Ultimate Tension Strength Research Articles

Effects of build orientation and strain rate on the tensile-shear behaviour of polyamide-12 manufactured via laser powder bed fusion

Laser powder bed fusion (L-PBF) of engineering thermoplastics is a well-established additive manufacturing technique. In this work, an experimental investigation of the tensile-shear behaviour of L-PBF processed polyamide-12 (PA12) is presented, with a particular focus on the concurrent effect of build orientation and rate dependency at strain rates ranging from 10−3 to 103s−1. Results show that the deformation behaviour features significant anisotropy at both low and high strain rates, while quasi-static ultimate strength in either tension or shear shows no dependence on the build direction. As the strain rate increases, the tensile strength is characterised by apparent positive rate dependence but remains insensitive to the build orientation; however the shear strength displays significant build orientation-dependent anisotropy, highlighted by the decreasing shear strength of specimens printed in the loading direction. Post-mortem scanning electron microscopy (SEM) demonstrates torn dimples with stretched filaments in quasi-static fractography, while cleavage facets with flake structures retrieved from high-rate loading. A fibrillar structure is observed from high-rate torsional loading indicating adiabatic decohesion during rapid crack propagation. These findings draw attention to the significant anisotropy of L-PBF PA12 parts in a high-rate loading regime and provide directions to improve the current L-PBF techniques.

Modeling and Model Verification of the Stress-Strain State of Reinforced Polymer Concrete.

This article considers the prospects of the application of building structures made of polymer concrete composites on the basis of strength analysis. The issues of application and structure of polymer-concrete mixtures are considered. Features of the stress-strain state of normal sections of polymer concrete beams are revealed. The dependence between the stresses and relative deformations of rubber polymer concretes and beams containing reinforcement frame and fiber reinforcement has been determined. The main direction of the study was the choice of ways to increase the strength characteristics of concrete with the addition of a polymer base and to increase the reliability of structures in general. The paper presents the results of experimental and mathematical studies of the stress-strain state and strength, as well as deflections of reinforced rubber-polymer beams. The peculiarities of fracture of reinforced rubber-polymer beams along their sections have been revealed according to the results of the experiment. The peculiarities of fracture formation of reinforced rubber-polymer beams have also been revealed. The conducted work has shown that the share of longitudinal reinforcement and the height of the fibrous reinforcement zone are the main factors. These reasons determine the characteristics of the strength of the beams and their resistance to destructive influences. The importance and scientific novelty of the work are the identified features of the stress-strain state of normal sections of rubber-concrete beams, namely, it has been established that the ultimate strength in axial compression and tension, deformations corresponding to the ultimate strength for rubber concrete exceed similar parameters for cement concrete 2.5-6.5 times. In the case of the addition of fiber reinforcement, this increase becomes, respectively, 3.0-7.5 times.

Creep behavior and creep mechanism of Mg-Gd-Y-Sm-Zr alloy

In this work, Mg-11Gd-2Y-3Sm-0.5Zr (GWS1123) alloy was arranged by vacuum melting and gas protection. The tensile mechanical properties at 20–300 °C and the creep properties at 200–300 °C/50–110 MPa were tested by tensile and creep testing machines, respectively. The microstructure changes were investigated by transmission electron microscopy before and after creep, and the strengthening mechanism and creep mechanism were discussed. In addition to its superior tensile strength at room and high temperatures, GWS1123 alloy exhibits excellent creep properties at high temperatures. At 250 °C, the ultimate tension strength and tensile yield strength are 319 MPa and 246 MPa, respectively, which are 26.6% and 22.4% higher than the ultimate tension strength (252 MPa) and tensile yield strength (201 MPa) at room temperature. The alloy has good creep resistance at 200–250 °C/50–110 MPa and 300 °C/50 MPa. The effect of creep temperature on the creep resistance is greater than that of stress. The creep mechanism of GWS1123 alloy at 200–300 °C/50–110 MPa is mainly grain boundary slip, dislocation slip and climb. It is the good heat resistance, strong Orowan strengthening effect and obvious coherent strengthening effect of β′ phase that are responsible for the high temperature strength and high temperature creep resistance.

