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Plasterboard, a commonly utilized construction material, comprises a gypsum core nestled between two paper layers. Gypsum after demolition of plasterboards is a recyclable waste that has been reused into new plasterboard or other purposes such as agricultural products. However, there is a lack of understanding on the potential for recycling the paper layers. This study investigates the use of wastepaper fibers, obtained from the paper layers, as a reinforcing material and metakaolin as a partial cement replacement material in concrete. This study demonstrates the ability of the paper from waste plasterboard for reinforcing concrete. Wastepaper fibers were used at different concentrations ranging from 0 to 2.5% by weight of binder. Bending test was conducted for assessing fracture behavior of concretes, including load bearing capacity, modulus of rupture, crack mouth opening displacement (CMOD) at the load bearing capacity, fracture toughness, and fracture energy. Slump, axial compression, and scanning electron microscopy (SEM) were also conducted on the concretes. It is found that incorporating wastepaper fiber by up to an optimum content of 1.5% results in an increase in the compressive strength (57%), flexural load bearing capacity and modulus of rupture (31%), CMOD displacement at load capacity (14%), fracture toughness (37%), and fracture energy (73%) of the metakaolin‐based concrete. However, further increase in the wastepaper fiber content results in decreased mechanical properties of the concrete, which is due to the fiber agglomeration and non‐uniform distribution within the concrete matrix. Based on the results, the concrete with 20% metakaolin and 1.5% wastepaper fiber experiences similar mechanical properties to the conventional concrete. The results of this study underscore the substantial potential of leveraging waste materials such as wastepaper and by‐products like metakaolin to diminish reliance on conventional cement. This approach not only enhances the mechanical properties of concrete but also fosters sustainable building practices by promoting the recycling of waste materials, reducing carbon footprint, and mitigating the environmental impacts inherent in traditional concrete production. [ABSTRACT FROM AUTHOR]

Plastic concrete is a kind of flexible concrete cutoff wall material, which is used to solve the problem of poor coordinated deformation ability between ordinary concrete cutoff wall and surrounding soil. It has the characteristics of small elastic modulus and large limit strain, which greatly improves the operation condition of cutoff wall. In order to save bentonite resources and recycle waste automobile tires, this paper crushed waste automobile tires into rubber particles and mixed them into plastic concrete, through the uniaxial compression test and triaxial compression test, obtained the corresponding stress–strain curve, rubberized plastic concrete strength and deformation properties are studied and the rubber particles and the relationship between dosage. The test results show that the compressive strength of rubberized plastic concrete decreases with the increase of rubber particles content, but the deformation capacity increases with the increase of rubber particles content. In this paper, the regression analysis of rubberized plastic concrete constitutive relation and failure criterion including the influence factor of rubber particles are helpful to promote the engineering application of rubberized plastic concrete and reduce the exploitation of natural resources and environmental pollution. [ABSTRACT FROM AUTHOR]

The paper proposes different statistical parameters for model uncertainties depending if we are designing a new structure or evaluating an existing one. The reason is that for existing structures lower values of the concrete compressive strength as well as lower ratios of concrete cover to bar diameter can be found, in comparison to new structures. In my opinion, the correct approach to take into account the different level of uncertainty in new or existing structures would be to deal with the model uncertainty by splitting the range of possible parameters in different sets and to find the best fit between the experimental and model values for the different sets, independent of the type of structure (new or existing). [Extracted from the article]

MC2020, with sustainability and performance‐based design at its core, is the model code for future thinking. It is designed so that both new construction and interventions can be completed based on this model code, bringing together the world's most advanced technologies. In this paper, the basic stance of fib toward sustainability is firstly described. Then, as the future envisioned by MC2020, examples of low‐carbon concrete structures will be presented. The paper also discusses the form and uses of conceptual design that MC2020 emphasizes and presents examples of new construction and the extension of service life/adaptation/upgrading of existing structures. New technologies for a circular economy will also be proposed. Sustainability has economic, social, and environmental aspects, and the optimization of each will eventually lead to carbon neutrality. It can be said that MC2020 will help us to arrive at solutions to those complex challenges. [ABSTRACT FROM AUTHOR]

Crystalline admixture (CA) has been extensively utilized as the commercial product for improving the performance associated with strengthening self‐sealing of cracks or decreasing the permeability of concrete. However, few researches characterizing the restrained shrinkage and cracking potential of concrete with CA at early age. This paper aimed to expand the limitation by means of the experiments including mechanical properties test and restrained ring test on high‐strength concrete (HSC) with CA from Xypex. The proportion of CA was 0%, 0.5%, 1.0%, and 1.5% by the mass of cement. The incorporation of CA enhanced the compressive and splitting tensile strength as well as modulus of elasticity tested in this paper. A significant increase was observed in free and restrained shrinkage of HSC with CA. Although incorporation of CA ameliorated the stress relaxation, residual stress in restrained concrete ring developed rapidly with the incorporation of CA due to the significant increase in restrained shrinkage at early age. Restrained concrete ring with CA demonstrated a higher stress rate, which implied a higher cracking potential. When CA proportion increased from 0% to 0.5%, 1.0%, and 1.5%, a higher cracking potential was revealed through calculation, and restrained concrete ring exhibited earlier cracking age. Caution should be exercised with the application of such CA in concrete mixtures under restrained conditions. [ABSTRACT FROM AUTHOR]

This paper presents a five-spring model capable of predicting the complete pre- and post-peak shear behaviour of deep beams. The model stems from a two-parameter kinematic theory (2PKT) for the shear strength and displacement capacity of deep beams under single curvature. Four of the springs of the model represent the shear resistance mechanisms of the beam, while the fifth spring models the flexural behaviour. The model predicts not only the load-displacement response, but also the deformation patterns of the beam and how these patterns change with increasing load. Validation studies are performed by using 28 tests from the literature, showing excellent results. The model is used to interpret the tests and to draw conclusions about the behaviour of deep beams. It is shown that shear strength variations of up to 60 % between nominally identical specimens can be caused by variations in the path of the critical shear cracks. It is also demonstrated that loss of bond of large reinforcing bars increases the shear capacity of deep beams. Finally, the five-spring model is shown to predict the post-peak shear behaviour effectively, which is important for the analysis of structures under extreme loading. [ABSTRACT FROM AUTHOR]

