Steel Plate Reinforcement Research Articles

Bending performance and design of reinforced concrete ribbed bridge deck slabs retrofitted with steel-plate reinforcement

ABSTRACT This study aimed to assess the bending performance and design of reinforced concrete ribbed bridge deck slabs with steel-plate reinforcement. Two reference members and three steel-plate reinforcements were designed for four-point bending loading tests, numerical simulations, and theoretical analyses. Steel-plate reinforcement improves the flexural load bearing capacity and stiffness of the bridge deck slab and effectively controls crack development, compared to old bridge reconstruction requirements. The bridge deck is best stressed when the bolt (M12 mm × 200 mm) spacing is 0.8 times the slab thickness. To prevent brittle damage to the bridge deck, a steel plate with a width of 160 mm and thickness of 10 mm should be used for strengthening. This aligns with engineering practice whereby the bolt shear capacity is used to assess the effectiveness of steel-plate reinforcement in bridge deck slabs. Bolt shear arrangement based on the slip effect and a sufficient increase in the diameter of the bolts at both ends of the steel plate are more appropriate for the bending effect of the bridge deck structure. The results provide a reference for the design of deck slab reinforcement for assembled ribbed bridges.

Study on the parameters of steel plate reinforcement rib-deck crack considering local stress disturbances

Local reinforcement will change the local stiffness distribution of the component, causing perturbation effects on the local stress of the fatigue detail. Only considering the reinforcement effect may lead to excessive strengthening and induce new fatigue-prone points. For the fatigue detail of the rib-deck weld, steel plate reinforcement test and numerical simulations were conducted. The stress changes of the deck weld toe and weld root before and after reinforcement were analyzed. The influence of parameters such as steel plate length, thickness, and width on the reinforcement effect of the weld toe crack and local stress disturbance was discussed, and reasonable parameters were recommended. The results show that after the cracking of the weld toe, the stress concentration locations at the weld toe and weld root of the deck shift from the center of the specimen to the crack tip. Steel plate reinforcement can effectively restrain the crack propagation, but can lead to an increase in the stress at the deck weld root within the reinforced area. A good reinforcement effect can be achieved while the steel plate covers the crack, and further increasing the steel plate length has limited improvement on the reinforcement effect but reduces the adverse effect of steel plate reinforcement on the stress of the deck weld root. Increasing the steel plate width will increase the adverse effect of steel plate reinforcement on the deck weld root stress, and it is recommended to use steel plates with a length greater than 120 mm and a length-to-width ratio greater than 4 for reinforcement. Increasing the width of the steel plate has a relatively small effect on the reinforcement effect and the stress at the deck weld root, and steel plates with the same thickness as the deck are recommended.

Rubber compounds made of modified ethylene propylene diene monomer (EPDM) for laminated bearings with excellent anti-peel strength

In order to enhance the design life of laminated rubber bearings in the field of highway bridges in the plateau region, a novel laminated bearing was made by the modified ethylene propylene diene monomer (EPDM) rubber that combines both low-temperature and ageing resistance properties in this work. The modified EPDM also exhibit a high anti-peel strength with reinforced steel plate layer. Experimental and numerical investigations were carried out to evaluate the mechanical properties and failure conditions for the EPDM laminated bearing. The results indicate that the bearing with different shape factors exhibit good mechanical properties, and its key performance parameters such as compressive modulus and shear stiffness meet the requirements of the current specification for highway bridges. Meanwhile, we have established a quantitative relationship between the proportion of void area and the total local shear strain for EPDM laminated bearing, and found that when the proportion of void area reaches more than 32 %, some of the performance indexes of the bearing will exceeds the design limit. The above research results can be used as an important criterion for evaluating the performance of modified EPDM bearings.

