Reinforcement Arrangement Research Articles

Effect of reinforcement arrangement on dynamic behaviour of back-to-back mechanically stabilised earth walls

Reduced-scale shaking table tests were performed on steel-strip back-to-back mechanically stabilised earth (MSE) wall models to evaluate the effect of the overlap length of the reinforcements (LR) and the connection arrangement of the opposing walls on the distribution of tensile force along the reinforcements and the propagation mechanism of the shear bands. The reinforcement elements were fully instrumented and particle image velocimetry (PIV) was utilised to identify the shear zones in the body of the models. On the basis of the PIV results, the combination of a concave surface and an inclined plane was determined to be the failure surface in the models. It was concluded that connecting two opposing walls can prevent the formation of a failure wedge in a back-to-back MSE wall (BBMSEW). It was observed that the geometry of the failure surface in the BBMSEWs was not affected by a change in LR, but depended on the connection arrangement of the walls. It was found that, although the use of overlapping reinforcement instead of the direct connection of two walls caused further development of shear bands, it could be a good solution in reducing the mobilised reinforcement forces in BBMSEWs.

Loss assessment of wind-induced damage for residential buildings groups based on engineering vulnerability

Loss predictions and assessments for residential building groups are crucial processes during extreme events such as wind hazards. The primary purpose of the present work is to improve the existing loss assessment methodology for residential building groups under wind hazards by considering the wind-induced interference effects between building groups, such as those based on the building locations, area density, wind direction, and wind speed. The failure characteristics of the envelope components under complex and strong wind loads are obtained, and the failure laws of the envelope components caused by strong winds are revealed as the wind speed, wind direction, and building area density are changed. The results can provide advice for government departments and residents regarding the arrangement of buildings and reinforcement of envelope components.

Assessment of children's and caregivers' preferences for treatments for escape-maintained problem behavior.

This study assessed children's and caregivers' preferences for various arrangements of negative reinforcement, including differential negative reinforcement of an alternative behavior (DNRA), noncontingent escape (NCE), and escape extinction. In the first treatment comparison, the DNRA and NCE treatments similarly decreased problem behavior, but all 3 children preferred DNRA. By contrast, 3 of 4 caregivers preferred escape extinction, likely due to increased compliance in this condition. In a second treatment comparision with 1 child, a multiple schedule and then a chained schedule were introduced to increase the practically of the initial DNRA treatment. The child continued to prefer the treatment with contingent reinforcement in both comparisons, and his caregivers preferred the chained schedule. Results further support the selection of treatments that include contingent reinforcement, and the evaluation serves as a model for progressing through treatment options until child and caregiver preferences align.

Performance of back-to-back MSE walls reinforced with steel strips under seismic conditions

One common type of reinforced wall is the back-to-back mechanically stabilized earth wall. These are used extensively for narrow road embankments, pedestrian ramps, bridge abutments and railway systems. In the current study, a series of 1 g shaking table tests were conducted to determine the dynamic performance of back-to-back strip-reinforced walls (BBSRWs). The models were constructed with different reinforcement overlap lengths (Lov) and connection arrangements for two connected opposing walls. They then were subjected to base harmonic accelerations at different peak acceleration intensities. The seismic responses of the models demonstrated that the reinforcement arrangement plays a dominant role in the failure pattern, lateral deformation and mobilized tensile forces of the BBSRWs. The findings showed that separating the opposing walls and reducing the length of the reinforcement overlap increased lateral deformation and reduced the wall stability, while these are effective solutions for reducing the dynamic reinforcement load in a BBSRW. A combined slip surface is proposed for BBSRWs with a geometry that is not affected by changes in Lov, but depends on the arrangement of the connected opposing walls.

Investigation of the effects of multiple and multi-directional reinforcement on corrosion-induced concrete cracking pattern

