Research

23 pages, 11388 KiB

Open AccessArticle

Semi-Precast Segmental Bridge Construction Method: Experimental Investigation on the Shear Transfer in Longitudinal and Transverse Direction

by Stephan Johann Fasching, Tobias Huber, Michael Rath and Johann Kollegger

Appl. Sci. 2021, 11(12), 5502; https://doi.org/10.3390/app11125502 - 14 Jun 2021

Cited by 3 | Viewed by 2812

Abstract

Large span concrete bridges with a box-shaped girder are usually built from prefabricated concrete segments or by in-situ casting of the concrete on a scaffolding system. Both technologies have their advantages and drawbacks. Recently a new approach to the construction of such bridges [...] Read more.

Large span concrete bridges with a box-shaped girder are usually built from prefabricated concrete segments or by in-situ casting of the concrete on a scaffolding system. Both technologies have their advantages and drawbacks. Recently a new approach to the construction of such bridges which combines the advantages of both existing solutions was proposed at the TU Wien. This method uses the standard precast segmental erection methods with their high construction speed, but divides the segments into easily transportable pre-fabricated thin-walled elements to create new, lighter versions of the segments. Following the installation of these lightweight segments, they are strengthened with additional concrete in their final position in the superstructure. This paper focuses on the transmission of shear forces during construction stages. Firstly, on the level of individual segments, where rigid cross-frames are necessary to guarantee the stability of the segments and secondly, on the level of a bridge girder built from such segments, where new joint types must be developed to ensure the force transfer between the segments. Different options for the formation of cross-frames as well as shear tests on double walls and concrete panels with steel girders are shown. In this experimental series, different shear transmitting elements were compared to each other and to calculations with non-linear finite element analysis, showing that all the investigated solutions are suitable for use in thin-walled bridge segments. Several methods, including a new concept for joining thin-walled pre-fabricated elements, are described for the joints between the segments. Push-off tests with a constant lateral force were carried out to assess the shear strength and deformation behaviour. The main parameters were the joint type (wet joints: plain, grooved, keyed; dry joints), the grout type, and the lateral force level. The test results are presented and the structural behaviour is further analysed using non-linear finite-element simulations. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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16 pages, 5871 KiB

Open AccessArticle

Shear Response of Members without Shear Reinforcement—Experiments and Analysis Using Shear Crack Propagation Theory (SCPT)

by Maximilian Schmidt, Philipp Schmidt, Sebastian Wanka and Martin Classen

Appl. Sci. 2021, 11(7), 3078; https://doi.org/10.3390/app11073078 - 30 Mar 2021

Cited by 19 | Viewed by 3343

Abstract

The determination of the ultimate shear capacity and the identification of the corresponding load-carrying mechanisms of concrete members without shear reinforcement has been an ongoing research topic for over 100 years. Based on a full mechanical model, the Shear Crack Propagation Theory (SCPT) [...] Read more.

The determination of the ultimate shear capacity and the identification of the corresponding load-carrying mechanisms of concrete members without shear reinforcement has been an ongoing research topic for over 100 years. Based on a full mechanical model, the Shear Crack Propagation Theory (SCPT) enables to analyze and understand the ever-changing interplay of crack propagation, evolution of stresses at the crack tip and in uncracked concrete parts, as well as the activation of shear transfer actions within the growing shear crack during the entire loading process. In this paper, selected experimental investigations for further validation of the SCPT are presented. These beam shear test results are then compared to the theoretical results emerging from the SCPT algorithm. Finally, the evolution of different shear transfer actions (e.g., aggregate interlock and dowel action) during the entire loading process is evaluated and discussed. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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20 pages, 16890 KiB

Open AccessArticle

Calibrating a New Constitutive Tension Model to Extract a Simplified Nonlinear Sectional Analysis of Reinforced Concrete Beams

by Alaaeldin Abouelleil and Hayder A. Rasheed

Appl. Sci. 2021, 11(5), 2292; https://doi.org/10.3390/app11052292 - 04 Mar 2021

Cited by 1 | Viewed by 2007

Abstract

Nonlinear analysis of structural members is vital to understand the behavior and the response of reinforced concrete members. Even though most design procedures concentrate on the ultimate stage of response towards the end of the post-yielding zone as the decisive design criterion, the [...] Read more.

