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Numerical modelling of reinforced concrete flexural members strengthened using textile reinforced mortars

《结构与土木工程前沿(英文)》 2023年 第17卷 第4期   页码 649-668 doi: 10.1007/s11709-023-0919-4

摘要: Externally bonded (EB) and near-surface mounted (NSM) bonding are two widely adopted and researched strengthening methods for reinforced-concrete structures. EB composite substrates are easy to reach and repair using appropriate surface treatments, whereas NSM techniques can be easily applied to the soffit and concrete member sides. The EB bonded fiber-reinforced polymer (FRP) technique has a significant drawback: combustibility, which calls for external protective agents, and textile reinforced mortar (TRM), a class of EB composites that is non-combustible and provides a similar functionality to any EB FRP-strengthened substrate. This study employs a finite element analysis technique to investigate the failing failure of carbon textile reinforced mortar (CTRM)-strengthened reinforced concrete beams. The principal objective of this numerical study was to develop a finite element model and validate a set of experimental data in existing literature. A set of seven beams was modelled and calibrated to obtain concrete damage plasticity (CDP) parameters. The predicted results, which were in the form of load versus deflection, load versus rebar strain, tensile damage, and compressive damage patterns, were in good agreement with the experimental data. Moreover, a parametric study was conducted to verify the applicability of the numerical model and study various influencing factors such as the concrete strength, internal reinforcement, textile roving spacing, and externally-applied load span. The ultimate load and deflection of the predicted finite element results had a coefficient of variation (COV) of 6.02% and 5.7%, respectively. A strain-based numerical comparison with known methods was then conducted to investigate the debonding mechanism. The developed finite element model can be applied and tailored further to explore similar TRM-strengthened beams undergoing debonding, and the preventive measures can be sought to avoid premature debonding.

关键词: fiber reinforced polymer     textile reinforced mortar     finite element analysis     concrete damage plasticity     calibration and validation     parametric study    

Experimental study on shear behavior of reinforced concrete beams with web horizontal reinforcement

Dong XU,Yu ZHAO,Chao LIU

《结构与土木工程前沿(英文)》 2014年 第8卷 第4期   页码 325-336 doi: 10.1007/s11709-014-0080-1

摘要: In determining the shear capacity of reinforced concrete beams, current codes do not provide any calculation method to evaluate the influence of web horizontal reinforcement, although they exist as structural reinforcements (or skin reinforcement). The present paper comprises results of 11 reinforced concrete beams in an effort to investigate the influence of web horizontal reinforcement on the shear behavior of reinforced concrete beams. The primary design variables are the shear-span-depth ratio, different reinforcement ratio of stirrups and web horizontal reinforcement. Influence of web horizontal reinforcement on crack patterns and failure mode was studied. It was found that web horizontal reinforcement can increase the shear capacity of the beams and restrain growth of inclined cracks effectively. Test results are very valuable, as very few references of shear tests can be found focusing on the effect of web horizontal reinforcement on the shear capacity of the beams.

关键词: reinforced concrete beam     shear strength     web horizontal reinforcement     experiments    

Experimental investigation on concrete overlaid with textile reinforced mortar: Influences of mix, temperature

《结构与土木工程前沿(英文)》 2023年 第17卷 第2期   页码 271-283 doi: 10.1007/s11709-022-0896-z

摘要: Textile reinforced mortar is widely used as an overlay for the repair, rehabilitation, and retrofitting of concrete structures. Recently, textile reinforced concrete has been identified as a suitable lining material for improving the durability of existing concrete structures. In this study, we developed a textile-reinforced mortar mix using river sand and evaluated the different characteristics of the textile-reinforced mortar under various exposure conditions. Studies were carried out in two phases. In the first phase, the pullout strength, temperature resistance, water absorption, and compressive and bending strength values of three different textile-reinforced mortar mixes with a single type of textile reinforcement were investigated. In the second phase, the chemical resistance of the mix that showed the best performance in the abovementioned tests was examined for use as an overlay for a concrete substrate. Investigations were performed on three different thicknesses of the textile reinforced mortar overlaid on concrete specimens that were subjected to acidic and alkaline environments. The flexural responses and degradations of the textile reinforced mortar overlaid specimens were examined by performing bending tests. The experimental findings indicated the feasibility of using textile reinforced mortar as an overlay for durable concrete construction practices.

