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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]

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 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]

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]

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]

This paper presents a numerical and experimental study aimed at the modeling and dynamic characterization of the reinforced concrete structure of the Palazzetto dello Sport in Rome, designed and by Pier Luigi Nervi with Annibale Vitellozzi, and built by Nervi & Bartoli contractors in 1956‐57. An experimental dynamic testing campaign has been performed to obtain the modal properties of the structure, identified using operational modal analysis (OMA). The axial symmetry of the Palazzetto's dome, expected to exist in an idealized perfect dome, has been observed to occur experimentally by noting that rotated modes possessed nearly identical frequencies, evidenced by closely spaced double peaks in the power spectral density. This observation recognizes the remarkable precision of Nervi's construction methodology. A numerical 3D model has been developed by relying on detailed information about the structure gathered from various sources, including archival documents, on‐site testing, and surveying. The model has been calibrated by means of modal updating based on the experimental measurements collected in this study. The reconstruction of the dome using laser‐scanning and aerophotogrammetry has revealed a slight asymmetry in its thickness distribution (and consequently its mass distribution) that, when incorporated in the numerical model, has been shown to contribute to the experimentally observed frequency split. It is expected that, by tracking these closely spaced frequencies on top of the typical variations of natural frequencies in a health monitoring approach, further insight might be gained into the detection of possible damages and/or degradation of the structure and its components. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) structures are mainly designed to withstand both static and dynamic loads. However, due to the highly nonlinear behavior of RC structures subjected to extreme dynamic loads, these structures have a very complex damage behavior under dynamic impact loading. In fact, current existing methods for damage‐simulation and prediction are generally based on either empirical data, simplified mechanical approaches or complex numerical simulations mainly using the finite element method. In this regard, empirical and semi‐empirical models can be considered to calculate the load‐bearing capacity in a simplified way with only a few input parameters. Hence, using current experimental test data, this paper aims to analyze and assess existing empirical and semi‐analytical approaches that are established in standards and guidelines. Accordingly, a functional relationship in terms of an impact factor is found. Based on the obtained results, different approaches are also developed to describe the resistance to projectile penetration of RC structures as well as the force interaction between projectile and RC structures. [ABSTRACT FROM AUTHOR]

The paper investigates the behavior of glass‐fiber reinforced polymer (GFRP) reinforced concrete columns with integrated steel spirals (hybrid reinforcement). Six concrete columns were tested under eccentric axial loading, resulting in failure due to bending. Columns with outer steel longitudinal bars experienced steel yielding at peak loads, while those with GFRP outer rebars failed due to concrete crushing. The results revealed that using GFRP as outer longitudinal bars led to peak loads 3–10% lower compared to columns with steel rebars. Inner confinement by steel spirals increased the load‐carrying capacity. Additionally, columns with inner tubular steel exhibited greater strength than those with steel spirals, indicating a slightly enhanced confinement effect. A finite element model was developed to analyze structural behavior, considering both material and geometric nonlinearity. The model's accuracy was validated by comparing predictions with test results. Parametric analysis from the nonlinear FE model showed that eccentricity significantly impacted column load‐carrying capacity. Increasing inner confinement area and the number of inner longitudinal bars improved structural stiffness and load‐carrying capacity. Furthermore, a simplified theoretical method was proposed. Comparison between experimental failure loads and theoretical predictions revealed differences within 20%, indicating satisfactory reliability of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents the experimental results of six full‐scale one‐way reinforced concrete slabs with variations in reinforcement detailing. Test specimens consisted of two reference concrete slabs reinforced fully with glass fiber reinforced polymer (GFRP) rebars or with steel rebars and four hybrid‐reinforced slabs. The variables included the arrangement of rebars, mechanical reinforcing ratio, and the ratio of steel rebar area to GFRP rebar area. The fabricated specimens were subjected to four‐point loading until failure in the strong floor laboratory. Experimental results indicated that hybrid reinforcement enhances stiffness compared to FRP reinforcement and provides a higher load‐bearing capacity than steel reinforcement. Also, it was observed that FRP bars placed as tensile reinforcement, similar in number and diameter size to steel bars placed as compressive reinforcement in a slab result in the highest ultimate capacity. Moreover, it was observed that while the mechanical reinforcing ratio contributes to the overall behavior of hybrid‐reinforced concrete slabs, the ratio of steel rebar area to GFRP rebar area is not considerably effective. Furthermore, image processing was employed to determine the exact crack widths of specimens after failure. Finally, finite element modeling results showed good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Alkali‐aggregate reaction (AAR) is a detrimental reaction between alkalis originating from cement and aggregates that contain reactive minerals. This reaction produces an expansive gel in hardened concrete that may cause internal stresses and cracking, after which it would be critical to evaluate the safety of the AAR‐affected structure. This paper presents a calculation framework primarily using the finite element method to simulate the structural behavior of reinforced concrete members affected by AAR. Numerical subroutines are used to calculate the anisotropic distribution of AAR‐induced expansions at each integration point, considering the stress field at each time step, whereas changes in the properties of concrete due to the progression of AAR are also considered. The modeling approach is successfully validated based on experimental data from several studies on AAR‐affected members that were reinforced in 1, 2, and 3 orthogonal directions in terms of load–deflection behavior and damage patterns. The mechanical properties of concrete were found to negligibly affect the distribution of AAR expansions. A better correlation was observed with experimental data if compressive and tensile strengths of concrete are assumed unchanged and only the modulus of elasticity of concrete is reduced as a function of AAR‐induced expansion. [ABSTRACT FROM AUTHOR]

The bond behavior between reinforcement and concrete has a significant influence on the load‐bearing behavior and serviceability of the composite material. This paper focuses on the characterization of the bond behavior between fine‐grained concrete and mineral‐impregnated carbon‐fiber reinforcement. In this study, the influence of different bond lengths on local bond behavior was experimentally investigated. To predict the bond stress along the bond length, an analytical bond stress‐slip model was specified, and its model parameters were determined based on the experimental tests using an iterative approximation approach. Based on the defined bond stress‐slip model, a numerical bond model was developed and adjusted for the first time. A three‐dimensional (3D) finite element analysis (FEA) allows the simulation of the local bond stress along the bond length. Finally, the results of the 3D FEA were compared with the results of the experimental investigations to validate the developed numerical model. [ABSTRACT FROM AUTHOR]

