Endplate Thickness Research Articles

Fatigue Performance of Groove-Welded Tube-to-End-Plate Connections in Highway Sign, Luminaire, and Traffic Signal Structures

Fatigue performance of full penetration groove-welded tube-to-end-plate connections was evaluated by parametric studies verified by laboratory testing of full-scale galvanized cantilevered highway sign and signal and high-level luminaire structures. In the absence of sufficient experimental basis, the fatigue resistance of this connection detail in the existing AASHTO specification is defined as Category E. Fatigue performance of tube-to-end-plate connections in thin-walled tubular structures is governed by secondary out-of-plane bending stress, the magnitude of which depends on relative stiffness of the tube and end plate. In some groove-welded connections, the backing ring is welded to the tube wall, adding more variability in fatigue performance of the connection. Twenty-three full-size specimens composed of five configurations of the groove-welded connections were fatigue-tested under constant amplitude loading simulating wind-induced aeroelastic oscillations, such as galloping and vortex shedding, that are typically experienced in service. Variation in six parameters of the connection geometry were considered: diameter of tube, thickness of tube, thickness of end plate, diameter of end plate opening, number of anchor bolts, and height of backing ring. The research results demonstrated that with a suitable combination of the geometric parameters, the constant amplitude fatigue threshold of the groove-welded tube-to-end-plate connections can exceed that of AASHTO Fatigue Category D for sections widely used in highway sign, luminaire, and traffic signal structures. The local stress-based approaches provided reasonable lower bound estimates of fatigue performance of the connection detail for different geometric configurations.

Determination of Internal Forces in End Plates of Simple End Plate Joints

In the paper the authors propose computer simulation of simple end plate joints. A computer model has been elaborated using the Autodesk Robot Structural Analysis Professional 2010 software programme. Maps of internal forces and stresses on end plates of a joint have been analysed. The analysis of the maps enabled the authors to determine the course of variation of bending moments in any cross-section of the joint and to compare the obtained diagram with a diagram of moments cited in the literature (ŻOŁTOWSKI et al. 2000, BIEGUS 1997), which serves the purpose of determination of the minimum thickness of end plates needed due to the lever effect. The paper also determines the dependence between the loading force acting on the joint and the thickness of end plates on the assumption of maximum stresses damaging the steel of the end plates, as this is one of the criteria for dimensioning end plate joints. In addition, effort of joint bolts was determined in relation to a value of the loading force. WYZNACZENIE WARTOŚCI SIŁ WEWNĘTRZNYCH W BLACHACH CZOŁOWYCH POŁĄCZEŃ DOCZOŁOWYCH ZWYKŁYCH Stefan Dominikowski, Piotr Bogacz Katedra Budownictwa i Konstrukcji Budowlanych Uniwersytet Warminsko-Mazurski w Olsztynie S l o w a k l u c z o w e: polączenie doczolowe, sily wewnetrzne, blacha czolowa.

Micro-computed tomography study of the subchondral bone of the vertebral endplates in a porcine model: correlations with histomorphometric parameters

Subchondral bone (SCB) of the vertebral endplates (VEP) is the principal site of changes in vertebral trabecular microarchitecture secondary to intervertebral disc degeneration. However, the microstructure of this region has not yet been clearly characterized. One thoracic and one lumbar vertebral unit (vertebra-disc-vertebra) was removed in nine pigs aged 4 months. Three samples (one central and two laterals) were taken from each VEP. Micro-CT examination and histomorphometric measurements of the subchondral trabecular bone of the VEP were carried out. Correlations between micro-CT and histological parameters were sought. Trabecular network was significantly denser [increased bone volume fraction (BV/TV) and trabecular number (Tb.N), decreased intertrabecular separation (Tb.Sp)] in the cranial endplates of the vertebral units. It was also significantly denser and less well organized [increased degree of anisotropy (DA)] in the centre of the VEP. The thickness of the cartilage endplate (CEP), SCB and growth cartilage were significantly lower in the centre of the VEP. There was a significant negative correlation between BV/TV, Tb.N and DA with the thicknesses of the CEP and SCB whereas Tb.Sp was positively correlated with these two parameters. We observed densification of the trabecular network in the centre of the VEP overlying the nucleus pulposus, partly related to thinner hyaline cartilage. Densification is associated with more anisotropic architecture that could cause lower mechanical strength in this area. This study provides new information on the microarchitecture of the SCB of the VEP which will make it possible to validate future models.