关键词: textile reinforced mortar     bending tests     acid and alkaline environment     concrete overlay    

Axial compression tests and numerical simulation of steel reinforced recycled concrete short columnsconfined by carbon fiber reinforced plastics strips

Hui MA; Fangda LIU; Yanan WU; Xin A; Yanli ZHAO

《结构与土木工程前沿(英文)》 2022年 第16卷 第7期   页码 817-842 doi: 10.1007/s11709-022-0844-y

摘要: To research the axial compression behavior of steel reinforced recycled concrete (SRRC) short columns confined by carbon fiber reinforced plastics (CFRP) strips, nine scaled specimens of SRRC short columns were fabricated and tested under axial compression loading. Subsequently, the failure process and failure modes were observed, and load-displacement curves as well as the strain of various materials were analyzed. The effects on the substitution percentage of recycled coarse aggregate (RCA), width of CFRP strips, spacing of CFRP strips and strength of recycled aggregate concrete (RAC) on the axial compression properties of columns were also analyzed in the experimental investigation. Furthermore, the finite element model of columns which can consider the adverse influence of RCA and the constraint effect of CFRP strips was founded by ABAQUS software and the nonlinear parameter analysis of columns was also implemented in this study. The results show that the first to reach the yield state was the profile steel in the columns, then the longitudinal rebars and stirrups yielded successively, and finally RAC was crushed as well as the CFRP strips was also broken. The replacement rate of RCA has little effect on the columns, and with the substitution rate of RCA from 0 to 100%, the bearing capacity of columns decreased by only 4.8%. Increasing the CFRP strips width or decreasing the CFRP strips spacing could enhance the axial bearing capacity of columns, the maximum increase was 10.5% or 11.4%, and the ductility of columns was significantly enhanced. Obviously, CFRP strips are conducive to enhance the axial bearing capacity and deformation capacity of columns. On this basis, considering the restraint effect of CFRP strips and the adverse effects of RCA, the revised formulas for calculating the axial bearing capacity of SRRC short columns confined by CFRP strips were proposed.

关键词: steel reinforced recycled concrete     CFRP strips     short columns     axial compression behavior     recycled aggregate concrete    

Investigation on modeling parameters of concrete beams reinforced with basalt FRP bars

Jordan CARTER, Aikaterini S. GENIKOMSOU

《结构与土木工程前沿(英文)》 2019年 第13卷 第6期   页码 1520-1530 doi: 10.1007/s11709-019-0580-0

摘要: Fiber-reinforced polymer (FRP) bars are widely used as internal reinforcement replacing the conventional steel bars to prevent from corrosion. Among the different types of FRP bars, basalt FRP (BFRP) bars have been used in different structural applications and, herein, three already tested concrete beams reinforced with BFRP bars are analyzed using three-dimensional (3-D) finite element analysis (FEA). The beams were tested in four-point bending. In the FEA the behavior of concrete is simulated using the “Concrete-Damaged Plasticity” model offered in ABAQUS software. The research presented here presents a calibrated model for nonlinear FEA of BFRP concrete beams to predict their response considering both the accuracy and the computational efficiency. The calibration process showed that the concrete model should be regularized using a mesh-dependent characteristic length and material-dependent post-yield fracture and crushing energies to provide accurate mesh-size independent results. FEA results were compared to the test results with regard to failure load and crack patterns. Both test the results and the numerical results were compared to the design predictions of ACI 440.1R-15 and CSA S806-12, where CSA S806-12 seems to overestimate the shear strength for two beams.

关键词: basalt Fiber-reinforced polymer bars     reinforced concrete beams     finite element analysis     damaged plasticity model     design codes    

Predetermination of potential plastic hinges on reinforced concrete frames using GFRP reinforcement

Dominik KUERES; Dritan TOPUZI; Maria Anna POLAK

《结构与土木工程前沿(英文)》 2022年 第16卷 第5期   页码 624-637 doi: 10.1007/s11709-022-0832-2

摘要: In the past, glass fiber-reinforced polymer (GFRP)-reinforcement has been successfully applied in reinforced concrete (RC) structures where corrosion resistance, electromagnetic neutrality, or cuttability were required. Previous investigations suggest that the application of GFRP in RC structures could be advantageous in areas with seismic activity due to their high deformability and strength. However, especially the low modulus of elasticity of GFRP limited its wide application as GFRP-reinforced members usually exhibit considerably larger deformations under service loads than comparable steel-reinforced elements. To overcome the aforementioned issues, the combination of steel and GFRP reinforcement in hybrid RC sections has been investigated in the past. Based on this idea, this paper presents a novel concept for the predetermination of potential plastic hinges in RC frames using GFRP reinforcement. To analyze the efficiency of the concept, nonlinear finite element simulations were performed. The results underscore the high efficiency of hybrid steel-GFRP RC sections for predetermining potential plastic hinges on RC frames. The results also indicate that the overall seismic behavior of RC structures could be improved by means of GFRP as both the column base shear force during the seismic activity as well as the plastic deformations after the earthquake were considerably less pronounced than in the steel-reinforced reference structure.