Optimizing borehole location for stress state assessment by geomechanical method of core discing

The article addresses the reliability of the stress–strain analysis and rockburst hazard assessment in rock mass using the geomechanical method of core discing. The theoretical experimentation used CAE Fidesys system. This system performs the strength and other-type computations using the finite element method—a numerical method of problem solution in applied physics. The experiments have two stages. At the first stage, the model of rock mass with core drilling for the stress state assessment by core discing is constructed; the computation aims to determine vertical stresses such that the tensile stresses along the core axis exceed the ultimate tension strength (discing condition). At the second stage, the rock mass with the destress boreholes is modeled; the aim of the modeling is to determine the influence zones of the destress boreholes. The applied experimentation was carried out in underground openings of Taimyrsky Mine. The research has found the influence exerted by some destress boreholes on the stress state assessment by core discing. The theoretical experiments and practical testing results show a good agreement, which proves their reliability. The final conclusions are: inside the protected zones formed by destress drilling, the stresses effectively reduce down to safe values; to avoid errors inrockburst hazard assessment by core discing, core drilling should be performed at a distance from the destressing surface not less than 5 diameters of the destress boreholes; interpretation of the stress state assessment results should take into account the nonuniform stress distribution in the plane of destressing. The authors appreciate participation of D. Kh. Gilyazev, Head of the Rockburst Prediction and Prevention Department, Taimyrsky Mine (till 2021) in this study.

The microstructure evolution, texture weakening mechanism and mechanical properties of AZ80 Mg alloy processed by repetitive upsetting-extrusion with reduced deformation temperature

Repetitive upsetting-extrusion (RUE) is known as a processing method that effectively improves the properties of a billet without changing its initial shape. In this paper, one pass RUE with reduced deformation temperature (re-upsetting at 360 °C and secondary extrusion at 340 °C) and different extrusion speeds (0.5 and 1 mm/s) is implemented to improve the strength and toughness of AZ80 Mg rods, and simultaneous reduction in tensile anisotropy is achieved. Influences of one pass RUE method on the resulting microstructure and texture evolution of the alloy are investigated alongside their correlated impact on its mechanical properties. After RUE processing, the grain structure of AZ80 alloy is characterized by numerous fine dynamic recrystallized (DRXed) grains, combined with large unDRXed grains obtained at high extrusion speed or coarse DRXed grain bands obtained at low extrusion speed. Besides, β-Mg17Al12 particles dynamically precipitated during deformation, acting as strong barrier against grain boundary migration through pinning effect. Through introduction of an interactive stress state, the RUE process promotes dispersion of the fiber texture that typically develops during the extrusion process. The key factor that promotes weakening of the fiber texture is derived from the refinement of basal orientated deformed grains, which form during upsetting deformation, into numerous non-basal orientated DRXed grains during early-stage extrusion. Compared with coarse deformed grains, these fine DRXed grains delay transformation of texture into the typical [10-10]–[11-20] fiber component. Grain refinement is implicated as the most significant factor with respect to simultaneous improvement of strength and toughness in the extruded rods, while tensile yield anisotropy in response to loading along the ED and TD is attributed to unDRXed grains with [10-10] fiber orientation. Compared to the as-cast state, extruded rods demonstrate increases in yield strength, ultimate tension strength, and elongation maximally up to ~2.6, ~2.2, and ~4.9 times, respectively. And when complete DRX structure is nearly achieved, the tensile yield anisotropy of extruded bar is effectively eliminated because the refined grains with relatively dispersed orientation inhibit the nucleation of tension twin and simultaneous enhance the Hall-Petch effect.

The Effect of Allogenic Bone Marrow on Integration Dev-Mesenchymal Stem Cell And Vascular Endothelial Growth Factor

Background: The integration of the tendon graft within the bone tunnel is one of the decisive success factors of the Anterior Cruciate Ligament (ACL) reconstruction. In ACL reconstruction that uses tendons as graft, the healing process that occurs in the bone tunnel is healing with fibrotic tissue. Aim: This study aims to determine the role of bone marrow mesenchymal stem cells and vascular endothelial growth factor intraarticularly in improving the biomechanical strength. Methods: This study uses experimental research design by using animal as a testing tool. The animals used in this study are male New Zealand white rabbits (Oryctolagus cuniculus), with the weight ranging of 2000 grams up to 3000 grams. Results: From the experiment, all samples from both treatment and control groups were all evaluated and no post-operative complication was found. At the evaluation time of 3 weeks, the difference between the mean of maximum strain rate between the treatment group and the control group was not statistically significant (p >0.05). At the evaluation time of 6 weeks, it was found that the difference in mean value of the maximum strain load force between the treatment groups versus the group was statistically significant. Conclusions: From this study, it can be concluded that intraarticular BM-MSC and VEGF administration can increase the ultimate tension strength of postoperative graft tendon rosary ACL reconstruction.

