Reinforced Concrete Structures Research Articles

Strategies for Teaching the Reinforced Concrete Structures Course in Engineering Majors

The cultivation of engineering capabilities aims to equip engineering professionals with high-level expertise to meet the demands of society and industry development, thereby enhancing their competitiveness and career potential. This article focuses on engineering capability development, exploring teaching strategies for the Reinforced Concrete Structure course. It aims to provide insights for educators in engineering programs at universities and vocational colleges in China. By doing so, teaching plans that meet the needs of engineering capability development, laying a solid educational foundation for the healthy growth of engineering professionals in the new era, and enhancing their application of knowledge and skills can be developed.

Reducing target reliability index of concrete bridge beams through compression yielding

Damage to reinforced concrete (RC) bridges due to accidental overloading is inevitable, especially for those that deteriorate over time due to various environmental and operational factors. When significant damage occurs, it needs to be replaced. However, replacing bridges is expensive and time-consuming. This problem can be well resolved by the concept of compression yield (CY) structures. When an overload occurs, the CY block in the beam is triggered like a fuse, forcing the beam to deform in a ductile manner, thus preventing further overloads. Additionally, the damaged CY blocks can be replaced without replacing the entire beam. Due to this safer failure mode and lower cost of failure, the safety reserve of the CY beam can be significantly lower than that of the traditional RC structure, which means that the target reliability of the CY bridge needs to be re-established. The objective of this study is to develop the target reliability of CY bridge. The target reliability of structures is determined through cost optimization. The life-cycle costs for bridges are determined based on the practical construction and post-construction management process. The calculated results indicate that although the initial cost of CY beams could be higher, the losses associated with failures are significantly lower compared to RC beams. Consequently, the target reliability and life cycle costs of CY bridge can be lower than those of the RC bridge.

Cross-Sectional Capacities of Reinforced Concrete Structures Using Abaqus and Staadpro Software

Cross-Sectional Capacities of Reinforced Concrete Structures Using Abaqus and Staadpro Software

Modelling of Steel Concrete Composite Elements Cross-Sections with Adhesive Connections

Abstract Nowadays, complex steel-concrete composite structures are widely used, which combine the advantages and eliminate the disadvantages of similar metal and rein-forced concrete structures. With the help of the LIRALAND software complex (automated design system), which is effectively used in the scientific and practical field of the construction industry of Ukraine, the article presents the study of composite cross-sections taking into account the modern experience of foreign specialists. Numerical modelling with the help of the “Section Designer” software module of “LIRA-SAPR” makes it possible to reliably assess the performance of structural elements, taking into account changes in a significant number of studied parameters.

Frequency Responses of a Graphene Oxide Reinforced Concrete Structure

This paper presents a comprehensive investigation on the vibrations of reinforced concrete structure by graphene oxide powders (GOPs) using a polynomial displacement field and the Generalized Differential Quadrature Method (GDQM). The study focuses on analyzing the dynamic behavior of the structure and assessing the effects of three different distribution patterns of GOPs on its vibrations. To accurately model the deformation of the pressure vessel, a polynomial displacement field is employed, taking into account the complex geometrical and material properties of the structure. The results highlight the significant influence of the distribution pattern of GOPs on the natural frequencies of the spherical concrete pressure vessel. The analysis reveals that variations in the weight fraction and arrangement of GOPs have a direct impact on the stiffness and dynamic characteristics of the structure. Specifically, increasing the weight fraction of GOPs generally leads to higher natural frequencies, indicating enhanced structural rigidity. Moreover, the polynomial displacement field and GDQM demonstrate their effectiveness in accurately predicting the vibrations of the reinforced pressure vessel. The combination of these numerical techniques enables efficient and reliable analysis of the dynamic response, allowing for optimization of the design and performance of spherical concrete pressure vessels.

Influence of Corrosion on Lifespan of Reinforced Concrete Structures: A Comprehensive Review

Carbonation-induced corrosion is a major concern for reinforced cement concrete (RCC) structures, impacting their long-term durability and structural integrity. This review synthesizes the findings on the deterioration mechanisms in concrete structures, focusing on carbonation, chloride-induced corrosion, and time-dependent deterioration. The analysis includes discussions on predictive likelihood methods for estimating bridge reliability, the impact of environmental factors on carbonation, and standardized testing methods for assessing concrete durability. The review highlights the importance of understanding material characteristics and environmental conditions in designing durable concrete structures, emphasizing the processes of carbonation, its impact on rebar corrosion, and strategies for mitigation. Sheltered concrete carbonation resistance in metropolitan tropical climates is 10-20% lower than open exposure. SCM concretes exhibit equivalent or greater long-term carbonation resistance to OPC concretes, as evidenced by the increase in carbonation depth ( Δ xd) at ages greater than 5 years. The paper concludes with recommendations for integrating advanced modeling techniques and empirical studies to develop robust maintenance strategies and improve concrete mix designs for enhanced durability.

