Bearing Capacity Of Connection Research Articles

Bearing Capacity of Steel Tube Tower Connection under Different Thickness of Gusset Plate

In this paper, a finite element model is established to study the influence of connection plate thickness on the bearing capacity of steel tube tower connections. Through the bearing capacity of connections under different connection plate thickness, the influence of connection plate thickness on the bearing capacity of steel pipe tower connections is analyzed. Finally, the relationship between the thickness of connection plates and the bearing capacity of steel tube tower connections is analyzed by regression analysis. The results show that with the increase of the thickness of gusset plate, the bearing capacity of steel tube tower connections increases linearly. The bearing capacity calculated by regression analysis is in good agreement with the finite element simulation results.

Tensile resistance and design model of an external double-layered flange connection

This paper puts forward a new type of flange connection to overcome the brittle fracture and lamellar tearing of traditional flange connections in long-span transmission towers. This new flange is called external double-layered (EDL) flange connection, which is usually applied to the connecting of circular hollow sections. Scale-down experiments and finite element analysis (FEA) were conducted to investigate the failure mode and bearing capacity of EDL flange connection under tensile load. Stress distributions and deformations of each component in the connection were measured and discussed. Parameter analysis was carried out to study some major influencing factors on the mechanical behaviours of the connection. Results manifested that the EDL flange connection had good ductility and failure mainly appeared in the upper flange plate. The flange plates were mainly subjected to compression in the thickness direction, so the lamellar tearing problem was avoided. The diameter of the bolts and the thickness of the upper plate had significant effects on the bearing capacities of the connection, while the thickness of the stiffened plates mainly affected the ductility. In the end, design methods of the flange plates, the stiffened plates, and the bolts were proposed based on the rigid plastic theory as well as the results of experiments and FEA.

Experimental and numerical study on the mechanical behavior of Q460D high-strength steel bolted connections

Based on static tensile test of 20 Q460D high-strength steel bolted connection joints, influences of high-strength steel material strength and bolt arrangement pattern on bearing capacity and deformation of connections were analyzed. According to differences of end distance, edge distance, and pitch between bolts, finite element modeling, theoretical calculation, and test results were compared, a quantitative analysis was carried out for mechanical property of high-strength steel bolted connections, and applicability of relevant standards was investigated. The study showed that bearing capacity and deformation of specimens for Q460D high-strength steel increased as pitch increased when bolts were under transversal arrangement. Influence of increased edge and end distance on bearing capacity of the connection was minimal after standard value of the structure was reached. Stress nephogram obtained from numerical analysis and plastic region presented symmetrical distribution with two holes bearing balanced stress, fitted curve points were dispersedly distributed, and margin of theoretically calculated value was large when EC3 standard was used. When bolts were under longitudinal arrangement, bearing capacity of the specimens only presented a linearly increasing trend as pitch increased, two holes bore unbalanced stress in stress distribution, stress borne by bolt hole at end part and its deformation were both large, and bearing capacities of end and middle bolts calculated according to the EC3 standard were relatively accurate. This study can provide a theoretical basis for design and connection structure of Q460D high-strength steel bolted connection joints.

Experimental and numerical study on the longitudinal-crack failure of double-shoulder tool joint

In recent years, the failure accidents of double-shoulder tool joint caused by longitudinal-crack occur frequently during drilling with increasing deep and ultra-deep wells, directional wells, extended reach wells and horizontal wells, which not only decreases rate of penetration, but also results in huge economic losses. Although the frictional heat check cracking can cause cracking initiation according to the standard API RP 7G, it has been found heat check cracking is just one of the cracking initiation mechanism rather than crack propagation mechanism; in other words, there are various other causes of crack initiation and propagation. Hence, in order to find out the failure mechanism caused by longitudinal-crack, the failure analysis of one typical double-shoulder joint with longitudinal crack has been investigated in detail from three aspects including its service load, its own structure feature and fracture toughness by combining experimental inspection and finite element simulation. The results from macro-analysis, micro-analysis, chemical component analysis, mechanical properties analysis, stress and deformation analysis, show that this failure mechanism of double-shoulder joint is closely and directly related to overlarge combined load (tensile force, torsion and bending), its own structure feature and difference of fracture toughness between transverse section and longitudinal section. Firstly, the martensite is produced on the thread surface due to severe fraction heat between threads caused by overlarge combined load during jarring releasing of double-shoulder joint, which leads to the inter-granular crack initiation. Secondly, the circumferential stress release is restricted by thread connection. Thirdly, the transverse fracture toughness of material is lower than longitudinal fracture toughness. Finally, the longitudinal-crack failure of this double-shoulder joint occurs under overlarge alternating combined load. It is suggested that if the thread taper of double-shoulder joint is decreased and the area of secondary shoulder is increased under extreme working environment, the bearing capacity of connection can be improved and the failure accident caused by longitudinal-crack can be avoided effectively.