The paper presents integrated effects of concrete samples size and fibers amount on compressive strength of high‐ and ultra‐high strength concretes based on reactive powders. Ready to use the self ‐ compacting mix of high‐performance concrete, was applied. The main aim of the work was to determine compressive strength correlation coefficients for size of cubic samples and integrated compressive strength correlation coefficients for the size of cubic samples including fibers ratio. The article presents the results of experimental tests of compressive strength for 3 sizes of cubic samples, i.e. 40, 100, and 150 mm, with the application of the steel fibers ratio of 0%, 2%, 4% for each sample size. Concrete air content and cone flow test studies were performed for all research series. The obtained results show a diversified influence of the size of the samples and the amount of steel fibers on the results of concrete compressive strength of high‐ and ultra‐high strength concretes based on reactive powders. Namely, the compressive strength correlation coefficient for the size of cubic samples was determined in the range 1.0–1.3, while the integrated compressive strength correlation coefficient the for size of cubic samples including fibers ratio is in the range 1.0–1.47. [ABSTRACT FROM AUTHOR]

Eurocode 2 consists of four parts that have to be applied in conjunction with the respective National Annexes of the CEN member states. The National Annexes were introduced, in particular, to maintain national safety levels and to account for regional aspects in the different states. The CEN (European Committee for Standardization) will revise and extend all structural Eurocodes by 2018. As part of that process, two main objectives for revising Eurocodes have been formulated: a reduction in the number of Nationally Determined Parameters (NDP) and improving the 'ease of use'. In order to reduce the number of NDP, improve the ease of use and allow for further harmonization without changing the main structure and the design models of Eurocode 2, the National Annexes of EN 1992-1-1 for the different CEN member states have been compared and analysed. Furthermore, the analysis of the National Annexes may help to identify some main aspects for the revision of Eurocode 2. This paper summarizes the analysis of the National annexes of EN 1992-1-1 and makes first proposals for further harmonization. [ABSTRACT FROM AUTHOR]

The paper portrays a comprehensive computational procedure for determining the global structural resistances of two existing bridges made of I‐73 and KA‐61 precast post‐tensioned concrete girders using advanced statistical assessment methods in combination with nonlinear fracture mechanics‐based finite element method analysis. Although this combination is a powerful tool for realistic modeling of structures, its practical application is still very time consuming. Therefore, a statistical sampling approach for the determination of the structural design resistance is compared to selected efficient semi‐probabilistic methods based on the estimation of coefficient of variation—estimation of coefficient of variation (ECoV) method according to fib Model Code 2010 and improved approach called Eigen ECoV method. Load‐bearing capacity is determined for the ultimate as well as several serviceability limit states. The sensitivity of the input parameters burdened with uncertainties on the response of the structure is quantified using a sensitivity analysis supported by a surrogate model based on polynomial chaos expansion. The paper shows that the applicability of nonlinear modeling with respect to uncertainties is possible when using these ECoV methods and a surrogate model and can be applied in a routine manner. The shortcomings and advantages of all the used safety design/assessment methods are discussed. [ABSTRACT FROM AUTHOR]

In modern construction, one of the most important factors in the execution of contracts is time. Standard procedures for assessing the frost resistance or concrete are usually very time‐consuming and can take up to 40 days. The current paper is experimentally and practically oriented. It presents an alternative testing method, based on air void network, that allows to assess the frost resistance of concrete within just a few days of taking the samples. X‐ray micro‐CT scans were introduced to obtain the quantitative and qualitative 3D information about the air void microstructure taking into account total air content: A (%), pores of the size below 300 μm in diameter content: A300 (%), specific surface of air voids: α (mm−1) and spacing factor: L (mm) to predict the freeze/thaw durability. To verify the assumptions of the frost resistance method, based on the analysis of pore microstructure, tests of freeze/thaw resistance in accordance with Polish supplement to European Standard were carried out. Presented research revealed that the appropriate microstructure of air pores, in particular, content of micropores with the diameter less than 0.3 mm: A300 combined with a spacing factor: L (mm) can constitute a reliable basis for determining concrete freeze/thaw durability. Thus, the method proposed in the current paper can be effectively used for fast and trustworthy determination of the air‐entrained concrete durability in a short time and without any special preparation of the tested sample that allows immediate preventive or repair actions to be taken if required. [ABSTRACT FROM AUTHOR]

This paper describes the use of joints with bent bars and postcast ultrahigh‐performance concrete (UHPC) joints to enable formwork‐free and support‐free construction of composite slabs. To investigate their flexural performance, static loading tests on three full‐scale simply‐supported slabs and one monolithic slab were carried out. Flexural capacity, stiffness, and crack development were recorded, resulting on flexural failure experienced by all specimens. Main cracks of composite specimens developed along the UHPC–normal concrete interface, and cracks on both sides of the UHPC joint developed evenly, similar with that of the monolithic specimen. Besides, composite slabs and a monolithic slab showed similar flexural capacity. UHPC joint was not cracked when failure occurred, and bottom bars were anchored and connected in the UHPC joint, proving that the flexural anchorage method is feasible. The average strain of the composite specimen across the UHPC joint was still consistent with the assumption of plain section, and there was an approximate linear relationship between the expansion width of the joint at the bottom of the slab and the maximum crack width at bottom bars. Moreover, middle bars contributed to the flexural capacity and stiffness of composite specimens, while horse stool reinforcement may effectively prevent the interface shear failure on the composite interface. Based on test results, the formula to control cracking of UHPC is given in this paper. The design methods on flexural capacity, stiffness, and expansion width of composite slabs are also presented and discussed. [ABSTRACT FROM AUTHOR]

In this paper, five specimens were designed to test under monotonic static loading to study the axial compression performance of steel tube‐reinforced high‐strength recycled aggregate concrete composite columns with steel bars. The design parameters for these specimens include the type of concrete, the sectional shape of the steel tube (circular or square), and the internal structure of the core column, specifically the presence or absence of cross‐shaped tie bars in the square steel tube. The effects of different parameters on the axial load–displacement curve, bearing capacity, and ductility were analyzed. The test results show that the failure of all specimens was caused by the concrete cover spalling of outer reinforced concrete, which occurred after the longitudinal strain of the steel tube exceeded the yield strain. The ultimate bearing capacity of the recycled aggregate concrete (RAC) specimen is higher than that of the natural aggregate concrete (NAC) specimen, but the latter has a more robust deformation performance. Furthermore, under the condition of the same steel tube cross‐sectional area and similar material strength, the bearing capacity and deformation capacity of specimens with circular steel tubes are higher than those of specimens with square steel tubes. A similar conclusion was also obtained for square steel tube specimens with cross‐shaped tie bars. Finally, four international design methods were applied to estimate the axial compression capacity of 40 composite columns, as detailed in this paper and other sources. [ABSTRACT FROM AUTHOR]