Experiments on rectangular concrete-filled steel tubes loaded axially on a partially stressed cross-sectional area

The present paper aims to experimentally investigate the behaviour of rectangular concrete-filled steel tubular (RCFST) stub columns loaded axially on a partially stressed cross-sectional area. A total of twenty-two specimens, including thirteen partially loaded composite specimens, six partially loaded plain concrete reference specimens and three corresponding fully loaded composite specimens, were tested under concentric loads. The main parameters varied in the tests are: (1) depth-to-width ratio of the rectangular sections: from 1.2 to 1.8; (2) partial compression area ratio (concrete cross-sectional area to partial compression area): from 1.44 to 17.42; (3) steel wall thickness of top endplate: from 0 mm to 12 mm; and (4) shape of the bearing plate for partial compression: rectangular and strip. The test results showed that, while being loaded on partial cross-sectional area, RCFST stub column had a favourable bearing capacity and ductility compared with the corresponding plain concrete specimens. Simplified formulae were used for the prediction of the ultimate strength of CFST stub columns loaded on partial cross-sectional area.

Subsidence of Metal Interbody Cage After Posterior Lumbar Interbody Fusion With Pedicle Screw Fixation

Posterior lumbar interbody fusion is considered to be an excellent fusion procedure to stabilize anterior support, correct alignment in the sagittal and coronal plane, and achieve foraminal decompression by lifting the disk height. The metal interbody cage in posterior lumbar interbody fusion is thought to be useful to prevent collapse of the graft bone and to correct and maintain disk height; however, some studies have noted a gradual decrease of disk height due to cage subsidence. Therefore, to investigate the significance of cage subsidence, 86 disk levels radiographically confirmed to have good union in 66 patients with posterior lumbar interbody fusion combined with pedicle screw fixation and a single metal cage for degenerative lumbar disease were retrospectively evaluated. The follow-up period ranged from 3 years to 10 years 3 months, with a mean of 7 years 9 months. Cage subsidence often showed a gradual increase over time. At final follow-up, subsidence averaged 4.0 mm on the cranial surface and 2.7 mm on the caudal surface. Although the average increase of disk height was 3.2 mm immediately postoperatively, the final disk height decreased by 4.2 mm on average from that time. The degree of cage subsidence and decrease of disk height were not correlated with the final clinical results. Subsidence was not correlated with bone mineral density in the vertebral body, body weight, or site of the insertion. On the other hand, the wedge shape of the cage and the thickness of the resected endplate had a significant influence on cage subsidence.

Subsidence of Metal Interbody Cage After Posterior Lumbar Interbody Fusion With Pedicle Screw Fixation

Posterior lumbar interbody fusion is considered to be an excellent fusion procedure to stabilize anterior support, correct alignment in the sagittal and coronal plane, and achieve foraminal decompression by lifting the disk height. The metal interbody cage in posterior lumbar interbody fusion is thought to be useful to prevent collapse of the graft bone and to correct and maintain disk height; however, some studies have noted a gradual decrease of disk height due to cage subsidence. Therefore, to investigate the significance of cage subsidence, 86 disk levels radiographically confirmed to have good union in 66 patients with posterior lumbar interbody fusion combined with pedicle screw fixation and a single metal cage for degenerative lumbar disease were retrospectively evaluated. The follow-up period ranged from 3 years to 10 years 3 months, with a mean of 7 years 9 months. Cage subsidence often showed a gradual increase over time. At final follow-up, subsidence averaged 4.0 mm on the cranial surface and 2.7 mm on the caudal surface. Although the average increase of disk height was 3.2 mm immediately postoperatively, the final disk height decreased by 4.2 mm on average from that time. The degree of cage subsidence and decrease of disk height were not correlated with the final clinical results. Subsidence was not correlated with bone mineral density in the vertebral body, body weight, or site of the insertion. On the other hand, the wedge shape of the cage and the thickness of the resected endplate had a significant influence on cage subsidence.

