Tie Bars Research Articles

Experimental Research on Impact Resistance of Half Steel Plate Concrete Structures with Different Tie Bar Details

Experimental Research on Impact Resistance of Half Steel Plate Concrete Structures with Different Tie Bar Details

Liquid Silicone Rubber Headlamp Lens Injection Molding Process Optimization Based on Tie Bar Elongation and NSGA III.

This study aimed to improve the injection molding quality of LSR material lenses by optimizing the process parameters. To achieve this goal, we employed the population-based optimization algorithm NSGA-III, which can simultaneously optimize multiple objective functions and identify an equilibrium point among them, thereby reducing the time required to find the optimal process parameters. We utilized analysis software to simulate the injection molding process of LSR material lenses, with a specific focus on examining the relationship between tie bar elongation and the optimized process parameters. During the study, we intentionally varied key process parameters, including the melt temperature, holding pressure, and holding time, to analyze their impact on the residual stress of the final product. In order to investigate the intricate relationship between the tie bar yield, injection molding process parameters, and lens residual stress, we installed strain sensors on the tie bar to continuously monitor changes in clamping force throughout the injection molding process. The experimental results showed that both the tie bar force and mold cavity pressure exerted significant influence on residual stresses. By applying the NSGA-III algorithm for optimization, we successfully determined the optimal process parameters, which included a melt temperature of 34.92 °C, a holding pressure of 33.97 MPa, and a holding time of 9.96 s. In comparison to the initially recommended process parameters during the design phase, the optimized parameters led to reductions of 12.98% in clamping force and 47.14% in residual stress. Furthermore, the average transmittance of the actual product remained within the range of 95-98%. In summary, this approach not only enables the prediction of the lens's residual stress trends based on the tie bar elongation, but also leads to a substantial enhancement of lens quality, characterized by reduced residual stress and improved transmittance through the optimization of process parameters. This methodology can serve as a valuable guide for optimizing real-world injection molding processes.

Analisa Perkerasan Kaku (Rigid Pavement) pada Ruas Jalan Simpang Pudak – Suak Kandis Kabupaten Muaro Jambi

The Simpang Pudak road section is a district road that connects Muaro Jambi with Jambi City. This road section is a link to the economic, social and cultural sectors of Muaro Jambi Regency and Jambi City, so that there are also factory vehicles crossing the Simpang Pudak road section, dominated by small and large trucks transporting economic products and other agricultural products. The condition of the Simpang Pudak Road is a flexible pavement that has destroyed its surface to the foundation layer below it. he purpose of this study is to analyze rigid pavement using the 1993 AASHTO method. Planning with a road length of 312.9 m and a width of 7 meters, with a subgrade CBR of 7.3%, with a W18 value in a year of 455,664,051. In this study, the ESAL value in 30 years was 24,814,115,134 ESAL, with a concrete slab thickness of 27.2 cm. With a continuous type of pavement connection with reinforcement with a plate length of 5.5 meters, M10–150 mm wiremesh reinforcement is installed. As well as installed Tie Bar reinforcement 16 mm with a length of 700 mm and a distance of 750 mm. As well as 32 mm Dowel reinforcement with a length of 450 mm and a distance of 300 mm.

Theoretical Models for Tie Bar Maximum Axial Force Demand in Composite Plate Shear Walls–Concrete Filled

Theoretical Models for Tie Bar Maximum Axial Force Demand in Composite Plate Shear Walls–Concrete Filled

Effect of Tie Bars on Axial Compressive Behavior of Round-Ended Rectangular CFST Stub Columns.

