High Tension Bolt Research Articles

Behavior of end plate connection for steel angles

This study investigated the behavior of bolted end plate connection for structural angle sections. For the splice of angles under tensile loading, thick end plates attached to the end of angles are connected by one single high-tension bolt. To improve connection performance and reduce required plate thickness, plate washers made of the same material as that of the end plates are used under the bolt head and nut. Tensile tests of twenty-two specimens with different connection details were conducted. The tests showed that the governing failure mode was bolt rupture and the connection performance was affected by the thickness of the plates. The minimum thickness of end plate and plate washer determined by the yield line theory was conservative. Due to prying action, the connection strength (i.e., the tensile load of angles) was reduced to about 85% of the tensile strength of high-tension bolt. The force transfer behavior of the end plate connection with and without plate washer was investigated in detail through finite element analysis.

Failure analysis and countermeasures of the SCM435 high-tension bolt of three-step injection mold

PurposeThe objective of this study was to perform damage analysis of SCM435 high-tension bolts connecting upper and lower parts of a three-stage injection molding machine.Design/methodology/approachDamage material used in this study was a SCM435 high-strength bolt connecting upper and lower molds of a three-stage injection mold. Causes of damage were determined by macroscopic observation. Microstructure observation was done using a metallic microscope, scanning electron microscope (SEM, S-2400, HiTachi, Japan), energy dispersive X-ray spectroscopy (EDS, Kevex Ltd., Sigma) and Vickers hardness tester (HV-114, Mitutoyo). Fatigue limit of the damaged material was evaluated using equivalent crack length.FindingsBolts were fractured by cyclic bending stress in the observation of ratchet marks and beach marks. The damaged specimen showed an acicular microstructure. Impurity was observed. Chromium carbide was observed near the crack origin. Both shape parameters of the Vickers hardness were similar. However, the scale parameter of the damaged specimen was about smaller than that of the as-received specimen. Much degradation occurred in the damaged specimen. Bolts should undergo accurate heat treatment to prevent the formation of chromium carbide. They must prevent the action of dynamic stresses. Bolts need accurate tightening and accuracy of heat treatment. Screws require compression residual stress due to peening.Originality/valueThis study conducted failure analysis of damaged SCM435 bolts connecting upper and lower parts of the three-stage injection mold. Fatigue limit of the damaged material was evaluated using equivalent crack length. In order to control this fracture, accurate tightening of bolts, accuracy of heat treatment and screws are required for compression residual stress due to peening.

Mechanical Properties of Single Shear Plane of Bolted Steel Connection

A 5-storey portable steel tower based on prefabricated frame concept has been built in Jamilus Research Centre, UTHM. It is now undergoing laboratory testing for static and dynamic performance. In this study, the mechanical properties of the connections were investigated via their connection condition between elements (beam and column) and connectors. The frame elements were designed based on S275 steel grade of 77 mm x 77 mm hollow section with 3 mm thickness, and 8 mm thickness of connectors’ plate. The connection was subjected to single shear plane action which fastened by bolts. Mild steel (grade 4.6) and high tension (grade 8.8) bolts with 10 mm diameter size were used. Shear, bearing and tensile strengths of the bolts and steel plates were determined via tension testing using 50 tonnes of Universal Testing Machine (UTM). From the results, all bolts and steel plates have satisfied the design strengths requirement of 640 N/mm2 (high tension bolt), 240 N/mm2 (mild steel bolt) and 275 N/mm2 as required by EN 1993-1-8. Meanwhile the ultimate shear force of bolts was found within ranges of 25% (high tension) and 12.5% (mild steel) from their respective ultimate tensile force. Bearing failure was occurred at bolt hole of 3 mm thickness of steel plate but only when it was fastened to high tension bolt. No bearing failure occurred when mild steel bolt was used. It has proven that all bolt spacing and edges distances were sufficient, without tearing failure observed in all testing. Finally, the permissible bearing resistance were checked based on the ratio of experiment against the EN 1993-1-8 relationships, when it has shown to satisfaction if the value is less than 1 as recommended by previous researcher.

