Reinforcement Arrangement Research Articles

Varying reinforcer dimensions during differential reinforcement without extinction: A translational model.

Procedural arrangements of differential reinforcement of alternative behavior without extinction often involve presenting the same reinforcers for problem behavior and appropriate behavior, which is typically ineffective at reducing problem behavior and increasing an alternative response. However, manipulating reinforcement dimensions such that the contingencies favor the alternative response may improve treatment outcomes when using differential reinforcement of alternative behavior without extinction by increasing appropriate behavior and reducing problem behavior. We conducted this translational study with 32 college students completing a button-pressing task on a computer program in which they could engage in analogs to problem behavior and appropriate behavior. The effects of manipulating magnitude, immediacy, quality, and a combination of all three dimensions for the alternative response were evaluated. Overall, all dimension manipulations reduced the analog to problem behavior, with the largest reductions observed during the quality probe and the probe with all dimensions combined. These results support the notion that differential reinforcement of alternative behavior without extinction can be an effective form of treatment.

Structural behaviour of post-installed reinforcement for 3D concrete printed shells – A case study on water tanks

Incorporating sufficient reinforcement to ensure a ductile structural behaviour is a persisting challenge in digitally fabricated concrete structures. This paper investigates the structural performance of a reinforcement approach for 3D concrete printed elements, consisting of an unreinforced 3D printed concrete shell and a sprayed shell reinforced with a conventional reinforcing mesh for application in water tanks. Four reinforced concrete elements produced with this approach were tested in direct tension and compared to a reference test of a monolithic specimen to analyse the behaviour of circular water tanks under hoop stresses. Two eccentric reinforcement arrangements and two different printing patterns were investigated. Despite the testing setup not perfectly representing the actual behaviour of circular water tanks, in which shell deformations are kinematically restrained, the feasibility of the fabrication method could be examined. The results did not show significant differences in the behaviour of the different fabrication methods, with similar ductility as expected in a conventionally reinforced shell. The eccentric reinforcement caused the crack formation to originate on the surface close to the reinforcement, accompanied by out-of-plane deformations. The cracks on the far side of the reinforcement opened suddenly and reduced the out-of-plane deformations. The predictions with models neglecting the eccentricity of the reinforcement overestimated the crack opening. The best predictions were obtained from the tension chord model by only considering the concrete area defined by twice the mechanical cover of the reinforcement.

A new genetic algorithm framework based on Expected Annual Loss for optimizing seismic retrofitting in reinforced concrete frame structures

The design of seismic retrofitting for existing reinforced concrete frame structures concerns the determination of the position and the arrangement of reinforcements. Currently, this design practice is mainly based on trial-and-error attempts and engineers’ experience, without a formal implementation of cost/performance optimization. Though, the implementation of this intervention is associated with significant costs, noticeable downtimes, and elevated invasiveness. This paper presents a new genetic algorithm-based framework for the optimization of two different retrofitting techniques (FRP column wrapping and concentric steel braces) that aims at minimizing costs considering indirectly the lessening of expected annual values. The feasibility of each tentative solution is controlled by the outcomes of static pushover analyses in the framework of the N2 method, achieved by a 3D fiber-section model implemented in OpenSees. Application of the framework in a realistic case study structure will show that the sustainability of retrofitting intervention is achievable by employing artificial intelligence aided structural design.

Reinforcement placement on mechanics and deformation of stepped reinforced retaining wall experimental study of characteristics

Abstract Three sets of indoor model tests of reinforced retaining walls were conducted to study the effects of reinforcing material placement on the displacement of reinforced retaining walls, wall top settlement, earth pressure distribution, and potential failure surface. The test results show that under different reinforcement laying conditions, the maximum horizontal displacement of the lower wall panel appears at the top of the lower retaining wall, and the maximum horizontal displacement of the upper wall panel appears at 0.6H. The settlement of the top of the wall decreases by about 9.1% when the reinforcement is laid in the lower layer. Under the condition of 160 kPa, the maximum horizontal and vertical earth pressures increase by about 19.2 and 12.4%, respectively, and the position of the potential fracture surface of the lower wall moves up to the back of the wall with the position of the reinforcement laying. When the reinforcement is laid in the upper layer, the fracture surface of the upper wall is furthest away from the panel.