Round-ended rectangular concrete-filled steel tube (RRCFST) columns are prone to local buckling that are close to straight steel plates when used as piers of a bridge and affect its long-term use. In order to solve this problem, tie bars were used in this research to stiffen RRCFST columns. Eleven specimens with tie bars and three specimens without tie bars were tested to analyze influences of cross-sectional aspect ratio, longitudinal spacing, limb numbers and diameter of the tie bar on failure model, confined effect, bearing capacity and ductility of RRCFST stub columns. Finite element models (FEM) with different concrete constitutive models for rectangular and circle parts were established and validated to reveal the mechanism of the constrained effect of tie bars. Experimental and FEM results show that the local buckling scope was decreased and gradually moved to middle height with decreased longitudinal spacings tie bars. The addition of tie bars in RRCFST columns with large aspect ratios slightly enhanced the ultimate bearing capacity, the diameter of tie bars changing from 8 mm to 12 mm greatly enhanced displacement and energy ductility by 58.4% and 85.1%, respectively. However, more tie bars (e.g., two or three limbs) utilization could not further improve the bearing capacity and failure mode. While, the tie bars had very limited contribution to bearing capacity and ductility for RRCFST columns with small aspect ratios, because the outer steel tubes already individually provided for enough confinement on inner concrete. By considering different concrete confined models for rectangular and round-ended parts, an analytical model was proposed and validated to predict the ultimate bearing load for RRCFST stub columns with tie bars.

Investigation of Tie Bars Axial Force Demands in Composite Plate Shear Walls—Concrete Filled

Tie bars axial force demands due to concrete dilation and prying action were investigated through numerical studies. In the first part of this study, the Karagozian and Case Concrete model, which proved to provide reasonable in-plane flexural cyclic inelastic wall response while accounting for concrete dilation effect, was used to investigate the variation of confinement inside the infill concrete, the distribution of passive confining pressures at the steel–concrete interface, and the resulting tie bar axial force demands. Finite element analyses involving C-PSW/CF having different tie spacings, wall depths, and wall thicknesses were performed. In the second part of this study, the influence of plate local buckling on tie bar axial force demand was investigated and explained by prying action. A separate finite element study was performed to investigate the significance of prying action and equations were developed from free-body diagrams. The results showed the significance of the passive confining pressures due to concrete dilation, and prying action due to local plate buckling, on imparting axial forces in tie bars. Neither of these behavior are currently considered as design parameters for tie bars. The numerical analyses and results presented here are intended to provide useful insights and direction for the design and instrumentation of future C-PSW/CF experiments by the broader research community.

Impact of concrete strength on seismic behavior of T-shaped double-skin composite walls

This study investigates the seismic performance of T-shaped double-skin composite walls (DSCWs), which are comprised of double-skin composite flange and web walls and concrete filled steel tubular (CFST) boundary elements, through experimental tests. Six T-shaped DSCW specimens, which are categorized into three groups, according to flange width and type of mechanical connectors (shear studs/tie bars), are tested under combined axial compressive loads and lateral cyclic loads. The DSCWs fail in a ductile flexural mode with similar damage patterns, characterized by buckling of steel tubes and faceplates, concrete crushing, and fracture of steel tubes at the wall base, and exhibit asymmetric hysteresis behaviors, with higher stiffness and strength but lower deformation capacities when the flange walls are under tension. Special focus should be placed on the design of CFST boundary element connected to the web wall, whose compressive failure triggers the loss of load carrying capacity of the specimens. The comparisons between the behaviors of two specimens in each group, which are infilled with high strength (C70) and normal strength concrete (C30) respectively, suggest that employment of high strength concrete improves the seismic behavior of T-shaped DSCW significantly regardless of the flange wall width when shear studs are used. Tie bars may impair the seismic behaviors of DSCWs by inducing premature local buckling of perforated steel faceplates. Numerical studies are conducted using detailed finite element models to investigate the buckling behaviors of steel faceplates which are connected to infilled concrete by tie bars and shear studs. The simulation results reveal that the former buckles earlier than the latter due to smaller critical stress. The slenderness ratio limits to prevent local buckling prior to yielding of steel faceplates are also suggested when these two types of mechanical connectors are used.

