Steel Reinforcement Cage Research Articles

The action of heated RC joints strengthened with a novel strategy combined CFRP and SSEMSM under a quasi-static cyclic load

The current work presents the application of a novel strategy for strengthening heated beam column (B-C) joints under a quasi-static cyclic load. This technique involves utilizing a layer of carbon fiber-reinforced polymers (CFRP) sheets with a layer of stainless-steel expanded metal sheet mesh (SSEMSM). These two layers are installed on the steel reinforcement cage inside the joint before concrete casting. Then the reinforced concrete B-C joints, after being cast and cured, were subjected to heat (i.e., 400 °C and 600 °C). The joints were divided into three groups: three joints were kept as is (i.e., reference joints; no strengthening was applied), whereas three joints were strengthened with the previously mentioned strategy. With a view to investigating the seismic behavior of RC joints, a quasi-static cyclic load was applied to the joints to simulate a seismic load. Results showed that the average maximum load capacity for upgraded joints (strengthened) increased by 30%, 19%, and 1% at ambient (i.e., 23 °C), 400 °C, and 600 °C temperatures, respectively, with respect to the reference joint (JCTA). More importantly, the experimental results reveal a significant increase in the cyclic response of strengthened joints (i.e., higher load capacity, greater displacement, higher dissipated energy, higher ductility, and slower degradation in the secant stiffness).

Mechanical performances of thin-walled high-strength concrete-filled steel tube square columns with high-strength reinforced cages under biaxial eccentric compression

In the current research that both steel tube and concrete use high-strength materials, there are few studies on the small wall thickness of steel tube exceeding the standard. In order to make full use of the mechanical properties of high-strength steel and enhance its restraint ability on concrete, this paper designs a steel cage dominated by transverse steel bars. A total of 15 square high-strength steel tube high-strength concrete medium-long column test pieces are tested and studied. The main parameters of the specimens are slenderness ratio, loading eccentricity and the form of internal steel reinforcement cage. After the loading test, according to the test results, the failure mode of the specimen is obtained and the mechanical properties of middle-long concrete-filled steel tubular columns are analyzed. The research results show that the ultra-thin high-strength steel pipe can restrain concrete well, but with the increase of eccentricity, its restraint capacity is slightly insufficient; the built-in steel cage can slow down the bulging of the specimen and help the steel pipe to further strengthen the restraint on concrete, but the steel cage as an indirect constraint cannot avoid the final bulging damage. Due to the existing formula overestimating the effect of ultra-thin steel tubes, this paper proposes a calculation formula for the axial compression of thin-walled high-strength concrete-filled steel tubes with steel cage short columns. Based on this method, the bearing capacity of medium-long columns under biaxial eccentric compression is calculated with good accuracy.

Review of The Structure of The Bored Pile and Pile CAP The Premiere MTH Project

The Premiere MTH is an apartment complex located in South Jakarta, constructed on land with a hard soil layer extending deeper than 16 meters. Given these conditions, a bored pile foundation was selected as the optimal solution. This foundation type can be tailored to the necessary depth while minimizing disruption to nearby structures during installation. A bored pile is a type of deep foundation created by drilling into the ground to a specified depth. The process involves drilling a hole with specialized equipment, inserting a steel reinforcement cage, and then pouring concrete into the hole. Special tools are used to lift and position the casing and reinforcement. Once the concrete is poured, the casing is removed. According to the design analysis, the bored pile foundations used in this project have a diameter of 800 mm, with varying depths of 30 m and 35 m.