Reinforced concrete (RC) structures are widely used, yet prone to damage induced by reinforcement corrosion which causes susceptibility of concrete spalling and eventually a reduced serviceable life. The visual inspection has been performed usually for structural assessment, but this does not account for the local interactions between rebars. Consequently, detailed scrutiny is required to consider the effects of various parameters on the initiation and propagation of corrosion-induced cracking. This experimental study considers the effect of multiple and multidirectional rebars on the development of corrosion cracking. Additionally, the effect of the location of corrosion and the change in order of corrosion occurrence is investigated in this research. For this purpose, reinforced concrete panels with unidirectional and multidirectional rebar arrangements and varying cover depth are tested using an accelerated corrosion technique. The results show a significant role of confinement in controlling the widths of cracks provided by both reinforcement arrangements. Moreover, the effect of boundary conditions along with increased confining pressure alters the generation of cracks in a unidirectional reinforcement arrangement. In the absence of enough surrounding concrete, cracks along non-corroding rebars can also form because of the expansion of adjacent corroding rebars. The inclusion of multidirectional reinforcement alters the crack direction and causes cracking along non-corroding rebars. Further, previously generated cracks may close considerably by the pressure from adjacent rebar corrosion. This study also facilitates the comprehension of the impact of influencing factors affecting corrosion cracking in real structures.

Experimental of Inverted-T Shape Reinforced Concrete Wall Subjected to Blast Load

Reinforced concrete (RC) widely used as the construction material for the main structural element for many significant structures such as bridge and building because of its relatively high strength and economical. However, there still lacks research published regarding the appropriate reinforcement steel arrangement in a complete RC structure subjected to blast load. Most of the published experimental works focused on the small rectangular or square RC panel. From the record search, the approved design by professional engineers, when RC wall subjected to the possibility of blast load, both RC wall details either retaining wall or shear wall implemented. Therefore, the full-scale blast experiment is vital to appraise the appropriate steel reinforcement arrangement in the RC wall. The blast experiment indicated, with different steel reinforcement arrangement in the RC wall, the better blast resistance with the number of cracks on the RC wall is significantly less from one another for the wall with the arrangement of horizontal flexural reinforcement tied-outside the vertical flexural reinforcement and the hooked-in direction of vertical flexural steel reinforcement into the wall base.

Damage assessment of buildings after 24 January 2020Elazig-Sivrice earthquake

The majority of Turkey's geography is at risk of earthquakes. Within the borders of Turkey, including the two major active faults contain the North-Eastern and Eastern Anatolia, earthquake, threatening the safety of life and property. On January 24, 2020, an earthquake of magnitude 6.8 occurred at 8:55 p.m. local time. According to the data obtained from the stations in the region, peak ground acceleration in the east-west direction was measured as 0.292 g from the 2308 coded station in Sivrice. It is thought that the earthquake with a magnitude of Mw 6.8 was developed on the Sivrice-Puturge segment of the Eastern Anatolian Fault, which is a left lateral strike slip fault, and the tear developed in an area of 50-55 km. Aftershocks ranging from 0.8 to 5.1 Mw occurred following the main shock on the Eastern Anatolian Fault. The earthquake caused severe structural damages in Elazig and neighboring provinces. As a result of the field investigations carried out in this study, significant damage levels were observed in the buildings since it did not meet the criteria in the earthquake codes. Within the study's scope, the structural damage cases in reinforced concrete and masonry structures were investigated. Many structural deficiencies and mistakes such as non-ductile details, poor concrete quality, short columns, strong beams–weak columns mechanism, large and heavy overhangs, masonry building damages and inadequate reinforcement arrangements were observed. Requirements of seismic codes are discussed and compared with observed earthquake damage.

BEHAVIOR OF HYBRID STEEL/GFRP REINFORCED COLUMNS UNDER LATERAL CYCLIC LOADING: A NUMERICAL STUDY

This paper proposed hybrid (steel/glass fiber-reinforced polymer (GFRP) composites) bars as primary reinforcement for modern reinforced concrete (RC) columns. A detailed two-dimensional finite element model (2D FEM), that considers material and geometric nonlinearity and the bond behavior of steel and glass FRP (GFRP) reinforcement, was created, and validated against the available experimental results. The built model predicted the experimentally obtained results representing in failure mode and deformation response with good accuracy. Hybrid system that consists of steel/GFRP combination was then studied. The results patently showed that hybrid reinforced columns can undergo large displacement with minimal damage. This; however, can be guaranteed through carefully selection of reinforcement arrangement.

Triaxial Shear Behavior of a Gravelly Sand with Different Forms of Reinforcement

To study the effect of three-dimensional reinforcement arrangement on the behavior of a gravelly sand, triaxial tests were performed on specimens reinforced with geogrid sheet, geogrid cell, and one and two layers of geogrid sheet and geocell combination. Specimens with a diameter of 100 mm and a height of 200 mm are sheared under drained condition to monitor the variation of axial and volumetric strains with axial loading under different confining pressures. The results showed that the reinforcement schemes have different effects on soil strength improvement. The inclusion of double layers of geogrid sheet and geocell reinforcement could increase both the apparent cohesion and friction of the reinforced soil. The stress-strain relationship could be modelled with a modified hyperbolic model, which can capture the softening strain behavior of the specimens after peak strength.