Mechanical Characteristics of Cracked Lining Reinforced with Steel Plate–UHPC Subjected to Vertical Load

The steel plate reinforcement method is widely used for strengthening damaged linings. Nevertheless, low durability is one of the disadvantages of the steel plate reinforcement method, which uses epoxy resin as the interface binder. To enhance the load-bearing performance and strengthening effect of steel-plate-reinforced structures, this study introduced ultra-high performance concrete (UHPC) as the reinforcing bonding layer and proposed a novel method for steel plate–UHPC reinforcement of cracked linings. A mechanical performance model test was conducted on a 1/5 scale lining model using a loading test device to evaluate the load-bearing performance and stress deformation of both conventional steel plate and steel plate–UHPC reinforced cracked linings. The characteristics, mechanisms of failure, and impacts of strengthening of the steel plate reinforcement method and steel plate–UHPC reinforcement method for cracked linings were compared. A numerical simulation model was developed to investigate the reinforcement effect of cracked linings using steel plate–UHPC reinforcement. The analysis included examining the influence of steel plate thickness, UHPC bonding layer thickness, and reinforcement timing. Model test results show that the overall damage mode of the steel plate–UHPC-reinforced structure had good elastic–plastic behaviour, and the deformation and damage process under the vertical concentrated load can be divided into four typical phases. Compared with the traditional steel plate reinforcement, the ultimate load-carrying capacity and ductility of the steel plate–UHPC-reinforced structure were increased by 53% and 366%, respectively, showing significantly better load-carrying capacity and deformation performance. Numerical simulation results show that the reinforced structure’s load-carrying capacity and stiffness enhancement rate increased non-linearly with the increase in UHPC layer thickness and steel plate thickness. However, reasonable reinforcement timing exists for steel plate-UHPC reinforcement, and too late reinforcement timing leads to a decrease in structural load-carrying capacity and stiffness enhancement rate.

Secondary flexural behaviour of reinforced concrete beams strengthened with special-shaped rivet bonded steel plates and prestressed CFRP bars

Special-shaped rivet and glued steel plate reinforcement is an innovative structural reinforcement technology. A riveted glued steel plate primarily relies on the rivet to transfer shear. Prestressed carbon fibre-reinforced polymer (CFRP) reinforcement is a new technique for strengthening concrete structures. These studies focus on the ‘primary load’, overestimate the ultimate flexural load of the components by neglecting the ‘secondary load’ of the components in real engineering. In this study, the flexural properties of concrete beams strengthened using special-shaped rivet steel plates and CFRP prestressed bars were studied theoretically and experimentally. The cracking load, ultimate load capacity, and strain of the steel plate, steel bar and CFRP bars were recorded during the tests. In addition, the failure mode of the beams was observed, and the effect of secondary stress on the flexural capacity of the beams was analysed. The failure load of the beams strengthened by CFRP prestressed tendons increased by 67.8% and 46.1% for beams with primary and active secondary loads, respectively. The failure load of the special-shaped rivet and glued steel plate strengthened beam increased by 115.7% and 160.5%, for beams with primary and active secondary loads, respectively. Both methods have a strong guiding significance for engineering practice.

Surface fatigue crack propagation behavior of CFRP-steel plates with improved J-integral driving model

This study presents an experimental investigation into fatigue surface crack propagation behavior of CFRP (Carbon Fiber Reinforced Polymer) reinforced steel plates under cyclic load. The investigation employs the beach marking method and digital image correlation (DIC) methods to measure crack propagation with CFRP covering. CFRP has a significant influence on crack propagation rate, with an approximately 40% improvement in the length direction, while only a negligible 10% improvement is observed in the depth direction. The crack propagation rule is expressed using the improved J-integral driving model which can be expressed as a power function in two directions. Both CFRP and crack length noticeably influence the coefficient parameter in Paris formula, while the index parameter is only affected by crack depth. The crack propagation predictive model was found to be accurate compared to the experimental results.

Experimental Study on Repairing/Restoration and Reinforcement Methods of the Reinforced Concrete Structures Damaged by Earthquakes

For earthquake-damaged reinforced concrete structures, the static loading test method is adopted to carry out loading tests under cyclic loading on reinforced concrete beams with different reinforcement rates and columns with different axial compression ratios, and the effect of reinforcing and repairing the damaged reinforced concrete structure by using adhesive steel plates and carbon fiber cloth is investigated. Through comparative studies of structural hysteresis curves and skeleton curves under different reinforcement methods, it is concluded that reinforcement has significantly improved the hysteresis characteristics and ductility of members, and the seismic performance of the carbon fiber reinforcement method is better than that of the steel plate reinforcement. This study provides valuable references and suggestions for practical earthquake-damaged building reinforcement and repair works and seismic reinforcement works.