Mechanical properties of CFSST with steel reinforcement cage under biaxial eccentric compression

To study the biaxial eccentric compression mechanical properties of high-strength concrete-filled square steel tube (CFSST) columns (high-strength materials are used for both steel tube and concrete) with steel reinforcement cage, twelve high-strength CFSST columns with the same cross-sectional dimensions were designed and fabricated with the form of the steel reinforcement cage, eccentricity, and the steel tube width-to-thickness ratio as the main parameters. The constraint enhancement mechanism of the concrete by the steel reinforcement cage and the effect of different parameters on the biaxial eccentric ultimate bearing capacity of column specimens was further analyzed by combining with ABAQUS simulation. The results show that the bearing capacity of the specimens decreases sharply with the increase of eccentricity and steel tube width-to-thickness ratio; the steel reinforcement cage can improve the bearing capacity and ductility of the specimen but has little effect on the stiffness; the arrangement of double orthogonal horizontal steel reinforcement can enhance the constraint effect of the steel tube in the middle of the cross-section edge length on the concrete of the specimens within a certain height range and weaken the constraint effect of the corner within the same height range; the enhancement effect of the steel reinforcement cage on the biaxial eccentric ultimate bearing capacity of the column specimens gradually decreases with the increase of eccentricity; when the eccentricity is constant, the effect of the steel reinforcement cage on the improvement of the biaxial eccentric ultimate bearing capacity of the column specimens with different width-to-thickness ratios is basically the same.

LEGO-Inspired and Digitally-Fabricated steel reinforcement cage for Ultra-High performance concrete (UHPC) beams

Reinforced concrete is one of the most used structural configurations in the world, but the production of reinforcement cage is a labor-intensive, time-consuming and strenuous task. This study develops a new LEGO-inspired reinforcement cage system that is digitally fabricated through waterjet cutting, which can be assembled in three steps. The experimental program tests two ultra-high performance concrete (UHPC) beams reinforced by this LEGO-cage system, one with smooth surface and one with deformed ribs. Results show that including deformed ribs slightly increase the post-cracking stiffness of the beams while both beams exhibit a post-yielding plateau and a displacement ductility ratio over 8. An existing UHPC flexural model predicts the flexural strength (both yield and maximum strength) of the LEGO-cage-reinforced beams with errors below 4%. A two-dimensional finite element model, which is originally developed for rebar-reinforced UHPC, is found to well predict the load–displacement responses of LEGO-reinforced UHPC beams. A cost analysis reveals that adopting this new cage system can reduce the production cost and manual labor time by over 17% and 86%, respectively.

A 3D analytical model for distributed low strain test and parallel seismic test of pipe piles

In this study, the authors proposed a new dynamic integrity test method of piles, namely, distributed low strain integrity test (DLSITs). The basic idea of DLSITs is that a series of accelerated sensors connected by cables are preinstalled on the steel reinforcement cage of cast-in-place pile or attached on the shaft of precast piles. Compared with the conventional methods (LSITs), the efficient detection depth of the DLSITs can be doubled and its detection accuracy is significantly improved. Accordingly, a coupled 3D analytical model is established for the theoretical analysis of the DLSITs. The developed theoretical model is also applied to investigate the 3D effect of the parallel seismic test (PSTs). A vibration mode analysis is conducted to clarify the forming mechanism of the high frequency interference during the DLSITs and PSTs. The main findings can be drawn as: Both the DLSITs and PSTs suffer obvious high frequency interference arisen from the 3D effect of piles. To reduce this adverse influence, the radius angle between the impact force location and the axial line of receiving sensors is advised to set as 90°.

Experimental study on the interfacial bond strength and energy dissipation capacity of steel and steel fibre reinforced concrete (SSFRC) structures

In this study, to address the problems faced while constructing steel reinforced concrete (SRC) structures, such as the positional conflicts between the shaped steel and steel bars or the difficulty in pouring concrete, we propose a novel ‘Steel and Steel Fibre Reinforced Concrete’ (SSFRC) composite structure, wherein the steel reinforcement cage in SRC is replaced with steel fibres. We designed 20 square-section specimens and performed push-out tests to evaluate the bond properties between the shaped steel and steel fibre reinforced concrete experimentally. The influence of the steel fibre volume rate (ρsf), length-to-diameter ratio (Le/D0), and thickness of concrete cover (Css) on the interfacial bond strength, energy dissipation capacity, and interfacial damage were investigated. In addition, the ultimate bond strengths of SSFRC and SRC were compared. The results indicate that the novel SSFRC composite structure increases the ease of construction and has an ultimate bond strength that is similar to that of SRC. The interfacial energy dissipation increases with the increase in Le/D0, ρsf, and Css, and the steel fibres slow down the development of damage in the concrete specimens. Based on the results, we present an economical and effective method for determining the critical thickness of the concrete cover for SSFRC members. The thicker the concrete cover, the slower the interfacial damage development during the later stages of the test.