Evaluation of Residual Structural Capacity in Corroded Reinforced Concrete Structures

Reinforcement corrosion is a critical issue that affects the durability and service life of reinforced concrete structures. This study focuses on evaluating the effectiveness of natural corrosion inhibitors in mitigating the corrosion attack on reinforced concrete beams in saline environments. The study utilizes extruded exudates/resins obtained from plants and characterizes their potential eco-friendly and non-hazardous properties. The corrosion resistance of uncoated and coated steel reinforcements is examined through exposure to a 5% sodium chloride solution for 360 days. The samples are subjected to flexural beam tests at regular intervals to assess changes in mechanical properties. The results indicate that natural corrosion inhibitors can effectively improve durability and maintain higher residual strength capacities, even under severe exposure conditions. Coated bars show higher residual capacities and yield strengths compared to uncoated bars, attributed to the protective effect of the coatings. The inhibitors also reduce corrosion rates and preserve mechanical properties like yield strength and ductility, enhancing the service life of reinforced concrete structures. The study emphasizes the use of locally available materials to counteract the negative effects of corrosion attack in marine environments.

Computational and Experimental Substantiation of Strengthening Reinforced Concrete Structures with Composite Materials of Power Plants under Seismic Action

In Russia, a significant number of power facilities built in the 1960s and 1970s are located in regions where seismic effects were revised upward. This has led to an increase in the seismicity of the sites of facilities’ locations by magnitude 1–2 (MSK-64) in comparison with the data of design documentation. During the long-term operating period of power facilities, the load-bearing capacity of building structures, as a rule, decreases. This article presents the results of computational and experimental studies of reinforced concrete structures of thermal power plants and hydroelectric power plants for seismic effects in the range of magnitude 4–10 (MSK-64). The computational studies were carried out using ANSYS 16.0 software, and experimental studies were carried out on stands modeling seismic impacts with the help of hydraulic cylinders. The results of the studies showed that cracking of reinforced concrete structures without strengthening occurs at magnitude 6.0 (MSK-64) of seismic impact, and destruction occurs at magnitude 7.5. Thus, the seismic resistance of structures without reinforcement does not meet the requirements for seismic resistance, and strengthening is required. This study considers a variant of strengthening based on external composite reinforcement with CFRP. It is shown that the strengthening of structures with composite material increases their earthquake resistance up to magnitude 9–10 (MSK-64). This article presents recommendations on the CFRP strengthening of building structures of power facilities, both after receiving damage under seismic impact and in a planned manner to increase seismic resistance. The novelty of this work lies in the fact that quantitative results of increasing the seismic resistance of structures depending on the placement and number of layers of composite material are given.

Multi-Objective Optimization in Support of Life-Cycle Cost-Performance-Based Design of Reinforced Concrete Structures

Surveys on the optimum seismic design of structures reveal that many investigations focus on minimizing initial costs while satisfying performance constraints. Although reducing initial costs while complying with earthquake design codes significantly ensures occupant safety, it may still cause considerable economic losses and fatalities. Therefore, calculating potential earthquake damages over the structure’s lifetime is essential from an optimal Life-Cycle Cost (LCC) design perspective. LCC analysis evaluates economic feasibility, including construction, operation, occupancy, maintenance, and end-of-life costs. The population-based, meta-heuristic Ideal Gas Molecular Movement (IGMM) algorithm has proven effective in solving highly nonlinear mono- and multi-objective engineering problems. This paper investigates the LCC-based mono- and multi-objective optimum design of a 3D four-story concrete building structure using the Endurance Time (ET) method, which is employed for its efficiency in estimating structural responses under varying seismic hazard levels. The novelty of this work lies in integrating the ET method with the IGMM algorithm to comprehensively address both economic and performance criteria in seismic design. The results indicate that the proposed technique significantly reduces minor injury costs, rental costs, and income costs by 22%, 16%, and 16%, respectively, achieving a total reduction of 10% in all structural Life-Cycle Costs, which is considered significant.