Parametric Study to Decide the Optimal Rebar Grade for Flexural Members

The growing interest of using higher strength reinforcing steel for certain applications within the reinforced concrete industry is driven primarily by relief of congestion; particularly in buildings assigned a high seismic design category. Construction efficiency can be improved by high strength bar or combined with high strength concrete which allows reinforced concrete to be used in more demanding applications. High grade steel generally increases the cost as well allows smaller concrete member which creates a problem of placement of reinforcement. Therefore there is a need to study the better option between lower quantity of high grade and high quantity of lower grade. This paper presents the parametric study to see the effect of beam span and member sizes on the results obtained in design of simply supported flexural members using different rebar grades, such as Fe415, Fe500, Fe550 and Fe600 in terms of crack width and member deflections for mild and moderate exposure conditions. It was observed that detailing plays vital role in cost saving and crack width limit governs final steel requirement in moderate exposure condition. Cost analysis was also performed for different grades and Fe500 is found optimum grade.

Influence of reinforcement design on seismic stability of full-height panel MSE walls

A numerical study was carried out to investigate the seismic stability of mechanically stabilized earth (MSE) walls using a finite element limit analysis (FELA) approach. The numerical method was validated using results from shaking table tests and limit equilibrium (LE) analysis. A series of parametric analyses was subsequently carried out to examine the influences of reinforcement design on seismic stability and failure mechanisms in full-height panel MSE walls. Results of the study indicate that, as opposed to the linear or bilinear failure mechanisms typically assumed in current design guidelines, more complex failure geometries could form in the backfills that involve extended reinforcement, which can be captured and analyzed using the FELA method employed in this study. The results also confirm the current consensus that placing longer reinforcement layers at the top of the wall (i.e. tapering-down arrangement) can help improve its seismic stability. However, in shorter walls or when high-strength reinforcement is used, a tapering-up reinforcement arrangement could also lead to increased seismic stability.

Seismic performance of short precast bridge columns with grouted splice sleeve (GSS) connectors for shear study: Quasi-static cyclic test and analytical estimation

In this study, shear damage development of four precast bridge columns with different connection design details are first examined via quasi-static test. The short columns are of identical dimension and reinforcement arrangement for both pier and footing segments, and the span-to-depth ratio is 0.85 for shear study. The connection utilizes grouted splice sleeve (GSS) couplers for all four specimens. Different bonding materials are compared, effectiveness of shear keys is investigated, and variation of steel rebar grades is carried out. It is found that epoxy retain lower bond strength than high strength mortar, lower grade of longitudinal rebar significantly reduces shear strength of bridge column, and shear keys are of limited effectiveness on the overall shear damage development. An analytical method for shear strength calculation is then proposed and calibrated based on different test results, which incorporates possible influencing factors for shear strength estimation. Maximum difference between the test results and estimated strength values are less than 10%, and it indicates that the proposed method can be used as a reference for shear strength estimation of short precast bridge columns for seismic strength estimation.

Deflection assessment of prestressed steel-concrete–steel sandwich panel: experiment and numerical simulation

A steel-concrete-steel sandwich panel with prestressed reinforcement was developed, named prestressed steel-concrete–steel sandwich panel. Nine specimens where the loading mode, top steel plate thickness, spacing of connectors and prestressed reinforcement arrangement were varied were experimentally tested to explore the failure mode, ultimate strength, ductility and deflection of the structure. The results show that prestressing enhanced the ultimate strength and ductility of the structure. Finite element analysis predictions were consistent with test results in terms of crack characteristics, load-displacement curve and ultimate strength. Deflection prediction analysis of the prestressed panels was also developed based on variational theory which provided good agreement with the finite element results.

