Continuous Bar Research Articles

МІНІМІЗАЦІЯ МІЖКЛІТЬОВОГО НАТЯГУ НА БЕЗПЕРЕРВНИХ СТАНАХ ЗА ЯКІРНИМИ СТРУМАМИ ЕЛЕКТРОПРИВОДІВ ПРОКАТНИХ КЛІТЕЙ

In the conditions of continuous rolling of graded profiles with no or too little metal deflection between adjacent rolling cages, the most promising is tension regulation based on information about the armature currents of the main electric drives. The effectiveness of the method of minimizing the tension of graded rolled products based on information about the armature currents of the main electric drives was investigated. The method is based on the hypothesis of the constant ratio of the armature current of the drive of the next cage to the armature current of the drive of the previous cage in the free rolling mode. The method involves predicting the free-rolling current in rolling electric drives based on information about the free-rolling current in the electric drives of previous cages. The study is based on a complex model of the process of continuous bar rolling in four finishing cages of a small-grade mill with individual electric drives equipped with subordinate speed control systems. Given the fundamental impossibility of approbation of the proposed method by the methods of an industrial experiment, verification of its operability requires computer simulation modeling. The created computer model allows for adequate simulation of the operation of the control system in the conditions of rolling in a continuous group of cages with an accuracy that is sufficient for conclusions about the effectiveness of its operation. According to the results of the study of the control system by means of computer simulation, the effectiveness of its work was proven, in particular, the reduction of the specific tension in all intercell spaces of the finishing group of roll stands to an acceptable level of 10 N/mm2 and a significant narrowing of the range of changes in the width of the finished rolled product.

Exploring distinct types of intertidal bars on either side of a small estuary using a multifaceted approach

Multiple intertidal bars are common sedimentary landforms found on low-gradient sandy coasts exposed to low to moderate wave energy with a significant tidal range. However, studying the factors that influence their morphology can be challenging due to limited high-resolution field data and tools for bedform analysis. To address this, a multifaceted approach was used to investigate the morphology of intertidal bars at two adjacent tidal beaches on the north and south coasts of a small estuary on the Lianyungang coast of China. This approach included repeated real-time kinematic-global positioning system (RTK-GPS) leveling, unmanned aerial vehicle (UAV) surveys, surface sediment sampling, satellite remote sensing analysis, and automated bedform analysis. The study revealed two distinct types of intertidal bars on either side of the estuary with similar hydrodynamic settings. The north coast presented low-amplitude ridges (also called ridges and runnels), while the south coast had sand waves. The north coast displayed 2–5 oblique, asymmetrical, and dynamic bars that appeared at the seaward end of the intertidal zone and migrated landward to eventually attach to the steep beach on the landward end of the intertidal zone, representing a life cycle. The south coast had 6–9 parallel, continuous, symmetrical, and stable sand bars occupying the lower part of the intertidal zone. Due to the nearly identical hydrodynamic background, the alongshore variability in sediment supply is suggested as a key factor driving the formation of distinct types of bars.

Effect of joint details on progressive collapse resistance of precast concrete structures

Recently, precast concrete (PC) structures are vulnerable to progressive collapse, because during construction, the structural integrity of the beam–column joint is poor. Even after construction, the interface between PC beam and column is a critical section, due to the discontinuity of concrete and reinforcement. In this study, to investigate the progressive collapse resistance of PC structures with various joint details, three moment sub-frames were tested under monotonic vertical loading. Addressing the actual joint details used in industrial PC buildings, such as warehouses and factories, prestressing was applied to the PC beam, and wet connection was used for beam–column joints. As a test parameter, the joint details were compared (i.e., monolithic reinforced concrete (RC) joint, PC with pinned joint, and PC with continuous joint). The test results showed that the PC specimen with continuous joint exhibited structural behavior equivalent to the RC specimen in terms of failure modes, peak strength, deformation, lateral support reaction, and strain. However, the PC specimen with pinned joint showed significantly less strength than that of the PC specimen with continuous joint, due to the discontinuous top and bottom rebars in the beam–column joint. Further, the deformation and failure modes of PC specimens with pinned joint differed from those of the other specimens (i.e., rigid rotation of PC beams without flexural yielding, and concrete breakout around dowel bar). Using a finite element (FE) model, a parametric study was conducted. According to the analysis results, the progressive collapse resistance was significantly affected by the continuous rebars of the PC beam in the beam–column joint. Based on the test and analysis results, the maximum allowable uniformly distributed floor loads sustained by PC system was estimated. Further, design recommendations to improve the progressive collapse resistance were discussed, such as use of continuous top bars, strength limitation of dower bars, and effect of prestressing force.