Grey Cast Iron Strength аs Function оf Primary Austenite Dendrites Volume Fraction

On the basis of approach to primary structure of gray cast iron as to an analog of the composite material, reinforced by discrete fibers, the quantitative contribution of dendritic crystals and the eutectic matrix to ultimate strength in tension is defined.

Selection of Nd:YAG laser beam micro-drilling parameters using multi-criteria decision making methods

Multi criteria decision making methods and response surface methodology based approaches are invariably utilized in improvement of quality in several manufacturing industries. This paper presents the technique to determine optimal process parameters during micro-drilling using Nd:YAG laser source on gamma titanium aluminide alloy using fuzzy-TOPSIS (fuzzy-technique for order preference by similarity to ideal solution) and RSM (response surface methodology) together. A new alloy, Gamma-titanium aluminide (Ti-44.5, Al-2, Cr-2, Nb-0.3B (at%)) has been chosen for experimentation. This material possesses desirable qualities like very high hardness, high strength temperature resistant, high yield stress and ultimate strength in tension, good creep, very low density, resistance to oxidation etc., found applications in technologically advanced industries like spacecrafts, aerospace, nuclear power plants, electronics, automobiles etc. A model has been developed which can be used for decision making in identifying the optimum laser parameters like lamp current, pulse frequency, air pressure and thickness of the workpiece, which affect several quality aspects of micro-machined job such as hole circularity at entry, hole circularity at exit and taper of drilled hole. Triangular fuzzy numbers are being utilized to calculate weighting factor of each machining criterion. Also, the combination of most desirable factor levels has been obtained using a fuzzy-TOPSIS method.

BIOMECHANIC STUDY OF GRAFT BONE TUNNEL MODEL IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING INTRATUNNEL ALLOGENIC BONE MARROW MESENCHYMAL STEM CELLS (BM-MSCs) AND VASCULAR ENDOTHELIAL GROWTH FACTOR (VEGF)

Successful anterior cruciate ligament (ACL) reconstruction using tendon graft requires good and rapid integration between the tendon graft and the bone tunnel. The strength of the tendon-bone tunnel graft in the initial phase is very important to facilitate aggressive rehabilitation and as early as possible to support rapid recovery to normal activities. The objective of this study was to determine ultimate tension strength (UTS) on the femoral tendon-bone tunnel graft model after reconstruction of anterior cruciate ligament (ACL) by administering allogenic bone marrow mesenchymal stemcells (BM-MSCs) and vascular endothelial growth factor (VEGF) intratunnel in experimental animals. The design of this research was Post-Test Only Control Group Design using 24 rabbits divided into treatment and control group. Biomechanical evaluation was done at week 3 and 6. Evaluation at week 3 found ultimate tension strength of treatment group significantly higher than control (p <0,05). In the 6th week evaluation, Ultimate tension strength was found that the treatment group significantly higher than the control group (p <0.05). Ultimate tension strength at week 3 did not differ significantly with week 6 (p> 0.05). Intravenous administration of BM-MSCs and VEGF on ACL reconstruction increased ultimate tension strength in graft-bone tunnel significantly since week 3. The study of Ferdiansis et al using BM-MSCs and VEGF intraarticular, only showed a significant increase in ultimate tension strength in graft-bone tunnel since week 6. Comparison of this method indicates acceleration in incorporation of tendon graft with bone tunnel on intratunnel method better thaninvitro intraarticular method.Keywords : Anterior cruciate ligament, allogenic bone marrow mesenchymal stem cells, vascular endothelial growth factor and biomechanic study.

