames with V-shaped bracing is only 87.5% of that of the counterpart without any braces. Because the compressive braces were severely buckled before the displacement reached 0.4% of the beam span, it had little effect on yield load but increased the initial stiffness of the bare frames. Thus, a majority of the benefits of the bracing system were attributed to the tensile braces. Moreover, the analytical results evaluated the differences in load resistance and development of load-resisting mechanisms in different stories. Furthermore, the contribution of compressive and tensile braces was decomposed individually by analytical analysis.

Pengaruh Variasi Diameter Filler Dan Kuat Arus Terhadap Kekuatan Tarik Hasil Pengelasan SMAW Material Stainless Steel 304

One of the railway facilities uses stainless steel as the main construction material. The method of joining stainless steel materials, especially the most widely used is the SMAW welding technique. The purpose of this study was to determine the tensile strength of SMAW welding joints on stainless steel 304 material with variations in diameter of rod filler as filler material an d variations in current from DC inverter electric welding machine. The diameter of rod filler as filler material is 1 mm, 2 mm and 3 mm. The variation of the current of the DC inverter of the electric welding machine is 70 A, 100 A and 120 A. The results show the highest tensile strength of the 304 stainless steel welded connection with an average tensile stress of 34.48 MPa on the current electric welding inverter. 120 A is used and the diameter of the rod filler is 2 mm. And the tensile strength of the welding connection of the 304 stainless steel material is the lowest with an average tensile stress of 17.01 MPa at the electric welding inverter current used is 70 A and the diameter of the rod filler is 3 mm.Keyword: SMAW welding, filler, current and stainless steel

Effects of Shear Tabs and High-Strength Bolts in Seismic Performance of Steel Moment Connections

A shear tab and high-strength bolts are often used to connect a steel H-beam to a column. The design demand and capacity of these elements vary from one standard to the other. To investigate the effect, this study applied a finite element method (FEM) to develop models for two steel moment connections and validated the effectiveness by test data. The connections were characteristic of bolted-web-and-welded-flange details. The FEM models were then used to study the design of shear tabs and high-strength bolts in accordance with the U.S. and Japan standards and compared to the Taiwan practice. The result showed a small difference in the peak loads of the connections. However, the U.S. direct welded flange connection had flange buckling and strength degradation at a relatively smaller drift. The connection had a thinner shear tab and fewer high-strength bolts. The other two connections had very similar design results and loading responses. The increase in shear-tab thickness reduced the stress concentration and fracture potential of the connections. It is, therefore, recommended to design a shear tab with moment capacity greater than the beam web. This will reduce the stress concentration of the base metal surrounding the beam-flange groove welds, increasing the connection ductility.

Investigation of breaks of the «Sparking» type of brass‑plated wire for metal cord and high‑pressure hoses and the causes of their formation

The article examines the breaks of thin brass‑plated wire for metal cord and high‑pressure hoses of the “sparking” type and the causes of their formation. The wire was manufactured in OJSC “BSW” – he Management Company of the Holding” BMC “ in the conditions of steel‑wire workshops. The appearance and microstructure of breaks of thin brassplated wire of the “sparking” type are investigated. As a result of the analysis of the appearance and microstructure of the breaks, it was assumed that surface defects are formed on the brass‑plated wire – billet during the welding connection in the jaws of the welding machine during annealing. To confi m this, experiments were carried out with the implementation of welded joints of brass – plated wire‑blanks in wet drawing areas, the appearance and microstructure of the obtained samples of welded joints were studied.As a result of experiments and metallographic studies, the assumption was confirmed that local defects such as “cauterization from sparking” on the surface of the workpiece wire are formed during welding during the annealing operation, it was established that the cause is a violation of contact between the wire and the pressure jaws of the welding machine, wear of the pressure jaws. Photos of the defect, a description of its appearance and microstructure are given.Based on the obtained studies, a number of measures were carried out aimed at eliminating the causes of this defect.