Evaluation and Improvement of the Current CRCP Pavement Design Method

Continuously reinforced concrete pavement (CRCP) is a representative type of concrete pavement constructed with continuous steel bars without intermediate transverse expansions. With reference to pavement conditions, CRCP is an exceptional type of concrete pavement according to the Highway Pavement Condition Index (HPCI) and International Roughness Index (IRI). The two main design methods for CRCP are AASHTO 86/93 and the Mechanistic-Empirical Pavement Design Guide (MEPDG). Because of limitations of the AASHTO 86/93 design method, the MEPDG method is more reliable. While incorporating the interactions among geometrics, pavement structure layers, material properties, subgrade, traffic, and environmental conditions, and the prediction values according to the MEPDG method, it matched the measured results of crack spacing and crack width. The MEPDG punchout, crack width and spacing, and load transfer efficiency (LTE) models were evaluated, and results were compared with the test sections in three European countries consisting of different construction details, which were investigated and recorded between 2019 and 2021. In this sense, a calculation tool was developed to consider the influence of different parameters in design process. In addition, sensitivity analyses were executed for the development of punchout, considering various input parameters. The track surveying and the evaluation of the results indicated that the design process can be improved with consideration of some criteria such as crack formation time or adjustment of the correlation between crack width and crack spacing. Due to the very important function of erosion and resulting pumping in the deterioration of CRCP, it is advisable to include the influence of the base layer and the influence of different shoulder type and heavy traffic volume or effect of deflection in the calculations.

Effect of confining stirrups and bar gap in improving bond behavior of glass fiber reinforced polymer (GFRP) bar lap splices in RC beams

Fiber-reinforced polymer (FRP) bars are becoming a popular replacement for steel rebars that are vulnerable to corrosion, especially under harsh corrosive environments. Despite several advantages for using FRP rebars, the bond between FRP bars and surrounding concrete has been a major concern that affects the behavior of FRP-reinforced structural members. The experimental program of this study comprises testing eight full-scale glass FRP (GFRP) reinforced beams under two-point loads. There were two control beams and six beams having rebar lap splices. The beams were reinforced using 2ϕ12 GFRP bars. The first control had continuous GFRP bars, and the 2nd control had GFRP lap splice conforming to the relevant ACI code. The lap splice was 65 times the bar diameter in six beams having lap splice. The contact lap and non-contact laps were used along with the variable spacing of shear stirrups in the lap zone (50, 100 mm, ∞, i.e., no shear stirrups). The lap splice, designed conforming to the ACI code, was found to be very conservative. The reduction in shear stirrups’ spacing in the lap zone and the gap between lapped bars was found to enhance the bond performance of GFRP bars by up to 31 %. The authors’ previous models for predicting development length and bond are found to show good predictions for the experimental results of the present study as well. Analytical models are developed for predicting with sufficient precision the peak load for GFRP reinforced beams with the two types of lap splices (non-contact and contact).

Enhancement of Concrete Properties using Steel Fibers - Review

Concrete is one of the most widely used building materials in the world. However, one of the undesirable properties of concrete as a brittle material is its low tensile strength and ability to flex. This brittle behavior leads to sudden failure without warning. Therefore it requires reinforcement in order to be used as a building material on a large scale, this reinforcement is in the form of continuous steel bars that are placed in the concrete structure at the appropriate locations to withstand the imposed tensile and shear stresses. On the other hand, they are generally short, discontinuous, and randomly distributed throughout the concrete member to produce a composite building material known as FRC. From this point of view, this review came to clarify the practical benefit of using this technology to inform researchers and workers in the construction sector about it and to provide modern sources for those wishing to conduct more research in the field of strengthening the mechanical properties of concrete in addition to the benefits of using steel fibers in improving the bending and shearing of concrete beams.