Local buckling of steel plates in composite members with tie bars under axial compression

Tie bars have been frequently used in square or rectangular concrete-filled steel tubular (CFST) columns and concrete-filled steel plate (CFSP) composite shear walls for delaying local buckling of the steel plates and also improving the concrete confinement. This study investigated the entire response of steel plates in composite members with tie bars. Twelve specimens were designed and tested under axial compression. In these specimens, only the steel plates resisted the axial load, and the concrete was only used to restrain the inward buckling of the steel plates. The effects of the width-to-thickness ratio of the steel plate and the ratio of the vertical spacing of the tie bars to the steel plate width (abbreviated as vertical-spacing-to-width ratio) were investigated. It was found that the increase in the performance of the steel plates due to the tie-bar restraint was quite limited when the vertical-spacing-to-width ratio was 1/2 and became more significant when this ratio decreased to 1/3. The elastic buckling stresses of rectangular plates having boundary conditions similar to those in composite members were computed using the finite element method for further strength evaluation of the steel plates. It was found that the effect of the columns of tie-bars on the elastic buckling stress increased as the vertical-spacing-to-width ratio decreased and was negligible when this ratio was larger than 0.6. Simplified equations for estimating the maximum strength and reserved strength (defined as the average stress corresponding to the average strain of 3%) of the steel plates in composite members with tie bars were developed based on the test results and elastic buckling analyses.

Environment-Induced Behavior of Transverse Tie Bars in Adjacent Prestressed Box-Girder Bridges with Partial Depth Shear Keys

AbstractAdjacent box-girder bridges are commonly built in United States because of their fast, easy, and economical construction. They have shown good performance and service life except for freque...

Study on the clamping force measurement and partial load regulation technology of injection molding machine

Tie bars are the most important parts of injection molding machine, and the partial load of tie bars will directly affect the product quality. According to the measurement of strain and stress of the tie bars, the partial load rate of tie bars was calculated, and the influence of different types of thread shape and template (mold) parallelism on the partial load rate of tie bars were analyzed. Experiments reveal that the partial load rate is changed within 0.8%–3.8%, and the partial load rate gradually decreases with the increase of the clamping forces. Besides, different types of the thread of tie bars have little influence on the partial load rate, while the parallel degree of the template (mold) has great influence on the partial load rate of the tie bars. Further experiments show that the partial load rate is located in 0.79%–1.81% when the parallelism of template (mold) is good, and the partial load rate of tie bars between 8.59%–11.46% when the parallelism of template (mold) is poor. Finally, the partial load adjustment system of tie bars were also designed to make the force of tie bars more uniform and the partial load rate can be reduced by detecting the partial load rate of the tie bar and using the closed-loop control.

Modern Hybrid Structures for Buildings and Constructions

Objectives: The study considers the areas of improvement of engineering structures and formulates the principles for developing hybrid structures combining the elements with different properties in one constructive system. Methods: The common feature of all approaches that have been described in this study is that the elements included in the hybrid (combined) structure possess different properties. This study provides the detailed analysis of the strut frame hybrid systems with artificial stress control. Findings: The principle of creating hybrid structures implies the efficient combination of different elements in one system that results in lower specific weight of the structure, in simpler production processes, in lower costs of the objects and in higher durability of the structures. The authors suggested and investigated principally new constructive forms of flat and spatial light hybrid (combined) strut frame type systems and the methods of their manufacturing. Technical solutions have been protected by the industrial patents. The stress-deformed conditions of the cross shaped spatial strut systems have been investigated. The rational parameters of the structures have been identified that ensure maximum effect obtained due to the metal consumption decrease. The study investigates the properties of the constructive nonlinearity of the strut frame systems under the conditions of vibrations. New active shapes of the tie bars of the strut frame beams have been found. Application of these new shapes of the tie bars makes it possible to improve the strength of the system by 5…23 %. Applications/Improvements: The combined method of prestressing the strut system applying different techniques of artificial stress and deformation control has been proposed. Application areas for the pre-stressing of this type have been identified. Keywords: Active Shapes of Tie Bars, Combined Pre-Stressing, Hybrid Structures Combined Structures, Pre-stressing, Strut Frame Systems, Spatial Crosswise Strut Systems