This paper describes the 3rd Blind Simulation Competition (BSC) organized by the fib WP 2.4.1 which aims to assess the predictive performance of models based on the finite element method (FEM) for analysis and design of fiber reinforced concrete (FRC) structures submitted to loading and support conditions that promote punching failure mode. Fiber reinforcement is used in an attempt to eliminate conventional punching reinforcement and provide technical and economic advantages. The two tested real‐size prototypes represent a column‐slab interior region of an elevated steel‐fiber reinforced concrete (E‐SFRC) slab where anti‐progressive collapse reinforcement is disposed in the alignment of columns/piles. Despite a punching failure surface being formed in both experimentally tested prototypes at the rupture stage, fiber reinforcement was able to mobilize the yield capacity of the conventional flexural reinforcement, providing high deformation capacity, and ductility to the prototypes. The average post‐peak load‐carrying capacity of the tested prototypes at a deflection seven times higher than the deflection at yield initiation of the conventional reinforcement was still 90% of the average peak load. Regarding the BSC, a total of 26 proposals were received and involved 94 participants from 29 institutions and 17 countries, with 53.9% using smeared crack models (SCMs), 30.8% a concrete damage plasticity (CDP) model, 3.8% discrete crack models (DCMs) and 11.5% considered as “other models.” From these simulations it was verified, in average terms, that SCM assured the best predictive performance apart from the average strain in the SFRC and the maximum crack width which were better predicted by DCM. More accurate predictions were obtained by using in‐house software than by adopting commercial software. [ABSTRACT FROM AUTHOR]

During the cantilever casting process of reinforced concrete arch bridges with cantilever cast‐in‐situ method, it is difficult to select representative training samples for reliability analysis due to its complex structural system. Many random variables and large computational sample size, this paper proposes to solve the reliability indexes based on the combination of the improved sparrow search algorithm (LGSSA) and the support vector regression (SVR) method. Firstly, random variables are selected according to the actual situation of the bridge structure. Then representative training samples are designed to be substituted into the finite element model through the homogeneous method. The resultant data samples are used to fit the functional function by the support vector regression. Then combined with the penalized function method to transform the nonlinear optimization into the problem of solving the extreme value of the function. Based on the improved SSA to solve the extreme value of the final function. Finally the reliability index of the structure is obtained. With the background of reinforced concrete arch bridge of 200 m, the method is used to analyze the reliability of its buckling cable stress, arch stress, buckling tower deviation and structural system reliability during the cantilever casting process. The results show that the overall structural reliability of the arch ring during cantilever casting is 3.502–3.608. The indexes of buckling cable stress reliability are 3.806–6.784. The indexes of arch ring stress reliability are 4.379–7.562, and the indexes of buckling tower deflection reliability are 3.608–8.123. [ABSTRACT FROM AUTHOR]

In this paper, seven half‐scale specimens are used to investigate the effects of the beam–column width ratio, concrete strength, and axial load on the seismic performance of wide exterior beam–column joints. The test results show that all the specimens undergo bending damage at the beam end. The concrete damage in the core column is not significant, meeting the seismic requirements of strong column–weak beams and strong joint–weak members. For specimens with small beam widths, the increase in axial load can effectively reduce the damage to the concrete in the outer joint and increase the strength of the specimen. Increasing the beam width and concrete strength reduces the ductility of the specimen while increasing the strength of the specimen. The bonding performance of the longitudinal bars anchored outside the core column is poor, as bond–slip with the concrete is observed during the test. In addition, compared with ACI 318‐19, GB 50011‐2010 is more conservative for calculating the shear strength of exterior wide beam–column joints. Finally, a corresponding finite element model is established by MSC Marc and verified based on the experimental results. [ABSTRACT FROM AUTHOR]

Columns have the most important role for overall stability of bridges and these elements are the most vulnerable structural components under extreme loading too. Therefore, studying and improving the performance of these elements under such loads has attracted widespread attention among researchers. The main objective of this paper is investigating the performance of bridge reinforced concrete columns which seismically retrofitted by steel or CFRP jacketing under blast load via finite element method. The finite element models' assumptions in Abaqus FE software are verified using the correlated experimental data from literature and good agreements have been obtained. Parametric studies are conducted to cover a wide range of factors including transverse and longitudinal reinforcement ratios, blast load intensity, type and thickness of conventional seismic retrofitting jacket. The results reveal that the longitudinal reinforcement ratio presents more effects on decreasing extreme loading demands than the transverse reinforcing. Moreover, utilizing seismically retrofitting jacket, especially CFRP jacket, tend to be an effective way to reduce demands of reinforced concrete column under extreme loading, where its effectiveness increases, in case of more severe events. Also, the current seismic damage state and performance level, can predict the damage level of columns in good agreement with the design specifications. [ABSTRACT FROM AUTHOR]

The objective of this paper is to explore the value of reliability‐based nonlinear finite element analysis (NLFEA) over the currently available, standardized assessment methods. To our knowledge, no studies are available on this subject, and this paper provides a first insight into the value and reliability level of these assessment methods. The exploration is illustrated through three reinforced concrete structural members: a continuous girder, a continuous deep beam, and a high‐strength deep beam. The analysis is performed gradually: step by step advancing the approximation level of the mechanical and the probabilistic models. The added value of the reliability‐based NLFEA over the semi‐probabilistic Eurocode (EC) method is found to be on average 0.60. In other words: even if according to the semi‐probabilistic EC method the design action (Ed) is 60% higher than the design resistance (Rd), the compliance with the target reliability criterion can be demonstrated by a reliability‐based NLFEA. Furthermore, it is observed that the gain and its cause (i.e., more advanced mechanical or probabilistic models) are different for the three cases. Though this outcome is restricted to the analyzed cases and should be interpreted as an upper limit added value, it indicates that a more detailed physical representation of the problem and an explicit treatment of uncertainties may uncover substantial reserves compared with the currently available, standardized assessment methods. Hence, the reliability‐based NLFEA method offers a promising alternative in the assessment of existing structures, enabling to avoid expensive measures that might be needed based on simplified methods. [ABSTRACT FROM AUTHOR]