Flexural performance of reinforced HS-HVFA-SCC beam with spliced plain bar

This research presents the use of flexural performance criteria for determining the required spliced length of tensile plain bar embedded in unconfined high strength-high volume fly ash-self compacting concrete (HS-HVFA-SCC) beam. Subsequently, the obtained splice length is compared with the splice length database of other concrete types. For the purpose of the investigation, five beams are designed with various spliced bars within the pure bending area. In addition, a beam with continuous bar is prepared as a reference beam. The beams are tested by a four-point loading scheme. The results show that splice lengths within a 342–570 mm (34.2db–57db) range provide sufficient development of strength in the reinforcements to sustain a higher flexural load than the reference beam. However, in term of stiffness and ductility, only beams with a splice length of at least 380 mm (38db) are superior compared to the reference beam. Based on the above consideration, the minimum splice length of tensile plain reinforcement for the investigated beams is 380 mm (38db). Comparison of the result with other concrete types suggests that the required splice length of tensile plain bar embedded in HS-HVFA-SCC follows the equations for estimating splice length of general concrete and self-compacting concrete (SCC) even though the equations are derived for deformed bars. This finding implies that an efficient splice length in HS-HVFA-SCC beam can be expected.Article HighlightsHS-HVFA-SCC beam with a lap-spliced plain bar of 38db gives an equal flexural performance to the beam with continuous bar.The required splice length of plain bar in HS-HVFA-SCC beam is comparable to that of deformed bar in other concrete types.An expected efficiency of splice length can encourage the use of HS-HVFA-SCC for a variety of structural applications.

Behavior of steel fiber reinforced concrete beams with CFRP wrapped lap splice bars

This research employed an experimental and numerical investigation of a new method for over-lap splicing rebar employing an epoxy resin-coated carbon fiber-reinforced polymer (CFRP) sheet to enhance the behavior of the splice tension bars. The normal concrete strength with Steel fiber mix were prepared for casting seven specimens for this purpose, and tested under monotonic, four-point bending load conditions. three of the specimens were made of CFRP over-lap splice in addition to three traditional lap-splice beams, with one specimen as a reference with full length continuous bar. In addition, three ratios of lapping length were studied, they are; 33%, 66%, and 100% for each type of splice. The used percentage of steel fiber (SF) was equal to 0.5% by mix volume. It was noticed a significant enhancement in the behavior and flexural strength with the use of CFRP over-lap splice as compared with the traditional lap splice. Moreover, this approach was simulated numerically by using Abaqus software. The simulation resulted according to the adopted criteria showed good agreement to the results of the work that was done in the lab.

Diagenetic controls on the reservoir quality of tight reservoirs in digitate shallow-water lacustrine delta deposits: An example from the Triassic Yanchang Formation, southwestern Ordos Basin, China