The current paper presents an innovative form of the cold‐formed U‐shape steel encasing concrete composite beam (CUCB). The suggested CUCB consists of a cold‐formed U‐shaped steel encasing plain concrete beam which are connected to each other using continuous transversal threaded stud bolts. The experimental program consisted of eight beam specimens tested in the four‐point bending set‐up. One of them was a normal reinforced concrete beam and considered as a reference specimen while the remaining specimens were CUCB specimens without ordinary flexural and shear reinforcement. Four parameters were studied in this paper: (i) the thickness of the U‐shaped steel, (ii) the spacing between the stud bolts, (iii) the arrangement of the bolts, and (iv) the number of the bolt's rows. Results indicated an overall improvement in the load‐carrying capacity and stiffness of most CUCB specimens in comparison with the reference specimen. It was found that the using of three rows of bolts can significantly improve the ductility and toughness of the CUCB specimen in comparison with two rows of bolts. On the contrary, an increase in the bolt spacing entails a decrease in the CUCB specimens' toughness. [ABSTRACT FROM AUTHOR]

This paper investigates the strengthening of non‐ductile reinforced concrete (RC) columns using partial steel‐plate jacketing to enhance ductile capacity. Quasi‐static cyclic loading tests were conducted on three rectangular RC columns with varying shear‐span‐to‐depth ratios, evaluating the effectiveness of steel‐plate jacketing. Results show improved ductile flexural response, high drift capacity, and maintained gravity‐loading capacity under high lateral displacements. A numerical investigation, adopting a multi‐spring fiber section model, predicted cyclic lateral strength, drift ratio, and failure mode, accurately simulating reinforcement behavior and capturing the shear‐strength enhancement due to steel‐plate jacketing. Numerical results demonstrated good agreement with experimental findings. Based on these outcomes, a simple design procedure for retrofitted concrete columns, applicable to design engineers, has been developed and reported in this paper. This study contributes valuable insights into the practical applications of steel‐plate jacketing for non‐ductile RC column retrofitting, offering a comprehensive approach to predicting their seismic performance. [ABSTRACT FROM AUTHOR]

This paper investigated the analytical solution of the bond strength between ribbed steel bar and engineered cementitious composites (ECC). In this method, ECC cover was regarded as a thick‐walled cylinder subjected to the uniform internal pressure which consisted of an elastic uncracked outer ring and a partially cracked inner ring. For the uncracked outer ring, it can be solved by the elastic mechanics theory. To solve the partially cracked inner ring, two key problems that had to be investigated were the crack width and the tensile stress–crack width relationship of ECC. According to the steady‐state cracking mode, the hoop deformation of ECC was expressed by the equal distribution and then the crack width can be determined. Besides, the fictitious crack model in fracture mechanic was introduced to describe the crack propagation process. Then a trilinear model was applied to reflect the tensile stress–crack width relationship of ECC materials, which considered the combined action of aggregate bridging and fiber bridging on the crack surface. Finally, the comparison between the calculation results and experimental results was carried out to prove the validity of the analytic method of bond strength proposed in this paper. Results indicated that the analytical solution and the experimental data fitted in well with each other. Then parameter analyses were conducted based on the analytical method proposed in this paper. [ABSTRACT FROM AUTHOR]

Estimating the stress of reinforcing bars and its variations in service conditions can be useful to determine the reserve capacity of structures or to assess the risk of fatigue in the reinforcement. This paper investigates the use crack width measurements to estimate the stress in the bars. In existing structures, crack width formulations can be used to estimate the stress in the reinforcement from crack width measurements, profiting from additional information that can be measured in‐situ, such as the crack spacing. Recent experimental results show that the values of the mean bond stress typically considered in code formulations overestimate the actual bond stresses activated in cracked concrete specimens. This paper presents the results of an experimental program consisting of reinforced concrete ties and beams instrumented with Digital Image Correlation and fiber optical measurements. The results confirm the differences with typically assumed bond stresses. A formulation to estimate the bond stresses in service conditions is derived from the results of the numerical integration of a previously developed local bond–slip relationship. Their pertinence for the estimation of the stress in the reinforcement from the measured crack width is evaluated with satisfactory results for monotonic loading and for the maximum force in cyclic tests. [ABSTRACT FROM AUTHOR]

Based on an analysis of the literature on fiber‐reinforced concrete (FRC), especially the development and formation of various types of FRC combined with reactive powder concrete (RPC) in recent years, this paper systematically expounds the research progress, particularly the mechanical properties, of steel fiber RPC, basalt fiber RPC and hybrid fiber RPC. This paper concludes the improvement in the mechanical properties of RPC under common curing methods, elaborates on the influence of steel fiber on the compressive, tensile, and flexural strength of RPC, and outlines the principle of fiber enhancing the mechanical properties of RPC. Additionally, it discusses the research progress in basalt FRC, and further examines the impact of basalt fiber on the mechanical properties of RPC. Referring to the research on single fiber reinforced RPC, the mechanical properties of hybrid fiber RPC are analyzed and summarized; based on the characteristics of steel fiber and basalt fiber, research on steel‐basalt hybrid fiber RPC is proposed. [ABSTRACT FROM AUTHOR]

In this paper, a probabilistic methodology based on image analysis is proposed for earthquake‐induced loss estimation in rectangular reinforced concrete shear walls (RCSWs) in compliance with FEMA P‐58. The methodology is developed using a databank of 285 surface crack patterns gathered from the result of experimental research on 99 rectangular RCSWs with wide‐ranging structural and geometric characteristics. For the complexity extraction, three fractal geometry indices of the damaged specimens are taken into consideration. Fragility functions are generated to determine the probability of exceeding a FEMA P‐58 compliant damage state based on the various methods of repair for specific complexity indices. The fragility functions are obtained using four common probabilistic distributions including lognormal, Weibull, gamma, and beta. The fitness of the fragility curves is examined by two goodness‐of‐fit tests, namely the Kolmogorov–Smirnov test and Lilliefors test. Results show that the Weibull is the best‐fitting distribution for the majority of damage states and succolarity possesses the best results in goodness‐of‐fit tests among fractal geometry indices. Empirical loss indices are also derived in this paper aimed at optimizing the goodness‐of‐fits. Finally, the proposed procedure is utilized for a sample specimen from the databank at various damage levels. [ABSTRACT FROM AUTHOR]

A cement‐based material that meets the general goals of mechanical properties, workability, and durability as well as the ever‐increasing demands of environmental sustainability is produced by varying the type and quantity of individual constituents in high‐performance concrete (HPC) and ultrahigh‐performance concrete (UHPC). Expensive and time‐consuming laboratory experiments can be used to estimate the properties of concrete mixtures and elements. As an alternative, these attributes can be approximated by means of predictive models created through the application of artificial intelligence (AI) methodologies. AI approaches are among the most effective ways to solve engineering problems due to their capacity for pattern recognition and knowledge processing. Machine learning (ML) and deep learning (DL) are a subfield of AI that is gaining popularity across many scientific domains as a result of its many benefits over statistical and experimental models. These include, but are not limited to, better accuracy, faster performance, greater responsiveness in complex environments, and lower economic costs. In order to assess the critical features of the literature, a comprehensive review of ML and DL applications for HPC and UHPC was conducted in this study. This paper offers a thorough explanation of the fundamental terms and ideas of ML and DL algorithms that are frequently used to predict mechanical properties of HPC and UHPC. Engineers and researchers working with construction materials will find this paper useful in helping them choose accurate and appropriate methods for their needs. [ABSTRACT FROM AUTHOR]