Utilizing Electrochemical Techniques for Assessing the Probability of Concrete Resistivity and Corrosion Potential in Reinforced Concrete Structures

Corrosion of reinforcing steel is a major durability issue for reinforced concrete structures exposed to aggressive environments. Early assessment of corrosion probability is important for effective maintenance planning. This study investigates the application of non-destructive electrochemical methods like concrete resistivity and half-cell potential measurement, along with integrated assessment and advanced techniques, for evaluating corrosion risk in reinforced concrete. Concrete specimens with and without Albizia amara resin coating were subjected to accelerated corrosion testing. Concrete resistivity and half-cell potential values showed an inverse correlation, with lower resistivity indicating higher corrosion risk. Resistivity and potential results for the coated samples exhibited intermediate values compared to the control and corroded samples, demonstrating the resin's partial passivating effects. Rebar diameter measurements before and after exposure confirmed corrosion led to reductions in diameter and cross-sectional area, which coating mitigated. Statistical analysis validated the significant impacts of original bar diameter and corrosion level on subsequent geometry changes. Mechanical testing of reinforcing steel bars found the control samples had the highest strength and ductility, while the coated bars exhibited properties closer to the controls than the corroded bars. The protective capabilities of the bio-based Albizia amara resin coating were validated through multipoint monitoring of material durability parameters. Overall, results demonstrated the effectiveness of integrated electrochemical testing with non-destructive techniques for comprehensive condition assessment and corrosion risk evaluation in reinforced concrete structures

Effect of Corrosion Inhibitors on Bond Strength of Reinforced Concrete Structures

Corrosion of steel reinforcement is a major factor affecting the durability and strength of reinforced concrete structures. This study investigated the influence of plant-derived corrosion inhibitors, applied as coatings, on the bond strength between reinforcing steel and concrete. Thirty-six 150 mm concrete cubes with 12 mm diameter embedded steel bars were prepared and divided into uncoated, corrosion inhibitor coated, and control groups. The samples were immersed in 5% sodium chloride solution over 360 days to accelerate corrosion. Pull-out testing measured the bond strength and failure load. The corroded samples showed 31-26% lower bond strength and 82-87% higher maximum slip than controls, indicating corrosion damage at the steel-concrete interface. However, inhibitor-coated samples displayed 24-36% higher bond strength and 42-43% lower maximum slip versus corroded samples. Although the coatings did not fully restore original bond strength, this demonstrates their effectiveness at protecting bond properties. Microscopic analysis revealed non-uniform, localized corrosion preferentially initiated at steel defects. Statistical correlations confirmed the direct relationship between steel weight loss and reductions in post-corrosion rebar weight due to material loss. While nominal rebar diameters showed minimal differences between sample types, localized diameter reductions and cross-sectional area increases in corroded samples highlighted discrete corrosion effects. These were mitigated in coated samples. Together with direct weight loss measurements, this proves corrosion occurred in unprotected samples. Overall, the significant recovery of bond strength, slip resistance, diameter, area, and weight in coated samples validates the success of the natural corrosion inhibitors in reducing steel deterioration and interface degradation. The results provide new insights on optimizing inhibitor coatings to maximize corrosion protection for reinforced concrete structures.

Carbon emissions of durable FRP composite structures in civil engineering

Conventional structural materials—concrete and steel—have been producing a substantial amount of carbon emissions to the earth, accounting for over 50 % of industrial emissions worldwide. An urgent call has been made for an alternative structural material with a better environmental impact. In this regard, this work investigated the carbon emissions of durable FRP composite structures in civil engineering. Three typical FRP composite structures were focused, including pedestrian bridges constructed by FRP structural profiles, concrete structures reinforced by FRP rebars, and existing concrete and steel structures strengthened by FRP sheets. Carbon emissions were investigated in terms of the carbon footprints per available dataset. Direct carbon reductions were observed in three FRP composite structures, and also, indirect carbon reductions were discussed, including FRP reinforcement for concrete structures and FRP enclosure for houses. The observed carbon reductions realized by FRP composite structures successfully showcased their great potential in reducing the carbon emissions in civil engineering.