Experiment of comparing coldformed steel shear connection using 2 self drilling screw and sikadur 31cf normal adhesive

Screw connection is prefered used by apllicator because of it’s simple. Type of screw usually used is Self Drilling Screw (SDS). This type of screw will become fix as it’s screwed by the applicator until its head . almost all applicator able to make this connection and do not need some course or sertificate to become an applicator, does not like applicator of High Tension Bolt, HTB. But this type of connection has some disadvantages, for example it’s connection doest not suit to dynamic loading.the experiment results that galvalume material has Yeilding Force, fy = 580 Mpa and Ultimate Force, fu = 590 Mpa. Connection of 2 SDS screw vertically configured fail on about tension loading 6000 N less than horizontally configured that fail on about 7500 N. Displacement of 2 SDS screw vertically configure on about 0.6 mm less than horizontally one that fail on displacement 0.85 mm. For adhesive of Sikadur CF 31 connection fail on loading about 6000 N tension loading but its displacement is less than 0.5 mm when it fail, for 2 type of connection configured.

Proposal of slack inspection method of high tension bolt of hexagon head using alternating magnetic field

The development of the inspection technique of detecting the slack of the high tension bolt is desired. The permeability inside the side of the bolt head is changed since the bolt head is compressed by bolting a plate. Therefore, the evaluation of the slack of the bolt is possible by detecting the difference of the magnetic characteristics. In this paper, the inspection method for measuring the slack of the steel high-tension bolt of hexagon head using a small electromagnetic non-contacting sensor is proposed. The distribution of stress, flux density and eddy current density near the bolt head is estimated by 3-D nonlinear electromagnetic finite element method (FEM) analysis taking account of the electromagnetic property under various compressive stresses. The results showed that the non-destructive inspection of the slack of the high-tension bolts is possible by detecting the change of flux density in the side of the bolt head.

電磁気を利用した高張力六角ボルトの緩み簡易検査法の開発

The development of the inspection technique of detecting the slack of the high tension bolt used in an elevated bridge, a railway viaduct, and various mechanical parts, etc. is desired. The permeability inside the side of the bolt head is changed since the bolt head is compressed by bolting a plate. Therefore, the evaluation of the slack of the bolt is possible by detecting the difference of the magnetic characteristics. In this paper, the electromagnetic inspection method for measuring the slack of the steel high-tension bolt of hexagon head using the small alternating magnetic field probe sensor is proposed. The stress and flux density near the bolt head are estimated by 3-D nonlinear electromagnetic finite element method (FEM) analysis taking account of the electromagnetic property under various compressive stresses. The results showed that the non-destructive inspection of the slack of the high-tension bolts is possible by detecting the change of flux density in the proposed small inspection probe sensor.

Cyclic Testing for Structural Detail Improvement of CFT Column-Foundation Connections

In this study, concrete-filled tube (CFT) column-to-foundation connections were investigated experimentally to improve the design of their structural details. Initially, five different types of foundation connections, which were classified according to the design parameters incorporating the types of anchor bolts, shear connectors, base members, and reinforced bars used, were fabricated. After conducting structural experiments on these foundation models, the performance and capacity of the individual model cases from the test results were compared with each other. The test results showed that some of the test models designed according to current design guidelines had problems related to the structural details. Therefore, this study proposed an adequate design methodology to improve the performance of foundation components, such as high tension bolt, base frame members, and embedded plate. An analytical investigation of the force-deformation relationship as well as the characteristic strains distributed over the individual foundation components was performed.

An Experimental Study on the Static Load Capacity of T-Type Tension Joints with High Tension Bolt

The tension type joint is a mechanically very efficient connection method, as it directly uses the load capacity of base metal or high tension bolt, the reduction of the number of drilling hole and fastening and the fatigue resistance. It is applied to the joint of girder and cross beam, horizontal joints of towers, beam to column joints, the secondary member joints of deck floor ends, and brackets. In this paper, static load tests for the T-type tension joint were conducted to investigate the structural behavior of the joint. The parameters were bolt diameter, flange thickness, and the reduction of clamping force of the joint. The failure modes and load capacity of joints and the effects of flange thickness, bolt diameter and clamping force were investigated.

