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"Studs"
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Virtual Modelling of the Stress-Strain State of the Bar Thrust System in the Chrome Plating Technological Process
Chrome plating of long bars in conventional batch plants proves to be challenging, requiring complex lifting equipment and considerable vertical space. Therefore, the use of continuous chrome plating plants, which allow controlled passage of the bars through the chrome plating bath, is preferred. The continuous hard chrome plating plant operates automatically, controlling the entire process from the loading to the discharge of chrome plated bars.The feed and discharge mechanisms must allow the flow of electric current through the bars subject to the chrome plating. This calls for the design of some mechanisms capable of ensuring a constant feed of bars and their efficient discharge.This paper presents a virtual study using finite element analysis (FEA) focused on the strength assessment of the mechanism including the drive pin, the levers and the sliding plates responsible for the movement of the bars.As a result of the study, essential data on critical stresses, local deformations and factor of safety (FOS) for the whole mechanism were obtained, thus providing valuable information for the optimization of the chrome plating process.
Journal Article
Behavior of Monotonically Loaded Slab-Column Connections Reinforced with Shear Studs
A total of five full-scale interior slab-column connections were tested under concentric monotonically increased loading. The slabs were 10 ft(3050 mm) square and 10 in. (254 mm) thick, and columns were 12 x 12 in. (305 x 305 mm). The specimens were built with Grade 60 reinforcement and 4000 psi (27.6 MPa) normalweight concrete. Slab flexural tension reinforcement ratios were 0.87% in three specimens and 1.25% in the other two. One specimen with a slab reinforcement ratio of 0.87% was built without shear reinforcement. The other specimens were reinforced with headed shear studs. The studs were placed in either a radial or an orthogonal layout. Test results show that shear strength equations in the ACI Building Code overestimated the strength of the slabcolumn connections with a 0.87% slab flexural reinforcement ratio. Also, significant differences in failure mode were observed between slab-column connections with shear studs arranged in a radial layout and those with an orthogonal stud arrangement. Recommendations to improve shear strength of slab-column connections are presented.
Journal Article
Study on the Shear Resistance Performance of Grouped Stud Connectors
In order to further investigate the grouped stud effect on the force properties of stud connectors, based on the premise that the correctness of the finite element simulation method, in this paper, a finite element model of grouped stud connectors was developed, and the grouped stud effect and its sensitivity factors were analyzed in order to validate the recommended formula for calculating the shear capacity of grouped stud connectors. Results show that the number of grouped stud rows and stud row spacing have a significant influence on the grouped stud effect, and the unevenness coefficient of grouped stud force is negatively correlated with the number of grouped stud rows as well as the grouped stud row spacing. Grouped stud connectors with commonly used concrete grades greater than C50 and height-to-diameter ratios of greater than 4 in steel–concrete composite structural bridges are insensitive to changes in the concrete strength grades and the length of the studs. The direction of force transmission for grouped stud changes with the change in loading angle and the unevenness coefficient of force for the grouped stud will therefore be reduced. By comparing the results of the 62 existing groups of grouped stud connectors push-out tests, the mean of the tested to calculated value ratio was found to be 1.12, the variance was 0.023, the dispersion was small, and it was shown that the recommended formula has a high degree of accuracy. The results of this paper can be used as a theoretical basis for the study of the shear stress performance of grouped stud connectors.
Journal Article
Experimental Investigation on the Static Performance of Stud Connectors in Steel-HSFRC Composite Beams
In this research, high strength fiber reinforced concrete (HSFRC) was used to replace the normal strength concrete (NSC) in steel-concrete composite beams to improve their working performance, which might change the static performance of stud connectors. Firstly, push-out tests were conducted to investigation on the static performance of stud connectors in steel-HSFRC composite beams and compared with steel-NSC composite beams. Studs of 8 sizes, 13 mm, 16 mm, 19 mm and 22 mm in diameter and 80 mm and 120 mm in height were adopted to study the influence of stud dimension. The test phenomenon shown that the crack resistance of HSFRC was better than that of NSC, and there were some splitting cracks on NSC slabs whereas no visible cracks on HSFRC slabs when specimens failed. Next, the load-slip curves of studs were analyzed and a typical load-slip curve was proposed which was divided into four stages. In addition, the effects of test parameters were analyzed according to the characteristic points of load-slip curve. Compared with NSC slab, HSFRC slab could provide greater restraining force to the studs, which improved the shear capacity and stiffness of studs while suppressed the ductility of studs. The shear capacity, stiffness and ductility of studs would significantly increase with the increasement of stud diameter and the studs with large diameter were more suitable for steel-HSFRC composite beams. The stud height had no obvious influence on the static performance of studs. Finally, based on the test results, the empirical formulas for load-slip curve and shear capacity of stud connectors embedded in HSFRC were developed which considered the influence factors more comprehensively and had better accuracy and applicability than previous formulas.