This article presents an experimental and numerical study of the collapse behavior of a 60‐m‐high cement silo structure under blast loading, analyzed using SAP2000 (FEM‐NDA) and LS‐DYNA (FEM‐NDA‐explicit code) models to simulate the collapse mechanism. Considering the seismic events in Kahramanmaras, Turkiye, on February 6, 2023, with magnitudes of 7.8 and 7.6, the necessity for the explosive demolition of hundreds of thousands of structures has underscored the urgency of rapid planning. This situation requires a particular focus on the expeditious analysis of demolition methodologies. The study includes pre‐planning stages, sudden column removals and the detonation of columns with blast loads for the controlled demolition of a full‐scale existing silo structure. To overturn the structure, the columns inside the wedge region were suddenly removed using SAP2000 nonlinear dynamic analysis (NDA) to understand the subsequent load redistribution. A study was conducted to compare the use of shell and plate elements in SAP2000 for a 1‐m‐thick wall silo. The results showed that using shell elements provided relatively closer results to real values than plate elements. For the explicit analysis part, the structural components were modeled as solid materials, and columns were detonated with blast loads. The models and actual demolition frame‐by‐frame results of the structure were compared, and the numerical model's accuracy was validated using experimental data from stationary cameras and drones, with the explicit analysis results found to be in agreement. While explicit analysis yielded results more in line with real data, SAP2000 NDA provided relatively distant results, although SAP2000‐NDA was more time‐efficient compared to explicit analysis models. However, a preliminary evaluation can be made if the characteristics of both programs are understood. The documented information on full‐scale structure demolition and findings presented in this paper will serve as a resource for future studies and provide a reference for researchers. [ABSTRACT FROM AUTHOR]

In this paper, a coupled concrete‐filled multicellular steel tube composite shear walls structure (CCSSW) is proposed. A finite element model (FEM) is developed to investigate the seismic behavior of CCSSW, and the model was validated by the tests. The effects of four parameters including axial compression ratio (ACR) on the hysteretic behavior of the CCSSW were studied. Then, a theoretical model for predicting the ultimate shear capacity (USC) of CCSSW was established. The results show that the failure mode of coupled walls exchanged from flexural failure to flexural‐shear failure with increasing the ACR, and it is recommended that the ACR should less than 0.6 to ensure the ductility requirement. To better realize the function of the first line of defense of steel coupling beam (SCB), following recommendations are concluded: the span‐to‐depth ratio range of SCB is 4.0–6.0, the wall stiffness ratio is 2.4–4.7, and low yield strength material should be used for SCB. The maximum error on USC between FEM results and theoretical results is 12.8%, and most of them are less than 10%, indicating the effectiveness of the proposed theoretical model. [ABSTRACT FROM AUTHOR]

The verification of dapped‐end beams degraded by corrosion is a problem, especially for existing bridges in service. This paper proposes a nonlinear finite element (NLFE) modeling procedure and a simple strut‐and‐tie based procedure for predicting the response of dapped‐end beams subjected to chloride corrosion. Firstly, the finite element modeling strategy, based on the adoption of multilayer shell elements and the PARC_CL 2.1 crack model is described. Then, the degradation effects on concrete, rebars, and steel‐to‐concrete interaction are defined as a function of the propagation period of corrosion. In particular, the effects of corrosion on the reinforcement are modeled by applying a reduction of tensile strength that considers for both the reduction of cross‐section and the ultimate strain caused by pitting. Concrete splitting cracking due to volume expansion during rust formation is modeled by reducing the mechanical properties of concrete. Corrosion effects in steel‐to‐concrete interaction are modeled by applying a bond strength decay to the spring elements connecting corroded rebars—modeled with truss elements—and concrete multilayer shell elements. The proposed finite element procedure is used to study two scenarios based on different spatial distributions of corrosion‐prone areas. Subsequently, a simplified analytical approach based on the strut‐and‐corroded tie method—called S&CT method—is proposed and compared with the finite element outcomes. Finally, the validations of the two proposed methods are presented with respect to a corroded dapped‐end beam, showing that corrosion of rebars affects the resistance mechanisms of the dapped‐end beam, by reducing both resistance and ductility. The proposed simplified analytical S&CT method provides conservative and safe results compared to the numerical NLFE model and to experimental data. [ABSTRACT FROM AUTHOR]

A new type of UHPC‐NC (normal concrete) structure in the negative moment zone was proposed to improve the bearing capacity of the connection structure in the negative moment zone of prefabricated prestressed concrete (PC) beam bridges. First, the distribution characteristics of the crack, cracking load, ultimate moment, and ductility coefficient of the new structure were obtained by the 1:4 scale model tests. The feasibility of the connection structure is verified. Then, the value ranges of critical structural parameters affecting the bearing capacity of the connection structure based on the plane section assumption analysis, including the reasonable thickness of the UHPC layer, the reinforcement ratio of the longitudinal tensile reinforcement, and the diameter of the reinforcement, are obtained. At the same time, based on the verification of the finite element model, the influence of crucial research parameters on the bending capacity of the connection structure is obtained by using the finite element method. Finally, a theoretical method for the bending moment capacity of the connection structure of the UHPC‐NC structure is proposed, considering the high ductility characteristics of UHPC materials. The average relative error between the calculation results and the finite element method is within 7.2%, which verifies the reliability of the calculation method in this paper and provides a reference for its design and engineering application. [ABSTRACT FROM AUTHOR]