Nonlinear analysis of structural members is vital to understand the behavior and the response of reinforced concrete members. Even though most design procedures concentrate on the ultimate stage of response towards the end of the post-yielding zone as the decisive design criterion, the structural members usually function at the service load levels within the post-cracking zone. Therefore, cracking is a critical aspect of concrete behavior that affects the overall response of reinforced concrete beams. The initiation and the propagation of the cracks are affected directly by the tension and shear stresses in the beam. In flexural beams, the tensile stresses dominate the crack onset and its growth. Cracks in reinforced concrete flexural beams leave non-cracked regions in between the cracked sections. In order to apply a consistent analysis strategy, the smeared crack approach averages the behavior of these different cracked sections and uncracked in between regions to generate an accurate global response of the entire beam. This study presents a numerical constitutive tensile model that captures the complete tensile response of the reinforced concrete flexural member, in terms of averaged/smeared crack response. As a second step, this model was examined against a large pool of experimental data to validate its accuracy. Overall, the main objective of this study is to develop a representative constitutive tensile model for reinforced concrete flexural members and validate its accuracy against experimental results. The full nonlinear sectional response is analytically realized, based on the assumed trilinear moment–curvature response and the assumed trilinear moment–extreme fiber compressive strain response. This is considered as the secondary outcome of the present study. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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19 pages, 9021 KiB

Open AccessArticle

Simulation of Crack Propagation in Reinforced Concrete Elements

by Jonas Cramer, Sara Javidmehr and Martin Empelmann

Appl. Sci. 2021, 11(2), 785; https://doi.org/10.3390/app11020785 - 15 Jan 2021

Cited by 7 | Viewed by 2598

Abstract

The crack widths in reinforced concrete structures are affected by various influencing parameters, such as the tensile strength of the concrete, which is a highly variable parameter. While safe predictions of crack widths are possible with the existing models supplied in the code [...] Read more.

The crack widths in reinforced concrete structures are affected by various influencing parameters, such as the tensile strength of the concrete, which is a highly variable parameter. While safe predictions of crack widths are possible with the existing models supplied in the code provisions accompanied by suitable safety factors, there are large discrepancies between the experimentally measured crack widths and the calculated values. Even within a uniaxial tensile test on reinforced concrete components, several crack parameters (spacings and widths) are usually measured. To further investigate the effects of scattering input parameters on the distribution of crack parameters, a crack propagation model (CPM) is developed, which is a powerful tool that can be used to observe sequential cracking of uniaxially loaded reinforced concrete components. In the present paper, the background of the scattering of the concrete tensile strength will be explained and the procedure for the simulation in the CPM, including the investigation of different bond–slip relationships, will be introduced. Finally, the CPM will be used to calculate experimental crack parameters and the distribution of the calculated crack parameters will be discussed. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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25 pages, 10409 KiB

Open AccessArticle

Structural Behavior of Floor Systems Made by Floor Plates—Mechanical Model Based on Test Results

by Tom Molkens and Ann Van Gysel

Appl. Sci. 2021, 11(2), 730; https://doi.org/10.3390/app11020730 - 13 Jan 2021

Cited by 4 | Viewed by 2368

Abstract

In daily engineering practice, the execution of concrete slabs by the mean of precast floor plates is seen as a common and reliable way to create massive slabs. In the last few decades, however, there has been an evolution to flat slabs and [...] Read more.

In daily engineering practice, the execution of concrete slabs by the mean of precast floor plates is seen as a common and reliable way to create massive slabs. In the last few decades, however, there has been an evolution to flat slabs and other uses where important bending moments must be transferred over the joints between the floor plates. For this kind of application, there is a lack of knowledge and experimental evidence based on large-scale tests to define accurate failure and design models. In this work, a comprehensive overview is given of 20 large-scale tests and some additional tests to support the findings and observations. It is confirmed that a purely bending-based design of the joints delivers reliable results, but some conditions are set; first, the maximum distance of the lattice girder to the joint may not exceed 400 mm without voiding elements. Second, only a 95 mm distance must be respected with voiding elements or additional protruding reinforcement must be applied. Attention is also given to how the system works when the major components—adhesion, mechanical interlock, and friction—are missing at the interface. Finally, repair possibilities are discussed and how they should be designed. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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20 pages, 5767 KiB

Open AccessArticle

A Thermomechanical Coupling Constitutive Model of Concrete Including Elastoplastic Damage

by Liang Li, Hongwei Wang, Jun Wu and Wenhua Jiang

Appl. Sci. 2021, 11(2), 604; https://doi.org/10.3390/app11020604 - 10 Jan 2021

Cited by 5 | Viewed by 1896

Abstract

The thermomechanical coupling constitutive model of concrete is a critical subject for the theoretical investigation and numerical simulation of the mechanical behaviors of concrete members and structures at high temperature. This paper presents a thermomechanical coupling constitutive model for the description of the [...] Read more.