Research on the Bearing Performance of Prefabricated New Type Subway Track Slab with Basalt Fiber

Currently, most ballastless tracks in Chinese subways are traditional cast-in-situ concrete structures, which require long construction progress. In contrast, prefabricated ballastless tracks can greatly reduce the construction period. However, there are few theoretical and experimental analyses on the prefabricated new type of subway slab track. Hence, to study the mechanical properties of the new type of subway track slab, static bending crack tests of one standard slab track and nine prefabricated full-scale track slabs with basalt fiber were carried out in this paper. The influence of the reinforcement arrangement method and the basalt fiber content on the performance of the track slabs was studied. Results showed that with the increase in the basalt fiber content in the range of 0.1–0.3%, the load–strain curve growth rate increased, the stiffness decreased, and the flexural resistance reduced. All the specimens exhibited a linear portion (elastic) and then a nonlinear portion (plastic) followed by flexural failure. During the elastic stage, the basalt fiber helped to improve the rigidity of the track slab. During the plastic stage, the influence of the basalt fiber content on the failure load varied with different reinforcement arrangements. With the reinforcement arrangement F2 and 0.1% basalt fiber content, the specimen had the smallest load–strain curve growth rate and the best overall flexural performance and crack resistance, and its strain was 23.35 με at an elastic limit of 95 kN. The results can provide a reference for the design of the prefabricated slab ballastless track.

HIGH-EFFICIENCY PRODUCTION TECHNOLOGY OF PREFABRICATED PRESTRESSED COMPOSITE BEAMS

This paper proposes a construction technology for the precision control of the pedestal table and the overall tensioning method of the composite beam steel strand Given because of the critical technical issues, such as the deformation and cracking of the pedestal table during the prestressed composite beam production process, group tensioning, and control of steel bar slippage. Reinforcement fixing device research and development for node reinforcement arrangement and its technologies based on BIM simulation ensures efficient tensioning of prestressed superimposed beams and avoids reinforcement slippage.

Arrangement of reinforcement in variable density timber slab systems for multi-story construction

The arrangement of columns and their spacing in multi-story timber construction is restricted to rectangular grids by the production and shipping sizes of floor assemblies. This is particularly true for hollow box floor systems, for which the punctual supports must be placed at the reinforced edges of the hollow boxes. The arrangement of the columns and their spacing is thereby restricted by the production and shipping sizes of the box ceilings to rectangular grids. To overcome these design limits a new wooden box building system is developed that allows for irregular column layouts through a tailored slab interior design. This development allows for the increased applicability of timber floor systems regardless of site shape or architectural design intent. The slab interior design is dependent on occurring forces and fabrication requirements. Three methods for the internal slab layout are developed and compared: a sequential method, a structurally informed agent-based method, and a geometrically informed agent-based method that uses both a sequential and agent-based approach. The structural performance of each method is compared through the analysis of three reinforcement layouts an architectural testing setup.

Verification of the secondary reinforcement influence on the strap beams design

The present work aims to expose a methodology for the design of strap beams between pile caps, and to investigate the effect of secondary reinforcement on the behavior of the pile cap located on the property line. For the study, it was selected the deep foundation geometry of a borderline pillar from the infrastructure design of a building. A design methodology was then presented for the foundations' reinforcement. In ABAQUS [1] software, based on the Finite Element Method, a non-linear analysis of four models related to the case study was performed, with the variation of the secondary reinforcement arrangement. It was found that the combined horizontal and vertical secondary reinforcements were efficient to ensure a more ductile failure for the concrete strut. However, the model with the secondary reinforcement inclined at 45º showed the highest resistance.