Experimental study on mechanical behavior of multi-riveted joint replaced to high tension bolt

Experimental study on mechanical behavior of multi-riveted joint replaced to high tension bolt

A Comparative Study between Welding and High-Tensile Vertical Bolt Methods in PHC Pile Coupling Work

Few studies have been conducted on the constructability or economic feasibility of the coupling of Pre-tensioned Spun High Strength Concrete (hereinafter PHC pile). For this reason, before applying it to actual construction sites, an analysis of constructability and economic feasibility is necessary. Therefore, this study aims to compare the welding method with the high-tension vertical bolt method. It is found that the use of the high-tension vertical bolt method can reduce expenses by 25 percent on average compared with the welding method.

Assessment of Combinatorial Support Assemblies and Their Energy Matrixes in High Tension Bolt Couplings

The bolt and nut coupling are fundamental design requirement for machines and steel structures and their relevance and utilization are of topmost priority in the areas of their application. The paper viewed the component parts and dimensions of this coupling from the perspective of energy content delivery, balancing and equilibrium. This result from the fact that the supply of compression torque on the coupling converts ingrained residual energy in the individual parts into utility energy assets for the support and sustenance of structures of interest. The mechanics and practicality of this energy matrix theory has been investigated using congruent scientific analysis, conventional tables, lab test data and graphics which depicts boundary behavioral tendencies resulting from structural realignments in the face of increasing load value. The extreme limit of this realignments, culminate in varying degrees of yield conditions particular viewed as deformation, which occurs at the point of lowest energy availability in the coupled system. Keyword: geometryof forces, shear stress, bolt preload, energy relativity, shear off, ultimate value shearing stresses, crushing stress, ingrained limits, synergetic value, micro-synergy centers

격자형 강합성 바닥판 이음부의 전단내력 평가

본 논문에서는 프리캐스트 방식으로 제작 가능한 격자형 강합성 바닥판의 이음부에 기계식 연결방식을 적용하고자 콘크리트 전단키와 고장력볼트로 구성되는 이음부에 대해 Push-out 시험으로 전단내력을 구하였으며, 이를 전단마찰 이론에 근거한 이론식 및 설계식과 비교함으로써 전단내력을 평가하였다. 분석결과에 따르면, 이음부 접합면을 에폭시로 부착한 경우가 전단키를 강판으로 보강한 경우 보다 약 10% 정도 더 큰 전단내력을 갖는 것으로 나타났으나, 실험체간 전단내력의 편차는 전단키를 강판으로 보강한 경우가 더 작게 나타났다. 실험결과를 계산식 및 설계식과 비교한 결과, 기존 설계식으로 안전하게 설계될 수 있음을 알 수 있었다. 그러나, ACI-318에 의할 경우 이음부 전단내력이 과소평가되기 때문에 LRFD에서 제시된 설계식의 적용이 더 적당한 것으로 분석되었다. In order to apply a mechanical deck joint to the prefabricated steel grid composite decks, shear resistance of a joint composed of concrete shear key and high-tension bolt is experimentally evaluated by the push-out test. Shear resistance evaluated by the test is compared with resistance estimated by empirical and design equations based on the shear friction theory. Test results show that joint specimens bonded by epoxy have about 10% more shear resistance than specimens with strengthened shear key by steel plates, but in the case of specimens with strengthened shear key there is smaller resistance deviation than specimens bonded by epoxy. In comparison with resistances estimated by empirical and design equations, the deck joint can be safely designed. But because the existed shear resistance of deck joint is underestimated by the ACI-318, application of the LRFD design equation could be more reasonable.