It is common knowledge that increased temperatures have a negative impact on the axial load‐capacity and stiffness of reinforced concrete (RC) rectangular columns. This is something that is commonly acknowledged. For the purpose of restoring the axial capacity and stiffness of heat‐damaged RC columns, it is absolutely essential to carefully pick a suitable method for strengthening and repairing the columns. This research paper investigates the performance of various strengthening methods, such as the use of carbon fiber‐reinforced polymer (CFRP) jackets with near‐surface mounted (NSM) steel bars and a combination of welded wire mesh (WWM) and CFRP strengthening techniques, for the rehabilitation of RC rectangular columns that have been damaged due to exposure to high temperatures. Specifically, the paper focuses on the performance of these methods in relation to the rehabilitation of RC rectangular columns. There were three groups of tested RC rectangular columns: pre‐heated and unstrengthened, post‐heated and unstrengthened, and post‐heated and strengthened. Over a period of 3 h, 600°C was applied to the heated columns. Both a scheme utilizing a combination of unidirectional CFRP strips and NSM steel bars and another utilizing a combination of unidirectional CFRP strips and WWM were evaluated. Axial compression tests were performed on each column until failure occurred. The experimental test outcomes revealed that exposure to high elevated temperatures led to a decrease in the axial load‐carrying capacity of 38.6% and a decrease of 75.9% in initial stiffness, compared to unheated RC columns. Both strengthening schemes proved effective in restoring and surpassing the initial load‐carrying capacity of undamaged RC rectangular columns by an average of 35%. Notably, the combination of CFRP strips and WWM exhibited superior performance in restoring the initial stiffness of post‐heated RC rectangular columns, representing a novel finding. The strengthening scheme employing WWM and CFRP recovered 61.3% of the lost axial strength caused by high temperature, while the NSM/CFRP scheme restored 34.5% of the lost axial strength. In addition, the utilization of NSM in combination with CFRP strips as well as utilization of the WWM and CFRP systems leads to stiffness enhancement of 52.1% and 123.7%, respectively, when compared to post‐heated and unstrengthened RC columns. However, the study's findings have clearly shown that combination of WWM and CFRP strips is efficient in enhancing the strength of heated and unheated damage RC beams. [ABSTRACT FROM AUTHOR]

For the assessment of concrete structures in the new fib Model Code 2020 (fib MC 2020), three categories are distinguished: (1) the residual capacity of existing structures without damage, (2) the residual capacity of structures suffering deterioration, and (3) the residual capacity of structures with noncompliant details. In the accompanying paper by Walraven and Dieteren in this volume, the backgrounds for this subdivision have been explained, and indications for the assessment of existing concrete structures in those categories have been given. In the actual paper, examples are given how to perform an assessment of concrete structures for the categories mentioned above. These examples have contributed to the formulations of the recommendations proposed for fib MC 2020. [ABSTRACT FROM AUTHOR]

The management of existing structures is raising a number of pertinent questions to the owners and engineers. Many structures built more than 50 years ago (even those built hundreds of years ago) usually no longer comply with safety requirements of current codes, which are typically addressed in new structures. This is not necessarily only caused by a poor original design or degradation with time, but it may be, for example, the consequence of increase in actions, reducing the level of reliability of a structure. This paper focuses on strategies to be adopted for existing structures which do not comply with code requirements for new constructions (e.g., to repair, to demolish, to rebuild, etc.) on the basis of a more holistic approach that includes economic, social, and environmental considerations. To that aim, first, a brief review of the background concepts on the reliability of structures is presented, highlighting the differences for new and existing structures. Following this analysis, suitable values for the reliability index (including sustainability considerations) are proposed, as well as tailored maintenance strategies. Finally, the paper presents a case study based on a real project to emphasize the benefits of adopting such a holistic perspective. [ABSTRACT FROM AUTHOR]

Fires are rare events, but in the case of their occurrence, they can have a significant effect on the structure. Concrete is a durable noncombustible material but can be damaged by fire. This damage does not often lead to structural collapse, but can significantly hinder the structure's future performance. A thorough post‐fire assessment of concrete structures is essential to determine the condition of the structure and select the best course of action to take. This paper reviews the current state of knowledge on the post‐fire assessment of concrete structures. The techniques that are commonly used are presented and discussed, highlighting their advantages and disadvantages. Furthermore, based on the literature case studies, an overview of different approaches and techniques is presented. Finally, the framework and goals of the post‐fire assessment are investigated. The paper concludes with a summary of the current state of knowledge and a list of key research needs. [ABSTRACT FROM AUTHOR]

A series of pull‐out tests were conducted on semi‐grouting sleeve and steel bar connections to investigate the mechanical behavior of the connectors. Taking the steel bar diameter, anchorage length, and grouting material strength as the parameters. The test results showed that when the anchorage length was small and the grouting material strength was low, sufficient anchorage strength cannot be provided, specimens were subjected to bond slip failure, which belongs to the brittle failure. When the anchorage strength between the steel bar and the grouting material was sufficient, the steel bar breaking occurred on the specimens, which belongs to the ductile failure. Then, the semi‐grouting sleeve and steel bar connection was modeled by finite element software, and the bond slip between the steel bar and grouting material was simulated by COMBIN39 element. The results indicated that the failure mode of the specimen obtained by finite element simulation was the same as the test result. The ultimate bearing capacity of the specimen was highly similar to the test result, which verified the feasibility of the modeling method in this paper. Next, the number of specimens and parameter levels were increased through finite element modeling, and the influences of steel bar diameter, anchorage strength, and grouting material strength on the ultimate bearing capacity of semi‐grouting sleeve and steel bar connections were analyzed. The results testified that the ultimate bearing capacity of the specimen increased with the increase of steel bar diameter. In a certain range, the ultimate bearing capacity of the specimen increased with the raising of anchorage length and grouting material strength. While the anchorage length increased, the ultimate bearing capacity of the specimen did not necessarily increase because of the uneven distribution of stress. The steel bar diameter had the most significant influence on the ultimate bearing capacity of the specimen, while the grouting material strength had the most negligible impact, that was, increasing the steel bar diameter is the most effective method to improve the ultimate bearing capacity of the specimen. Finally, according to the results of finite element analysis, the calculation method of ultimate bearing capacity with different failure modes was obtained, and it has been proved to be effective and accurate by the comparison of calculated results and test results. The results of this paper have great significance for improving the calculation theory and design method of relevant engineering. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present the methodology used to validate the threshold levels of durability indicators from data acquired from existing reinforced concrete structures that may present corrosion problems resulting from carbonation or chloride ingress. This study was conducted in the framework of the French National Project PERFDUB in close collaboration with the MODEVIE ANR project. Durability tests form the basis of a performance‐based approach for the durability of concrete structures, and in order to set the threshold level for each of these durability indicators, it is important to take into account the experience feedback that can be obtained from the actual behavior of existing structures. This paper presents the investigations carried out on eight reinforced concrete structures, all of them having an age well in excess of 50 years, and the main data gathered on some relevant durability and lifetime indicators. Based on all these data, predictive models of carbonation and chloride penetration are applied in order to validate the threshold levels to be adopted for the durability indicators, and several other conclusions are drawn. [ABSTRACT FROM AUTHOR]