Journal Article
Mechanical and microstructural assessment of conventional carbon and stainless steel shear stud welded connections
Shear studs are crucial for composite action between a bridge’s superstructure and deck. While carbon steel shear studs weld well onto ASTM A709 Grade 50 steel, their use with weathering bridge steels, particularly ASTM A709 Grade 50CR, has been associated in the literature with potential service-life concerns such as galvanic corrosion arising from metallic dissimilarities. Austenitic stainless steel shear studs have therefore been proposed for use with martensitic ASTM A709 Grade 50CR; however, literature on their mechanical behavior is limited, and code guidance is lacking. This study aims to investigate the mechanical performance and failure mechanisms in conventional carbon and austenitic stainless steel shear studs welded to ASTM A709 Grade 50 and Grade 50CR base metals. Shear and tensile tests were performed on three stud–base metal configurations: (1) a carbon steel shear stud welded to an ASTM A709 Grade 50 plate, (2) a carbon steel shear stud welded to an ASTM A709 Grade 50CR plate, and (3) an austenitic stainless steel shear stud welded to an ASTM A709 Grade 50CR plate. Weld-zone microstructural analysis and microhardness traverses were conducted for each stud–plate assembly. Tensile and shear testing demonstrated an increase in tensile and shear capacities and an increase in ductility for austenitic studs compared with carbon steel studs. Microstructural analysis revealed martensite formation in the coarse-grained heat-affected zone (CGHAZ) of the carbon steel stud welds with Vickers hardness measurements reaching 390 HV0.5. The stainless steel shear stud welds consistently reached 430 HV0.5 in the CGHAZ and weld microstructure, which may be attributed to the formations of martensite, secondary phases, and carbides in these regions. These elevated hardness levels may affect local toughness and increase susceptibility to cold cracking. This significant hardness increase underscores the need to maintain pre‑qualified stud‑welding parameters including heat input, correct stud seating and hold, and surface cleanliness, to ensure consistent weld reliability. The results obtained from this study aim to provide bridge owners valuable insights into the performance and reliability of stainless steel shear studs for bridge applications.
Journal Article
KP solitons and total positivity for the Grassmannian
Soliton solutions of the KP equation have been studied since 1970, when Kadomtsev and Petviashvili proposed a two-dimensional nonlinear dispersive wave equation now known as the KP equation. It is well-known that one can use the Wronskian method to construct a soliton solution to the KP equation from each point of the real Grassmannian
G
r
k
,
n
. More recently, several authors (Biondini and Chakravarty, J Math Phys 47:033514,
2006
; Biondini and Kodama, J. Phys A Math Gen 36:10519–10536,
2003
; Chakravarty and Kodama, J Phys A Math Theor 41:275209,
2008
; Chakravarty and Kodama, Stud Appl Math 123:83–151,
2009
; Kodama, J Phys A Math Gen 37:11169–11190,
2004
) have studied the
regular
solutions that one obtains in this way: these come from points of the totally non-negative part of the Grassmannian
(
G
r
k
,
n
)
≥
0
. In this paper we exhibit a surprising connection between the theory of total positivity for the Grassmannian, and the structure of regular soliton solutions to the KP equation. By exploiting this connection, we obtain new insights into the structure of KP solitons, as well as new interpretations of the combinatorial objects indexing cells of
(
G
r
k
,
n
)
≥
0
(Postnikov,
http://front.math.ucdavis.edu/math.CO/0609764
). In particular, we completely classify the spatial patterns of the soliton solutions coming from
(
G
r
k
,
n
)
≥
0
when the absolute value of the time parameter is sufficiently large. We demonstrate an intriguing connection between soliton graphs for
(
G
r
k
,
n
)
>
0
and the
cluster algebras
of Fomin and Zelevinsky (J Am Math Soc 15:497–529,
2002
), and we use this connection to solve the
inverse problem
for generic KP solitons coming from
(
G
r
k
,
n
)
>
0
. Finally we construct all the soliton graphs for
(
G
r
2
,
n
)
>
0
using the triangulations of an
n
-gon.
Journal Article
Punching Shear Behavior of Glass Fiber-Reinforced Polymer-Reinforced Concrete Slab-Column Interior Connections
This paper deals with punching shear behavior of flat plates reinforced with glass fiber-reinforced polymer (GFRP) reinforcing bars. Six full-scale reinforced concrete (RC) slab-column interior connections were constructed and tested to failure. Two variables were investigated; the flexural reinforcement ratio when high-strength concrete (HSC) is used and the type of GFRP shear reinforcement (headed studs and corrugated bars) when normal- strength concrete (NSC) is used. All specimens were tested under concentric shear force and unbalanced bending moment with a constant moment-to-shear ratio. Increasing the reinforcement ratio increased punching capacity and post-cracking stiffness for HSC connections. Both types of shear reinforcement increased the punching capacity and deflection of NSC connections. Test results were compared with the predictions of the available fiber-reinforced polymer (FRP) design provisions in North American codes.
Journal Article
Punching of Reinforced Concrete Flat Slabs with Double- Headed Shear Reinforcement
Twelve slabs, 11 of which contained double-headed studs, as shear reinforcement were tested, supported by central column and loaded concentrically. Their behavior is described in terms of deflections, rotations, strains of the concrete close to the column, strains of the flexural reinforcement across the slab width, and strains of the studs. All failures were by punching, in most cases within the shear reinforced region. The treatments of punching resistance in ACI 318, Eurocode 2 (EC2), and the critical shear crack theory (CSCT) are described, and their predictions are compared with the results of the present tests and 39 others from the literature. The accuracy of predictions improves from ACI 318 to EC2 to CSCT -- that is, with increasing complexity. However, the CSCT assumptions about behavior are not well supported by the experimental observations.
Journal Article
Theoretical research of the layout of shear studs on steel-concrete composite beams
This research is focused on the distribution of shear studs on steel-concrete composite beams. In practise, two different centre to centre spacings of coupling elements are commonly used, depending on the shear force. The main aim of this work is to find the best position on the beam to change the axial distance of the coupling elements, so that the smallest possible number of them can be used. Making a change at this point on the beam will ensure the most economical solution for the amount of the shear studs used as well as their appropriate utilization. In this work, equations for the design of the amount and the placement of the coupling elements on the beam, which can speed up the design in practice, were derived. In addition, the influence of the individual input parameters of the calculation on the distribution of shear studs was also investigated.
Journal Article