Contribution of Transverse Tie Bars to Load Transfer in Adjacent Prestressed Box-Girder Bridges with Partial Depth Shear Key

AbstractAdjacent box-girder bridges have become a popular choice as they can be constructed quickly, easily, and economically. In spite of their good performance during many years of service, one major problem has been recurrent longitudinal cracking of the grout material in the shear key. A combination of shear keys and transverse posttensioning (TPT) ties in such kind of bridges is typically used to connect the bridge girders together so that they would behave as a single integrated unit. However, information regarding the contribution of the TPT tie bars on load transfer between adjacent box girders is limited. In this study, a single-span precast prestressed concrete adjacent box-girder bridge was instrumented and monitored to study the effect of TPT tie bars on load transfer mechanism and overall bridge behavior under static and dynamic truck loads. Two sets of instruments were installed in the girders and tie bars during and after the construction of the bridge. A good correlation was achieved betwe...

A Study on Verification Tests according to Connection Design Methods of Steel Plate Concrete Structures

본 연구에서는 원전 구조물 내 철근 콘크리트 구조와 강판 콘크리트 구조가 이질접합된 경우를 모사하기 위하여, 상하부 표면강판 간에 타이바를, 상하부 리브재 간에 타이형강을 구성한 보형 실험체를 제작하여 실험체의 면외 휨 거동특성을 확인하고자 하였다. 실험결과, 실험체의 연성거동을 검증하였으며, 타이바와 타이형강이 콘크리트 및 강판의 분리를 방지함으로써 접합부의 취성파괴를 막아주고 있음을 확인하였다. 또한, #14 주철근으로 구성한 강판 콘크리트 구조 접합부에 대하여 두 가지 형태의 기계적 정착이음 방식에 따른 인장실험을 수행함으로써 본 방식의 설계 적정성을 평가하였다. 실험결과, 두 실험체 모두 주철근이 항복에 도달할 때까지 철근의 정착 및 연결 기능을 탄성한도 내에서 건전히 수행하고 있음을 확인하였다. In this study, out-of-plane flexural test was performed to analyze behavior properties for a beam specimen which imitated a structure with connection member between reinforced concrete and steel plate concrete part. Tie bars between a upper and a lower steel plate, and tie wide flange shapes between upper and lower ribs were designed to prevent the steel plate or the ribs from breakaway in the connection of the specimen. As a result of the test, ductile failure behavior of the specimen and the functionality of the tie members were conformed as originally intended. Also, tension tests were performed to evaluate the design appropriateness of two specimens produced to anchor and connect mechanically #14 bars. The two test results showed that the anchorage connection system behaves in elastic limit during the main bars yielded, and the integrity of the designed system was verified.

Behaviour of uni-axially loaded CFST columns confined by tie bars

Concrete-filled-steel-tube (CFST) columns have been widely adopted for column construction of tall buildings due to its superior strength and ductility performance contributed by the composite action. However, this beneficial composite action cannot be fully developed at early elastic stage as steel dilates more than concrete and thereby causing imperfect interface bonding, which reduces the elastic strength and stiffness. To resolve the problem, confinement in the form of tie bars is proposed in this study to restrict the elastic lateral dilation of concrete. For verification, 30 CFST columns of various dimensions cast with normal- (NSC) or high-strength concrete (HSC) and installed with tie bars were tested under uni-axial compression in this study. From the results, it was evident that: (1) tie-confined CFST columns had uni-axial strength larger than those of unconfined CFST columns. (2) Tie bars can increase slightly the elastic stiffness of the CFST columns. (3) Tie bars can restrict effectively the lateral dilation of CFST columns. (4) The failure modes of tie-confined NSCFST and HSCFST columns were the local buckling at the ends and formation of longitudinal steel cracks initiated at bolt holes. Lastly, based on the test results, analytical model taking into account the confining effects of steel tube have been developed to predict the uni-axial strength of tie-confined CFST columns.