Analytical Solution for the Ultimate Compression Capacity of Unbonded Steel-Mesh-Reinforced Rubber Bearings

Unbonded steel-mesh-reinforced rubber bearings (USRBs) have been proposed as an alternative isolation bearing for small-to-medium-span highway bridges. It replaces the steel plate reinforcement of common unbonded laminated rubber bearings (ULNR) with special steel wire meshes, resulting in improved lateral properties and seismic performance. However, the impact of this novel steel wire mesh reinforcement on the ultimate compression capacity of USRB has not been studied. To this end, theoretical and experimental analysis of the ultimate compression capacity of USRBs were carried out. The closed-form analytical solution of the ultimate compression capacity of USRBs was derived from a simplified USRB model employing elasticity theory. A parametric study was conducted considering the geometric and material properties. Ultimate compression tests were conducted on 19 USRB specimens to further calibrate the analytical solution, considering the influence of the number of reinforcement layers. An efficient solution for USRBs’ ultimate compression capacity was obtained via multilinear regression of the calibrated analytical results. The efficient solution can simplify the estimation of USRBs’ ultimate compression capacity while maintaining the same accuracy as the calibrated solution. Based on the efficient solution, the design process of a USRB with a specific ultimate compression capacity was illustrated.

Study on the monitoring method of debonding between concrete beams and reinforced steel plates based on piezoelectric smart materials

Concrete reinforcement is essential for ensuring the safety and durability of concrete structures. Bonding steel plates to reinforce concrete is widely used to renovate or strengthen concrete beam structures. Due to construction quality and the influence of factors such as environment and fatigue, debonding often occurs between the steel plate and concrete, making monitoring and early warning after concrete structure reinforcement challenging. This paper proposes a novel approach to monitor the degree of debonding between the steel plate and concrete beam using active sensing technology. The method uses lead zirconate titanate (PZT) as an actuator to generate stress waves. It prepares strip sensors with polyvinylidene fluoride as the sensing element to monitor stress waves passing through the steel plate and concrete beam. The monitoring system detects the degree of debonding between the steel plate and the concrete beam by monitoring the change in surface voltage of the sensor. Experiments show that the degree of debonding significantly correlates with the received voltage signal; the higher the debonding, the larger the received voltage signal. It is also observed that, at the same degree of debonding, the actuator and sensor attachment position have a particular impact on the received voltage signal. Through experiments and numerical simulation analysis, it is found that when the sensor is attached to the left side of the steel plate, that is, the bonded section of the steel plate, the amplitude of the voltage signal collected by the dynamic information acquisition system is the smallest, i.e., V_debonded section > V_middle > V_bonded section. Based on the above research, the active sensing technology proposed in this paper has good sensitivity to the degree of debonding between the steel plate and concrete. It is expected to become an effective monitoring and evaluation method for the degree of debonding between steel plates and concrete.

Research on fatigue vulnerable details of cross beam joints after reinforcement for steel truss bridges

In this research, fatigue tests on full-size specimens are conducted for a steel cross-beam joint before and after reinforcement. Combined with a three-dimensional (3D) numerical simulation, the 3D stress parameters, and their redistribution rules study anew with a web crack and new crack initiation locations and fatigue weakness details are predicted. The research results include the following: 1) The empirical formula parameter m of the Z-axis stress for the new crack tip is approximately 0.05. 2) The fatigue performance of the web’s new crack tips is significantly improved by bolting reinforced steel plates, the stress range is reduced by 60%-98.78%, and the original crack stops growing in size. The health monitoring system can choose the predicted weak details as valid monitoring points so that the fatigue damage can be intelligently perceived after the reinforcement of steel bridges.