Improvement of the bonding and interaction between concrete and steel is crucial to achieving an optimal reinforced concrete member. The proposed technique in this paper is using perforated steel plates (PSPs) to reinforce two‐way concrete slabs. In this method, ordinary steel bar reinforcements in the tension region of the concrete slabs were replaced by PSPs. Concrete slabs reinforced with PSPs enhance structural characteristics with respect to concrete slabs reinforced with ordinary reinforcement (OR) due to the higher lateral stiffness of PSPs, the better confinement of concrete within the holes of PSPs, the biaxial performance of the steel in the tension region, and the efficient load transmission mechanism between the steel and concrete. In this paper, a comprehensive experimental investigation was conducted on two‐way concrete slabs reinforced with PSPs and ordinary steel bars. The behavior of PSPs slabs was evaluated in comparison with OR slabs in terms of failure types, ductility, energy absorption, stiffness, ultimate load, cracking load, and force transmission mechanism. Findings revealed that the PSPs slabs have higher ductility, energy absorption, and ultimate strength compared to the OR slabs. [ABSTRACT FROM AUTHOR]

Bonded concrete overlays are widely used for strengthening and repair of concrete members. The aim of a concrete repair is to restore the load‐carrying capacity and stiffness of a concrete member, and to extend the service life of a structure. The bond between substrate and overlay is one of the main factors concerning the serviceability of a composite member consisting of concrete of different ages. This paper aims at better evaluating, through an extensive experimental program, the shear bond strength between existing concrete and a subsequently applied fiber reinforced overlay. The main purposes of this test program are to study the influence of the substrate strength and of the substrate surface roughness on the interface bond strength between a substrate and overlay concrete. A refinement of a novel bond test, proposed by some of the authors of this paper, is also implemented. Results indicate that there is an increase in the bond strength with an increase in the substrate compressive strength. On the other hand, the results suggest that, for the substrate strength classes investigated, the surface roughness does not influence the interface bond strength. [ABSTRACT FROM AUTHOR]

The restraint of lateral reinforcement can effectively improve the bearing capacity and deformation capacity of confined concrete columns. Generally, the behavior of confined concrete column under axial compression and lateral cyclic loading is a complex process and has been the subject of numerous studies dating from last century. This paper presents a review to summarize and discuss the investigations of concrete columns confined by lateral reinforcements under axial compression and lateral cyclic loading with the aim of obtaining a clear understanding on the mechanism and performance of confined concrete column. In this paper, a test database of confined concrete columns under axial compression and lateral cyclic loading is established, presented, and evaluated. The detailed provisions of confined concrete columns from current codes are concluded and it is found that these codes neglect the beneficial effect of lateral reinforcement on shear bearing capacity of confined concrete columns under lateral cyclic loading. Additionally, the stress–strain models and development of lateral reinforcement strain/stress in confined concrete columns under axial compression are mainly presented and discussed. Moreover, theoretical and experimental studies on seismic behavior of confined concrete columns are evaluated, including compression‐flexure calculation, shear bearing capacity, ductility, energy dissipation capacity, and other detailed requirements. Furthermore, main influential factors of confined concrete columns under axial compression and lateral cyclic loading are discussed, respectively and it is founded that the synergy work of longitudinal and lateral reinforcement, and the deformation coordinated relationship between lateral reinforcement and core concrete significantly affect the bearing capacity and deformation capacity of confined concrete columns. Therefore, further studies are suggested to optimize and quantify the strength grade combination relationship between lateral reinforcement, longitudinal reinforcement, and concrete to achieve economical design and construction. [ABSTRACT FROM AUTHOR]

Basic magnesium sulfate cement (BMS) is a new type of magnesium cementitious material, which has similar advantages with magnesium oxychloride cement, such as lightweight, fast setting, high strength, wear resistance, and is not easy to absorb the moisture. It can widely replace magnesium oxychloride cement in the field of building insulation materials. In addition, the BMS has 2.5 times the flexural strength of Portland cement of the same strength grade, and its durability and reinforcement protection performance is similar to Portland cement, which also has a good application prospect in the field of civil engineering. The preparation and hydration process of BMS is reviewed in this paper. The microstructure and properties of BMS, magnesium oxychloride cement and magnesium oxysulfate cement are comparatively analyzed. The effects of content and activity of α‐MgO in the magnesium materials, the type of blending solution, the α‐MgO/MgSO4 ratio, the type and dosage of chemical admixture on the microstructure and properties of BMS were clarified. This paper is helpful for the application of BMS in civil engineering. [ABSTRACT FROM AUTHOR]

Cement used in structural concrete accounts for 60% of all cement. Thus, the amount of CO2 emission by cement in structural concrete in a year is about 5% of the amount emitted by mankind. However, the Life Cycle Assessment (LCA) of structural concrete emits CO2 not only at the product stage but also at the use stage after construction. In this paper, carbon neutrality is viewed from an economic point of view. Then a rough indicator is presented to grasp the CO2 emissions of structural concrete. This paper also shows that LCA of structural concrete should consider not only the materials but also the maintenance phase. And low‐carbon technologies currently in use is introduced. Then the need for multi‐cycle structural concrete with a circular economy is presented. Moreover, it is estimated that CO2 emissions due to disasters in the use stage could be enormous. The carbon neutrality of concrete is not a risk but an opportunity for us. [ABSTRACT FROM AUTHOR]