Performance of Thin-Wall Synthetic Fiber–Reinforced Concrete Pipes under Short and Long-Term Loading

Abstract Synthetic fibers have been recently used as a replacement for conventional steel reinforcement in concrete pipes to enhance their durability, ductility, shear strength, and flexural strength. However, there is very limited understanding of the long-term performance of thin-wall synthetic fiber–reinforced concrete pipes, as synthetic fiber has material properties that may change with a sustained load over time. This research investigates the performance of polypropylene fiber–reinforced concrete pipe under short and long-term loads in terms of strength, deflection response, strain response, crack width, and crack patterns. Concrete pipes with diameters of 1,200 and 1,500 mm with respective wall thicknesses of 50 and 63 mm were subjected to the short-term three-edge bearing test. To ensure maximum fiber contribution to pipe strength, a 9 kg/m3 fiber dosage was used with different amounts of steel reinforcement. For the long-term three-edge bearing test, a pipe with a diameter of 1,200 mm reinforced with fiber dosage of 9 kg/m3 along with steel reinforcement with an area of 5.7 cm2/m was tested for 30 days at 40 % of the ultimate load (Load Stage 1) obtained from the short-term test, for another 30 days at 50 % ultimate load (Load Stage 2), and subsequently at 70 % ultimate load for a final 30 days (Load Stage 3). Short-term results showed that synthetic fiber was a viable replacement for the steel reinforcement cage, as some of the tested pipe achieved the strength requirement specified by ASTM C76-15a, Standard Specification for Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe. In response to sustained load, the tested pipe initially exhibited a linear response, followed by a stable response with a slight increase in deflection over time. Fiber creep did not significantly increase the crack width or affect the time dependence of the strain, indicating that the fibers adequately transfer the stress in the pipe wall and limit the crack width. The cracks propagated longitudinally at the invert, crown, and springline, where there were high flexural tensile stresses.

Experimental investigation of the behavior composite steel-concrete composite beams containing different amounts of steel fibres and conventional reinforcement

In this paper, an innovative method to replace steel reinforcement cage by steel fiber to form a steel shape and steel fiber reinforced concrete has been proposed to solve the problems of steel reinforced concrete structure during construction, such as position conflict between shape steel and steel bars, or difficulty of concrete placement, etc. Eighteen beams were tested under a four-point bending configuration to study the effectiveness of steel fibers on shear and flexural strengths, failure mechanisms, crack control, and ductility. The major factors considered were shear span depth ratio (λ = 2.5, 3.5), with or without longitudinal reinforcement and web reinforcement (none, stirrups and/or steel fibers). The response of Steel Fiber Steel Reinforcement Concrete (SFSRC) beams were assessed depending on the results of crack patterns, load at yielding, failure and ultimate bearing capacity, failure modes, ductility and displacement increment of plastic development, The experimental results showed that the addition of steel fibers improves the mechanical response, specifically speaking, flexural and shear strengths and ductility of the tested specimens. The longitudinal reinforcement can greatly enhance the bearing capacity, and the stirrups and steel fibers can make the reinforcement effect more prominent. The stitching effect of steel fiber between cracks leads to stable bearing capacity of the specimens always stable after the peak load. Increasing the content of steel fiber contributes to delay or even avoid bond failure. Steel fibers can be an alternative to shear reinforcement. A formula was proposed to predict the bearing capacity of SFSRC specimens, and the comparison between predictions and experiment results proved the reasonable of the formula. A formula was proposed to predict the bearing capacity of SFSRC specimens, and the comparison between predictions and experiment results proved the the formula.