Uni-axial Compression Test of Concrete-filled-steel-tube Columns Confined by Tie Bars

Concrete-filled-steel-tube (CFST) columns have been adopted due to its superior strength and ductility performance contributed by the composite action. However, this beneficial composite action cannot be fully developed at early elastic stage as steel dilates more than concrete and thereby causing imperfect interface bonding. Hence, it reduces the elastic strength and stiffness of the CFST columns. To resolve the problem, confinement in the form of tie bars is proposed in this study to restrict the lateral dilation of concrete and steel at initial elastic stage. In this paper, CFST columns of various dimensions, concrete strength and installed with tie bars were tested under uni-axial compression. From the results, it was evident that: (1) Tie bars could increase the axial load-carrying capacity (Maximum 16%; average, 5%) and decrease the strength degradation rate of CFST columns. (2) Tie bars were not effective in improving the elastic stiffness of CFST columns. (3) Tie bars were effective to limit the lateral deformation of the core concrete and the steel tube at the location of tie caps. However, the confining pressure decreased between tie caps at both horizontal and vertical planes.

Effect of tie bars on the field performance of full-depth repair on concrete pavement

Many Full-Depth Repairs (FDRs) have suffered recurring failures and thus there is a critical need to enhance the understanding of the failure mechanisms. Three premature failure projects were investigated. Recurring pumping, settlement and cracks are strongly related to poor Load Transfer Efficiency (LTE), which was obtained with a falling weight deflectometer. Cores were taken to examine the condition of the tie bars. The results from highway IH20 reveal that recurring failures occurred on the same slabs that had poor anchoring to the adjacent slabs. There was zero resistance on the pull-out test before the concrete was poured in 2009. Low LTEs of less than 40% were measured in 2010. Cores taken in 2010 revealed significant surrounding voids at the tie bar, indicating that the epoxy did not ever develop sufficient anchoring strength. The deflections at the joints were 3-5 times higher than those at the center slab. Similar failure mechanisms were observed on the IH35 and US75 projects that had poor LTE. There was a good correlation between lower LTE, higher deflections, visible pumping, and settlement. Tie bars were not properly anchored in the IH35 pavement. Tie bars were ruptured in the US75 pavement. Because of these ineffective tie bars, pumping and settlement were prevalent. In contrast, a good performing FDR on SH78 also was investigated. All LTEs had remained above 90% even after 16 years of trafficking. It was concluded that when LTE exceeds 90%, it lead to a successful FDR. By comparison, if was concluded when LTE was less than 40%, premature failures occurred. Additional data is needed to verify what will be the performance when the LTE is between 40% and 90%. A threshold value can be established for acceptable LTE value. The superior performance of the SH78 pavement suggests that proper procedures are critical when anchoring the tie bars. Pull-out tests should be performed to ensure that proper anchoring and sufficient strength is developed on the tie bar before concrete is placed.

Simulation Analysis and Process Control of an Arch Bridge for Replacement of Tie Bars

The numerical simulation analysis, by using senior nonlinear finite element analysis software MSC.Marc, was achieved in this paper for the tie-replacing procedures of a steel tube tied-arch filled with concrete. Through this analysis, the control parameters were accurately determined for the installing of new ties and the removing of old ties. Results of numerical analysis ensured the bridge structure stable during the replacement, made the construction of safe and convenient, and played a guiding role in the maintenance and reinforcement. The successful experience could be referenced by other similar projects.