Diagenesis is a very important factor to determine the quality of clastic reservoirs, especially in tight sandstone reservoirs. The tight reservoir of Triassic Yanchang Formation in southwestern Ordos Basin is the foremost hydrocarbon exploration target. The shallow-water lacustrine delta developed in Chang 8 reservoir of the study area is distributed in digitate shape, which are mainly composed of distributary channel, continuous mouth bar and together with natural levee above. The typical tight reservoir of Chang 8 member experienced a complex diagenetic evolution process, but the relationship among diagenetic alteration, deposits and lithofacies, as well as their control and influence on reservoir quality is still unclear. In this study, casting thin section, scanning electron microscope (SEM) and backscatter scanning electron microscope (BSE) combined with energy spectrum analysis, together with stable isotope analysis, X-ray diffraction analysis, and homogenization temperature test of fluid inclusions are used to analyze the reservoir characteristics including petrology, lithofacies, history and intensity of diagenesis. The control and influence of these characteristics on ultimate reservoir quality of digitate shallow-water lacustrine deltas are further evaluated. The results show that four lithofacies can be identified (namely, “i”, “ii”, “iii”, “iv”) with the decrease of grain size and increase of ductile components in the tight sandstones of digitate shallow-water lacustrine delta, respectively corresponding to preferential development positions in the deposits. There are similarities and differences on the diagenetic processes among various lithofacies. The strong mechanical compaction after burial primarily decrease the original pore space in all lithofacies, and the largest loss of pore space occurs in lithofacies iv sandstones (siltstone with wavy bedding). The chlorite is mainly in the morphology of pore-lining, but coating and rosette-like chlorite are rare. The ability to resist compaction in sandstones of lithofacies i and lithofacies ii is enhanced due to the moderate development of pore-lining chlorite, thus retaining partial pore space. Carbonate cements are abundant in relatively coarser-grained sandstones close to the sandstone-mudstone interface, and the occurrence of these cements is closely related to the adjacent mudstone, indicating that Fe and Mg ions necessary for carbonate cementation are most likely from adjacent mudstone where ions are released by mechanical compaction and subsequent hydrocarbon generation pressurization during the burial process. Weak carbonate cementation occasionally occurs at the architectural bounding surface far away from mudstone, which probably related to the transformation of clay minerals. Five typical diagenetic evolution patterns in digitate shallow-water lacustrine deltaic reservoir are summarized by considering the diagenetic processes with deposits and lithofacies. From pattern I to pattern V, the corresponding reservoir quality gradually deteriorates. The results in this study are of great help to deepen the understanding of diagenetic alteration process and reservoir heterogeneity of tight sandstones, and provide theoretical basis for exploration and sustainable development of similar lacustrine shallow-water lacustrine delta reservoirs, especially for bar fingers in shallow-water deltas.

Synchronous monitoring of axial vibration and rotation speed of rotating cylinder by linear array scanning

The axial vibration (AV) and rotation speed (RS) signals of a rotating cylinder contain rich condition information. In order to harness such quantitative information, an effective measurement method for synchronous monitoring of the AV and RS is highly desirable. However, traditional approaches are restricted either by limited test distance or multiple isolated sensors, which makes the approaches impractical to synchronously acquire the AV and RS signals through a single device. In this paper, a generalized visual measurement method for synchronous monitoring of the AV and RS via linear array scanning (LAS) is proposed. The basic idea is to paste a mark containing a printed black continuous bar and a black block (BCBB) on the surface of a rotating cylinder, and use a linear array camera to synchronously sample the bar and blocks. For the extraction of mark edges, we propose a single edge pixel extraction method through gray gradient of row pixels based on the observation of relatively stable gray level distribution. Line scanned signals disturbed by seam error or axial offset are automatically corrected through seam compensation and axial offset correction respectively. Experimental validation of the proposed method is presented for the cylinder under static hammering, variable speed condition and steady speed condition at a scanning distance of 500 mm. Bilinear interpolation is applied to the scanned linear array images before extracting the edge features and helps improve measurement accuracy. Analyses in the time domain and frequency domain verify the effectiveness of the LAS. The average error between the RS signal obtained by LAS and the reference value is 0.1420 rpm. The correlation coefficient between the AV time-domain signal of LAS and the reference signal is up to 0.900 and the resonance frequency error in the frequency spectrum is less than 1 Hz.

Gamma oscillations in primate primary visual cortex are severely attenuated by small stimulus discontinuities.

Gamma oscillations (30 to 80 Hz) have been hypothesized to play an important role in feature binding, based on the observation that continuous long bars induce stronger gamma in the visual cortex than bars with a small gap. Recently, many studies have shown that natural images, which have discontinuities in several low-level features, do not induce strong gamma oscillations, questioning their role in feature binding. However, the effect of different discontinuities on gamma has not been well studied. To address this, we recorded spikes and local field potential from 2 monkeys while they were shown gratings with discontinuities in 4 attributes: space, orientation, phase, or contrast. We found that while these discontinuities only had a modest effect on spiking activity, gamma power drastically reduced in all cases, suggesting that gamma could be a resonant phenomenon. An excitatory-inhibitory population model with stimulus-tuned recurrent inputs showed such resonant properties. Therefore, gamma could be a signature of excitation-inhibition balance, which gets disrupted due to discontinuities.