Experimental study on hollow steel-reinforced concrete-filled GFRP tubular members under axial compression

Hollow steel-reinforced concrete-filled GFRP tubular member is a new kind of composite members. Firstly set the mold in the GFRP tube (non-bearing component), then set the longitudinal reinforcements with stirrups (steel reinforcement cage) between the GFRP tube and the mold, and filled the concrete between them. Through the axial compression test of the hollow steel-reinforced concrete-filled GFRP tubular member, the working mechanism and failure modes of composite members were obtained. Based on the experiment, when the load reached the ranges of 55-70%Pu (Pu-ultimate load), white cracks appeared on the surface of the GFRP tubes of specimens. At that time, the confinement effects of the GFRP tubes on core concrete were obvious. Keep loading, the ranges of white cracks were expanding, and the confinement effects increased proportionally. In addition, the damages of specimens, which were accompanied with great noise, were marked by fiber breaking and resin cracking on the surface of GFRP tubes, also accompanied with concrete crushing. The bearing capacity of the axially compressed components increased with the increase of reinforcement ratio, and decreased with the increase of hollow ratio. When the reinforcement ratio was increased from 0 to 4.30%, the bearing capacity was increased by about 23%. When the diameter of hollow part was decreased from 55mm to 0, the bearing capacity was increased by about 32%.

The effect of the type of fixators reinforcement on strength and deformation characteristics of reinforced concrete

Rebar fixators of various types (plastic and concrete) became widespread with manufacturing of building structures of precast and monolithic reinforced concrete in order to fix steel reinforcement cage in strictly design position and to exclude the probability of its displacement during concreting. Such sufficiently rigid fixing is necessary for the following reliable operation of the structure in the building, as well as for the preservation of steel reinforcement which protected by a necessary layer of concrete from corrosion. Information available in the literature does not allow us to judge about the effects that different types of fixators apply to exploitative properties (such as strength and crack resistance) of reinforced concrete. The experiments, according to the accepted method, showed that these characteristics are slightly worse for the samples with plastic fixators and fixators made of low grade concrete than for the samples without fixators or fixators made of high grade concrete. On the base on the research results it becomes possible to substantiate the distinction between the areas of application of plastic and concrete fixatives

Full-scale testing of high-strength RACFST columns subjected to axial compression

The axial compression performance of concrete filled steel tubular (CFST) columns using high-strength recycled aggregate concrete (RAC) instead of normal concrete (NC) was studied in an attempt to use demolition debris for effective recycling in construction works. Five specimens (three RAC-filled steel tubular (RACFST) columns and two reference CFST columns) were tested to investigate the influence of tube shape (circular or square), concrete type (NC or RAC) and internal structure (installation of a steel reinforcement cage or not). The test results indicate that damage development and failure mode of RACFST columns are similar to those of CFST columns. For the same cross-sectional area, steel ratio and material strength, circular section specimens were found to have a higher load-bearing capacity and better deformability than square section specimens. The replacement of NC with RAC has relatively less influence on the axial compressive behaviour of square section specimens than on circular specimens. A steel reinforcement cage inside the square section specimen was found to strengthen confinement to the core concrete, which significantly improved the bearing capacity and deformability. The results obtained are compared with the ultimate strengths of RACFST columns predicted using existing design codes. Considering the size effect, a formula for calculation of the bearing capacity of square CFST columns is suggested; comparisons of the predicted results show good agreement with the experimental data.