Improving the performance of full-depth repairs by understanding the failure mechanisms

In order to understand the reoccurring failures on the slabs or adjacent slabs that received Full-Depth Repair (FDR) treatments, efforts were made to investigate the causes of the failures on IH35W and US75. In addition, one successful FDR project on SH78 was studied to verify and validate the hypothesis of the failure mechanisms. Load Transfer Efficiencies (LTEs) were evaluated with a falling weight deflectometer, and the base and subgrade moduli were determined by Dynamic Cone Penetration (DCP). Cores were taken to examine the condition of the tie bars. Furthermore, design and construction practices were reviewed and evaluated. The common symptom for both IH35W and US75 projects was the poor LTE (less than 40%). When the LTE was lower, there were higher deflections, visible pumping, and settlement. Settlement is strongly related to the poor LTE. Tie bars were found to be ruptured in the US75 pavement, and they were not properly anchored in the IH35W pavement. Because of these ineffective tie bars, poor LTE and settlement was prevalent. On SH78, all LTEs remain above 90% even after 14 years of trafficking. The superior performance of the SH78 pavement suggests that proper procedures are critical when removing concrete and drilling holes for new tie bars, to avoid damage to, and subsequent failure of the adjacent slabs. The anchoring of the tie bar is critical to the performance of the FDR. Pull out tests should be performed to determine the type of epoxy, time before concrete pouring, embedment depth, and other construction parameters will provide adequate strength. Based on the DCP and field performance results, it is concluded that the most accurate indicator of joint performance is LTE, while the base and subgrade support are secondary.

Effects of Base Support and Load Transfer Efficiency (LTE) on Portland Concrete Pavement Performance

Abstract This paper presents the results of seven field investigations (US59, IH20, SH342, US75, US90, MLK Blvd., and US96) to identify the underlying causes of settling and irregular cracking in Portland cement concrete (PCC) pavement. Settling and cracking are not intended, and they are detrimental to the long-term performance of PCC pavement. The falling weight deflectometer and dynamic cone penetrometer were utilized to characterize the load transfer efficiency (LTE) and base support conditions. It was found that when there is adequate base support (e.g., a modulus>345 MPa), the irregular cracks remain tight even after decades of truck trafficking, as evident in the IH20 and MLK projects. Irregular cracks on these projects were caused by late or too-shallow saw cutting. In areas that had 50 % lower base moduli, the cracks typically grew to about 57 mm. The subsidence and settling on US59 and US75 were observed in the areas with LTE in the range of 40 %. Tie bars were found to be ruptured in those areas. When LTE exceeds 80 %, the tie bar was intact and no settling was observed. The maximum deflections were approximately eight to ten times higher in the area with settling than the area without settling. It is because the low load transfer efficacy would lead to higher deflection under truck trafficking. The high deflection would initiate pumping and then settling. Despite severe spalling observed before the overlay on US96, the stone-mastic asphalt overlay is now 5 years old, and no visible cracks can be observed. This is because of the high LTE (exceeding 85 %) and sufficient base support (modulus exceeding 1378 MPa). The results from the seven projects investigated indicate that base support and LTE play a critical role in concrete pavement performance. To minimize the cracking and settling, it is preferable to have a base modulus and LTE exceeding 345 MPa and 80 %, respectively.

Behavior of Tied Multiple-Lane Portland Cement Concrete Pavement

Tie bars are used at longitudinal construction joints (LCJs) in portland cement concrete (PCC) pavement primarily to keep lanes from separating. As more lanes are tied together because of ever-increasing traffic volume, concerns about the potential for longitudinal cracking have led to the use of dowel bars at LCJs. However, a survey of a number of state highway agencies (SHAs) revealed that few of them have guidelines and design standards for the use of dowel bars at LCJs and that no in-depth studies conducted in this area have been identified. The effects of multiple lane ties and dowel bar placements in PCC pavements are analyzed in this paper to provide basic information on whether dowel bars are really needed, and if they are, where they should be placed and what their advantages and disadvantages are. Field testing verified that the longitudinal cracking potential is greater as slab thickness and lane width increase. The effects of multiple lane ties and dowel bar placements at LCJs are evaluated with numerical analysis. Placing dowel bars in lieu of tie bars reduces the longitudinal cracking potential, and the effectiveness of using dowel bars is enhanced when they are applied to thicker and wider pavements. However, the use of dowel bars could result in increased potential for lane separations.