부재 및 고장력볼트 구멍치수에 따른 미끄러짐계수의 실험적 연구

Abstract Slip coefficient, whose value is dependent on the condition of contact surface at the friction joint of high tension bolt, is determined by slip load. Because contact area affects slip load, contact area that varies with bolt hole size is also related to the slip coefficient. In this study, we manufactured 32 specimens and performed bending and tension tests in order to examine changes in slip coefficient and load with material type, bolt diameter, and size of bolt hole. Slip load of specimens with oversize bolt hole had strength that was more than 80% higher than the slip load of specimens with standard bolt hole, and it also exceeded the design slip strength. In addition, we observed significant correlation between net-section ratio and slip ratio of specimens with oversize and standard bolt hole. However, some differences between the specimens are thought to have been caused by reduction in initial axial force of high tension bolt, which is an important parameter of slip coefficient. It is self-evident that increased bolt hole size would lead to decrease in design strength as it reduces both slip coefficient and bolt axial force. Nevertheless, we suggest that some flexibility in regulation of bolt hole, as long as it does not threaten the structural stability, may be a positive factor in terms of workability and efficiency.

고력볼트를 이용한 유리섬유-강판복합판넬의 지압내력 평가

FRP는 최근에 보강재로서 많이 사용되고 있다. 유리섬유-강판 복합 판넬(GSP)는 이러한 FRP의 한 종류로서 기존에 개발되었던 유리섬유 강화 플라스틱(GFRP)에 비하여 연성 능력을 향상시키고자 상, 하부의 유리섬유층 사이에 얇은 강판을 삽입한 것이다. 이러한 GSP는 자중 대비 높은 강도와 연성 능력이 우수하여, 구조물에 적용되는 사례가 늘어나고 있다. 그러나 GSP를 구조물에 적용시에, 부착을 위해 일반적으로 에폭시를 사용하게 되는데, 이 경우 균일한 품질 확보가 어려우며, 에폭시가 경화되기까지 공사 기간이 늘어나게 된다는 단점이 있다. 이에 본 연구에서는 GSP의 시공성을 향상시키고자 고력볼트를 사용하여, GSP를 부착시키기 위해 지압 내력 실험을 실시하였고, GSP의 지압 내력 평가식을 제안하였다. Recently, FRP(Fiber Reinforced Plastics) is being widely used as a reinforcement material. GSP(Glass Fiber-Steel Composite Plate) is a sort of FRP to improve ductility of GFRP(Glass Fiber-Reinforced Plastics) installing steel plate between top and bottom GFRP Plates. Due to very high strength of GSP comparing to the weight of material, applying of this material is increasing for the building structures. As for the attaching of GSP to the structures, epoxy has been generally used. In this case, however, the quality of epoxy does not remain consistently, and it causes long period of work by hardening epoxy. In this study, to increase workability of GSP, the bearing tests of GSP were performed for applying of building structures with high-tension bolt. And the design equation for bearing capacity could be derived by performing the bearing tests.

Electromagnetic Inspection Method of Slack of High Tension Bolt

The inspection of the slack of the steel high-tension bolt is important in the maintenance of various mechanical parts and buildings, etc. There occurs the difference of the magnetic property of the bolt head when the axis force of the fastened bolt is increased. Therefore, the evaluation of the slack of the bolt is possible by detecting the difference of the magnetic characteristics. In this paper, the electromagnetic method for measuring the slack of the steel high-tension bolt using an alternating magnetic field is proposed. The stress and flux density in the bolt head are estimated by 3-D stress analysis using the finite-element method and nonlinear electromagnetic finite element analysis taking account of the electromagnetic property under various compressive stresses. In addition, the experimental verification is also carried out.

극한 상태에서 A490 고장력 볼트 세트의 체결 품질 연구

This test focuses on the correlation between the lubrication, ductility and strength through the change of nut lubricant which decides joining angle for A490 bolt sets required in the AASHTO (American Association of State Highway & Transportation Officials). Because the lubrication of high tension bolt, nut, washer sets becomes an important factor to ductility and joining load, the quality improvement is required for improving reliability and securing enough lubrication of maker and user. This study examines the quality characteristics required in the specification through tests because only this standard specifies joining quality in the extreme conditions (as much about two times of the joining angle on site as normal condition). Moreover, this study is limited to the test on joining axial force required in the AASHTO for the three nut lubrication conditions of A490 bolt set. It is concluded that the nuts should be coated or waxed enough for the improvement of the joining axial force and ductility of bolts required in the standards. It is shown that in the case of plain high tension bolt sets, a rust preventing lubricative oil shall be applied and the torque coefficient value for A490 bolt sets should be maintained below 0.175.