Openings in flat slabs near to columns are often needed to supply the building with utilities. The presence of these openings can lead to a decrease of the punching resistance which is related to (i) the reduction of the control perimeter, (ii) the stress concentrations at the edges of the openings, (iii) the reduction of the unitary shear resistance caused by increased flexural deformations, and (iv) the moment transfer in the slab connection in case of unsymmetrical openings. The effect of the openings on the punching shear resistance is strongly related to the geometry, the location, the number, and the size of the openings. To quantify the strength reduction due to the openings, current code approaches account for a reduction of the control perimeter defined by radial lines from the centroid of the column to the edges of the opening. Even though slabs with opening have been investigated since the 1960s, available experimental evidence on the behavior of slabs with openings without shear reinforcement is scarce and some effects are neglected in current design codes. Eurocode 2 and fib Model Code do not consider the effect of unsymmetrical openings leading to moment transfer in the slab‐column connection. ACI 318:2019 recommends considering these cases as free edges; however, additional information is necessary to perform the analysis. The present paper analyses a database of 68 flat slab specimens with openings according to ACI 318:2019, current Eurocode 2 (EN 1992‐1‐1:2004), the draft for the second generation (prEN 1992‐1‐1:2021), fib MC 2010:2013, and the Critical Shear Crack Theory. This paper proposes a new approach and a new definition of the control perimeter to improve the prediction of the punching shear resistance of slabs with openings based on the results of the database, the previous studies, and the linear‐elastic analyses of the shear force distribution along the control perimeter. [ABSTRACT FROM AUTHOR]

The iterative nature of the design processes for building structures requires computational models to be robust, efficient, and accessible while reflecting the actual structural behavior with sufficient accuracy. For limit state analysis of reinforced concrete structures, efficient linear‐elastic models are generally inaccurate, while the modeling and computational complexity of most high‐accuracy nonlinear models inhibit their use in design processes for large‐scale structures. A recently proposed framework for elasto‐plastic analysis of cracked reinforced concrete panels was demonstrated to be capable of analyzing models with more than 10,000 finite elements within minutes on a standard personal computer. This paper proposes an extension of this work in terms of a finite shell element for elasto‐plastic analysis of fully cracked reinforced concrete wall structures subjected to monotonic loading. Using nonlinear‐elastic constitutive models to imitate elasto‐plasticity, the proposed shell element couples the in‐plane section force variation to the nonlinear through‐thickness stress variation in a stress‐based formulation using a layer‐based submodel. The method is validated with exact solutions, and its applicability in design processes involving large‐scale structures is demonstrated using a finite element model of a four‐story stairwell with more than three million variables, which is solved within minutes on a personal computer. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of material properties, boundary conditions, and related modeling and design uncertainties on the fire behavior of statically indeterminate reinforced concrete beams and slabs by means of a parametric study based on a comprehensive model. This model uses material properties specified by EN 1992‐1‐2, complemented by considerations concerning the biaxial compressive strength of concrete, strain hardening and limitations of the ultimate strain of reinforcement, as well as tension stiffening. The parametric study identifies and explains the most influential parameters governing the fire behavior of statically indeterminate reinforced concrete beams and slabs. The implementation and generalization of these parameters are evaluated and compared to current design rules in EN 1992‐1‐2 derived from the evaluation of experimental testing and real fire cases. Overall, the detailing rules given in EN 1992‐1‐2 are found to be reasonably safe, and they can be easily used for practical applications. Furthermore, the results of the study indicate that model predictions for the studied statically indeterminate systems are subject to considerable uncertainty because (i) information on the used material is possibly incomplete and (ii) the models given in design codes do not (or only insufficiently) cover all relevant aspects of the thermo‐mechanical behavior. Specifically, the concrete aggregate type with its corresponding thermal expansion, the strain hardening properties of the reinforcement and tension stiffening with its detrimental effect on the ductility of the tension chord may affect the rating across several standard fire resistance times of statically indeterminate reinforced concrete members subjected to bending. [ABSTRACT FROM AUTHOR]

Small amounts of shear reinforcement are often assumed to increase the shear capacity of RC beams, compared to an identical beam without shear reinforcement. However, in a recent experimental campaign, the shear capacity of beams with a shear reinforcement ratio below the minimum requirements according to the design standards turned out to be similar to identical beams without shear reinforcement. This paper presents a detailed analysis of why the shear capacity may be similar for beams without‐ and beams with small amounts of shear reinforcement. This includes the influence of small amounts of shear reinforcement on the shear behaviour and shear‐transferring mechanisms. The analysis shows that the crack development is more severe at the ultimate load for beams with a small amount of shear reinforcement compared to beams without shear reinforcement. This more severe crack development is shown to cause an overestimation of the shear contribution from aggregate interlock when applying a well‐known constitutive model often used for beams without shear reinforcement. Therefore, a new expression for the aggregate interlock stresses is proposed. A comparison of the proposed expression with Mixed‐Mode crack opening tests shows a good agreement with the test for both small and large crack openings. By applying the proposed expression on the measured crack kinematics it is shown that for a large shear contribution from aggregate interlock the shear contribution from the shear reinforcement is very limited and as the aggregate interlock stresses decrease the shear contribution from the shear reinforcement increases. This shift in the governing shear‐transferring mechanism can help to improve the requirements for the minimum shear reinforcement often found in the design standards. [ABSTRACT FROM AUTHOR]

In a recent paper in Structural Concrete, the authors Dönmez and Bažant explain that the theoretical background of the Model Code 2010 equations for one way and punching shear are not sufficiently grounded in theory and should instead use an energy‐based size effect law in their formulation to match behavior. To support this claim, finite element simulations were presented. In this paper the basic assumption that an energy‐based method must govern the shear failure of beams without stirrups is questioned. These questions are shown to be based on the hardening behavior of aggregate interlock tests and the inability for slip strains to localize during shear failure. In addition to these theoretical arguments finite element analyses were conducted with a constitutive model that is energy‐based but that also does an appropriate job at modeling aggregate interlock, an aspect that appears to be lacking in the analyses of Dönmez and Bažant. These new results are shown to better model the test results and confirm that aggregate interlock is important in explaining shear strength and therefore the size effect in shear for slender members. As such any concerns about the safety of the Model Code shear equations appear unwarranted. [ABSTRACT FROM AUTHOR]

Corrosion of posttensioned bridges raises great concern, since the only way to safely assess the condition of the tendons is through destructive evaluation. In this scenario, this paper presents the results of an extensive literature review on reported cases of corrosion of posttensioned bridges and few prestressed structures. The aim is to increase knowledge about the structural consequences of possible corrosion‐induced failure mechanisms. The cases were rated according to the increasing severity of the observed damage and consequent interventions as follows: ordinary maintenance is effective, extraordinary maintenance is necessary, and maintenance is insufficient or absent. It was found that most corrosion‐sensitive structures were segmental and box section beam bridges. Most cases required extraordinary maintenance. Warning signs were often observed. The damage was mainly ascribed to design and execution mistakes that facilitated the ingress of external chlorides causing corrosion. The paper concludes with a discussion of the consequences for structural safety. [ABSTRACT FROM AUTHOR]