The thermomechanical coupling constitutive model of concrete is a critical subject for the theoretical investigation and numerical simulation of the mechanical behaviors of concrete members and structures at high temperature. This paper presents a thermomechanical coupling constitutive model for the description of the mechanical behaviors of concrete at different temperatures. The expression of the elastic strain increment is derived with the free energy function including the temperature variable. The expression of the plastic strain increment is derived from the yield function based on the Drucker–Prager strength criterion. The elastoplastic damage effect is included in this constitutive model. The damage variable is included in the yield function to consider the effect of the damage on the elastoplastic mechanical behaviors of concrete. The proposed constitutive model is validated by the comparison of the simulation results of the uniaxial compression tests of concrete at different temperatures with the corresponding test results. The simulation results accord well with the test results at different temperatures. This indicates that the proposed constitutive model can characterize the mechanical behaviors of concrete at different temperatures with considerable accuracy. The proposed constitutive model was applied to simulate an axially compressive concrete column. The simulation results are consistent with the essential mechanical response behaviors of concrete members at different temperatures. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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25 pages, 9657 KiB

Open AccessArticle

Seismic Response Analysis of Prestressed Concrete Rocking Frame

by Zixiang Zhao and Xiaozu Su

Appl. Sci. 2021, 11(2), 585; https://doi.org/10.3390/app11020585 - 08 Jan 2021

Cited by 1 | Viewed by 1509

Abstract

In order to investigate the seismic performance of prestressed concrete rocking frame (PCRF), a theoretical model based on rigid body is established for a one-story single-span PCRF. The PCRF studied in this paper has the connecting interfaces set at the column feet and [...] Read more.

In order to investigate the seismic performance of prestressed concrete rocking frame (PCRF), a theoretical model based on rigid body is established for a one-story single-span PCRF. The PCRF studied in this paper has the connecting interfaces set at the column feet and at the inner faces of the beam–column joints, allowing the columns to be uplifted with the accompanying separation of the beam–column interface and rotation of the beam and column around the interface. The tendons are arranged along the centerline of the beam and columns. The connections between the beam and columns and the anchoring of columns are accomplished by prestressing the tendons. The theoretical model consists of a rigid beam, rigid columns and elastic tendons. The governing motion equation of the PCRF is derived based on the model and a numerical solution of the equation of motion is obtained. The energy dissipation of the PCRF is analyzed and the calculation method for the coefficient of restitution is derived. Time history analysis and parameter analysis of seismic response of the PCRF are conducted and the results show that the PCRF has promising seismic behavior. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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20 pages, 9549 KiB

Open AccessFeature PaperArticle

Optimization Study on Longitudinal Joints in Quasi-Rectangular Shield Tunnels

by Weixi Zhang, Wouter De Corte, Xian Liu and Luc Taerwe

Appl. Sci. 2021, 11(2), 573; https://doi.org/10.3390/app11020573 - 08 Jan 2021

Cited by 5 | Viewed by 1939

Abstract

There are large bending moments in quasi-rectangular shield tunnels due to their deviation from the circular shape, and as for other types of shield tunnels, the longitudinal joints are the most critical parts in the lining structure. A new type of joint with [...] Read more.