Experimental and theoretical studies on SHS column connection with external stiffening ring under static tension load

In order to investigate mechanical properties in the core area of Square Hollow Section(SHS) column connection with external stiffening ring, four specimens were tested under the static tension load. The failure modes, load-displacement curves and strain distribution were analyzed to study the mechanical properties and the load transfer mechanism of the core area of connections. The connections behave good ductility and load-bearing capacity under the static tension load. Parametric analysis was also conducted, in which the thickness of steel tube, extended width and thickness of the stiffening ring were considered as the parameters to investigate the effects on mechanical properties of the connections. Based on the experimental results, an analytical method for the bearing capacity of connection with external stiffening ring under the static tension load was proposed. The theoretical results and the experimental results are in good agreement, which indicates that the theoretical calculation method of the bearing capacity is advisable.

EFFECT OF BOLT DIRECTION ON THE BEARING CAPACITY OF DOUBLE SHEAR CONNECTIONS

The direction of bolts and its effect on the bearing capacity of double shear bolted connections has been examined in this paper. Sixteen specimens with up to four bolts have been tested under tensile load. These specimens have been sorted into two series (L, T) according to the bolt direction with applied loads. The experimental results have clearly indicated that the bearing capacity of connections had been considerably affected by changing the direction of bolts. With tear-out failure, All specimens of L series showed high bearing capacity and good ductility while block shear failure was the distinguishing feature of specimens of T series.

Experimental determination of load bearing capacity of connections realized by punched metal plate fastener

This paper demonstrates the results of experimental determination of load bearing capacity of structural timber member connections realized by WOLF and LKVC metal connector plates. Considering the complexity of the connections realized by these modern mechanical fasteners, this paper deals only with plate anchorage capacity (stress in the metal-wood contact). The aim of the conducted experimental study was to determine the metal connector plate anchorage capacity in accordance with the provisions of Eurocode 5 and also to analyze the ratio of the load bearing capacities of these two types of connectors in terms of their geometry. Experimental testing was conducted by loading of multiple samples up to the limit plate anchorage capacity. Discussion of the test results included the analysis of the connection deformation for different levels of load, as well as the mode of reaching the limit plate anchorage capacity. Review of the determined limit plate anchorage capacities, for the determined displacements of connection, was given in the conclusion, together with the comment on test results.

Experimental Study on Seismic Behavior of Cold-Formed Square Tube Beam-Column Connection with Welded Haunch

The cold-formed thin-walled tube has been widely applied in high seismic fortification intensity region and post-seismic reconstruction area because of light quality, high strength and small deformation. But the connection mode and mechanical properties of beam-column connections still need further study. According to the "strong column and weak beam" seismic design principle and the thinking of control the position of plastic hinge, adding haunch slabs at the end of beam to reduce the number of repeated welding and avoid brittle fracture. Through the low cyclic loading experiment, four beam-column connections with welded haunch under different axial compression ratios have been studied, and connection’s hysteretic performance, energy-dissipating capacity, bearing capacity, rigidity and failure mode have been discussed. The result shows that: 1) the ultimate bearing capacity of connection with welded haunch is much great, and the energy dissipation capacity is very well, which can make this connection to absorb and consume great energy in earthquake. This connection can meet the need of seismic design very well. 2) The connection with welded haunch experiences much cycling time, has long yield platform after yield, has great cumulative energy-dissipating capacity and well ductility. 3) the final destruction of connection with welded haunch is caused by the beam’s local buckling. And the yield surface is almost located at the outside of connections. 4) The axial compression ratios has great effect on the hysteretic performance, bearing capacity and stiffness degradation for the connection with welded haunch.

Load Bearing Capacity of Connections in Tempered Glass Structures

In the design of high load bearing capacity beams made of tempered flat glass, connections cannot be avoided when large-span or high-stiffness beams are considered. The aim of this paper is to contribute to a method to calculate the load bearing capacity that can help the design of dowel type joints in tempered glass structures in buildings. The technology presented is derived from the one used for hanging glass in facades. In a first step, residual stresses due to thermal tempering are modelled with the Finite Element Method. Narayanas-wamy’s model is used to describe the thermo-mechanical behaviour of glass. The different heat transfers are identified and modelled for a given tempering process. In a second step, the state of stresses due to the loading of the metallic connector is analysed. The numerical prediction of stresses is validated by means of experiments. The superposition of these two stress states is combined to get a design criterion for holed tempered glass plates loaded by dowel type joints.