When shear cracking occurs in existing reinforced concrete deep members, engineers are faced with the challenge of determining the safety of the members. This paper presents a crack‐based assessment approach that utilizes the Two‐Parameter Kinematic Theory (2PKT) as a framework for the assessment of lightly reinforced concrete deep beams. The paper presents three assessment approaches with progressively increasing levels of approximation (LoAs). The first level of approximation (LoA I) involves using the 2PKT in a predictive manner for situations where the crack shapes are unknown, LoA II improves upon LoA I by incorporating more detailed modeling of the strain in the transverse reinforcement at the location of the critical cracks, and LoA III includes the details of LoA II but also uses the detailed crack geometry as an input in the assessment. Each of the LoAs is presented and compared with experimental data from a 4‐m deep beam test in the literature. The shear carrying mechanisms determined from the kinematic model are evaluated and compared across LoAs. Finally, the paper utilizes LoA III to study the size effect in shear for deep beams. The results quantify the influence of aggregate interlock on the size effect in shear critical deep beams. [ABSTRACT FROM AUTHOR]

This paper proposes a novel glass fiber‐reinforced polymer (GFRP)‐timber‐steel tube‐concrete composite column (GTSC) that combines an outer steel tube with GFRP fabric reinforcement, an inner timber core, and concrete for the rest of the space. The mechanical behavior of eight specimens of novel composite columns was investigated considering diameters of timber cores, layer numbers, and angles of GFRP laminates. The results showed that as the size of the timber core increased from 0 to 50 mm, the ductility and the energy dissipation capacity of the composite column maximum increased by 61.5% and 63.4%, respectively. Conversely, the ultimate load carrying capacity and stiffness decreased. It was also found that the timber core weakened the strength of the confined concrete. However, timber core reduced the weight of columns, which slowed down the reduction of the ultimate load carrying capacity of per unit GTSCs, with the stiffness remains unchanged. GFRP laminates with an angle of 60° provide the best stiffness and ductility, and the layer numbers of GFRP has a positive effect on GTSC's mechanical performance. In addition, an analytical model was proposed based on the ultimate equilibrium method, which accounts for the ultimate bearing capacity of GTSC based on the influence of timber. Analyses revealed a good correlation between analytical and experimental results. [ABSTRACT FROM AUTHOR]

The geometry and mechanical behavior of concrete bridge towers are complex. Hence, it is important to generate a rational mechanical analysis model for structural design. The method of strut‐and‐tie models (STMs) is an effective way to analyze disturbed regions (D‐regions) such as the anchorage zones of cables in bridge towers. This paper provides a detailed analysis of the elastic stress distribution on the bridge tower of a cable‐stayed bridge with two cable planes. The vertical component of the stay cable force was considered for the analysis. Additionally, two different STMs of the bridge tower were developed with the load path method using different horizontal spacings of the stay cables. Based on the minimum energy principle, the optimal STMs of the two different STMs were generated. A detailed calculation method for the configuration of the optimal STMs is presented. In the paper, computational expressions of the internal force for the tie members in the two STMs are also proposed. Overall, this study demonstrated the strong applicability of the proposed STMs for a bridge tower in a cable‐stayed bridge with two cable planes. This can be considered an effective simplified method in the structural design of bridge towers. Furthermore, the study established that the influence of the horizontal distance between stay cables on the mechanical response‐behavior of the structure should be considered in the design of concrete bridge towers. [ABSTRACT FROM AUTHOR]

Reinforced concrete flat slab projects usually require openings close to the columns for electrical and hydraulic installations. Since such openings reduce the punching shear of slabs, a comprehensive study is needed. In this paper, numerical models of slabs tested in literature were elaborated upon, using the commercial software in finite elements DIANA. The physical nonlinearity of the materials was considered. After the calibration and validation of the numerical parameters related to concrete and reinforcement, 62 numerical models were created for performing a parametric analysis. The numerical analysis aimed to study the effect of openings close to the columns and verify the punching resistance reduction. In this parametric study, the main variables were the compressive strength of the concrete, the bending reinforcement ratio, the number of openings, and the distance from the openings to the column's face. Finally, the numerical results obtained were compared with the punching strength values provided by the main structural design codes, viz., NBR 6118 (2014), Eurocode 2 (2004), ACI 318 (2019), fib Model Code (2010), and the next generation of Eurocode 2, which are constantly questioned in academic papers regarding their safety. [ABSTRACT FROM AUTHOR]

It is widely known that corrosion is one of the main problems that reinforced concrete structures may endure during their life‐cycle. This problem is usually tackled in a prescriptive manner, by limiting the crack width allowed to occur during structures' service life. In an attempt to better understand the effect that cracking and crack width can have on the corrosion process, as well as systematize the existing work in the field, this paper presents a summary of an in‐depth literature review on the topic of reinforcement corrosion in concrete. The main focus is devoted to chloride‐induced corrosion since that is the most widely studied corrosion mechanism, even though carbonation‐induced corrosion is also relatively briefly discussed. The paper also presents an overview of the existing guidelines that have been used in the past to analyze and support decision‐making regarding corrosion in reinforced concrete structures. [ABSTRACT FROM AUTHOR]

Most of the Italian infrastructures have been built since the mid‐twentieth century. Prestressed concrete (PC) has been widely used, especially for bridges and viaducts. These structures have proved effective over time, but their performance could be affected by degradation phenomena (i.e., corrosion of the tendons and residual prestressing) or construction defects (i.e., grouting of the ducts), which need to be accurately modeled. This paper focuses on the flexural response of two reduced‐scale, posttensioned, PC bridge girders, prestressed with two different jacking forces and tested under four‐point bending configuration. Four multidimensional numerical models were developed to simulate the experimental behaviors of the selected specimens, using two alternative computational strategies, namely, the finite element method (FEM) and applied element method (AEM). Three FEM modeling were considered, ranging from one‐dimensional lumped‐plasticity models to two‐dimensional and three‐dimensional (3D) spread‐plasticity models. Besides, 3D AEM models were developed into another software package. The accuracy and the computational costs of the two numerical strategies are discussed in this paper. Also, the main features of each numerical modeling technique are addressed, including comparisons between numerical and experimental global response data as well as the statistical characterization of the model error. Based on these different features, the authors also suggest the most suitable numerical strategy for future studies on PC girders. [ABSTRACT FROM AUTHOR]