There are large bending moments in quasi-rectangular shield tunnels due to their deviation from the circular shape, and as for other types of shield tunnels, the longitudinal joints are the most critical parts in the lining structure. A new type of joint with ductile iron joint panels (DIJPs) was installed in quasi-rectangular tunnels to solve these problems. The distance from the bolts to the segment’s inner surface was improved for better performance under specific bending moment types. Both tests and finite element modeling (FEM) simulations were conducted to investigate the effect of the bolt position improvements. The resistances to crack appearance increased by 33.6% and 18.0% for positive and negative moment cases, respectively. The resistances to crack penetration increased by 13.8% and 18.4% for positive and negative cases. From the FEM approach, it was found that the behavior of the joint under the design bending moment range can be divided into three stages, whereby the bolts are only active from the second stage on. The effects of other optimizing methods, such as enhancement of concrete properties and increase of bolt diameters and numbers, are explored. Through comparison, it is believed that optimizing the joint section to increase the lever arm between bolts and the compression zone can improve the joint behavior most effectively. This optimization direction is recommended when designing a shield tunnel joint with DIJPs. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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26 pages, 9140 KiB

Open AccessFeature PaperArticle

Multi-Field Models of Fiber Reinforced Concrete for Structural Applications

by Yaming Pan, Jingu Kang, Sonoko Ichimaru and John E. Bolander

Appl. Sci. 2021, 11(1), 184; https://doi.org/10.3390/app11010184 - 27 Dec 2020

Cited by 9 | Viewed by 2432

Abstract

Short fiber reinforcement is added to concrete materials to improve a variety of performance measures related to structural safety, serviceability, and health diagnosis. Mesoscale models have been developed to understand the individual and collective actions of these fibers on various material properties. Those [...] Read more.

Short fiber reinforcement is added to concrete materials to improve a variety of performance measures related to structural safety, serviceability, and health diagnosis. Mesoscale models have been developed to understand the individual and collective actions of these fibers on various material properties. Those modeling efforts have predominately focussed on the mechanical (i.e., stiffness and strength) contributions of fibers. This paper introduces computationally efficient, semi-discrete representations of fibers within coupled mechanical and transport processes in cement-based matrices. Basic simulations are done to study: the use of conductive fibers for self-sensing; and the influences of fibers on early-age plastic settlement. It is found that the models can account for directional bias on fiber orientation, as may occur during material casting. With respect to plastic settlement, fibers may play competing roles: mechanical restraint offered by the fibers reduces settlement, whereas enhanced hydraulic conductivity along the fiber–matrix interface may increase settlement by facilitating the bleeding process. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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19 pages, 16918 KiB

Open AccessArticle

Design of Anchorage Zones of Pretensioned Concrete Girders: A Comparison of Nonlinear 3D FEM Results with Measurements on a Full Scale Beam

by Wouter De Corte, Kizzy Van Meirvenne, Veerle Boel and Luc Taerwe

Appl. Sci. 2020, 10(22), 8221; https://doi.org/10.3390/app10228221 - 20 Nov 2020

Cited by 4 | Viewed by 2147

Abstract

Pretensioned concrete beams are widely used for constructing large load-bearing structures and bridging long spans. Crack formation may occur in the end zones of these elements due to tensile splitting, spalling and bursting actions. Investigation of these zones is typically done by means [...] Read more.

Pretensioned concrete beams are widely used for constructing large load-bearing structures and bridging long spans. Crack formation may occur in the end zones of these elements due to tensile splitting, spalling and bursting actions. Investigation of these zones is typically done by means of analytical methods, strut and tie modelling, 2D linear or nonlinear analysis, or full 3D nonlinear analysis. Especially challenging in this last approach is the modelling of the force transfer from the strands to the surrounding concrete as it strongly influences the magnitude of the tensile stresses. This paper presents a 3D nonlinear analysis of the anchorage zone of a pretensioned girder, and a comparison with experimental results (mechanical strain measurements, embedded strain gauges). Material modelling, steel-concrete interaction properties, as well as convergence problems are addressed systematically. The comparison indicates that a good agreement is found, both for concrete and rebar strains, and that a friction coefficient of 0.7 can be adopted, although the results for values from 0.5 to 0.9 do not differ that much. The results demonstrate that a 3D nonlinear analysis provides an excellent insight in the behavior of the end zones of pretensioned girders which opens perspectives for an optimization of the end zone design based on this type of analysis. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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20 pages, 9328 KiB

Open AccessArticle

XFEM-Based Multiscale Simulation on Monotonic and Hysteretic Behavior of Reinforced-Concrete Columns

by Hongbing Chen, Bin Xu, Jiang Wang, Xin Nie and Yi-Lung Mo

Appl. Sci. 2020, 10(21), 7899; https://doi.org/10.3390/app10217899 - 07 Nov 2020

Cited by 12 | Viewed by 2937

Abstract

The extended finite element method (XFEM) is efficient in simulating crack initiation and its evolution process for reinforced-concrete (RC) structures due to its ability to solve fracture problems. Moreover, the multiscale numerical simulation helps understand global and local failure behavior of RC structures [...] Read more.