Flexural Strength of Reinforced Concrete Structures Exposed to Corrosive Media

This study investigated the effect of corrosion on the flexural behavior and midspan deflection of reinforced concrete beam members. Control, corroded, and resin-coated concrete beam specimens were tested to determine their failure load, midspan deflection, rebar diameter measurements, and mechanical properties. The results showed that corrosion significantly reduced the flexural strength and increased the midspan deflection of beams due to weakening of the reinforcing steel. The average failure load of corroded beams decreased by 25.73% compared to the control beams. Similarly, the average midspan deflection of corroded beams increased by 103.8% over the control beams. Measurements of rebar diameters before and after corrosion revealed reductions of up to 0.87% in corroded samples, substantiating corrosion-induced thinning. Additionally, mechanical properties testing showed decreases in ultimate tensile strength, yield strength, and strain ratio while increasing ductility for corroded rebars. Resin coating prevented much of the strength loss and provided protective benefits near that of the control specimens. The relationship between failure load, midspan deflection, diameter measurements, mechanical properties and corrosion damage was investigated through analytical comparisons. Corroded samples consistently demonstrated lower failure loads, higher deflections, reduced diameters and strengths versus controls. Conversely, coated samples performed similarly to controls, validating the coating's effectiveness. This research quantitatively confirms literature reports that corrosion degrades reinforced concrete through weakening of rebar-concrete bond and steel deterioration over time if left unprotected. The findings emphasize the importance of mitigating corrosion to ensure structural integrity, safety and durability of reinforced concrete infrastructure.

An improved peridynamic model for mechanical behavior of steel-concrete interface

The steel–concrete interface is an important component of reinforced concrete (RC) materials, and accurately expressing the mechanical properties of the interface is crucial to the failure analysis of RC members. The unique superiorities of peridynamic (PD) theory in dealing with discontinuities make it extensively applied in the failure analysis of RC structures. This paper introduces a modified PD model for describing the mechanical behavior of the steel–concrete interface. The ideal microplastic PD model and bilinear PD model are applied to express the mechanical behavior of steel and concrete respectively. Furthermore, the strain rate effect of materials is also incorporated in the analysis of dynamic damage to RC members subjected to blast load. A parallel (OpenMP) program was developed using FORTRAN to implement the computation of the modified PD model. Finally, the modified PD model was utilized for the numerical simulation of the RC beam shear-flexural failure experiment and the RC slab explosion failure experiment. Research shows that the modified PD model can correctly describe the mechanical behavior of the steel–concrete interface.

Resilient and Sustainable Structures through EMI-Based SHM Evaluation of an Innovative C-FRP Rope Strengthening Technique

Reinforced Concrete (RC) members in existing RC structures are susceptible to shear-critical due to their under-reinforced design. Thus, implementing a retrofitting technique is essential to eliminate the casualties that could arise from sudden and catastrophic collapses due to these members’ brittleness. Among other proposed techniques, using Carbon-Fiber Reinforced Polymers (C-FRP) ropes to increase the shear strength of RC structural elements has proved to be a promising reinforcement application. Moreover, an Electro-Mechanical Impedance (EMI-based) method using Lead Zirconate Titanate (PZT-enabled) was employed to assess the efficiency of the strengthening scheme. Initially, the proposed technique was applied to C-FRP rope under the subjection of pullout testing. Thus, a correlation of the rope’s tensile strength with the EMI responses of the PZT patch was achieved using the Root Mean Square Deviation (RMSD) metric index. Thereafter, the method was implemented to the experimentally acquired data of C-FRP ropes, used as shear reinforcement in a rectangular deep beam. The ropes were installed using the Embedded Through Section (ETS) scheme. Furthermore, an approach to evaluate the residual shear-bearing capacity based on the EMI responses acquired by being embedded in and bonded to the ropes’ PZTs was attempted, demonstrating promising results and good precision compared to the analytical prediction of the C-FRP ropes’ shear resistance contribution.

Life-cycle performance prediction and interpretation for coastal and marine RC structures: An ensemble learning framework

Long-term exposure to coastal and marine environments accelerates the aging of reinforced concrete (RC) structures, impacting their structural safety and society impact. Traditional assessments of long-term performance deterioration in RC structures involve complex, nonlinear, and time-intensive studies of physical mechanisms. While existing machine learning (ML) methods can assess the lifetime of these structures, they often prioritize data regression over mechanistic interpretation. To enhance the efficiency and interpretability of predicting the life-cycle performance of RC structures, this study introduces a generic framework based on interpretable ensemble learning (EL) methods. The framework predicts life-cycle performance efficiently and accurately, with optimal hyperparameters automatically tuned through Bayesian optimization. Interpretability algorithms clarify the influence of environmental, durability, and mechanical parameters on structural durability and mechanical predictions. Validation employs real-world cases of RC hollow beams in the coastal area of the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). The comprehensive model for RC structures integrates actual data on temperature, humidity, and surface chloride content in the GBA, considering diffusion, convection, and binding effects of chloride ions, corrosion non-uniformity, and crack impact on durability estimation. Comparative analysis with existing ML methods underscores the effectiveness of the framework. The findings highlight the dynamic evolution of feature importance rankings throughout the service life, shedding light on the continuous changes in the significance of different factors when predicting mechanical resistance.