Mechanical properties of the composite sandwich structures with cold formed profiled steel plate and balsa wood core

Fiber reinforced plastic (FRP) sandwich structure are increasingly used in construction areas recently for its high strength, light weight and corrosion resistance performance. This paper proposed an innovative composite sandwich structure incorporating GFRP skins, a cold formed profiled steel plate and a light weight balsa wood core. The interaction between the different components was connected by stainless steel core rivets. Three-point bending tests were conducted on eleven specimens to investigate the parameters (shear span to depth (a/d) ratio, thickness of cold formed profiled steel plate and spacing of the stainless steel core rivets) effect on the performance (deflection, ultimate load bearing capacity, and failure modes) of the new proposed structure. The test findings indicate that a reduction in ultimate load-bearing capacity ranging from 13% to 41%, accompanied by an escalation in deflection between 1.7 and 13.9 times, as the a/d ratio ranges from 1 to 6. All beams experienced failure at deflections ranging from span/114 to span/50. Specifically, specimens displayed core shear failure for a/d ratios ≤ 4, transitioning to top skin compression failure at an a/d ratio of 6. Compared to specimens without cold formed profiled steel plate reinforcement, the load bearing capacity of the new proposed composite structure at serviceability limit states and ultimate limit states was increased by 68%−194% and 53%−83%, respectively. Moreover, the reinforcement of the stainless steel core rivets can ensure the coordinated working of different components, and the smaller the spacing, the better the working effect. Finally, an analytical model was developed to account for the impact of cold-formed profiled steel plates on specimen stiffness and load-bearing capacity. This model was subsequently validated through experimental results. Both the experimental and theoretical analysis verified the favorable performance of the proposed new composite structure.

Research on Lateral Deformation Control Criteria of Metro Shield Tunnels with Excessive Ellipticity

In recent years, excessive lateral deformation of subway shield tunnels has been observed due to adjacent engineering activities. This study examines the monitoring of excessive lateral deformation of the shield tunnel and the special steel plate reinforcement process to enhance the safety and stability of the operating subway tunnel structure. It uses a three-dimensional refined finite-element model of the shield tunnel for parametric structural loading simulation analysis to propose a structural deformation limit value suitable for the subway shield tunnel. This study’s findings indicated the following: (1) as observed from the engineering examples, a tunnel with significant elliptical deformation increases the likelihood of cracking and other structural issues in the adjacent subway shield tunnel segment; (2) as observed from the post-reinforcement monitoring data, the steel plate reinforcement method effectively enhances the load-bearing stability of the damaged tunnel structure; (3) based on the finite-element simulation results and the comprehensive review of practical conditions, the standard warning value for lateral deformation, using ellipticity evaluation of the subway shield tunnel, is established at 20‰, with a control value of 25‰. The outcomes of this research offer valuable insights into the operation, maintenance, and health monitoring of subway shield tunnels.

Post-buckling shear capacity of steel plates with opening strengthened by fiber fabric

Shear capacity is one of the most important factors of steel plates and the steel plates with opening is widely adopted in engineering. This study investigates steel plates reinforced with fiber fabric. Opening shapes, positions, panel thicknesses, and material strengths, are considered to assess the effectiveness of fiber fabric in reinforcing steel plates. Two types of fibers, carbon fiber and basalt fiber, are employed. Specimens with various opening positions and shapes are meticulously designed. The study includes an analysis of how effectively fiber fabric improves shear capacity and examines the resulting failure modes. A comparison is made regarding the shear behavior of plates reinforced with different types of fiber fabrics. The study also explores how plate thickness influences the strengthening effect. The results indicate that the presence of fiber fabric does not enhance the shear capacity of steel plates without openings. Carbon fiber demonstrates a greater enhancement in shear capacity compared to basalt fiber. The use of fiber fabric and epoxy resin to reinforce thin steel plates shows limited improvement in shear capacity. A numerical model is proposed to simulate plates reinforced with fiber fabric, incorporating a nonlinear spring element to represent the behavior of epoxy resin.