The extended finite element method (XFEM) is efficient in simulating crack initiation and its evolution process for reinforced-concrete (RC) structures due to its ability to solve fracture problems. Moreover, the multiscale numerical simulation helps understand global and local failure behavior of RC structures simultaneously. In this study, the XFEM-based multiscale modeling approach was proposed to investigate the monotonic and hysteretic performance of RC columns. Firstly, two-scale models composed of fiber beam elements and XFEM-based solid elements with homogeneous material assumptions were established using compiled material subroutines for fiber beam elements. Secondly, the accuracy of XFEM-based two-scale analysis in predicting the hysteretic behavior of tested RC columns was verified by comparing the crack morphology and load-displacement curve obtained from tested specimens under different axial compression ratios (ACRs) and two-scale models using the concrete damaged plasticity (CDP) model. Thirdly, multiscale models of RC columns were constructed with fiber beam elements, XFEM-based solid elements and mesoscopic concrete models composed of mortar, interfacial transition zone (ITZ) and aggregates with different geometric shapes and distribution patterns. Finally, the XFEM-based multiscale simulation was employed to investigate the influence of mesoscale structure variation of concrete on both global behavior and local failure patterns of RC columns subjected to monotonic loading. The simulation results of multiscale models established with CDP model and XFEM were comparatively discussed in depth. The XFEM-based multiscale simulation developed in this study provides an efficient modeling approach for investigating the stochastic nature of cracking behavior in RC columns. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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18 pages, 6177 KiB

Open AccessArticle

Safety Concept for Textile-Reinforced Concrete Structures with Bending Load

by Sergej Rempel, Marcus Ricker and Josef Hegger

Appl. Sci. 2020, 10(20), 7328; https://doi.org/10.3390/app10207328 - 20 Oct 2020

Cited by 16 | Viewed by 2196

Abstract

In most countries, for the production and execution of concrete structures with textile reinforcement, building owners must have a general approval (e.g., “abZ” in Germany) or an individual license (e.g., “ZiE” in Germany). Therefore, it is quite common for building authorities to request [...] Read more.

In most countries, for the production and execution of concrete structures with textile reinforcement, building owners must have a general approval (e.g., “abZ” in Germany) or an individual license (e.g., “ZiE” in Germany). Therefore, it is quite common for building authorities to request experimental tests that evaluate the ultimate limit state (ULS) and the serviceability limit state (SLS). However, these experimental tests are detailed, time-consuming and expensive. A practical and simple design model would help to reduce the number of tests needed and would offer structural planners a useful tool. An important aspect is that such design model must fulfil a set of reliability requirements in order to guarantee an adequate safety standard. To this end, probabilistic calculations are required. For the setup of such model, different parameters must be considered, namely the effective depth d and the tensile failure stress of the textile f_t for the concrete compressive strength f_c. This article presents the probabilistic calculations needed to attain a general safety factor γ_T that satisfies all the safety requirements for the textile reinforcement of concrete structures with bending load. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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14 pages, 6443 KiB

Open AccessArticle

Structural Analysis and Design of Reinforced Concrete Bridge Corbels

by Sara Cattaneo, Pietro Crespi and Luigi Biolzi

Appl. Sci. 2020, 10(19), 6727; https://doi.org/10.3390/app10196727 - 25 Sep 2020

Cited by 2 | Viewed by 3312

Abstract

Post-installed systems for the anchorage of safety barriers to bridge corbels are widely used today thanks to their flexibility and easiness of installation. Because of commonly found in situ boundary constraints, however, the design requirements for post-installed fasteners and rebars are frequently not [...] Read more.