关键词: glass fiber-reinforced polymer     GFRP     hybrid section     plastic hinge     seismic design     reinforced concrete    

Slender reinforced concrete shear walls with high-strength concrete boundary elements

《结构与土木工程前沿(英文)》 2023年 第17卷 第1期   页码 138-151 doi: 10.1007/s11709-022-0897-y

摘要: Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

关键词: slender walls     high-strength concrete     rectangular and barbell-shaped walls     cold joints    

Punching of reinforced concrete slab without shear reinforcement: Standard models and new proposal

Luisa PANI, Flavio STOCHINO

《结构与土木工程前沿(英文)》 2020年 第14卷 第5期   页码 1196-1214 doi: 10.1007/s11709-020-0662-z

摘要: Reinforced concrete (RC) slabs are characterized by reduced construction time, versatility, and easier space partitioning. Their structural behavior is not straightforward and, specifically, punching shear strength is a current research topic. In this study an experimental database of 113 RC slabs without shear reinforcement under punching loads was compiled using data available in the literature. A sensitivity analysis of the parameters involved in the punching shear strength assessment was conducted, which highlighted the importance of the flexural reinforcement that are not typically considered for punching shear strength. After a discussion of the current international standards, a new proposed model for punching shear strength and rotation of RC slabs without shear reinforcement was discussed. It was based on a simplified load-rotation curve and new failure criteria that takes into account the flexural reinforcement effects. This experimental database was used to validate the approaches of the current international standards as well as the new proposed model. The latter proved to be a potentially useful design tool.

关键词: punching shear strength     reinforced concrete     slabs     reinforcement ratio    

Strengthening of reinforced concrete beams using fiber-reinforced cementitious matrix systems fabricated

《结构与土木工程前沿(英文)》   页码 1100-1116 doi: 10.1007/s11709-023-0967-9

摘要: The performance of a new fiber-reinforced cementitious matrix (FRCM) system developed using custom-designed mortar and fabrics is investigated in this study. The behavior of this system is evaluated in terms of both the flexural and shear strengthening of reinforced concrete beams. Eight beams are designed to assess the effectiveness of the FRCM system in terms of flexural strengthening, and four specimens are designed to investigate their shear behavior. The parameters investigated for flexural strengthening are the number of layers, span/depth ratio, and the strengthening method. Unlike previous studies, custom fabrics with similar axial stiffness are used in all strengthening methods in this study. In the shear-strengthened specimens, the effects of the span/depth ratio and strengthening system type (fiber-reinforced polymer (FRP) or FRCM) are investigated. The proposed FRCM system exhibits desirable flexural and shear strengthening for enhancing the load capacity, provides sufficient bonding with the substrate, and prevents premature failure modes. Considering the similar axial stiffness of fabrics used in both FRCM and FRP systems and the higher load capacity of specimens strengthened by the former, cement-based mortar performs better than epoxy.

关键词: fiber-reinforced cementitious matrix     flexural strengthening     shear strengthening     carbon fiber-reinforced polymer     shear span    

Fatigue shear performance of concrete beams reinforced with hybrid (glass-fiber-reinforced polymer+ steel

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 576-594 doi: 10.1007/s11709-021-0728-6

摘要: Reinforced concrete beams consisting of both steel and glass-fiber-reinforced polymer rebars exhibit excellent strength, serviceability, and durability. However, the fatigue shear performance of such beams is unclear. Therefore, beams with hybrid longitudinal bars and hybrid stirrups were designed, and fatigue shear tests were performed. For specimens that failed by fatigue shear, all the glass-fiber-reinforced polymer stirrups and some steel stirrups fractured at the critical diagonal crack. For the specimen that failed by the static test after 8 million fatigue cycles, the static capacity after fatigue did not significantly decrease compared with the calculated value. The initial fatigue level has a greater influence on the crack development and fatigue life than the fatigue level in the later phase. The fatigue strength of the glass-fiber-reinforced polymer stirrups in the specimens was considerably lower than that of the axial tension tests on the glass-fiber-reinforced polymer bar in air and beam-hinge tests on the glass-fiber-reinforced polymer bar, and the failure modes were different. Glass-fiber-reinforced polymer stirrups were subjected to fatigue tension and shear, and failed owing to shear.