The Maintenance Effect of Diaphragm-to-Rib Fatigue Cracks in Orthotropic Steel Deck via Steel Plate Reinforcement

To investigate the maintenance effect of diaphragm-to-rib fatigue cracks via steel plate reinforcement, finite element models of different-shaped steel plates were established. Stress intensity factors at the crack tip before and after reinforcement were obtained, and the variations in stresses were studied. Polygonal steel plate reinforcements were then carried out on a real bridge based on the finite element calculation results. The changes in stress amplitudes and fatigue damage degrees at the crack tip were analyzed via the rain-flow counting method and Miner’s linear damage accumulating theory. The results show that both the polygonal steel plate and the rectangular steel plate could effectively eliminate the stress concentration and restrain the propagation of cracks. The stresses in other parts of the arc notch increased after reinforcement and polygonal steel plates had less influence. After the reinforcement in a real bridge, the cycle number of high stress amplitudes at the crack tip decreased significantly. The fatigue damage degree of the repaired part reduced by 70.1%, which verified the maintenance effect via polygonal steel plate reinforcement on diaphragm-to-rib fatigue cracks.

Flexural tests on composite basement walls with socket-type shear connectors

The effect of a recently developed socket-type shear connector (SSC) on the flexural behaviour of a composite basement wall (CBW) was examined in this work. To this end, 12 CBWs composed of cast-in-place (CIP) piles fabricated with H-shaped steel beams or reinforcing steel plates were prepared by varying the arrangement and amount of SSCs. Two-point loading was applied to simply supported CBW specimens. The CBW specimens with more SSCs had a higher effective stiffness in the elastic state and higher moment capacity in the ultimate state, irrespective of the cross-sectional details of the CIP piles. These trends were particularly prominent when a reinforcing steel plate was used in the SSCs. The post-peak behaviour of the CBW specimens subjected to a simulated load with a negative external moment tended to be more ductile. Consequently, a higher degree of composite action was fully exerted on the CBWs with greater numbers of SSCs. Using established equations for the sectional details of CBWs with SSCs, the nominal partially composite to full composite flexural capacity ratios of the CBW specimens subjected to simulated loads with positive and negative external moments were calculated to be, respectively, 0.83 and 0.91 for 0.5ηsc and 0.79 and 0.90 for 0.75ηsc, where ηsc is the normalised shear connector capacity specified in ANSI/AISC 360-16.

ИССЛЕДОВАНИЕ РАБОТЫ ДЕРЕВЯННОЙ БАЛКИ, АРМИРОВАННОЙ СТАЛЬНЫМИ ПЛАСТИНАМИ

The article describes the main problems of engineering reinforced wooden structures associated with the justification of their reliability. Tasks to study the operation of a wooden reinforced beam taking into account the nonlinear operation of wood have been set and solved. A girder structure reinforced in the compressed and tensile zones by plate elements was used as the object of the research. To achieve the aims, the authors carried out an experimental study using strain-gauge equipment, numerical simulation of the structure in the ANSYS PC and analytical calculations. Based on the results, conclusions about the effectiveness of steel plate reinforcement in wooden beams have been made. The results can be applied in the engineering, and the developed structure can be used as the elements of the frame structures and as floor beams.

Failure of urban subway segments in coastal area and reinforcement effect of bonded steel plate: a case study in China

The construction of metro in coastal areas is prone to safety accidents when it encounters unfavourable geology. Serious water inrush and sand gushing occurred during the construction of the shield tunnel connection channel of Shenzhen Metro Line 20, resulting in extensive deformation and even cracking of the shield segment. With the event as the background, it is conducted in this article with a further analysis of the causes of sand gushing in the connecting channel. Using convergence displacement and crack width as indicators, the shield segments are classified as strong influence zone, moderate influence zone, weak influence zone and no influence zone. Furthermore, by combining numerical simulation and field investigation, the innovative method of epoxy bonded steel plate reinforcement is proposed. In particular, it should be noted that the steel plate needs to be opened at the connection channel, so four small right-angle steel plates are designed to reduce the concentrated stress of the split ring. According to finite element analysis and on-site measurement, it can be known that after the steel plate is reinforced, the internal force of the segment is greatly reduced, and the deformation is stable, which can ensure the safe service of the tunnel. This research provides a new idea for the damaged reinforcement of urban subway segments in coastal areas in the future.