Buckling of the longitudinal rebar is one of the main forms of plastic hinge failure in reinforced concrete (RC) columns after an earthquake. This rebar buckling significantly impacts the seismic bearing capacity and energy dissipation capacity. To restrain the development of longitudinal rebar buckling behavior and delay the degradation of lateral strength in RC columns, this paper developed a new type of buckling restraint rebar (BRR) consisting of three components: longitudinal rebar, a restraint sleeve, and foam material. First, the BRR mechanical properties under compression and tension‐compression cyclic loading were obtained through quasi‐static loading tests. Then, the BRR compression and tension‐compression cyclic loading processes were numerically simulated based on ABAQUS finite element software. The simulated results were compared with the test results. Finally, a stress–strain constitutive model for this new BRR was proposed based on this study. Results showed that the restraint sleeve could significantly enhance the lateral stiffness and the bearing capacity of longitudinal reinforcement after yielding. The compressive performance of BRR was mainly affected by the length and wall thickness of the sleeve. The cyclic performance was mainly affected by the length of the sleeve and the clearance between the sleeve and the reinforcement. The BRR constitutive model proposed in this paper can accurately reflect the influence of restraint sleeves on the stiffness of longitudinal reinforcement after yielding. [ABSTRACT FROM AUTHOR]

There are a large number of interfacial zones of new–old concrete in precast concrete structures, and the wall effect causes the reduction of coarse aggregate in the interfacial zones, which leads to the weaker physical, mechanical and durability properties of this part. In the present paper, some new–old concrete specimens with different chiseled depths at the interfaces were made to simulate the wet joints of precast concrete structures. The distribution characteristics of the coarse aggregate volume fraction in the interfacial zones of new–old concrete specimens were obtained by DIP (Digital Image Processing) technology. The results show that the distribution of the coarse aggregate volume fraction in the interfacial zones is similar to a positive V‐shape (no chiseling) or partial V‐shape (chiseled interface), and is generally lower than that of the noumenons of new and old concrete (constant values). With the increase of chiseled depth, the valley point (i.e., the minimum value) of the distribution curve of coarse aggregate volume fraction in the interfacial zone will move upwards and offset toward the old concrete. When the offset reaches 2 mm from the interface, it remains stable. The multiple irregular cone‐shape small pits on the actual chiseled surface are abstracted into a single bulging slope pit, and the area ratio of new–old concrete on the cross section within the chiseled range is derived. On this basis, the model of the coarse aggregate volume fraction in the interfacial zone varied with the distance from the interface is proposed. [ABSTRACT FROM AUTHOR]

In this paper, flexural fatigue test of self‐compacting concrete (SCC) with waste tire 0% and 20% rubber content was studied. Meanwhile, the acoustic emission (AE) was used to monitor the whole process of the fatigue. The results show the dissipation energy presents obvious three stages, which are similar to the stiffness attenuation. The plateau value (PV) of radio of dissipated energy change has a double logarithmic linear relationship with fatigue life. Moreover, there is a linear relationship between the dissipated energy and cumulative AE parameters at about half of fatigue life. At last, the relationship between PV value calculated by cumulative AE counts changes and fatigue life is determined. Therefore, AE technology can be used to monitor the fatigue evolution of concrete. [ABSTRACT FROM AUTHOR]

This paper describes an experimental program, which investigates the validity of using Expression 7.21 in Eurocode 2 for calculating shrinkage curvatures of loaded reinforced concrete beams cracked in flexure, this Expression having previously been validated for use with uncracked sections but not for cracked sections. The experimental method used a heating technique, which exploited the differing coefficients of expansion of limestone concrete and stainless steel reinforcement to impose simulated shrinkage strains on a range of rectangular beams of various sizes and reinforcement percentages. The results indicate that Expression 7.21 is valid for use with sections cracked in flexure but may overestimate curvatures by significant amounts. It is shown that improved estimates of curvature are given by using Expression 7.18 in conjunction with Expression 7.21 with the best results being obtained by setting β = 0.3 or by using an adjusted value for the cracking moment (Mcr), as detailed in the paper. [ABSTRACT FROM AUTHOR]

Textile‐reinforced concrete (TRC) has great potential to be used for strengthening concrete structures, and a combination of carbon fiber‐reinforced polymer (CFRP) grid and ultra‐high‐performance concrete (UHPC) could be more desirable. Although the UHPC is known for good durability, the bond degradation between UHPC and CFRP under freeze–thaw cycles (FTCs) remains unclear. Therefore, this paper conducted single fiber bundle and grid pull‐out tests on UHPC‐based TRC (TRUHPC) plates under FTCs to study the bond behavior between CFRP fiber and UHPC matrix. It was found that, after exposed to 700 FTCs, the pull‐out load of the single bundle of CFRP decreased by a maximum of 33.9%, while it dropped by 19.0% in case of the CFRP grid. Finally, a trilinear bond‐slip model was developed and verified against the experimental results. The findings of this study hold significant importance in assessing the tensile behavior of TRC plates under FTCs. [ABSTRACT FROM AUTHOR]

Tendon breaks significantly threaten the safety of prestressed concrete structures. Failure of embedded tendons does not necessarily indicate as surface cracks, demonstrating the need for early detection methods. This paper presents a novel ultrasound‐based approach for detecting and localizing tendon breaks using coda wave interferometry. Already few embedded ultrasonic transducers form a robust monitoring network able to detect subtle changes in the structure. To demonstrate the feasibility of detecting tendon breaks, a post‐tensioned concrete beam was fabricated at Ruhr University Bochum, Germany. A break of a centric and eccentric tendon was artificially created by drilling from the outside. Both were successfully detected and localized through characteristic changes in the ultrasound results without any evidence of damage on the concrete surface. Measurements with fiber optic sensors validate the ultrasonic findings and provide insights into the re‐anchoring behavior after tendon failure. [ABSTRACT FROM AUTHOR]

Fully embedded and spatially diffuse sensors are central to the advancement of civil and construction engineering. Indeed, they serve as an enabling technology necessary for addressing the current challenges associated with through‐life management and structural health monitoring of existing structures and infrastructures. The need to identify structural issues early on has driven the integration of such embedded sensing capabilities into construction materials, turning passive structures into proactive, self‐aware “entities,” commonly referred to as Smart Structures. The economic rationale behind this endeavor is underscored by the vital significance of continuous monitoring, which enables prompt anomaly assessment and thus mitigates the risks of potential structural failures. This is particularly relevant for road and rail infrastructures, as they represent a substantial and enduring investment for any nation. Given that a large majority of these large infrastructures are composed of concrete and reinforced concrete, both academics and construction companies are continuously researching micro‐ and nano‐engineered self‐sensing solutions specifically tailored for this building material. This comprehensive review paper reports the latest advances in the field of self‐sensing concrete as of 2024, with an emphasis on intrinsic self‐sensing concrete, that is, electrically conductive functional fillers. A critical analysis and a discussion of the findings are provided. Based on the perceived existing gaps and demands from the industry, the field's future perspectives are also briefly outlined. [ABSTRACT FROM AUTHOR]