Flexural Performance of Concrete Beams Reinforced with Continuous FRP Bars and Discrete Steel Fibers under Cyclic Loads.

This research investigated the flexural behavior of high-strength concrete beams reinforced with continuous basalt fiber-reinforced polymer (BFRP) bars and discrete steel fibers. Five concrete beams with the dimensions of 150 × 300 × 2100 mm3 were constructed and tested to failure under four-point bending cyclic loading. The specimens consisted of four BFRP-reinforced concrete beams with various reinforcement ratios (ρf), namely, 0.56%, 0.77%, 1.15%, and 1.65%, and one conventional steel-reinforced concrete beam for comparison purposes. The cracking behavior, failure modes, load-deflection behavior, residual deformation, and stiffness degradation of the beams were studied. Additionally, a deformation-based approach was used to analyze the deformability of the beams. The results show that an increase in the ρf effectively restrained the crack widths, deflections, and residual deformation while also enhancing the flexural bearing capacity of the beams. In comparison to the first displacement cycle, the bearing capacity dropped by 10% on average in the third cycle. The stiffness exhibited a fast to slow degradation trend until failure. The residual stiffnesses were higher in beams with a higher ρf. The over-reinforced beams had superior deformability than the under-reinforced beams, according to the deformability factors.

Flexural behavior and a new model for flexural design of concrete beams hybridly reinforced by continuous FRP bars and discrete steel fibers

This research investigates the flexural behavior of concrete beams hybridly reinforced by continuous basalt fiber-reinforced polymer (BFRP) bars and discrete steel fibers. Eleven steel fiber reinforced concrete (SFRC) beams reinforced with BFRP bars were tested under four-point bending. The main test parameters included steel fiber volume ratio, SFRC layer thickness, and BFRP reinforcement ratio. The failure modes, load–deflection behavior, crack initiation and propagation, service load and ultimate load of the beams were studied. The results revealed that steel fibers could significantly restrain the deflections and crack propagation of the beams. The beam with a SFRC layer of 57% of its depth obtained similar behavior as its counterpart of a full-depth SFRC beam. Increasing fiber volume ratio improved both service load and ultimate load of the beams but had a greater impact on the former. Increasing BFRP reinforcement ratio significantly improved structural behavior of the beams but only had a marginal impact on the ultimate strength of over-reinforced beams. Based on the model of ACI440.1R-15, a new and improved analytical model which can consider the contribution of steel fibers in BFRP bar-reinforced SFRC beams was proposed for flexural design of beams which agreed better with experimental results than the ACI440.1R-15 model.

Lateral Deformation Capacity and Plastic Hinge Length of RC Columns Confined with Textile Reinforced Mortar Jackets

This paper presents a nonlinear finite element analysis (FEA) of textiles reinforced mortars (TRM)-confined reinforced concrete (RC) columns through jacketing, under combined axial and cyclic loadings. The FEA models were validated with an experimental study in the literature that was conducted on full-scale square columns reinforced with continuous steel bars (no lap splices). Subsequently, parametric study was performed on the validated FEA models. The parameters considered include various jacket’s lengths and mortar strengths. Moreover, semiempirical models were developed to evaluate the plastic hinge length (LP) and the ultimate drift ratio of RC columns confined with TRM and FRP jackets, while considering the jacket length effect. The FEA models and experimental results were in good agreement. The finite element results revealed that the increase in the jacket length improved the lateral deformation capacity and increased the plastic hinge length linearly up to a confinement ratio of 0.2. Beyond this point, the plastic hinge length shortened as the confinement ratio raised. Moreover, mortars with higher flexural strength resulted in a slightly higher deformation capacity. However, the difference in the mortar compressive strength did not affect the ultimate lateral deformation capacity. The semiempirical models show that the average difference in the predicted LP and the ultimate drift ratio values as compared to the experimental and simulated columns was 3.19 and 16.06%, respectively.