关键词: fatigue     shear     hybrid stirrups     hybrid reinforcement     fiber-reinforced polymer    

Experimental flexural behavior of SMA-FRP reinforced concrete beam

Adeel ZAFAR, Bassem ANDRAWES

《结构与土木工程前沿(英文)》 2013年 第7卷 第4期   页码 341-355 doi: 10.1007/s11709-013-0221-y

摘要: The most critical drawback in currently used steel reinforcement in reinforced concrete (RC) structures is susceptibility to accumulation of plastic deformation under excessive loads. Many concrete structures due to damaged (yielded) steel reinforcement have undergone costly repairs and replacements. This research presents a new type of shape memory alloy (SMA)-based composite reinforcement with ability to withstand high elongation while exhibiting pseudo-elastic behavior. In this study, small diameter SMA wires are embedded in thermoset resin matrix with or without additional glass fibers to develop composite reinforcement. Manufacturing technique of new proposed composite is validated using microscopy images. The proposed SMA-FRP composite square rebars are first fabricated and then embedded in small scale concrete T-beam. 3-point bending test is conducted on manufactured RC beam using a cyclic displacement controlled regime until failure. It is found that the SMA-FRP composite reinforcement is able to enhance the performance of concrete member by providing re-centering and crack closing capability.

关键词: re-centering     shape memory alloys     concrete     composite     fiber reinforced polymer     scanning electron microscopy    

Experimental and modeling studies on installation of arc sprayed Zn anodes for protection of reinforcedconcrete structures

Xianming SHI

《结构与土木工程前沿(英文)》 2016年 第10卷 第1期   页码 1-11 doi: 10.1007/s11709-016-0312-7

摘要: Arc sprayed zinc (Zn) anode on concrete surfaces has been an emerging technology for protecting reinforced concrete structures from rebar corrosion in coastal environments. Many cathodic protection (CP) systems with arc sprayed Zn anodes will reach or exceed their design life in the near future and thus may function improperly or insufficiently, making it necessary to replace the aged anodes. However, prior to this study, little was known about the most effective profile for the concrete surface, for either new concrete or old concrete with existing Zn anodes removed. This work develops criteria to properly prepare the concrete surface before the application of new Zn anode. Experimental studies were conducted both in the laboratory and for a field structure in Oregon. Artificial neural network was used to achieve better understanding of the complex cause-and-effect relationships inherent in the Zn-mortar or Zn–concrete systems and was successful in finding meaningful, logical results from the bond strength data. The goal is to achieve strong initial bond strength of new Zn to concrete, which is essential for long-term performance of the CP system. The results from this case study suggest that it is necessary to adjust the anode removal and surface sandblasting based on the electrochemical age of the existing concrete. In all cases of sandblasting, minimize the exposure of large aggregates (e.g., those bigger than 19 mm in diameter).

关键词: arc sprayed Zn     anode replacement     reinforced concrete     bridge preservation     neural networks     surface profile    

Deflection behavior of a prestressed concrete beam reinforced with carbon fibers at elevated temperatures

Mohammed FARUQI, Mohammed Sheroz KHAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 81-91 doi: 10.1007/s11709-018-0468-4

摘要: Fiber reinforced polymer(FRP) have unique advantages like high strength to weight ratio, excellent corrosion resistance, improving deformability and cost effectiveness. These advantages have gained wide acceptance in civil engineering applications. FRP tendons for prestressing applications are emerging as one of the most promising technologies in the civil engineering industry. However, the behavior of such members under the influence of elevated temperatures is still unknown. The knowledge and application of this could lead to a cost effective and practical considerations in fire safety design. Therefore, this study examines the deflection behavior of the carbon fiber reinforced polymer(CFRP) prestressed concrete beam at elevated temperatures. In this article, an analytical model is developed which integrates the temperature dependent changes of effective modulus of FRP in predicting the deflection behavior of CFRP prestressed concrete beams within the range of practical temperatures. This model is compared with a finite element mode (FEM) of a simply supported concrete beam prestressed with CFRP subjected to practical elevated temperatures. In addition, comparison is also made with an indirect reference to the real behavior of the material. The results of the model correlated reasonably with the finite element model and the real behavior. Finally, a practical application is provided.