Research on temperature effect on reinforced concrete bridge pylon during strong cooling weather event

The temperate continental mountain climate is typically characterized by strong solar radiation, high wind speed, obvious temperature fluctuations between day and night, and frequent strong cooling weather. The reinforced concrete (RC) bridge pylon under such harsh environment could suffer from severe temperature-induced durability and serviceability issues. In this paper, a general analytical methodology for evaluating the temperature effect on RC bridge pylon during strong cooling weather event is proposed considering the effect of wind, reinforcement as well as sheltering. A numerical simulation program is developed by integrating the FLUENT and ANSYS based on this model. Subsequently, a typical case study is performed and the effects of several key factors, i.e., wind, reinforcement arrangement, mutual sheltering, and terrain sheltering, on the temperature field and temperature-induced stress field are examined. The results show that the consideration of heat convection due to wind speed could result in a remarkable increase in temperature-induced stress during strong cooling weather event. Meanwhile, the influence of wind speed and wind direction cannot be ignored either, since the heat convection across the pylon exterior surface under different wind speed and directions varies greatly. In addition, relative high reinforcement ratio and the inclusion of the stirrup bar could help to reduce the temperature-induced stress at both interior and exterior surface of the RC bridge pylon. Moreover, the mutual sheltering has negligible influence on the temperature-induced stress of the entire cross-section of the bridge pylon, while the terrain sheltering leads to an increase in the temperature-induced stress difference between the interior and exterior surface.

Developmental implications of preschool children’s affective experiences during organized activities

ABSTRACT This study examined Chinese preschoolers’ affective experiences during organized activities. One-on-one child interviews were conducted in which children were asked to rate their general affect during each organized activity in which they participated, and then provide reasons for their responses. Child-reported emotional engagement was related to children’s social-emotional development, approaches to learning, as well as cognitive development. The reasons children mentioned for both their positive and negative affect were coded into six major categories: interest-utility value, activity format, activity difficulty level, interpersonal relationships, external reinforcement, and activity arrangement. Notably, interest-utility value was most frequently used by children to explain their positive affect, while difficulty level was most frequently cited to explain their negative affect. The findings underline the need to better understand young children’s organized activity experiences from their own perspectives, as well as the importance of children’s affective experiences during organized activities for their development in multiple domains.

Parameters Affecting the Strength and Behavior of RC Dapped-End Beams: A Numerical Study

The finite element method has been used in this paper to investigate the behavior of precast reinforced concrete dapped-ends beams (DEBs) numerically. A parametric investigation was performed on an experimental specimen tested by a previous researcher to show the effect of numerous parameters on the strength and behavior of RC dapped-end beams. Reinforcement details and steel arrangement, the influence of concrete compressive strength, the effect of inclined load, and the effect of support settlement on the strength of dapped-ends beams are examples of such parameters. The results revealed that the dapped-end reinforcement arrangement greatly affects the behavior of dapped end beam. The failure load decreases by 25% when insufficient development length for main dapped-end reinforcement is provided, and nib shear reinforcement has less effect than nib main reinforcement. The results also showed that the shear strength of dapped-end beams increased as concrete strength increased. When the compressive strength of concrete increased by 100% led to an enhancement of strength capacity by about 34%. The strength of the dapped-ends beams is significantly affected by the settlement of the supports.

Flexural performance of CFRP strengthened beams - comparison with analytical model

ABSTRACT In recent years, strengthening methods for reinforced concrete structures using fibre-reinforced polymer (FRP) composites have been gaining widespread interest and growing acceptance in civil engineering industry. Near surface mounted (NSM) reinforcement as well as externally bonded reinforcement (EBR) sheets have emerged as new strengthening methods in which external reinforcement (in the form of bars or sheets) is embedded into grooves or adhered to the section with epoxy adhesive. This paper proposes a simplified analytical approach to predict flexural behaviour of simply supported reinforced-concrete (RC) beams strengthened with carbon fibre-reinforced polymer (CFRP) using the above-mentioned methods. The flexural capacity and deformational behaviour of FRP strengthened beams are analysed using trilinear moment curvature relationship at three critical points namely (i) crack initiation point (ii) steel yield initiation point and (iii) ultimate capacity point, based on strain compatibility and principles of equilibrium. A good predictive performance of analytical model is appraised by simulating force-deflection response registered in the experimental program composed of RC beams strengthened with NSM as well as EBR methods. The analytical solutions have also given accurate prediction of experimental results in the literature regardless of the arrangement of CFRP reinforcement.