This paper presents the findings of a large‐scale experimental study that focus on assessing structural behavior of reinforced concrete (RC) cantilever slabs with carbon/epoxy fiber‐reinforced polymer (CFRP) composite strips using a near‐surface‐mounted (NSM) approach. The NSM/CFRP system evaluated in this study was implemented in strengthening the shoulders of the Slide Canyon Bridge in California, USA. The experimental phase is divided into two main parts: (i) determining the design parameters for NSM, including the bondline strength through pull‐out tests, and (ii) conducting a practical evaluation of the bending behavior of original and retrofitted RC cantilever slabs, each with varying NSM reinforcement and three different development lengths. Results of this study indicated that the use of NSM‐CFRP has a considerable benefit in that it significantly improves ductility and changes the failure mode of the unstrengthened RC slab from the typical brittle shear‐based failure mode to a more ductile flexural‐based failure mode. The large‐scale slab specimens' performances, which had different development lengths, showed little variance, except for the slab specimen with a development length of 457.0 mm that exhibited an appreciable flexural stiffness as compared to other specimens evaluated in this study. In order to simulate the serviceability and ultimate behavior of the RC slab specimens, linear and nonlinear finite element analyses were performed. A satisfactory agreement between numerical and experimental results was achieved especially at load level prior the initiation of large‐size cracks. [ABSTRACT FROM AUTHOR]

In this paper, the ordinary reinforced UHPC T‐shaped beam, steel plate reinforced UHPC T‐shaped beam and prestressed UHPC T‐shaped beam were compared by conducting the flexure test. The vertical displacement, crack development, strain change, and crack resistance were discussed. The steel plate reinforced UHPC T‐shaped beam shown better cracking resistance and mechanical properties. Based on the research, the multi‐scale finite element model of the steel plate reinforced UHPC T‐shaped beam was established, and the influence parameters were analyzed. The beam height, steel plate thickness and web thickness shown great influence on the ultimate bearing capacity of the beam. The bearing capacity calculation formulas of the steel plate reinforced UHPC T‐shaped beam based on the plastic strengthening model of the steel were proposed. The calculation results shown good agreement with the test value. [ABSTRACT FROM AUTHOR]

The paper describes the authors' contribution to the evolution of numerical simulation of concrete structures based on the nonlinear finite element method. The formulation of constitutive relations for concrete material is a keystone of this approach, whereas cracking is the dominant feature. Two distinct methods of crack modeling were developed, namely, the discrete and the smeared crack models. Blind prediction benchmarks of the experimental tests are used for model verification. Application of the numerical simulation in the design of concrete structures is supported by the global safety format, where the uncertainty sources, due to the material and the resistance model, are considered. A structural assessment of a prestressed reinforced concrete viaduct is shown as an example of application. [ABSTRACT FROM AUTHOR]

This paper investigates the shear strengthening of reinforced concrete (RC) beams incorporating engineered cementitious composite (ECC) and stainless steel plates (SSPs). The use of ECC, characterized by strain‐hardening in conjunction with SSPs, was investigated in this study to improve the shear performance of RC beams. Total 10 RC beams were tested under static loading up to failure to investigate a few key parameters, namely: material of strengthening (ECC and SSPs), the thickness of ECC, and shape and configuration of SSPs. Experimental findings showed that the proposed strengthening methods can significantly improve the failure pattern and increase the ultimate shear capacity of the studied RC beams by 36%–97% compared to the unstrengthened beam. Experimental results were compared against the predicted ultimate shear strength of RC beams using design equations specified by various design codes. Nonlinear three‐dimensional finite element modeling was developed for beams strengthened with ECC layer and validated against the test results and found to be accurate. Based on the experimental and numerical results, new shear capacity formulae were proposed considering the ratio of ECC‐to‐concrete beam cross‐section (ρECC) and then verified against the numerical predictions. [ABSTRACT FROM AUTHOR]

In this paper, a total of six different ribbed and two nonribbed L‐shaped concrete‐filled steel tubular (CFST) short columns are designed; finite element modeling and calculations are carried out and verified with measured results. The optimal ribbing method among the ribbing methods applied is proposed. The mechanisms of the longitudinal stress of the concrete, longitudinal stress of the outer steel tube, and lateral compressive stress of the concrete for the L‐shaped CFST short column without ribs and with the optimal ribbing method are compared and analyzed. The results show that the optimal ribbing method involves setting half‐width longitudinal stiffening ribs in the middle of the two wide sides of the L‐shaped steel tube. The stiffening ribs can delay the occurrence of local buckling failure of the steel tube, thus strengthening the restraining effect of the steel tube on the concrete and improving the uniformity of the longitudinal stress of the core concrete. In addition, based on an analysis of a large number of parameters, four methods for calculating the bearing capacity of nonribbed L‐shaped CFST short columns are compared. A design formula for the bearing capacity of ribbed L‐shaped CFST columns is proposed by considering the improvement in the concrete performance. The calculation results agree well with the finite element and experimental results, and the error is <5%. [ABSTRACT FROM AUTHOR]

Lateral impact damage from over-height vehicle collisions with bridge superstructures is of increasing concern in the United States. However this issue is not fully addressed in current bridge specifications. Previous researchers have conducted a number of small-scale tests to study the impact process. Also, the finite element method has largely been used to analyze the complicated collision mechanism. This paper provides an opportunity for full-scale lateral impact testing of a prestressed concrete girder, which leads to a realistic level of damage and mechanism analysis. A full-scale lateral impact testing facility was designed and built on a construction site in Knoxville, Tennessee. The over-height vehicle impact was simulated by impacting the bottom of an AASHTO Type I prestressed concrete girder with an impact cart. This paper describes the details of the impact testing facility as well as the response of the prestressed concrete girder during lateral impact. The collected test data were calibrated by using finite element software ABAQUS. [ABSTRACT FROM AUTHOR]