INTRATUNNEL THE EFFECT OF ADMINISTRATION OF BONE MARROW MESENCHYMAL STEM CELLS (BM-MSCs) AND VASCULAR ENDOTHELIAL GROWTH FACTOR (VEGF) TENDON-BONE TO INTERFACE HISTOLOGICAL GRAFT ANTERIOR CRUCIATE LIGAMENT APPEARANCE AFTER RECONSTRUCTION IN RABBITS

The success of the Anterior Cruciate Ligament (ACL) reconstruction using a tendon graft is determined by integration in the bone tendon-graft interface on the bone tunnel. The use of stem cells and growth factors proved to accelerate the healing of the bone tendon-graft interface. The aim of this study was to inveestigate the difference of histology picture in the tendon-bone tunnel model after ACL reconstruction with intratunnel intravenous allogenic bone marrow mesenchymalstemcells (BM-MSCs) and intratunnel vascular endothelial growth factor (VEGF). This research used Post-Test Only Control Group design with 20 rabbits divided into treatment group and control group. Each group performed histologic image evaluation (thickness of collagen fiber or sharpey fiber) at week 3 and 6. Evaluation of histology overview at week 3 and week 6 showed a significantly thicker thickness of collagen fiber or sharpey fiber in treatment group compared with control group (p <0.05). Intravenous administration of BM-SCs and VEGF after ACL reconstruction can speed healing of the bone tunnel significantly from week 3 and 6. The study by Faridyan et al has concluded that intravenous BM-SCs + VEGF increased ultimate tension strength in the bone-tendon interface significantly. In this study, intravenous administration of BM-SCs and VEGF gave histologic images showing acceleration of bone tunnel healing.Keywords:Anterior cruciate ligament reconstruction, allogenic bone marrow mesenchymal stem cells, vascular endothelial growth factor, graft tunnel healing, and Sharpey fiber.

Tension strength and design method for thread-fixed one-side bolted T-stub

Failure modes and their corresponding tension strengths of thread-fixed one-side bolted T-stub were investigated experimentally and theoretically. The thread resistances of bolts fixed directly to plates were evaluated by experimental analysis. Except for the three failure modes described in the current Eurocode 3, two new failure modes and their corresponding design methods were proposed, which were (a) hole thread failure and (b) T-stub flange yielding with hole thread failure. Influences of the bolt pre-tension force, the thickness of T-stub flange, the existence of the standard nut, the screw depth of the bolt on the failure mode and the ultimate tension strength were studied. The bolt pre-tension force had little influence on the ultimate tension strength; however, it could improve the initial stiffness of the connection. The ultimate tension strength and tension stiffness of the T-stub increased with the increase in flange thickness. For the T-stub with thin flange, the thread hole could also provide sufficient clamping force to ensure the bolted T-stub not fail by thread failure. The existence of the nut did not improve the yield strength of the T-stub; however, it could prevent the separation of two T-stubs after flange yielding, thus the ultimate tension strength was increased. It depended on the screw depth whether the partially screwed bolt was failed by thread failure or bolt failure. Ultimate tension strengths of the T-stub measured from tests were much higher than those calculated by design equations. And under the design load, the bolted T-stub was still in elastic state, which demonstrated the applicable of the thread-fixed one-side bolted T-stub.

Structural Hybrid Supercapacitor

Supercapacitors (SCs) have attracted tremendous attention due to their high specific power and long cycle life. The two major issues with SCs are low specific energy and self-discharge. The benefits of doping mediators or redox species in electrolytes include: 1) providing extra pseudocapacitance out of bulk of electrode materials, 2) increasing the electronic and ionic conductivities of electrolyte in the composite electrodes; and 3) releasing the ions into electrolyte to promote the capacity of electrolyte. Redox species or mediators as dopants in electrolytes are reported to realize the specific capacitance up to 400-500 F/g and the specific energy up to 30-50 Wh/kg. For the issue of self-discharge, adding primary cell materials into the mediator SC is proposed because the materials can provide a micro-current to compensate the self-discharge current. In this research, Cu powder/CuSO4 and Zn powder/ZnSO4 were added into the positive and negative electrodes respectively. The positive electrode also contained PVDF/LiTFS polymer electrolyte doped with K4Fe(CN)6 as mediator whereas the negative electrode contained PVDF/LiTFS doped with (VO)SO4 as mediator. A mixture of epoxy/PVDF/LiTFS thin film was used as the separator between the electrodes also to provide adhesion. Figure 1 shows the galvanostatic charge/discharge (GCD) curves of a structural hybrid SC. A cyclic voltammetry (CV) curve obtained at a scan rate of 10 mV/s of this hybrid SC is illustrated in Figure 2. The broad peak from 0.4V to 0.8V is an indication of pseudocapacitance behavior related to the redox reactions of the mediators. The asymmetric shape of CV curve is related to the electrochemical reactions of Cu and Zn during charging/discharging. It was found that the voltage of the SC can be withheld at 1V for more than 3 months. The mechanical strength of the SC was tested using a MTS machine. It was found that the elastic constant as 20 MPa and ultimate tension strength was 2 MPa. Figure 1