THE NATURAL HISTORY OF AGE-RELATED DISC DEGENERATION: THE INFLUENCE OF AGE AND PATHOLOGY ON CELL POPULATIONS IN THE L4???5 DISC

Introduction: The age-related reduction of water-trapping proteoglycans needed to maintain optimal disc hydration may be caused by reduced synthetic ability or fewer chondrocytes but there is a paucity of objective quantitative studies of disc cellularity. Methods: Sagittal sections of L4–5 discs were subdivided into a nucleus zone and 18 annulus zones prior to determining cell density (cells/mm2) in the mid-sagittal plane of 10 male and 10 female discs aged 13–79 years; 7 parasagittal slices through a single disc; discs showing various types of tears. Results: Most chondrocytes were unicellular but bicellular and multicellular chondrons were common in the margins of large tears and the nucleus in degenerate discs. Cellularity was highest in the right posterior quadrant, lowest in the left anterior quadrant, about equal in the left posterior and right anterior quadrants, and substantially higher in the right half of the nucleus. The correlation of increasing age with declining cell density was much stronger for the nucleus than for the annulus. Nucleus cellularity continued to decline throughout life whereas the annulus ceased its decline after the age of 50. Cell density was low in the vicinity of tears but elsewhere the disc was unaffected. Extensive inferior and superior end-plate separations reduced cellularity throughout the disc. Increased thickness of the cartilage end-plate was associated with higher cellularity in the nucleus. Discussion: The findings that cell density is higher in the posterior annulus and in the right half of the disc, tends to be increased if the cartilage end-plate is thicker, and is not uniformly diminished by large tears, indicates that disc cellularity is influenced by a complex interplay of factors which needs to be understood before attempts are made to restore the structural and functional integrity of degenerate discs.

Research on end-plate connection with non-completely penetrated welds

A series of tests were executed for H-shaped beams whose flanges were connected to end-plate by non-completely penetrated welds. The welds were designed by equal capacity rule and the beams were mainly composed of non-compact or slender elements. The parameters introduced are width–thickness ratios of beam flange and web, end-plate thickness, angle between flange plane and end-plate plane and so on. 24 pieces of specimens were tested to failure under monotonic loading and 6 under cyclic loading. For comparison, a few of the specimens are those with completely penetrated groove welds. Finite element (FE) analysis was also carried out to study the effect of parameter change on the resistance of the welds. The parameters involved end-plate thickness, weld size, column flange thickness and bolt gauge. The results show that thinner end-plate and greater bolt gauge will deteriorate the resistance of weld. As long as the components are properly designed, as done in tests, the connections will not fail at the welds no matter what kind of weld form is adopted. In addition, weld form has no obvious effect on the ultimate loads and cyclic behavior of specimens. It is confirmed that the non-completely penetrated welds connecting flanges of H-shaped beams and end-plates can be used both under static loading and seismic loading in low-rise building structure where local buckling of the member is the predominant factor.

Regional variation in vertebral bone morphology and its contribution to vertebral fracture strength

Vertebral fractures may result in pain, loss of height, spinal instability, kyphotic deformity and ultimately increased morbidity. Fracture risk can be estimated by vertebral bone mineral density (BMD). However, vertebral fractures may be better defined by more selective methods that account for micro-architecture. Our aim was to quantify regional variations in bone architecture parameters (BAPs) and to assess the degree with which regional variations in BAPs affect vertebral fracture strength. The influence of disc health and endplate thickness on fracture strength was also determined. The soft tissue and posterior elements of 20 human functional spine units (FSU) were removed (T9 to L5, mean 74.45 ± 4.25 years). After micro-CT scanning of the entire FSU, the strength of the specimens was determined using a materials testing system. Specimens were loaded in compression to failure. BAPs were assessed for 10 regions of the vertebral cancellous bone. Disc health (glycosaminoglycan content of the nucleus pulposus) was determined using the degree of binding with Alcian Blue. Vertebrae were not morphologically homogeneous. Posterior regions of the vertebrae had greater bone volume, more connections, reduced trabecular separation and more plate-like isotropic structures than their corresponding anterior regions. Significant heterogeneity also exists between posterior superior and inferior regions (BV/TV: posterior superior 12.6 ± 2.8%, inferior 14.6 ± 3%; anterior superior 10.5 ± 2.2%, inferior 10.7 ± 2.4%). Of the two endplates that abutted a common disc, the cranial inferior endplate was thicker (0.44 ± 0.15 mm) than the caudal superior endplate (0.37 ± 0.13 mm). Our study found good correlations between BV/TV, connective density and yield strength. Fracture risk prediction, using BV/TV multiplied by the cross sectional area of the endplate, can be improved through regional analysis of the underlying cancellous bone of the endplate of interest ( R 2 0.78) rather than analysis of the entire vertebra ( R 2 0.65) or BMD ( R 2 0.47). Degenerated discs lack a defined nucleus. A negative linear relationship between disc health and vertebral strength ( R 2 0.70) was observed, likely due to a shift in loading from the weaker anterior vertebral region to the stronger posterior region and cortical shell. Our results show the importance of considering regional variations in cancellous BAPs and disc health when assessing fracture risk.