This paper presents the comparison of advanced semi‐probabilistic methods for the design and assessment of concrete structures represented by mathematical models solved by non‐linear finite element methods. The special attention is given to the advanced methods focused on the estimation of the coefficient of variation of structural resistance. Numerical examples represent a replication of laboratory experiments of beams with different failure modes. The obtained results are discussed with respect to the accuracy of the employed methods and the influence of the assumed statistical correlation among basic variables. Simplified methods give a good estimation of the design values, though their accuracy is dependent on the type of the failure mechanism. Moreover, it is shown that mutual correlations among random variables may significantly affect the design value of resistance, and they should be carefully defined and modeled. [ABSTRACT FROM AUTHOR]

A curved composite box girder bridge has a coupling effect of bending and torsion under external load. The existence of interface slip will reduce the stiffness of the curved box girder and generate additional deflection. Because the curved composite box girder has multiple junction surfaces, under the action of external load, the different junction surfaces present asymmetrical slip distribution, and the shear connector force is complicated, so it is difficult to obtain its analytical solution. In this paper, an analysis model of a curved steel‐concrete composite box girder is established by selecting the appropriate element type and material constitutive relationship model. And by comparing the numerical simulation results with the experimental results, the correctness and rationality of the constitutive relationship between the element type and the material are verified. Based on the cross‐section parameters obtained by numerical simulation and experimental verification, combined with nonlinear optimization theory, the relationship between the optimized parameters is analyzed, and the cross‐section of the curved composite box girder is optimized. The research results can provide a theoretical basis for the optimal design of curved box girder bridges. [ABSTRACT FROM AUTHOR]

The effect of openings left in reinforced concrete shear walls due to functional requirements or architectural reasons is an important issue that should not be underestimated mainly since shear walls are considered as one of the most critical load‐carrying members in a structure owing to playing an active role against seismic forces. In this paper, a parametric study was carried out by creating a nonlinear finite element model to determine the effects of openings in reinforced concrete shear walls on the maximum shear force bearing capacities, initial stiffness, displacement ductility ratios, and energy dissipation capacities of the shear walls. The variables examined in the study were the size of the openings left in the reinforced concrete shear walls, opening location, the number of openings, and the concrete compressive strength used in the production of the shear walls. In the first part of the study, nonlinear finite element models of three experimental shear wall test elements: one with no opening (solid), and two with openings: were created using ABAQUS finite element software package, then verified by comparing the numerical analysis results with the experimental results. In the second part of the study, a nonlinear finite element model of 44 reinforced concrete shear walls, including the parameters planned to be investigated, was created by using the verified model, and finite element model (FEM) analyses were performed. As a result of numerical analyses, a capacity reduction coefficient proposal has been developed to calculate the shear force capacities of reinforced concrete shear walls with openings. [ABSTRACT FROM AUTHOR]

This paper investigates a novel variable‐grade prefabricated concrete (PC) slab with surrounding composited which has high prefabrication rate, sufficient installation rigidity, high on‐site construction efficiency, and good overall working performance. To improve the crack‐resistance performance of the transverse superposed surface and the overall working performance of the proposed novel PC slab, we optimize the position of variable‐grade and arrange it at the location where the bending moment is close to zero. We perform comparatively bending tests on three two‐span full‐scale slab strips that include boundary and intermediate beam‐slab joints to systematically investigate the flexural behavior of the proposed novel slab. The load versus deflection relationship, failure mode, distribution of cracks, development law of crack width and development of steel strain are comparatively studied. The test results confirm that the flexural behavior of the proposed novel PC slabs are similar and slightly better than that of the cast‐in‐place slab in general. No crack or slippage appears at the interface between the precast panel and the post‐pouring concrete. The connection method of L‐shaped anchorage rebars lap splicing in this study is cost‐effective, efficient, and reliable. Furthermore, we establish a finite element model and perform a parametric investigation on the proposed novel PC slab. Parametric simulations conclude that the increase of the strength of post‐pouring concrete and post‐pouring layer thickness can improve the bearing capacity of the proposed novel PC slabs. [ABSTRACT FROM AUTHOR]

With the plethora of data on how CFRP layers enhance RCs under static loads, research on how the reinforced structural components react to unequal lateral impact loads from a derailed train striking metro station columns or a car accident is lacking. A similar motivation inspired the current study, which sought to create a numerical technique backed by actual testing to evaluate RC members with CFRP in a range of unequal lateral impact scenarios. This paper uses explicit nonlinear finite element techniques to numerically analyze the response of unequal lateral impact‐loaded RC members wrapped in (CFRP) layers. Diverse variables related to CFRP, concrete, steel reinforcement, and impact energy are investigated. This kind of thorough analysis provides unique insights to strengthen RC members against unequal lateral impact loads. The effects of internal forces and deflections, as well as absorbed energy on the impact response of CFRP‐RC components, were investigated and verified by prior experimental results. A parametric sensitivity analysis was conducted after the strain characteristics of steel bars confirmed the finite element model, reinforcement ratio, impact velocity, CFRP properties, and ductility index all influence the member's impact response. This study's results will help advance the field's understanding of CFRP‐RC components analysis and design under unequal lateral impact. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical investigations on circular concrete‐filled double steel tubular (CFDST) members under flexural load. Seven specimens including five CFDST specimens were tested and the test parameters included the effects of concrete compressive strength, the thickness of the steel tubes, and the diameter ratio on their flexural performance. The final failure modes, moment (M)‐curvature (ϕ) curves, deflection curves of specimens, and distributions of section longitudinal strains were analyzed and reported in this study. A nonlinear finite element model (FEM) was then developed for the CFDST members. After successful validation in ultimate strengths and failure modes, parametric studies were performed by using the verified FEM. A simple formula for calculating the flexural capacity of CFDST members was proposed and compared against several design codes to investigate the design accuracy. Based on this study, it was found that the CFDST members exhibit ductile behavior under flexural load. Increasing the steel area, particularly for the outer tube improved the flexural capacities of the members. Furthermore, the existing design codes were found to be remarkably underestimating the moment capacities of CFDST members whereas the design formula proposed can predict the ultimate flexural capacity with reasonable accuracy. [ABSTRACT FROM AUTHOR]