Investigation of the mechanical properties and failure modes of hybrid natural fiber composites for potential bone fracture fixation plates

The purpose of this study is to investigate the mechanical feasibility of a hybrid Glass/Flax/Epoxy composite material for bone fracture fixation such as fracture plates. These hybrid composite plates have a sandwich structure in which the outer layers are made of Glass/Epoxy and the core from Flax/Epoxy. This configuration resulted in a unique structure compared to prior composites proposed for similar clinical applications. In order to evaluate the mechanical properties of this hybrid composite, uniaxial tension, compression, three-point bending and Rockwell Hardness tests were conducted. In addition, water absorption tests were performed to investigate the rate of water absorption for the specimens. This study confirms that the proposed hybrid composite plates are significantly more flexible axially compared to conventional metallic plates. Furthermore, they have considerably higher ultimate strength in tension, compression and flexion. Such high strength will ensure good stability of bone-implant construct at the fracture site, immobilize adjacent bone fragments and carry clinical-type forces experienced during daily normal activities. Moreover, this sandwich structure with stronger and stiffer face sheets and more flexible core can result in a higher stiffness and strength in bending compared to tension and compression. These qualities make the proposed hybrid composite an ideal candidate for the design of an optimized fracture fixation system with much closer mechanical properties to human cortical bone.

Critical tension–shear load of elastomeric seismic isolators: An experimental perspective

When the height-width ratio of isolated high-rise building is excessive large, elastomeric isolators may suffer from tension accompanying with large horizontal shear strains under strong earthquake excitations. It may be not safe if only considering isolators suffering from purely tension without considering horizontal shear strain.In order to investigate the critical behavior of isolator under tension–shear load, five linear natural rubber bearings with the same inner structure have been experimentally evaluated at different horizontal strain amplitudes, ranging from zero to 483%, including axial tension and purely shear. At the same time, test results have been compared with the theory results.Test results show that the critical load decreases nonlinearly with the increase of horizontal shear strain, which reveals that it is unreasonable to define the threshold value of tension independent of amount of horizontal shear strain. Comparing with test results of five rubber bearings, the theory results overestimate the ultimate tension strength of elastomeric seismic isolators in most cases. The photos of damage show isolator may occur in different damage pattern at different shear strains, 100% shear strain can be thought as the dividing line. All of the before-mentioned conclusions are drawn by only five isolators, more researches needs to be done in the future.

Room temperature mechanical properties of Mg–Cu–Al alloys synthesized using powder metallurgy method

Conventional powder metallurgy method was used to fabricate Mg–1Cu–xAl (x=1wt%, 3wt%, 6wt%, 9wt%) alloys to study the influence of copper and aluminum on mechanical behavior of pure magnesium. Microstructural evaluation revealed the presence of Mg17Al12 and Mg2Cu intermetallic phases in synthesized alloys. Experimental results exhibited that the increase in aluminum content lead to increase in Vickers hardness, 0.2% yield strength and ultimate strength (both in tension and compression). The tensile failure strain of alloys increases till the threshold of 3wt% Al is reached. The decline in failure strain for the alloys containing higher wt% Al contents (i.e., 6 and 9wt% Al), might be attributed to the formation of brittle intermetallic phase Mg17Al12.

Mechanical behavior of walnut (Juglans L.) shell particles reinforced bio-composite

AbstractIn the present work walnut particle reinforced composite material was developed. Ten wt%, 15 wt%, 20 wt% and 25 wt% (weight percentage) of walnut particles were mixed with epoxy resin (CY-230). Scanning electron microscopy (SEM) shows that the walnut particles were well dispersed in the epoxy resin matrix. Addition of walnut particles increased the modulus of elasticity of the bio composite. Addition of walnut particles in bio composite decreased the ultimate strength both in compression and tension. However, addition of walnut particles in bio composite increased the hardness. Flexural modulus of elasticity also increased with increasing walnut particles weight percentage, whereas flexural strength and strain decreased with increased weight percentage of walnut particles.