Development of Multi-Tee-Type Precast Concrete Slabs with Insulating Materials for Structural Safety at the Construction Stage

Multi-tee-type precast concrete (PC) slab systems are widely used for the construction of modular high-load long-span buildings. However, the structural safety of the dapped end is uncertain, owing to the unanchored shear reinforcement at the construction stage. This study proposes the use of clip-type shear reinforcement at the dapped ends of multi-tee PC slabs to secure their structural performance at the construction stage. To investigate the performance of this approach, a monotonic loading test was performed on simply supported PC slabs, considering structural safety at the construction stage. The reinforcement details of the PC slab’s dapped end (with existing Z-type or proposed clip-type shear reinforcement) and the shear-to-span ratio (12.8 or 6.4) were considered as test parameters. The load–deflection relationship, failure mode, strength ratios to the predicted strength, and shear reinforcement strains were analyzed. The results showed that the tested flexural strength ratio of the PC slabs at the construction stage to the design flexural strength was 1.20–1.40. The enclosed shape and diagonal arrangement of the clip-type shear reinforcement enabled sufficient anchorage performance at the dapped end, indicating that clip-type shear reinforcement can be viable for use at the dapped ends of PC slabs under construction loads.

Integrating reinforcement in digital fabrication with concrete: A review and classification framework

This article offers a comprehensive, systematic overview of the existing solutions for integrating reinforcement in digital concrete technologies with particular emphasis on Additive Manufacturing (AM) with concrete, also called 3D concrete printing (3DCP). While the functionalities of various types of reinforcement are briefly addressed, the major focus is on the integration process as such, i.e., on its technological aspects. On this basis a generic classification and process description outline has been developed for reinforcement integration, which is regarded as an extension of the RILEM process classification framework for Digital Fabrication with Concrete (DFC). In many instances, the integration occurs in a separate process step prior to or after concrete shaping. This holds true for all formative digital concrete shaping processes and for many 3DCP solutions. 3DCP approaches enable, however, integration of the reinforcement during concrete shaping as part of a single-step AM process in a simultaneous or contiguous manner, while placement of reinforcement is considered to be a sub-process.

Numerical Investigation of Steel Reinforcement Arrangement in Reinforced Concrete Wall Subjected to Blast

Three-dimensional (3D) numerical modelling of inverted-T shape reinforced concrete (RC) wall subjected to blast load is study in this paper. The walls have the same moment resistance with different steel reinforcement arrangements. It is subjected to 13.61 kg Trinitrotoluene (TNT) explosive at 1.21 m standoff distance from the centre. The Arbitrary Lagrange Euler (ALE) solvers coupling approach is employed for the interface analysis between air and structure to simulate the damage mechanism in AUTODYN numerical commercial software. The numerical damage indicator indicated, with mesh dependency assessment, the damage pattern vs experimental appeared precisely on the steel reinforcement grid due to the smaller element size compared to the coarse element used.

Numerical study on the behavior of utility tunnel subjected to ground surface explosion

Over the past few decades, underground utility tunnels have become increasingly popular in many countries, especially in North America and China. Utility tunnels host multiple services’ infrastructures inside an accessible underground space that allows regular inspection, maintenance, and easy replacement. Previous studies on the safety of underground utility tunnels were mainly focused on the seismic performances, their dynamic behaviors under accidental/hostile blast loads were seldomly investigated. TM 5-855-1 is frequently employed to calculate the ground shock load and responses of buried structures. However, it is only applicable for the cases with a scaled distance larger than 0.4 m/kg1/3. The present study performs a comprehensive numerical investigation on the blast performance of utility tunnel subjected to ground surface explosion with small scaled distance. With validated material and structural models, a FEM model based on a utility tunnel project is established. The influence of charge weight on blast resistance of the utility tunnel is studied numerically. The effect of the reinforcement ratio, shear reinforcement arrangement, buried depth and wall thickness are investigated under the scenario of a sedan car bomb overhead explosion. It is found that over 200 kg TNT ground surface explosion will cause a great threat to the utility tunnel with 2 m burial depth (scaled distance smaller than 0.4 m/kg1/3). The shear reinforcement arrangement is of great importance to the blast resistance of the utility tunnel. The failure mode of the roof can be changed from combined shear and flexural failure to flexural failure, with an increased reinforcement ratio. Increased wall thickness and buried depth can improve the blast resistance of the utility tunnel as expected. Safety buried depth, and wall thickness for a sedan car bomb overhead explosion are discussed in the present study.