In order to develop a calculation method for the ultimate flexural capacity of high strain‐hardening ultra‐high performance concrete (UHPC) T‐beams, four‐point loading tests on five specimens were carried out. The design parameters were the ratio and the strength of reinforcement. Based on the assumption of plane section, a linear regression analysis was carried out and the ultimate tensile strain of high strain‐hardening UHPC was obtained. The analysis results proved that the bond between reinforcement and UHPC is reliable and these two materials can maintain strain consistency before the reinforcement reaches its yield strain. A finite element model of the specimens was established using ANSYS and distributed reinforcement was added to simulate the behavior of UHPC after cracking. Considering the tensile contribution of the high strain‐hardening UHPC after cracking, the calculation method for flexural capacity of high strain‐hardening UHPC T‐beams was derived. The finite element simulation method and the theoretical formula calculation method proposed in this paper are in good agreement with the experimental values, and they can be applied for the theoretical analysis and the design of high strain‐hardening UHPC beams. The theoretical calculation method proposed in this paper is compared with calculation methods proposed by standards. The study shows that the proposed calculation method is accurate and generally applicable. [ABSTRACT FROM AUTHOR]

This paper analyses the performance of the experimental setups to assess the punching strength of slab‐column connections in continuous flat slabs under vertical and horizontal loading. In the last years, several experimental campaigns have been performed to investigate the punching strength of slab‐column connections, but most of the experimental tests concerned isolated slab‐column connections. Among the few setups aimed at reproducing the eccentric punching failure in continuous flat slabs, the setup developed at the NOVA School of Science and Technology in Lisbon is considered in this paper. The performance of the Lisbon setup is assessed through nonlinear finite element analyses, calibrated on experimental data, by comparison with numerical results of a theoretical continuous setup. Then, the performance of the isolated setups, used in many researches and at the base of some international codes, is also evaluated through the same finite element model. Numerical analyses highlight that the setup developed in Lisbon could provide reliable ultimate rotations of continuous flat slab connections, but it underestimates the punching strength. Despite isolated setups lead to similar results when compared with the Lisbon setup, the latter seems to provide a better representation of a continuous slab‐column connection. The numerical analyses presented in this paper have been performed assuming monotonic lateral loading. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present through a practical example, some recommendations to properly model confined concrete in three‐dimensional nonlinear finite element analysis. The example chosen is of particular interest for tunneling and structural engineers as it compromises the joints between segments of the concrete lining used with the tunnel boring machine technique. These sections are designed to transmit high pressures, sometimes exceeding the Standards' recommendations. To carry out the nonlinear finite element analyses (NLFEAs) a dedicated software, was employed. A discussion about which parameters play a fundamental role to efficiently model the problem is carried out. Finally, a comparison between NLFEA results and an experimental campaign is presented highlighting the differences in terms of stress values within the steel bars, the failure mechanism and evaluation of the contribution of steel to the resistance of confined concrete. [ABSTRACT FROM AUTHOR]

This paper is concerned with the finite element modeling of strengthened interior slab‐column connections in the existing continuous flat slab structural system by employing steel angle plates at the slab‐column junctions and fastened by shear bolts. This technique utilizes the advantage of combined action between the angle plates and bolts in resisting shear particularly at the slab‐column edges. Three‐dimensional analysis was carried out on such slabs employing concrete damaged plasticity model in ABAQUS to investigate their performance in terms of punching shear resistance, load–displacement response, and crack pattern at failure. The numerical models were first validated against the experimental results reported by other researchers. The proposed strengthening technique results in a substantial increase of load‐carrying capacity ranging from about 59 to 79% compared to the unstrengthened slab, and has also provided better stiffness, ductility and energy absorption in the slab system that change the mode of failure from a pure punching shear to flexural failure. The finite element results are compared with the calculated values according to provisions in the current design codes for evaluation purposes. A simple but reliable approach which is based on yield line theory to estimate the flexural capacity of the strengthened slabs is also outlined in this paper. [ABSTRACT FROM AUTHOR]

This paper presents the experimental study and finite element modeling of the flexural behavior of concrete beams reinforced with reused steel bars as longitudinal reinforcements. The experimental program and results of eight reinforced concrete (RC) beams constructed with and without reused steel bars are described in detail. The replacement percentages of brand‐new bars with reused steel bars in the tested beams were 50% and 100%. The reused steel bars were coated with and without epoxy. Steel fibers with fractions of 0.5% and 1.0% of the concrete volume were added to the concrete mixes. The load‐deflection relationship, ductility index, toughness, and failure modes of the tested beams are presented and discussed. It is shown that utilizing reused steel bars decreases the ultimate load of RC beams but increases their deflection at the ultimate load compared with the control beam. Increasing the steel fiber ratio increases the ultimate load and the deflection at the ultimate load of RC beams incorporating reused steel bars. However, the zinc‐rich epoxy used to coat the reused steel bars does not affect the behavior of the beams. Three‐dimensional nonlinear finite element (FE) models of the tested beams were developed using ABAQUS and validated against the test results. The developed FE models are capable of accurately simulating the experimentally observed behavior of RC beams with reused steel bars. [ABSTRACT FROM AUTHOR]