Study of reducing ground resistance for transmission tower on rocky mountain tops with constrained area

An effective device to reduce the earth resistance of grounding systems for power transmission towers on rocky mountain tops with high soil resistivity and constrained area is proposed in this paper. In these scenarios, conventional methods such as using horizontal electrodes to reduce ground resistance require more space and fine‐grained soil for backfill. These methods are not applicable to scenarios where the ground consists of rock or crushed stone. To tackle such limitations, we propose an effective approach with less space and soil requirements. Based on the steady electric current field theory and the electrostatic field, the proposed approach designs a central grounding system by a special steel reinforcement cage. The layout of the cage is strictly based on theoretical calculations. The resistance of the central grounding system can be obtained by calculation and measurement. Results show that this scheme can reduce ground resistance effectively in comparison with the traditional method of imbedding horizontal radial electrodes in high‐resistivity soil on mountain tops where space is limited and excavation conditions are poor. The proposed method has also been validated in practical applications. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Research on Concrete-Filled Rectangular Steel Tube Stiffeners and Axial Compression Bearing Capacity

Concrete-filled rectangular steel tube four sides restraint effect on the core concrete was weaker than the corner, which made the effect not significant. The paper studied a new kind of stiffening rib –PBL stiffener to strengthen restraint effect of concrete-filled rectangular steel tube , and evaluated its advantages compared with other stiffening ribs. 9 PBL stiffened concrete-filled rectangular steel tube columns under axial compressive load were tested. It also collected the test with other stiffened rids, such as straight ribs, binding bars, knee brace, steel reinforcement cage, steel bar stiffeners, saw tooth shaped stiffeners, stitching straight stiffeners and no rib concrete filled rectangular steel tube to compare. It evaluated increasing coefficient of bearing capacity by stiffening ribs. The results showed that: the PBL stiffeners and binding bar of concrete-filled rectangular steel tube bearing capacity was greater than other reinforcement measures by more than 20%; PBL stiffener could be a new prominent type of stiffener because of its excellent mechanical performance and simple construction.

Manufacturing and Hoisting Technology for Reinforcement Cage of Deep Foundation Excavation Bored Piles

Combined with the Beijing Business Center (CBD) core district Z14 plots commercial finance project (hereinafter referred to as the "CBD project") foundation pit construction, introduces the deep foundation pit of bored pile reinforcement cage fabrication and erection construction technology. In the construction process, through the site set up a special steel processing and production platform, the localization of the flange and other measures to solve the steel reinforcement cage positioning and connection construction difficulties. Combining the engineering fact, detailed calculation process of lifting steel cage hanging position, lifting machinery and hoisting rigging selection, and through the ANSYS software of finite element analysis and put forward specific measures to ensure the quality of steel reinforcement cage.

Effect of corrosion-damaged RC circular columns enveloped with hybrid and non-hybrid FRP under eccentric loading

The paper presents the effect of corrosion-damaged reinforced concrete (RC) columns with circular cross section enveloped (i.e. wrapped) with externally bonded hybrid and non-hybrid fibre-reinforced polymer (FRP) reinforcement. This study consisted of 18 RC circular columns with a diameter and height of 130 mm and 780 mm, respectively. These specimens were divided into three divisions, namely (i) no corrosion, (ii) mild corrosion and (iii) severe corrosion activities. All the mild and severe corroded columns, except control column, were exposed to corrosion activity, repaired with FRP and tested under eccentric loading. However, the columns without any corrosion activity were enveloped with FRP reinforcement and tested under eccentric loading. The corrosion process in RC columns was accelerated by impressing direct current on the steel reinforcement cage, adding 5% of NaCl in concrete mixture and wet/dry cycles. The variables investigated were different period of corrosion levels, plies of FRP (carbon and glass) reinforcement, hybrid (i.e. combination of carbon and glass FRP plies) and non-hybrid FRP (i.e. carbon or glass) reinforcement. From the experimental results, it was found that the external FRP confinement significantly increased the load-carrying capacity of the corrosion-damaged RC circular columns by 8% to 36% for mild corrosion level and 21% to 34% for severe corrosion level over the unconfined corrosion-damaged RC circular columns. Moreover, the results show that the performance of corrosion-damaged RC circular columns enveloped with hybrid FRP was better over the non-hybrid CFRP and GFRP RC circular columns. However, the results of CFRP enveloped circular columns were close to the hybrid FRP strengthened circular columns.