One-dimensional thermal model of cold-start in a polymer electrolyte fuel cell stack

A transient, one-dimensional thermal model for a generic polymer electrolyte fuel cell (PEFC) stack is developed to investigate the cold-start ability and the corresponding energy requirement over different operating and ambient conditions. The model is constructed by applying the conservation of energy on each stack component and connecting the component's relevant boundaries to form a continuous thermal model. The phase change of ice and re-circulation of coolant flow are included in the analytical framework and their contribution to the stack thermal mass and temperature distribution of the components is also explored. A parametric study was conducted to determine the governing parameters, relative impact of the thermal mass of each stack component and ice, and anticipated temperature distribution in the stack at start-up for various operating conditions. Results indicate that 20 cells were sufficient to accurately experimentally and computationally simulate the full size stack behavior. It was observed that an optimum range of operating current density exists for a chosen stack design, in which rapid start-up of the stack from sub-zero condition can be achieved. Thermal isolation of the stack at the end plates is recommended to reduce the start-up time. Additionally, an end plate thickness exceeding a threshold value has no added effect on the stack cold-start ability. Effect of various internal and external heating mechanisms on the stack start-up were also investigated, and flow of heated coolant above 0 °C was found to be the most effective way to achieve the rapid start-up.

The semi-rigid behaviour of three-dimensional steel beam-to-column joints subjected to proportional loading. Part I. Experimental evaluation

An experimental investigation of statically loaded extended end-plate connections in both major and minor column axes was undertaken at the University of Navarra, Spain. The aim was to provide insight into the behaviour of these joints when a proportional load is applied to both axes (three-dimensional loading). The rotational stiffness of the joints increases with this type of three-dimensional loading. The findings also show that an increase in the end-plate thickness results in an increase in the connection’s flexural strength and stiffness, and a decrease in its rotation capacity.

Experimental Behavior of Stiffened and Unstiffened End-Plate Connections under Cyclic Loading

To compare the hysteretic behavior, stiffness, and strength of stiffened and unstiffened extended end-plate connections of beam–column joints, six specimens with eight high strength bolts were tested under cyclic load. During the test, the axial force of the column was kept constant. The end plates of three specimens and column webs of five specimens were reinforced with rib stiffeners, and the thickness of end plates was varied with the same configuration of beams and columns of all the specimens. Although the plastic rotation of all connections exceeded 0.03rad, they showed different hysteretic behavior, the stiffened ones exhibited higher load carrying and energy dissipation capacities, and the end-plates’ stiffness had a crucial influence on their cyclic behaviors. For thinner end plates, stiffeners can increase the stiffness of the connection greatly, and delay the premature fracture of welds. Stiffeners of the column web can change the stress dissipation panel zone and reduce the possibility of strength failure of column flange.

Behaviour of end-plate moment connections under earthquake loading

A series of eight full-scale structural steel beam-to-column end-plate moment connection specimens was tested under cyclic loads. The parameters investigated were end-plate thickness, bolt diameter, end-plate extended stiffener, column stiffener, type of flush and extended end-plate. The experimental results are presented in terms of moment capacity, rotational stiffness, rotation capacity and hysteretic curves. The test results indicate that extended end-plate connections have adequate strength, joint rotational stiffness, ductility and energy dissipation capacity required for use in seismic moment frames. Based on the test results and analysis, details on end-plate moment connections for seismic steel frames has been proposed, three failure mode requirements and the corresponding resistance have been recommended to assure that the end-plate connection can provide enough rotation capacity and energy dissipation capacity under earthquake loading and its ultimate failure mode is ductile. A bilinear kinematic hardening hysteretic moment–rotation (M–ϕ) model for the end-plate connection extended on both sides has been proposed.