Post-installed systems for the anchorage of safety barriers to bridge corbels are widely used today thanks to their flexibility and easiness of installation. Because of commonly found in situ boundary constraints, however, the design requirements for post-installed fasteners and rebars are frequently not satisfied or only partially satisfied. This paper assesses the mechanical response of a corbel where an innovative solution concerning the placement of post-installed reinforcement in reinforced concrete members was suggested. With reference to the refurbishment of bridge curbs, which usually requires concrete removal in the damaged top layers, the proposed method was based on the introduction of additional U-shaped post-installed rebars connecting the existing portion of the corbel to the newly cast top layer, in order to allow the transfer of the tension pull-out force exerted by the posts restraining the safety barrier. The layout investigated in this paper consisted of three anchors connecting the baseplate of the post supporting the safety barrier to the corbel (a layout commonly found in Italy). These anchors transfer the external actions (bending moment and shear) to the corbel thanks to the formation of a strut-and-tie system where the U-shaped rebars and the existing reinforcement play a crucial role. A strut-and-tie model of the corbel was presented to allow the use of a simplified approach to assess the safety of the corbel. The tests on real-scale specimens were also modeled numerically and additional models were considered to evaluate the effect of characteristics parameters (i.e., size of the corbel, existing shear reinforcement, etc.) on the overall response of the corbel. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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23 pages, 5340 KiB

Open AccessFeature PaperArticle

Punching Shear Stress in Post-Tensioned Transfer Plate of Multi-Story Buildings

by Byeonguk Ahn, Thomas H.-K. Kang, Su-Min Kang and Jang Keun Yoon

Appl. Sci. 2020, 10(17), 6015; https://doi.org/10.3390/app10176015 - 31 Aug 2020

Cited by 2 | Viewed by 5761

Abstract

The design of a post-tensioned transfer plate is typically controlled by shear force—in particular, punching shear at the slab-column connection. To verify the accuracy of the separated model only for one floor currently used in the design of a post-tensioned transfer plate, results [...] Read more.

The design of a post-tensioned transfer plate is typically controlled by shear force—in particular, punching shear at the slab-column connection. To verify the accuracy of the separated model only for one floor currently used in the design of a post-tensioned transfer plate, results were compared to a complete model with multi-story building system for which two representative residential building plans were used to emulate physical structural systems. Punching shear stress for the separated model was calculated using the eccentric shear stress model presented in ACI 318. Punching shear stress was found to be overestimated in the separated model, given that interaction between transfer plates and upper shear walls cannot be reflected therein. Differences at column locations were also noted as the number of stories below the transfer floor increased. Consequently, the separated model is not recommended for design of post-tensioned transfer plates. A complete model is more suitable for more realistic and potential cost-effective design, through the inclusion of the interaction between transfer plates and upper shear walls. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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16 pages, 3291 KiB

Open AccessArticle

Fatigue Testing of Shear Reinforcement in Prestressed Concrete T-Beams of Bridges

by Matthias Hillebrand and Josef Hegger

Appl. Sci. 2020, 10(16), 5560; https://doi.org/10.3390/app10165560 - 11 Aug 2020

Cited by 10 | Viewed by 2922

Abstract

In the recent years, bridges, as an important part of the national and international infrastructure, had to comply with stricter requirements due to increased heavy load traffic. Many of these bridge structures built in the 1960s and 1970s often contain less web reinforcement [...] Read more.

In the recent years, bridges, as an important part of the national and international infrastructure, had to comply with stricter requirements due to increased heavy load traffic. Many of these bridge structures built in the 1960s and 1970s often contain less web reinforcement than the modern required minimum web reinforcement. In this context, the shear resistance under cyclic loading is of special interest. For this reason, experimental tests were conducted on prestressed concrete beams with and without shear reinforcement at the Institute of Structural Concrete of RWTH Aachen University to investigate the shear fatigue strength. This paper describes the recent tests on ten Tshaped prestressed beams with web reinforcement. The specimens were able to resist more load cycles than predicted by the approaches implemented in the Eurocodes for bridges. Based on the test results, design models for shear under cyclic loading should be reviewed and improved, especially regarding the assessment of existing structures. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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14 pages, 4967 KiB

Open AccessArticle

Multiscale Analysis of the Influence of Steel Fiber Reinforcement on the Shear Strength of Post-Tensioned Dry Joints

by Jorge Marin-Montin, María Alcalde, Héctor Cifuentes and Francisco Montero-Chacón

Appl. Sci. 2020, 10(16), 5486; https://doi.org/10.3390/app10165486 - 07 Aug 2020

Cited by 2 | Viewed by 1962

Abstract

In this work we follow a multiscale methodology to characterize the structural performance of post-tensioned steel fiber-reinforced concrete dry joints. At the material level, we use an experimentally validated lattice-particle model whose input parameters are the properties of the different phases themselves (i.e., [...] Read more.