In bridge engineering, the use of precast post‐tensioned segmental (PPS) piers is increasingly expanding due to the Accelerated Bridge Construction viewpoint. Recent experimental and numerical researches have studied general seismic performance and nonlinear behavior of PPS piers without much attention to segment arrangements or joint openings. The aim of this paper is to utilize innovative segment arrangements to reduce the residual deformation, without reducing the energy dissipation capacity of PPS piers with internal energy dissipation (ED) bars. For this purpose, nonlinear rocking dynamics of a multiple‐block assembly of tied rigid rocking blocks equipped with ED bars at joints are firstly developed so that uplift moment for each joint is derived to obtain the threshold joint opening height (height above which no joint opens). Then, nonlinear static, quasi‐static, and dynamic analyses are conducted on different segment arrangements of finite element models of PPS piers. It is proposed to place more segments within the threshold joint opening height by using unequal segments so that the total rotation is shared among critical joints (joints that open), and the nonlinear extent of ED bars at the bottom joint is reduced, resulting in the reduced residual deformation. It is also proposed to place a lower ratio of ED bars at the critical intermediate joints or place ED bars of a lower yield stress there so that the intermediate joints can be more effective even with small rotations. Results indicate that using the proposed segment arrangement, enhances both seismic and post‐earthquake performance of PPS piers. [ABSTRACT FROM AUTHOR]

This paper presents the structural behavior of precast concrete sandwich panels (PCSPs) containing recycled tyre crumb rubber core under uni‐axial compression and compared with that containing commonly used expanded polystyrene (EPS) foam. A total of six panels were cast and tested. Two for each category of precast concrete panels that is, solid concrete panel, crumb rubber sandwich panel and foam sandwich panel. Results showed that the ultimate axial load of crumb rubber sandwich panel was found to be 91% of solid concrete panel and also exhibited higher structural response in comparison to foam sandwich panel. It was observed that all panels failed in a similar manner by crushing of concrete at ultimate load. Moreover, a finite element model was developed in ABAQUS using in‐built model of concrete plasticity damage to simulate the ultimate axial capacity of recycled tyre crumb rubber concrete sandwich panel and its failure in uniaxial compression. Analysis showed that the finite element modeling slightly overestimated the experimental results. Furthermore, the experimental test results showed that the recycled tyre crumb rubber can be utilized as an alternate core material in PCSPs without substantially compromising the ultimate strength or any change in structural response. [ABSTRACT FROM AUTHOR]

This paper details the invention of a tensioning and anchoring device based on the "wedge‐cutting effect" that can tension and anchor multi‐layer carbon fiber reinforced polymer (CFRP) fabric. To achieve a high active confinement effect on an RC column, the device is characterized by its capability to lift the applied prestress to the greatest extent and minimize prestress loss. All eight RC columns with identical structural dimensions were designed and fabricated, including three unstrengthened and five strengthened columns. The seismic performance test and finite element simulation were conducted under a low cyclic reciprocating load. The test parameters include active confinement force and axial compression ratio, with active confinement force varying as a function of the number of layers of CFRP fabric. The results indicate that the seismic performance of RC columns with high active confinement can be significantly improved. Under a high axial compression ratio, the maximum displacement ductility coefficient and ultimate drift ratio of specimens strengthened with four layers of prestressed CFRP fabrics can increase by 87% and 152%, respectively, while the energy consumption can increase by 4.3 times. Additionally, the ultimate horizontal bearing capacity can be raised by 41%. The seismic performance of strengthened columns increases with the increase of active confinement, particularly under high axial compression. The finite element model is in good accord with the experiment. With an increase in active confinement force, the properties of confined concrete and CFRP are utilized to a greater extent, and more energy is dissipated by the opening and closing of numerous micro cracks. [ABSTRACT FROM AUTHOR]

Multistory concrete buildings may resort to the strategy to cast columns and slabs with high and normal compressive concrete strength, respectively. Current design codes propose expressions to specify the effective compressive strength of interior columns confined only by flat slabs or beams with the same width as the column. However, when thin slabs and narrower beams are used, the confinement may not be enough to increase the lateral stress. The structural behavior of these interior columns is investigated in this paper using numerical nonlinear models. The influence of concrete strength column‐slab ratio, the steel reinforcement ratio of the column and the beam, beam height and the column width ratio and the biggest dimension of the column's cross section were tested with and without vertical load on the beam. The results were compared with expressions found in the literature. [ABSTRACT FROM AUTHOR]

This paper presents a mechanical and numerical approach to model localized deformations occurring in concrete structures with less than minimum reinforcement. The presented models are based on, and validated against large‐scale experiments conducted in a previous study to investigate the behavior of a less than minimally reinforced slab in the framework of the structural safety assessment of an existing cut and cover tunnel. The model deploys rotational springs embedded in a nonlinear finite element analysis to capture deformations concentrating in an inclined crack. An iterative solution procedure ensures equilibrium and compatibility in the inclined crack section by adjusting the spring stiffnesses, which depend on the acting loads. A case study shows that the localized crack has a minor effect on the global structural behavior. In contrast, localization strongly influences deformations and stress resultants in the crack, and compressive membrane action significantly impacts the load–deformation behavior of the localized crack, which is relevant particularly for the shear strength. [ABSTRACT FROM AUTHOR]

Precast concrete structures have been widely applied in the construction industry worldwide. However, the current construction method for the reinforced concrete frame–shear wall structure (FSWS) is semi‐precast because the shear wall is commonly cast‐in‐place. This paper proposes a full precast FSWS and investigates three new vertical joints with different lap splices that can facilitate on‐site construction. Push‐off tests are conducted to investigate the shear performance on the aspect of cracking and failure patterns, the evolution of deformation, stiffness reduction, and energy dissipation. A finite element model with delicate consideration of the contact is developed and validated against experimental data. A further parametric study is conducted. This study shows that the lap splice with a more uniformly distributed reinforcement layout yields the crack distribution more uniformly and increases the ductility of the joints. The proposed three vertical joints exhibit an improvement in ductility compared to the monolithic one. Furthermore, the shear keys change the failure mechanism of the precast joints into the multi‐struts failure mechanism thus increasing the shear strength. The parametric study shows that the decreasing of the splice lap length could increase the shear capacity of the vertical joints but decreases the ductility. However, the ductility reduction depends on the variation of lap splices. [ABSTRACT FROM AUTHOR]