Vertebral Endplate Architecture and Vascularization: Application of Micro-Computerized Tomography, a Vascular Tracer, and Immunocytochemistry in Analyses of Disc Degeneration in the Aging Sand Rat

Lower lumbar vertebral endplates from young and old sand rats were assessed in an Institutional Animal Care and Use Committee approved study for architectural endplate features using micro-computerized tomography (CT) 3-dimensional (3D) models and vascularization studies by an in vivo vascular tracer or immunocytochemical identification of blood vessels. To assess endplate porosity and vascularization using microCT architectural analysis, an in vivo vascular tracer, and immunocytochemical identification of blood vessels in the endplate. The vertebral endplates, also called cartilage endplates, form the superior and inferior, or cranial and caudal, boundaries of the disc. In the human being and sand rat, the cartilaginous endplate undergoes calcification with aging and is replaced by bone. Endplate sclerosis has long been thought to play a role in disc degeneration by decreasing nutrient availability to the disc, but this is still poorly understood. Previous work has identified increasing bone mineral density with aging and disc degeneration in the sand rat model. microCT models of the lower lumbar endplates of vertebrae at L5-6 and L6-7 were constructed from 6 younger (mean age 11 months) and 21 older (mean age 25.6 months) sand rats. Architectural features were scored on a semiquantitative scale for smoothness of the endplate face, irregularities on the endplate margin, and endplate thickness. There were 2 smaller sets of animals (n = 18) evaluated for endplate vascularity following in vivo injection of a fluorescent vascular tracer or by the use of immunocytochemistry to identify blood vessels. microCT revealed a solid bony surface to the endplate, which was not penetrated by vasculature; with aging/disc degeneration, there was roughening and pitting of the plate surface, and the development of irregular margins. In L5-6 and L6-7, sites of prominent disc degeneration evident on radiographs, the proportion of abnormalities in surface smoothness, margin irregularity, and endplate thickening were all statistically significant in both younger and older animals (P < or = 0.0027). More severe changes were evident in the caudal versus cranial endplate surfaces. Histologic study of vascular tracer showed that there was no penetration of the disc by vascular supply from the endplate; this was verified by immunocytochemical identification of blood vessels. The canal system within the endplate was a complex 3D interconnected network. Findings show that disc degeneration in the sand rat occurs concomitantly with marked architectural bony changes on the endplate face, including loss of smoothness and development of irregular bony margins. Vascular connections were not present between the endplate and disc; this was verified with microCT studies, in vivo vascular tracers, and traditional immunocytochemistry. The canal system within the imaged endplate was revealed to consist of a complex 3D interconnected network.

The strength of steel end-plated connections

A yield line approach that uses straight yield lines only is developed to assess the strength of four ‘standard’ end-plated beam-to-column connections. The proposed procedure can be used to analyse the full range of moment connections, including wind moment connections. The strength of the connection can be predicted using relatively simple formulae. The strength predictions are found to agree well with available experimental results. A simple procedure is suggested for designing such connections to provide both adequate strength and adequate ductility. It is used to analyse some standard connection designs contained in a publication by the Steel Construction Institute (the Green Book). The designs in the Green Book appear to be very conservative. Applying the procedure proposed herein to these designs leads to a significant reduction in the end plate thickness though it may require the bolt size to be increased in some cases.

The strength of steel end-plated connections

A yield line approach that uses straight yield lines only is developed to assess the strength of four ‘standard’ end-plated beam-to-column connections. The proposed procedure can be used to analyse the full range of moment connections, including wind moment connections. The strength of the connection can be predicted using relatively simple formulae. The strength predictions are found to agree well with available experimental results. A simple procedure is suggested for designing such connections to provide both adequate strength and adequate ductility. It is used to analyse some standard connection designs contained in a publication by the Steel Construction Institute (the Green Book). The designs in the Green Book appear to be very conservative. Applying the procedure proposed herein to these designs leads to a significant reduction in the end plate thickness though it may require the bolt size to be increased in some cases.

Experimental assessment of the ductility of extended end plate connections

An experimental investigation of eight statically loaded extended end plate moment connections was undertaken at the Delft University of Technology to provide insight into the behaviour of this joint type up to collapse. The specimens were designed to confine failure to the end plate and/or bolts without development of the full plastic moment capacity of the beam. The parameters investigated were the end plate thickness and steel grade. The results show that an increase in end plate thickness results in an increase in the connection flexural strength and stiffness and a decrease in rotation capacity. Similar conclusions are drawn for the effect of the end plate steel grade, though no major variations in the initial stiffness are observed. The failure modes involved weld failure in two test specimens, nut stripping in four tests and bolt fracture in the remaining, always after significant yielding of the end plate and bolt bending. Comparisons of the joint ductility and the corresponding equivalent T-stub for the end plate side are drawn.