关键词: FRP     CFRP     concrete     elevated temperatures     deflections     prestress    

Numerical simulation of squat reinforced concrete wall strengthened by FRP composite material

Ali KEZMANE,Said BOUKAIS,Mohand Hamizi

《结构与土木工程前沿(英文)》 2016年 第10卷 第4期   页码 445-455 doi: 10.1007/s11709-016-0339-9

摘要: The advanced design rules and the latest known earthquakes, have imposed a strengthening of reinforced concrete structures. Many research works and practical achievements of the application of the external reinforcement by using FRP composite materials have been particularly developed in the recent years. This type of strengthening seems promising for the seismic reinforcement of buildings. Among of the components of structures that could affect the stability of the structure in case of an earthquake is the reinforced concrete walls, which require in many cases a strengthening, especially in case where the diagonal cracks can be developed. The intent of this paper is to present a numerical simulation of squat reinforced concrete wall strengthened by FRP composite material (carbon fiber epoxy). The intent of this study is to perform finite element model to investigate the effects of such reinforcement in the squat reinforced concrete walls. Taking advantage of a commercial finite element package ABAQUS code, three-dimensional numerical simulations were performed, addressing the parameters associated with the squat reinforced concrete walls. An elasto-plastic damage model material is used for concrete, for steel, an elastic-plastic behavior is adopted, and the FRP composite is considered unidirectional and orthotropic. The obtained results in terms of displacements, stresses, damage illustrate clearly the importance of this strengthening strategy.

关键词: simulation     strengthening     reinforced concrete wall     squat wall     FRP composite material     damage     Abaqus    

Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fineconcrete shells

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0955-0

摘要: This paper proposes an innovative column composed of a core column (including both reinforced concrete (RC) and plain concrete (PC) columns) and a prefabricated textile-reinforced fine concrete (TRC) shell. To study the confinement properties of TRC shells on this novel type of concrete column, 20 circular specimens, including 12 PC columns and 8 RC columns, were prepared for axial compressive tests. Four key parameters, including the column size, reinforcing ratio of the carbon textile, concrete strength, and stirrup spacing, were evaluated. The results indicated that the compressive properties of the columns were improved by increasing the reinforcing ratio of the textile layers. In the case of TRC-confined PC columns, the maximum improvement in the peak load was 56.3%, and for TRC-confined RC columns, the maximum improvement was 60.2%. Based on the test results, an analytical model that can be used to calculate the stress–strain curves of prefabricated TRC shell-confined concrete columns has been proposed. The calculated curves predicted by the proposed model agreed well with the test results.

关键词: textile-reinforced fine concrete     prefabricated shell     confined concrete column     confinement properties     stress–strain relationship    

标题 作者 时间 类型 操作

Numerical modelling of reinforced concrete flexural members strengthened using textile reinforced mortars

期刊论文

Experimental study on shear behavior of reinforced concrete beams with web horizontal reinforcement

Dong XU,Yu ZHAO,Chao LIU

期刊论文

Experimental investigation on concrete overlaid with textile reinforced mortar: Influences of mix, temperature

期刊论文

Axial compression tests and numerical simulation of steel reinforced recycled concrete short columnsconfined by carbon fiber reinforced plastics strips

Hui MA; Fangda LIU; Yanan WU; Xin A; Yanli ZHAO

期刊论文

Investigation on modeling parameters of concrete beams reinforced with basalt FRP bars

Jordan CARTER, Aikaterini S. GENIKOMSOU

期刊论文

Predetermination of potential plastic hinges on reinforced concrete frames using GFRP reinforcement

Dominik KUERES; Dritan TOPUZI; Maria Anna POLAK

期刊论文

Slender reinforced concrete shear walls with high-strength concrete boundary elements

期刊论文

Punching of reinforced concrete slab without shear reinforcement: Standard models and new proposal

Luisa PANI, Flavio STOCHINO

期刊论文

Strengthening of reinforced concrete beams using fiber-reinforced cementitious matrix systems fabricated

期刊论文

Fatigue shear performance of concrete beams reinforced with hybrid (glass-fiber-reinforced polymer+ steel

期刊论文

Experimental flexural behavior of SMA-FRP reinforced concrete beam

Adeel ZAFAR, Bassem ANDRAWES

期刊论文

Experimental and modeling studies on installation of arc sprayed Zn anodes for protection of reinforcedconcrete structures

Xianming SHI

期刊论文

Deflection behavior of a prestressed concrete beam reinforced with carbon fibers at elevated temperatures

Mohammed FARUQI, Mohammed Sheroz KHAN

期刊论文

Numerical simulation of squat reinforced concrete wall strengthened by FRP composite material

Ali KEZMANE,Said BOUKAIS,Mohand Hamizi

期刊论文

Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fineconcrete shells

期刊论文