Novel Reinforcing Techniques and Bearing Capacity Analysis for Tunnel Lining Structures with Extensive Corrosion

Affected by the erosive environment, tunnel lining concrete in the long-term service zprocess often exhibits engineering diseases such as concrete corrosion degradation and loss of strength, decreasing the stability of the tunnel lining structure and the traffic safety. Based on HTG tunnel project, the basic distribution rule of tunnel lining corrosion and macro mechanical properties of corroded concrete were explored in this paper through engineering disease site investigation. Then, on this basis, aiming at large-scale corrosion of tunnel lining structure, two reinforcement and repair schemes are proposed, corrugated steel plate reinforcement method and channel steel reinforcement method. Indoor component tests are carried out on the two reinforcement schemes. The failure characteristics and stress and deformation law of tunnel lining members after reinforcement and repair were verified. The analysis showed that the failure process of the reinforced specimens on the tensile side could be divided into the non-cracking stage and the working stage with cracks, and the cracking load and failure load of the specimens were significantly increased. The bearing capacity of the reinforced specimens was divided into the ultimate bearing capacity against cracking and the ultimate bearing capacity during failure. Finally, the calculation methods of the bearing capacity of the channel steel reinforcement method and the corrugated steel plate reinforcement method were derived. Comparative analysis shows that the results of numerical simulation, experimental testing and theoretical simplification methods are close to each other, and the maximum deviation is less than 8%. The established method for calculating the bearing capacity of corroded components after reinforcement is reliable and can be used for the design calculation of corroded lining reinforcement.

Theoretical Analysis of Flexural Time-Varying Properties of Aluminum Alloy-Reinforced RC Beam under Atmospheric Environment

This paper aims to reveal the degradation of the flexural load capacity of reinforced concrete (RC) beams reinforced with aluminum alloy (AA) under atmospheric conditions. For the same, first, time-varying models of the flexural load capacity of RC beams were developed before and after reinforcement with AA and steel plate based on the time-varying properties of the materials. Subsequently, upon collecting existing test data, the reliability of the models was verified. Finally, the parameters of AA-reinforced and steel plate-reinforced RC beams were analyzed to investigate the influence of factors such as concrete cover depth, cross-sectional area of reinforcing material, and cooperative working coefficient of reinforcing material and concrete (demonstrate the ability of reinforcement material and concrete to work together) on the remaining service life, rust initiation time, and cracking time. The results show that under atmospheric environment, the flexural time-varying degradation model for RC beam can be divided into three stages: pre-rusting, rusting-pre-cracking, and post-cracking, with differences in the dominant factors at each stage. In terms of long-term performance, AA reinforcement is significantly more efficient than steel plate reinforcement. This study provides some theoretical basis for the design of AA reinforcement in the atmospheric environment.

Study on Lateral Distribution Coefficients of Hollow Slab Bridges After Reinforced by Pasted Steel Plates

This paper adopts a new method of pasting steel plate to restore the transverse connection of hollow slab bridge, so that the strengthened bridge can meet the requirements under the state of serviceability. The original beam of the concrete hollow slab with a span of 8m from the Suizhong to Shenyang section of Jing-Shen highway was reinforced by a method of pasting steel plates. In the test the eccentric load condition was loaded and the abaqus software was used for numerical calculation after the reinforcement. Based on the theory of load transverse distribution coefficient of bridge structure, different calculation methods were used to obtain the transverse load distribution coefficient of the strengthened test beam, and it is verified that the hinged plate method can be used to calculate the hollow slab beam strengthened with steel plate. In addition, combined with previous calculations, test results and numerical analysis, this paper discusses the restoration effect of the new type of pasted steel plate reinforcement method on the bridge lateral connection. The results show that the hinged plate method can be used to calculate the load lateral distribution coefficient of hollow slab beams strengthened by pasted steel plates. therefore, the pasted steel plate reinforcement method can effectively restore the horizontal connection between the hollow slabs and meet the use of bridge structures.