Influence of reinforcement-arrangements on dynamic response of geogrid-reinforced foundation under repeated loading

Dynamic tests were carried out on a square footing resting on unreinforced and reinforced foundation to investigate the influence of the geogrid-reinforcement arrangements on load-carrying characteristics of the footing under repeated loading. In this paper, the arrangements considered include the depth of the first geogrid layer (u), the number of geogrid layers (N) and the method of wraparound ends reinforcement. The settlement of footing, the strain of geogrid and the acceleration rate in soils were measured, and these results were analyzed in detail. The results showed that the bearing capacity of footing on reinforced foundations was at least 12% higher than that of unreinforced foundation. For the single-layer reinforced foundations, the bearing capacity first increased and then decreased with the increase of u. When u was equal to 0.6B (B = footing width), the bearing capacity was maximum, which was 21% and 15% higher than that of 0.3B and 0.9B, respectively. For the multi-layer reinforced foundations, the bearing capacity increased with increasing the N value from 1 to 3, and the maximum increase was 29%. Through analyzing the bearing capacity ratio (BCR) and the attenuation rate of acceleration (AAR), the influence of reinforcement arrangements on the bearing capacity of footing was in the order: the u value, the method of wraparound ends of reinforcement, the N value. The various reinforcement arrangements caused different dynamic responses, and the sensitivity of arrangement on acceleration responses was in the order: the N value, the method of wraparound ends of reinforcement and the u value. Additionally, it is also found that reinforcement arrangements significantly affected the geogrid strain and the failure mode of footing.

EFFECT OF IMPACT LOAD ON THE PERFORMANCE OF CONCRETE SLABS REINFORCED BY CFRP BARS

Using FRP bars in the concrete structures under harsh environment produces extension of those service life and dropping of the cost of their lifecycle. This study investigated the influence of slab thickness, material of rebar, arrangement of reinforcement and mass’s dropped on the dynamic behavior of RC slabs by using laboratory experiments. Seven specimens 1550×1550 mm dimension with two thickness 120 and 150mm, single control specimen reinforced with steel bars and six specimens reinforced by CFRP bars were experimentally investigated under sequential dropping-weight ranged from 50 to 150kg, it was a rigid steel projectile, used to apply impacting load. 2.5m was the height of dropping. For estimated penetration depth, three empirical formulas have been used, ACE formulae was preferable predictor than other formulas. Different codes were used to calculation punching shear capacity and critical velocity of perforation and compared the experimental results with these codes. The experimental results showed that the shear properties of slabs have a significant effect in their general behavior. And preferable performance in FRP slabs than slabs reinforced with steel can be achieved which considering high strength and corrosion resistance of this material, which makes it a suitable choice for reinforcing materials.

Designing of Slab-Column Structures Due to Additional Loads

The introduction of Eurocodes in the designing practices led to the change of methodology of the floor reinforcement, particularly for slab-column floors. Until now, the most important decisive factor was the determination and arrangement of reinforcement due to the limit states; any other problems were treated as additional information. At present designers - constructors of reinforcement in slab-column structures have to follow Eurocodes (PN-EN 1990:2004, PN-EN 1991-1-1:2004, PN-EN 1991-1-7:2008) in taking into account first and foremost the following threats accidental loadings and fires, as they influence further stages of the designing process. The article presents the most important design guidelines for slab-column structures due to accidental loads.

Torsional strength of RC members using a plasticity-based variable-angle space truss model accounting for non-uniform longitudinal reinforcement