Application to Steel Girder Bridges of Super High Tension Bolt

Application to Steel Girder Bridges of Super High Tension Bolt

TENSILE TEST AND SHEAR TEST OF IMPROVED TYPE OF REINFORCED ANCHOR-BOLTS

In this study, reinforcing method by screwing a high-tension bolt into anchor-bolt is proposed to improve plastic deformation capacity, where a gap of five millimeters is secured between the top of anchor-bolt and a high-tension bolt. Tension test of this type of reinforced anchor-bolt shows that performance is much upgraded comparing to the reinforced anchor-bolt without a gap, and the maximum strength and deformation capacity are predicted well by proposed equations (1) , (2) and (3). Shearing test shows that maximum strength of the thread of reinforced anchor-bolt is larger than that of original anchor-bolt.

휨을 받는 고장력볼트 체결부에서 과대공에 따른 사용성에 관한 연구

고장력볼트를 이용한 강부재의 연결부에서 마찰력을 초과하는 설계하중이 작용하여 미끄럼이 발생하는 점을 기점으로 볼트와 모재의 전단강도 및 지압강도에 의해 설계하중을 지지하게 된다. 미끄럼량은 볼트의 장력, 접촉면의 마찰계수, 모재구멍내에서 볼트의 위치에 따라 결정되어 질 수 있다. 본 연구에서는 모재 및 덮개판에 대하여 볼트구멍의 크기를 변화시켜 제작된 고장력볼트 체결부에 순수굽힘과 인장력이 작용하는 경우 표준공과 과대공에 따른 미끄럼을 측정하고 비교분석하였다. 표준공을 가지는 경우보다 과대공을 가지는 경우에 <TEX>$74\sim94%$</TEX> 작은 하중에서 미끄럼이 발생하였다. 인장력을 받는 부재에서는 과대공치수가 클수록 미끄럼 하중비가 작게 나타났으며 모재의 과대공치수가 덮개판의 과대공치수보다 미끄럼하중변화와 연관성이 많은 것으로 나타났다. If a design load exceeding the frictional force of the contact surface is applied to the connection of steel members using a high-tension bolt friction joint, sliding occurs and the connection of the steel members bears the design load through the shear strength and bearing strength of the bolt and the base plate. The sliding distance can be determined by the tensile force of the bolt, the friction coefficient of the contact surface, and the position of the bolt in the base plate hole. This study measured and analyzed sliding according to standard bolt hole and oversize bolt hole when pure bending moment and tensile force were applied to high-tension bolt joints with different sizes of bolt holes made in the base plate and the cover plate. In a high-tension bolt joint receiving pure bending moment and tensile force, the load causing sliding in an oversize bolt hole was <TEX>$74\sim94%$</TEX> of that in a standard bolt hole. In a member receiving tensile force, the sliding load ratio was lower when the size of oversize bolt holes in the base plate and the cover plate was large. In addition, the size of the oversize bolt hole in the base plate was more closely correlated with the change of sliding loadthan the size of the oversize bolt hole in the base plate.

단면결손에 따른 고장력볼트 체결부의 내하력 변화에 관한 연구

This study conducted a static tensile test in order to prevent the lowering of load carrying capacity caused by critical sections made by over bolt holes in the base plate and the cover plate of steel member joints using high-tension bolts. The change of the load carrying capacity of joints was examined by comparison of the maximum load on joint fracture obtained from the tensile test with critical section rate and design strength. According to the results, the rate of decrease in strength was higher when the critical section rate was high, and in particular, decrease in strength was affected much more by critical sections in the base plate than by those in the cover plate. In high-tension bolt joints using over bolt holes for the base plate and the cover plate, load carrying performance was somewhat lower than that in joints using standard bolt holes, but the maximum tensile strength on facture was over 15% higher than design fracture strength. According to the results of this study, the use of over bolt holes in high-tension bolt joints had an insignificant effect on the lowering of load carrying capacity, so the allowance of over bolt holes in the joints of steel members is expected to enhance to the economy and efficiency of the works.