New moment-resisting beam-column joints to increase progressive collapse resistance of precast concrete buildings

Since existing precast RC (reinforced concrete) structures are lacking structural continuity at regions of beam-column connections, they are less resistant to progressive collapse in the event of column removal than CIS (cast-in-situ) RC structures. The prime objectives of current research are to revise the existing precast simple shear beam-column connections and to develop new precast moment connections for increasing the progressive collapse robustness of precast buildings. To achieve these goals, 11 half-scale beam-column assemblies – comprising two beams and three columns – were numerically investigated under the middle column removal scenario using nonlinear 3D FE (finite element) modeling. Two specimens represented typical existing precast simple beam-column connections, and three specimens had revised precast simple connections. Four assemblies were designed with new precast moment connections. The last two specimens represented CIS concrete beam-column connections with continuous and discontinuous longitudinal beam bars to be compared with the precast assemblies. The FE modeling incorporated strain rate-dependent nonlinear constitutive models, contact between different parts in the connection region, and bond-slip at steel bars-to-concrete interface. As a key outcome of this research, the newly developed precast moment connection with the highest rotational ductility was recommended for diminishing the potential of progressive collapse in precast concrete buildings.

Stress Control of a Piezoelectric Lumped-element Model − Theoretical Investigation and Experimental Realization

This contribution focuses on force- and stress-tracking of a multi-degree of freedom system by eigenstrain actuation. The example under consideration is an axially excited piezoelectric bar which can be modeled as a lumped parameter system. The piezoelectric effect serves as actuation source and the question is answered how to prescribe the piezoelectric actuation in order to achieve a desired stress distribution, or, in the lumped case, a desired distribution of internal forces. First, the equations of motion are set up in matrix notation where the state vector contains the displacement components. After some basic manipulations, the governing equation can be written in terms of the internal force vector. Now, if one intends to have a certain desired internal force distribution, it is straightforward to find a condition for the piezoelectric control actuation. The developed theory is first verified by using a continuous piezoelectric bar, where the motion of one end is prescribed. Then the theory is experimentally verified: a lumped two-degree of freedom system is investigated and the goal is to reduce the stress or the internal force in order to avoid mechanical damage. The force-controlled configuration is exposed to a sweep-signal excitation between 1000−4900 Hz, running for 22 minutes without any signs of damage. Then the same system is excited by the same excitation but without piezoelectric control. After some seconds the test sample is visibly damaged, going along with a significant reduction of the first eigenfrequency. This gives strong evidence for the appropriateness of the proposed stress or force control methodology.

Seismic performance of precast shear walls prestressed via post-tensioned high strength bars placed inside grouted corrugated pipes

The seismic performance of precast concrete shear walls depends on the mechanical behavior of the connections to the foundation and especially on the energy-dissipation capacity that is strongly related to connection deformability. With the focus on wall-to-foundation connections, the seismic performance of four vertically-elongated shear walls (height-to-width ratio close to two) is investigated by testing as many full-scale specimens, either cast-in-place (one “reference” specimen) or precast (three specimens). The three precast specimens are equipped with front and back metallic corrugated pipes into which three types of reinforcements are placed in concrete close to the vertical sides, i.e., ordinary bars (PW1), high-strength bars (PW2) and post-tensioned bars (PW3), whereas ordinary spliced bars are placed in the central part of the precast specimens. The cast-in-place specimen (CW) is vertically reinforced only with ordinary continuous bars. After bar placement, the pipes are filled with grout. In this way, the connection between the bars protruding from the footing and the bars reinforcing the shear wall is very effective face to seismic action. Coupling post-tensioned bars with ordinary spliced bars improves the stiffness of the shear walls. The specimens are tested under low-cycle loading, to investigate the lateral resistance, the energy dissipation capacity and ductility, to monitor crack evolution and to study hysteretic behaviour. The local deformation of the concrete at the wall-footing interface (into which epoxy-coated concrete keys are incorporated) is also examined. The test results show that (a) the four shear walls have a similar bearing capacity (PW2 and PW3 have slightly stronger bearing capacities than CW and PW1); (b) the shear walls PW2 and PW3 exhibit similar ductility to the shear wall CW under cyclic loading; and (c) the shear wall PW1 is the least ductile of the investigated specimens.