Variation of endplate thickness in the cervical spine.

The purpose of the study was to investigate possible variation of thickness of the cervical spine endplate with respect to endplate orientation (superior or inferior endplate) and level distribution (C4-C7). Six human cervical spine segments C4-C7 were used to create six specimen of C4, C5, C6, and C7, respectively. The bony endplates of each vertebra were cleaned carefully from disc tissue without damaging the endplates. Six endplates with severe degenerative changes were excluded from the study. The posterior elements were removed, and a midaxial cut using a bone saw was performed through each vertebral body, thus producing a superior and inferior half. Each half-vertebra was then glued onto a piece of wood with the endplate oriented upwards and horizontally. For each specimen, four computed tomography scans were taken and thickness of the endplate was measured at five points on each scan perpendicular to the midaxial cut. Factorial analysis of variance (ANOVA) and Scheffe-test were used to detect significant differences. All peripheral regions were significantly thicker than the central point of the endplate if all measuring points were considered for statistical analysis, regardless of scan, endplate orientation or level (Scheffe-test, P<0.001). In both superior and inferior endplates, peripheral areas were thicker than the central region (Scheffe-test, P<0.001). For all levels, the endplate within the peripheral regions was thicker than within the central region and the difference reached significance for the superior and inferior endplate of C4, C5, and C6 and the inferior endplate of C7 (Scheffe-test, P<0.05). The peripheral regions of the cervical spine endplate are usually thicker than its central region, regardless of endplate orientation and level (C4, C5, C6, C7) distribution.

Sacral and iliac articular cartilage thickness and cellularity: relationship to subchondral bone end-plate thickness and cancellous bone density.

To measure the thickness and cellularity of adult human sacral and iliac articular cartilages and the thickness and density of the subchondral bones. The right sacroiliac joints of 15 adult patients were examined post-mortem. HOME (Highly Optimized Microscope Environment) microscopy was used to measure articular cartilage and subchondral bone end-plate thickness. Conventional morphometric techniques were employed to estimate cartilage cellularity and cancellous bone density. Sacral articular cartilage was thicker than iliac (1.81 vs 0.80 mm, P<0.001). Iliac cartilage cell density in all zones was higher than sacral. The overall mean was 31.19 x 10(-3) vs. 23.23 x 10(-3)/mm(3), P<0.001. Superficial zones contained more cells than middle and deep zones but there were large differences between the cell numbers of the middle and deep zones of both sacral and iliac cartilages. Iliac subchondral bone end-plates were thicker than sacral (0.36 vs 0.23 mm, P<0.001). The thickness of these plates was related inversely to that of the overlying articular cartilages. Iliac subchondral cancellous bone was twice as dense as sacral (22.07 vs. 12.05%, P<0.001), a ratio recognized anteriorly, centrally and posteriorly. Adult human sacral cartilage is thick and of low cell density. It rests upon a thin bone end-plate supported by porous, cancellous bone. Iliac cartilage and bone display the converse proportions. The identification of these variables may assist understanding of normal sacroiliac joint function and the interpretation of tissue changes in the spondylarthropathies.

Bolted endplate connections revisited

Despite the detailed design rules in annex J of EC3, bolted endplate design is still a discipline, which causes structural engineers great problems. Engineering authorities, who are not affiliated with the EC3 normalisation environment, often do not accept a design based on these rules and structural engineers in general can hardly verify them. In addition, for certain configurations, it is easy to derive upper bound solutions, the load bearing capacity of which are far less than those predicted in EC3. Therefore a new design method based on easy-to-understand mechanical principles has been derived. Firstly, based on uniaxial bending of the endplate, an endplate thickness and required bolt force capacities are derived, preventing web crushing, thereby determining a redistribution of stresses in the adjoining section. The strength of the connection derived is based on these stresses. Secondly, another uniaxial analysis is performed, now with regard to bending of the endplate parallel to the web, applying the well-known T-stub model, ensuring that the tensile stresses in the web can be sustained by the endplate connection.