Construction Technology of Super-Deep Diaphragm Wall under Complicated Geological and Hydraulic Conditions

Supper-deep diaphragm wall construction of a Tianjin traffic hub project penetrated through many soil layers and two layers of confined water, geological and hydraulic conditions were complicated. Some special technologies including grooving methods,anti-collapse measures,verticality controlling measures, joint treatment measures and steel reinforcement cage hoisting measures were adopted for the construction. The project was finished with short time, low cost and good quality. Engineering practice shows that these technologies were appropriate for constructing supper-deep diaphragm wall under complicated geological and hydraulic conditions. These experiences can give some references to the similar super-deep diaphragm wall construction of Tianjin and other regions in future.

Hollow Threaded Rebar for Cross Hole Sonic Logging Access Tubes Combined with Longitudinal Concrete Reinforcing in Drilled Shafts

AbstractCrosshole Sonic Logging (CSL) of drilled shafts requires 1.5-in (38-mm) or 2-in (51-mm) I.D. sonic access tubes to be installed inside the steel reinforcement cage. The sonic access tubes do not contribute to the structural capacity of the drilled shaft. The proposed use of Ischebeck TITAN T73/56 CSL/Hollow Threaded Rebar for Cross Hole Sonic Logging Access Tubes Combined with Longitudinal Concrete Reinforcing in Drilled Shafts (patent pending) is discussed as an alternative method of construction and CSL probe access. The T73/56 hollow threaded rebar/sonic access tube performs as a high strength rebar while at the same time creating a 2.2-in (56-mm) I.D. sonic access tube. The deformed high strength hollow bar provides better adhesion to concrete thus reducing the problem of debonding associated with smooth PVC and steel pipe. A cost comparison using conventional rebar with added sonic access tubes is discussed. The use of T73/56 CSL/Hollow Threaded Rebar as a value engineering alternative can re...

Experimental Research on Seismic Behavior of RC Column with Different Concrete under Horizontal Low Cyclic Loading

On the premise of maintaining certain vertical bearing capacity, the frame structure dissipates seismic energy by elastic-plastic deformation in elastic-plastic stage of earthquake action. Using lightweight concrete in structure not only can reduce the its dead weight, decrease the earthquake power; also meet the concrete strength, stiffness and elastic modulus requirements of important structure, so as to improve its energy dissipation capacity. This paper researched the effect of concrete materials, including or such as C60 high strength Lightweight concrete (HSLC), high strength concrete (HSC) and high strength Light weight aggregate concrete (HSLAC), on the seismic behavior of RC column under horizontal low cyclic loading, respectively and the match relationship between concrete and steel reinforcement cage was analyzed.

Behavior of shear studs in steel frames with reinforced concrete infill walls

This paper reports on the behavior of headed shear stud connectors for use in steel frames with partially restrained connections and reinforced concrete infill walls, attached compositely to the steel frame around the perimeter of each wall panel (S-RCW system), subjected to seismic loading. In infill walls, the shear connectors lie in the plane of the concrete panel, which results in different behavior from studs in composite beams, for which the majority of past research has been conducted. In particular, shear connectors in infill walls are subjected to axial tension and compression forces due to sidesway and overturning of the S-RCW system, are influenced by the parallel edges of the wall, and are subjected to cyclic forces. An experimental program was developed to quantify the strength and deformation capacities of shear studs for use in S-RCW infill systems addressing the above issues, and to verify existing AISC, PCI, ACI, and Japanese design equations. A modification of the classic push-out test setup was made to accommodate the application of cyclic shear loading and axial tensile loading. Two different steel reinforcement configurations were used, one providing little confining reinforcement around the shear studs, and the other utilizing a steel reinforcement cage to provide ample confinement to the shear stud.