In this work we follow a multiscale methodology to characterize the structural performance of post-tensioned steel fiber-reinforced concrete dry joints. At the material level, we use an experimentally validated lattice-particle model whose input parameters are the properties of the different phases themselves (i.e., mortar, aggregates, fibers) and mixing information. This model is used to obtain the mechanical properties used in the structural-level simulations of the joints in terms of constitutive laws. The structural analyses are performed using the concrete damage plasticity model, which allows us to quantify the effect of fiber addition on the shear strength of the dry joints and their ductility. Our simulations agree well with other macroscopic models in the case of plain concrete and show, once again, that the American Association of State Highway Transportation Officials (AASHTO) code overestimates the nominal shear capacity of multiple-keyed joints. Regarding the fiber addition, we observe that it promotes an important increase in the shear capacity, but the prestress level is still more relevant in this sense. Based on our simulations, we propose an updated shear capacity estimate accounting for the fiber volume fraction. Finally, a clear increase in the ductility of the joint is observed when the fiber volume content is increased. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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32 pages, 13443 KiB

Open AccessArticle

Numerical Verification of Interaction between Masonry with Precast Reinforced Lintel Made of AAC and Reinforced Concrete Confining Elements

by Łukasz Drobiec, Radosław Jasiński, Wojciech Mazur and Tomasz Rybraczyk

Appl. Sci. 2020, 10(16), 5446; https://doi.org/10.3390/app10165446 - 06 Aug 2020

Cited by 7 | Viewed by 2395

Abstract

This paper describes results of numerical analyses of reinforced lintels made of autoclaved aerated concrete built into unconfined walls and walls confined with reinforced concrete. The combination of the Menétrey–Willam elastic-plastic failure criterion (M-W-3) and the Rankine criterion was used for numerical analysis [...] Read more.

This paper describes results of numerical analyses of reinforced lintels made of autoclaved aerated concrete built into unconfined walls and walls confined with reinforced concrete. The combination of the Menétrey–Willam elastic-plastic failure criterion (M-W-3) and the Rankine criterion was used for numerical analysis of masonry. The parameters were determined by laboratory tests. Rebars were modelled using the Huber–Mises–Hencky yield criterion. The numerical model included interface elements att the interface between masonry units, at interfaces between reinforced concrete and masonry, and at interfaces between elements of test stands with a model using the Coulomb–Mohr (C-M) criterion. The majority of parameters of interface elements were assumed from laboratory tests. Results of numerical analysis were compared with laboratory tests. Results of numerical analysis and experiments were compatible in the range of load-carrying capacity of models and the failure method. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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36 pages, 2136 KiB

Open AccessArticle

Tridimensional Long-Term Finite Element Analysis of Reinforced Concrete Structures with Rate-Type Creep Approach

by Giovanni Di Luzio, Luigi Cedolin and Carlo Beltrami

Appl. Sci. 2020, 10(14), 4772; https://doi.org/10.3390/app10144772 - 11 Jul 2020

Cited by 15 | Viewed by 2750

Abstract

This paper presents a general procedure for a rate-type creep analysis (based on the use of the continuous retardation spectrum) which avoids the need of recalculating the Kelvin chain stiffness elements at each time step. In this procedure are incorporated three different creep [...] Read more.

This paper presents a general procedure for a rate-type creep analysis (based on the use of the continuous retardation spectrum) which avoids the need of recalculating the Kelvin chain stiffness elements at each time step. In this procedure are incorporated three different creep constitutive relations, two recommended by national codes such as the ACI (North-American) and EC2 (European) building codes and one by the RILEM research association. The approximate expressions of the different creep functions with the corresponding Dirichlet series are generated using the continuous retardation spectrum approach based on the Post–Widder formula. The proposed rate-type formulation is implemented into a 3D finite element code and applied to study the long-term deflections of a prestressed concrete bridge built in Romania, which crosses a wide artificial channel that connects the Danube river to the port of Constanta in the Black Sea. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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23 pages, 34496 KiB

Open AccessArticle

Structural Behavior of Large-Scale I-Beams with Combined Textile and CFRP Reinforcement

by Jan Bielak, Maximilian Schmidt, Josef Hegger and Frank Jesse

Appl. Sci. 2020, 10(13), 4625; https://doi.org/10.3390/app10134625 - 03 Jul 2020

Cited by 27 | Viewed by 3479

Abstract

With the innovative composite material carbon-reinforced concrete, thin-walled, high-performance components can be realized. A combination of carbon fiber reinforced polymer (CFRP) bars and non-metallic textile grids is advantageous as it exploits the full potential of the high-performance materials to reduce dead loads, increases [...] Read more.