Study on the fire resistance of RC beams reinforced with BFRP and HFRP bars

For non-metallic reinforcement to be successfully integrated into residential and commercial construction, extensive research is required to understand the structural performance of Fiber Reinforced Polymer (FRP) reinforced concrete (RC) elements in various conditions, including the effect of elevated temperatures on structural performance. To accomplish this, a full-scale investigation was performed on the structural performance of FRP-RC elements subjected to elevated temperatures. The study involved conducting fire tests on beams, where the midsection was heated from below (tension zone) and the sides while being simultaneously loaded with 50% of their ultimate loads. The beams were reinforced with Basalt FRP (BFRP) bars and a hybrid composite of Carbon and Basalt Fibers (HFRP) bars. The HFRP-RC beams showed better resistance to the combined effect of loading and elevated temperatures compared to BFRP-RC beams. This study provides insights into the behavior of FRP materials in RC structures subjected to high temperatures, and contributes to the advancement of knowledge in this field.

Analysis of Progressive Collapse Resistance in Precast Concrete Frame with a Novel Connection Method

The configuration of beam–column joints in precast concrete (PC) building structures varies widely, and different connection methods significantly affect the progressive collapse resistance of the structure. This study investigates the progressive collapse resistance of an innovative beam–column connection node frame. Finite element models of four-story, two-span space frame structures made of reinforced concrete (RC) and PC were developed using ANSYS 14.0/LS-DYNA R5.x software, employing nonlinear dynamic and static analysis to examine structural collapse behavior under bottom middle or corner column damage. Numerical results indicate that following the failure of the middle or corner column due to explosion loading, the vertical displacement and collapse rate of the PC structure with the novel connection method are less than those of the RC structure during collapse progression. Furthermore, upon removal of the middle or corner column, the residual load-carrying capacity of the PC structure with the innovative connection increased by 7% and 3.7%, respectively, compared to the RC structure. This suggests that PC structures with this type of connection demonstrate superior performance in resisting progressive collapse, offering valuable insights for future engineering applications.

Nonlinear Static Soil-Structure Interaction Analysis of Time-Dependent Soil Deformation Effects on RC Structures

Soil response and superstructure behavior are two major factors influencing the long-term performance of reinforced concrete (RC) structures. Maintaining the structural integrity of these structures over time is crucial due to the complex static interactions between the soil and the structure. This study uses a finite element model to examine the stability of RC structures, considering the long-term static interactions between the nonlinear behavior of the soil and the structure. Numerical simulations are performed on real RC beam constructions at serviceability limit states (SLS) under various loading scenarios in both homogeneous and heterogeneous soil conditions. The parametric study's results indicate that soil heterogeneity and static soil-structure interactions significantly influence the design of RC structures. The nonlinear behavior of the soil over time intensifies these impacts further. This study shows how important it is to think about different types of soil and how they interact with structures when they are not moving. This is especially true when it comes to soil that is easily compressed and changes shape over time in a nonlinear way. By incorporating these factors, the research highlights the critical need to integrate soil heterogeneity and static interaction into the design process to ensure the stability and safety of RC structures. Ultimately, the results demonstrate that accounting for these complex interactions can greatly improve the durability and reliability of RC structures in diverse soil conditions.

3D FRP Reinforcement Systems for Concrete Beams: Innovation towards High Performance Concrete Structures.

Despite the advantages of using lightweight and non-corrosive carbon fiber reinforced polymer (CFRP) reinforcements in concrete structures, their widespread adoption has been limited due to concerns regarding the brittle failure of CFRP rupture and its relatively softer load-deflection stiffness. This work offers logical solutions to these two crucial problems: using aggregate coating to strengthen the CFRP-concrete bond and ultimately the load-deflection stiffness, and using CFRP-concrete debonding propagation to create pseudo-ductile behavior. Subsequently, the concrete cracking behavior, the apparent CFRP modulus with aggregates, and the post-peak capacity and deflection of three-dimensional (3D) CFRP-reinforced concrete are all described by equations derived from experiments. These formulas will be helpful in the future design of non-prismatic concrete components for low-impact building projects. The potential of this innovative design scheme in terms of increased capacity and deflections with less concrete material is demonstrated through comparisons between non-prismatic CFRP-reinforced concrete and measured steel reinforced equivalency.