Characterizing the bond properties of automatically placed helical reinforcement in 3D printed concrete

The incompatibility of 3D concrete printing (3DCP) with conventional reinforcement methods is well known. Recently, solutions have suggested the insertion of helical reinforcement rods through a screwing motion into the freshly printed material. The current study focuses on the bond properties of such reinforcement and its relation to placement time relative to the 3D printed concrete age, of which until now hardly any data exists. Confined pull-out tests and micro-computed tomography (μCT) scans were performed to characterize the time-dependent bond properties for automatically placed screw-type reinforcement in 3D printed concrete in the range of 0–200 min after material deposition. An experimental program was carried out using a gantry type 3D concrete printer and a robotic hand with the Automated Screwing Device to automate the reinforcement placement process. In total 200 specimens were produced and tested in pull-out. μCT scans were done on the specimens to quantify air content in the vicinity of the reinforcement, for every other time stamp. Two different screw geometries were used. A high mechanical interlock was achieved resulting in a high bond strength in confined pull-out tests. It was concluded from the confined pull-out tests that the pull-out performance is not influenced significantly by the time of application after mortar deposition in a time frame of up to 200 min. This firmly positions automatically applied helical reinforcement as a viable method to reinforce 3DCP structures.

Study on Dynamic Response Characteristics of Stepped Reinforced Retaining Wall

In order to further explore the influence of reinforcement materials laying position on the dynamic characteristics of reinforced retaining walls, based on FLAC3D finite difference methods for solving nonlinear problems, established with the same size of the retaining wall in practical engineering, the reinforcement material’s relative position in the retaining wall for the normalized processing, under seismic load, and the panel under the conditions of different reinforcement arrangement were analyzed, and the horizontal displacement of slope, the vertical and horizontal earth pressures behind the wall, and the distribution of potential sliding surface were calculated. The relationship between the maximum horizontal displacement of the panel and the laying position of the reinforcement was fitted by MATLAB. The results show that the horizontal displacement of the panel is about 40% smaller when the upper layer of the reinforcement is arranged than that in the lower layer for step 1, and the horizontal displacement of the reinforcement in step 2 is about 30% lower than that in other conditions when the reinforcement is arranged at the top of the slope. The reinforcement arranged in the lower layer of step 1 and the upper layer of step 2 can minimize the wall top displacement. In step 1, the vertical earth pressure and horizontal earth pressure are 19% and 5% smaller than those in other conditions when the reinforcement is arranged near the middle and lower layer of the step. In step 2, the difference between vertical and horizontal earth pressure is not obvious, and the difference between the two conditions is controlled within 5%. At the same time, soil liquefaction and uplift occur under the action of earthquake. The position of sliding crack surface has no obvious regularity with the position of reinforcement, but the position of reinforcement at the step classification is obviously better than other conditions. The fitting formula can describe the relationship between the panel displacement and the position of the reinforcement well. The conclusions can provide a point of reference for practical engineering.

Axial behavior of precast segmental hollow bridge columns confined by grouted steel tubes

To avoid the problems of the conventional precast segmental bridge columns (PSBCs) such as the concrete crushing at column ends, joint openings between segments, and torsional deformation under seismic attacks, a novel type of precast segmental bridge column confined by a grouted steel tube (TPSBC) was proposed, and herein the axial compressive behavior of the TPSBCs was investigated by testing of 14 specimens. The main parameters of the tested specimens included the diameter-thickness ratios of the steel tubes, the number of the precast segments, reinforcement arrangements in the precast hollow segments, initial prestress levels, sandwich concrete strengths, and loading forms. The effects of the parameters on the failure modes, loading bearing capacity, ductility, and steel strain development of the specimens were evaluated. The test results indicate that the proposed TPSBCs with proper configurations exhibited desirable compressive behavior with significantly improved load bearing capacity and deformability compared with the PSBCs. Based on the analysis of the confinement effects, analytical models were developed for predicting the axial bearing capacity of the TPSBCs under the different loading forms.

Scaled Model Test for Efficient Arrangement of Steel Reinforcement in Bridge Pier Caps

Scaled Model Test for Efficient Arrangement of Steel Reinforcement in Bridge Pier Caps