The torsional strength of reinforced concrete (RC) members is typically calculated through the thin-walled tube, space truss analogy. The governing equations are simple equilibrium conditions satisfied by closed stirrups, longitudinal reinforcement and spiral concrete diagonals at a variable angle. In building codes, like EC2 and ACI 318, the contribution of longitudinal reinforcement is averaged among the walls, considering the total amount of longitudinal re-bars of the overall cross section. However, longitudinal re-bars may be non-uniformly distributed along the walls. This is particular evident in beams with large aspect ratios and re-bars mainly located at the corners, or in beams with unsymmetrical bending-type longitudinal reinforcement arrangement. This paper presents a plasticity-based variable-angle space truss model accounting for non-uniform distribution of longitudinal reinforcement along the walls. The model, which is based on equilibrium conditions and the lower-bound theorem of plasticity, is first elaborated for a polygonal cross-section with an arbitrary number of walls incorporating arbitrary longitudinal reinforcement ratios and corresponding variable-angle concrete strut inclinations, and then particularized to the more common case of rectangular section with two representative longitudinal reinforcement ratios and two corresponding variable-angle strut inclinations. For practical design purposes, the results of this model are illustrated through normalized torsional strength curves in terms of non-dimensional reinforcement indexes. The model is validated by comparison with more than 200 experimental results of RC members under pure torsion collected from the literature, and very good agreement is found. The predictions of the model are also compared with those of some codes of practice and better results are obtained especially for beams with markedly non-uniform longitudinal reinforcement arrangement.

Finite element analysis on failure of reinforced concrete corner in sewage tank under opening bending moment

The paper discusses a failure mechanism of reinforced concrete (RC) sewage tank in a wall corner that failed during a filling test through excessive horizontal displacements of walls under opening bending moment. To explain the reasons for failure, comprehensive finite element (FE) calculations of the RC sewage tank were carried out under plane strain conditions. Concrete was modeled with a coupled elasto-plastic-damage constitutive model. The model was enriched in a softening regime by a characteristic length of micro-structure to provide the mesh objective results. FE analyses were performed for different arrangements of flexural reinforcement in the corner. The focus was on the evolution of strain localization and corner strength. Reasons for the tank failure were discussed. The FE results showed a high sensitivity of both the load bearing capacity of the tank wall corner and strain localization to flexural reinforcement arrangement. In addition, two laboratory experiments on RC corners subjected to opening bending moments were numerically analyzed under plane stress conditions.

A novel FRP composite with high-strength, high extensibility in tension: 1-D constitutive relation

A FRP reinforcement has been developed to deliver desired nonlinear stress–strain responses upon various demands for reinforcements in Civil Engineering. The application of this FRP reinforcement will get rid of corrosion and achieve favourable interactions between reinforcement and other structural materials, suggesting a new paradigm especially for reinforced concrete elements. Suitable numerical models in aid of guiding their fabrication upon diverse demands are essential but yet presented. In this paper, a simple but robust one-dimensional (1-D) constitutive model has been developed for predicting the behaviour of the FRP reinforcement under the tension. The proposed model considers a detailed description for the 2D arrangement of the FRP reinforcement that characterizes the texture by non-linear beam-column and bar elements. The model has been validated by experimental measurements and sophisticated FE models. It is shown that the use of proposed model allows the consideration of different loading behaviour and energy absorption processes upon increasingly updated demands for more sophisticated and efficient FRP reinforcement in the future.

Experimental, analytical and numerical performance of RC beams with V-shaped reinforcement

Nowadays the construction process is very much challenging and difficult for the civil engineers. The reinforced concrete (RC) is the most essential and extensively used material which possesses various important properties like compressive and strength. Several attempts have been made in the field of RC technology to flourish such concretes with special characteristics. Investigators all over the world are making efforts to develop high-performance RC by using different arrangements of reinforcement in concrete. The objective of this research work is to evaluate the performance of V-shaped reinforcement in RC beams subjected to four-point loading by experimentally, analytically and numerically. The results are compared with equivalent similar RC beams with conventional reinforcement. During the study, a comparison between all the investigation methods is also carried out. The maximum load, deflection, stresses, ductility and failure patterns of the specimens are monitored, analyzed and compared. From the investigation, it has been observed that the experimental results are closely matched with numerical analysis performed by using ANSYS software and numerical results. Therefore, the benefit of using V-shaped reinforcement can be observed significantly. From the study, it is also found that the load–deflection have a stiffer response, and there is an increase in ductility as well as strength level in compression zone due to the arrangement of V-shaped reinforcement. The V-shaped reinforcement develops the folded plate action, which not only increases the ductility but also allows redistribution of moments and reversal of loading in the beam which leads to avoid the collapse during hazards impact. It is also observed that the mode of damage has been changed from brittle to ductile for the V-shaped reinforced beams in comparison with the conventional reinforced beams. However, the observed failure patterns are identical in both the arrangements. From the study, it is concluded that the beam with V-shaped reinforcement is a good alternative over the beam with conventional reinforcement because it not only enhanced structural performance in all directions but also reduced the total cost.