Due to the low lateral stiffness of slabs supported on columns alone, reinforced concrete flat plates are typically combined with other structural elements, such as shear walls. In these structures, the slab–column connections are designed to carry gravity loads only, and the shear walls are required to resist both gravity and lateral forces. Therefore, the slab–wall connections are essential for the performance of both the gravity and lateral force resisting systems. However, most punching shear research and design provisions are focused on slab–column connections, even though punching failures around slab–wall connections have occurred experimentally. Empirical testing of slab–wall connections is difficult due to the specimen size. This paper investigates the punching shear behavior of interior slab–wall connections subjected to concentric vertical loading, and combined concentric vertical loading and uniaxial unbalanced moment using a plasticity‐based nonlinear finite element model (FEM) in ABAQUS. The analysis of isolated slab–wall connections demonstrates that punching failures can occur before one‐way shear failures. Since the overall connection capacity is much higher than the expected loads in most structures, if these punching failures happen they would be localized to the region around the wall end and are not expected to lead to structural collapse. [ABSTRACT FROM AUTHOR]

The paper presents the tridimensional numeric model of an inner slab‐column connection of reinforced concrete, which was previously tested against the punching shear in the lab of the University of Brasília. The numerical analysis has been carried out by the finite element method, using the software ABAQUS. To evaluate the sensitivity of the main factors that influence the responses of the model, a parametric investigation was conducted as per the finite element mesh, mechanical properties of the concrete and plastic parameters of the assumed model for the concrete, named by concrete damaged plasticity model (CDPM). The results of the resistance capacity, displacements, strains, cracking pattern, and failure mode were compared with those obtained experimentally. From this comparison, it was concluded that the numerical model was able to reproduce the punching shear phenomenon with a high level of precision. [ABSTRACT FROM AUTHOR]

Electrochemical chloride extraction (ECE) is an effective method to remove chloride ions in reinforced concrete. In addition, cracks in concrete have self‐healing properties. The self‐healing properties of concrete may affect the ECE process. Based on moving mesh technology, this paper simulates the ion migration process of ECE in crack‐self‐healing concrete. According to the simulation results, the distribution of ions in the reinforced concrete and the electric potential change law inside the concrete are analyzed during the ECE process. The effects of cracks or no cracks in the anode area of ECE, self‐healing or no self‐healing, and different self‐healing rates on the efficiency of ECE were discussed. This research will have a positive impact on ECE's research. [ABSTRACT FROM AUTHOR]

In this paper, the behaviour of RC slab strips subjected to transverse loads and axial tensile forces is investigated by means of analytical and numerical simulations. The results obtained are compared to the experimental results from tests performed at the Swiss Federal Institute of Technology (ETH). The prediction of the structural response was part of an international benchmark study [1]. The aim of the paper is to investigate the capability of the adopted models and their main influencing parameters, especially from the perspective of a reliable structural robustness assessment. It is known that in some cases axial tensile forces have a beneficial effect on the bearing capacity of slab strips, thanks to the development of catenary actions. Such hidden strength resources are usually not taken into account in the current design process. For this reason, validation of suitable numerical tools, able to properly predict the structural response, is useful for a reliable structural robustness assessment. The paper underlines the importance of benchmark development, especially for specimens, in which both mechanical and geometrical nonlinearities play an important role. [ABSTRACT FROM AUTHOR]

Today, the development of innovative shear connectors for steel-concrete composites is accompanied by a large number of experimental investigations, which are obligatory when proposing suitable design formula and carving out their limitations of use. Using the example of the so-called pin connector, the present paper illustrates to what extent validated finite element models of novel shear connectors can be used to replace expensive and time-consuming shear tests and how these finite element models can support the deduction of design concepts. The pin connector considered was developed for connecting steel sections to very slender high-strength concrete slabs in which conventional shear connectors such as headed studs cannot be used due to the limited embedment depth. In order to clarify the shear behaviour and load-carrying mechanisms of these novel connectors, non-linear finite element models were set up using the commercial FE software Abaqus. Subsequently, the FE models were used to perform systematic parametric studies. This paper describes the numerical results and also explains the stepwise development of an entire engineering model for determining the longitudinal shear capacity of small-scale pin connectors, including all the necessary limitations of use. The proposed modelling strategy and the methodology for the deduction of design rules can be transferred and assigned to other types of shear connectors. [ABSTRACT FROM AUTHOR]

This paper analyzes the potential influence of the construction process on the serviceability stage of the structure of reinforced concrete (RC) buildings. For this, a number of cases of buildings erected by habitual construction processes were simulated by a finite elements model, including and excluding the construction process. The shoring–clearing–striking method was seen the least harmful to the long‐term behavior, but even so maximum loads during construction exceeded the design loads. On the other hand, shoring–reshoring–striking procedure had construction loads similar to the design loads but worse long‐term behavior. In view of the results obtained, it is of the utmost importance to consider the construction phase when designing building structures. Some practical recommendations are given to improve the consideration of the construction process in the design as well as to take into account the long‐term behavior of structures due to load history during construction. [ABSTRACT FROM AUTHOR]

Assessment of the cracked behavior at service load and verification of sufficient deformation capacity in the ultimate state are often required when designing reinforced concrete structures. Most existing methods dedicated to nonlinear analysis of reinforced concrete, however, are not well‐suited in practice for use in design processes involving large‐scale structural problems due to an enormous modeling effort and lack of numerical stability. This paper presents a new finite element framework for efficient elasto‐plastic analysis of two‐dimensional reinforced concrete structures subjected to in‐plane forces. The basic concept is to adopt a stress‐based finite element formulation and cast the problem as a convex optimization problem where energy principles are invoked through a formalistic application of nonlinear‐elastic material models. The method accounts for reinforcement yielding and concrete crushing, including the strength reduction due to cracking, and can be used to imitate the elasto‐plastic response of fully‐cracked structures subjected to monotonic loading. The efficiency of the method is demonstrated, inter alia, by an analysis of a complex structure, where the discretized problem has more than 1 million variables and is solved within a few minutes on a standard personal computer. [ABSTRACT FROM AUTHOR]