Biomechanical properties of an advanced new carbon/flax/epoxy composite material for bone plate applications

This work is part of an ongoing program to develop a new carbon fiber/flax/epoxy (CF/flax/epoxy) hybrid composite material for use as an orthopaedic long bone fracture plate, instead of a metal plate. The purpose of this study was to evaluate the mechanical properties of this new novel composite material. The composite material had a “sandwich structure”, in which two thin sheets of CF/epoxy were attached to each outer surface of the flax/epoxy core, which resulted in a unique structure compared to other composite plates for bone plate applications. Mechanical properties were determined using tension, three-point bending, and Rockwell hardness tests. Also, scanning electron microscopy (SEM) was used to characterize the failure mechanism of specimens in tension and three-point bending tests. The results of mechanical tests revealed a considerably high ultimate strength in both tension (399.8MPa) and flexural loading (510.6MPa), with a higher elastic modulus in bending tests (57.4GPa) compared to tension tests (41.7GPa). The composite material experienced brittle catastrophic failure in both tension and bending tests. The SEM images, consistent with brittle failure, showed mostly fiber breakage and fiber pull-out at the fractured surfaces with perfect bonding at carbon fibers and flax plies. Compared to clinically-used orthopaedic metal plates, current CF/flax/epoxy results were closer to human cortical bone, making the material a potential candidate for use in long bone fracture fixation.

Prediction of the initial thickness of shear band localization based on a reduced strain gradient theory

Plastic flow localization in ductile materials subjected to pure shear loading and uniaxial tension is investigated respectively in this paper using a reduced strain gradient theory, which consists of the couple-stress (CS) strain gradient theory proposed by Fleck and Hutchinson (1993) and the strain gradient hardening (softening) law (C–W) proposed by Chen and Wang (2000). Unlike the classical plasticity framework, the initial thickness of the shear band and the strain rate distribution in both cases are predicted analytically using a bifurcation analysis. It shows that the strain rate is obviously non-uniform inside the shear band and reaches a maximum at the center of the shear band. The initial thickness of the shear band depends on not only the material intrinsic length l cs but also the material constants, such as the yield strength, ultimate tension strength, the linear hardening and softening shear moduli. Specially, in the uniaxial tension case, the most possible tilt angle of shear band localization is consistent qualitatively with the existing experimental observations. The results in this paper should be useful for engineers to predict the details of material failures due to plastic flow localization.

Glulam beams reinforced with FRP externally-bonded: theoretical and experimental evaluation

The glued- laminated lumber (glulam) technique is an efficient process for the rational use of wood. Fiber-reinforced polymer (FRPs) associated with glulam beams provide significant improvements in strength and stiffness and alter the failure mode of these structural elements. In this context, this paper presents guidance for glulam beam production, an experimental analysis of glulam beams made of Pinus caribea var. hondurensis species without and with externally-bonded FRP and theoretical models to evaluate reinforced glulam beams (bending strength and stiffness). Concerning the bending strength of the beams, this paper aims only to analyze the limit state of ultimate strength in compression and tension. A specific disposal was used in order to avoid lateral buckling, once the tested beams have a higher ratio height-to-width. The results indicate the need of production control so as to guarantee a higher efficiency of the glulam beams. The FRP introduced in the tensile section of glulam beams resulted in improvements on their bending strength and stiffness due to the reinforcement thickness increase. During the beams testing, two failure stages were observed. The first was a tensile failure on the sheet positioned under the reinforcement layer, while the second occurred as a result of a preliminary compression yielding on the upper side of the lumber, followed by both a shear failure on the fiber-lumber interface and a tensile failure in wood. The model shows a good correlation between the experimental and estimated results.

ULTIMATE STRENGTH OF HIGH-STRENGTH BOLT CONNECTION INCLUDING BEARING CAPACITY

To clarify the bolt bearing effect to the ultimate strength of the high-strength bolt connections, two series of testing, bolted connection applied with tension force or bending moment, were conducted in this study. From the test results, design formula, considering the bearing deformation explicitly, was proposed to evaluate the ultimate tension strength of the high-strength bolt connection; the improved accuracy compared with current design formula was also shown. Extending the proposed design formula to the bolted connection applied with bending moment, improved accuracy to predict the maximum bending strength was also shown; however, it was also reminded some refinement still needed to improve the accuracy.