Study of effects of sleeve grouting defects on the seismic performance of precast concrete shear walls

Precast concrete wall systems are effective means of resisting seismic forces in many structures. However, their performance is affected by the ability to properly connect elements – usually with grout sleeves. Grout sleeve connections are known to be susceptible to backflow during grouting resulting in partially grouted or occasionally entirely ungrouted sleeves. In this study an investigation of the impact of sleeve grouting defects on the seismic performance of precast concrete shear walls is presented. Grouting defects of different sizes and at different positions in the walls were intentionally introduced. Reversed cyclic loading tests of precast concrete shear wall specimens and a comparable monolithically cast-in-place concrete shear wall specimen were performed. The defect-free grouted sleeve panels were shown to be equivalent to monolithic cast walls having continuous bars in terms of capacity although, due to the short sleeve embedment, the precast walls are less stiff and therefore demonstrate reduced ductility. Energy dissipation, however is similar and both monolithically cast and precast walls meet the requirements for use as seismic resistant systems. The study showed that grout sleeve defects adversely affect wall behavior – primarily when the spliced bar is in tension. The impact of defects can be assessed through standard design equations by assuming that the degree of the defect impacts the force the bar can develop. As demonstrated in this study, wall performance becomes an issue of quantifying and predicting defects and their effect, not on the individual bars, but on the wall panel assembly. The panels in this study were dominated by flexural behavior; thus the reduction in panel moment capacity provides a means of differentiating behavior. Panels that maintained at least 92% of their theoretical flexure capacity were mostly indistinguishable from defect-free panels. Noticeable loss of performance was evident at panel capacities of 85% and lower.

Evaluating the Early-Age Crack Induction in Advanced Reinforced Concrete Pavement Using Partial Surface Saw-Cuts

The technological innovation of continuously reinforced concrete pavement (CRCP) that contains a significantly reduced amount of reinforcement and the same fundamental behavior as CRCP is called advanced reinforced concrete pavement (ARCP). This new concept of a rigid pavement structure is developed to eliminate unnecessary continuous longitudinal steel bars of CRCP by using partial length steel bars at predetermined crack locations. In Belgium, partial surface saw-cuts are used as the most effective crack induction method to eliminate the randomness in early-age crack patterns by inducing cracks at the predetermined locations of CRCP. The reinforcement layout of ARCP is designed based on the distribution of steel stress in continuous longitudinal steel bar in CRCP and the effectiveness of partial surface saw-cuts as a crack induction method. The 3D finite element (FE) model is developed to evaluate the behavior of ARCP with partial surface saw-cuts. The early-age crack characteristics in terms of crack initiation and crack propagation obtained from the FE simulation are validated with the field observations of cracking characteristics of the CRCP sections in Belgium. The finding indicates that there is fundamentally no difference in the steel stress distribution in the partial length steel bar of ARCP and continuous steel bar of CRCP. Moreover, ARCP exhibits the same cracking characteristics as CRCP even with a significantly reduced amount of continuous reinforcement.

Flexural behaviour of RC beams substituted with GFRP reinforcement in aggressive environments

Reinforced concrete (RC) in aggressive environments has higher concrete clear cover provided to protect the reinforcement against corrosion. However, providing such higher cover in severe environments could result in increased crack widths for the structural member. Hence, using a combination of fibre-reinforced polymer (FRP) bars and steel reinforcement bars (hybrid reinforcement) has been considered as a suitable solution to develop the full flexural capacity of the section without significantly affecting the serviceability and ductility requirements. This includes utilising the non-corrodible nature of FRP by adding a layer of longitudinal reinforcement made of FRP bars at the corner areas of the cross-section and keeping the main steel reinforcement at sufficient cover depth. This paper studies the flexural behaviour of hybrid glass-fibre-reinforced polymer (GFRP) beams consisting of continuous GFRP bars along with conventional steel reinforcement and comparing them with conventional RC beams through experimental and analytical studies. The test results indicated that the hybrid GFRP beams possess better flexural strength and ductility compared to conventional RC beams and could be considered as a suitable alternative to replace RC beams in aggressive environments.