With the innovative composite material carbon-reinforced concrete, thin-walled, high-performance components can be realized. A combination of carbon fiber reinforced polymer (CFRP) bars and non-metallic textile grids is advantageous as it exploits the full potential of the high-performance materials to reduce dead loads, increases durability, and extends lifespan. For new components with such mixed reinforcement, applicable design concepts and engineering rules are necessary to accurately determine the structural and deformation behavior. To validate models and detailing rules previously developed, three large carbon reinforced concrete I-beams were designed and tested to failure with a realistic line load. CFRP bars served as principal bending reinforcement, whereas shear and flange reinforcement consisted of textile grids. Results showed that existing models for bending using variation of strain distribution as well as non-linear finite-element analysis predicted the flexural behavior of structural components with mixed reinforcement in ultimate limit state (ULS) appropriately. Yet, calculation of shear capacity requires further studies to determine textile reinforcement contribution and estimate reduction for concrete strength in reinforced compression struts. For serviceability limit state (SLS), three methods for determination of deflection delivered good results. In future, a rethinking is required with regard to the ductility and robustness of CFRP-reinforced concrete components. In this respect, pronounced cracking as well as the large ultimate strain and deflection compensate for the lacking yield capacity of the reinforcement. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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17 pages, 9525 KiB

Open AccessArticle

Verification of Optimized Real-time Hybrid Control System for Prediction of Nonlinear Materials Behavior with 3-DOF Dynamic Test

by Okpin Na and Jejin Park

Appl. Sci. 2020, 10(11), 4037; https://doi.org/10.3390/app10114037 - 11 Jun 2020

Cited by 1 | Viewed by 2201

Abstract

Real-time hybrid method is an economical and efficient test method to evaluate the dynamic behavior. The purpose of this study is to develop the computational algorithm and to prove the reliability of a real-time hybrid control system. For performing the multi-direction dynamic test, [...] Read more.

Real-time hybrid method is an economical and efficient test method to evaluate the dynamic behavior. The purpose of this study is to develop the computational algorithm and to prove the reliability of a real-time hybrid control system. For performing the multi-direction dynamic test, three dynamic actuators and the optimized real-time hybrid system with new hybrid simulation program (FEAPH) and a simplified inter-communication were optimized. To verify the reliability and applicability of the real-time hybrid control system, 3-DOF (3 Degrees of Freedom) non-linear dynamic tests with physical model were conducted on a steel and concrete frame structure. As a ground acceleration, El Centro and Northridge earthquake waves were applied. As a result, the maximum error of numerical analysis is 13% compared with the result of shaking table test. However, the result of real-time hybrid test shows good agreement with the shaking table test. The real-time hybrid test using FEAPH can make good progress on the total testing time and errors. Therefore, this test method using FEAPH can be effectively and cheaply used to evaluate the dynamic performance of the full-scale structure, instead of shaking table and full-scale test. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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18 pages, 3485 KiB

Open AccessArticle

Impact Resisting Mechanisms of Shear-Critical Reinforced Concrete Beams Strengthened with High-Performance FRC

by Carlos Zanuy and Gonzalo S.D. Ulzurrun

Appl. Sci. 2020, 10(9), 3154; https://doi.org/10.3390/app10093154 - 01 May 2020

Cited by 11 | Viewed by 2203

Abstract

Reinforced concrete (RC) structures typically present brittle failures by shear or punching under impact loading. High-performance fiber-reinforced concrete (HPFRC) has great potential due to its superior strength and energy absorption. The higher price and environmental cost of HPFRC compared to conventional RC can [...] Read more.

Reinforced concrete (RC) structures typically present brittle failures by shear or punching under impact loading. High-performance fiber-reinforced concrete (HPFRC) has great potential due to its superior strength and energy absorption. The higher price and environmental cost of HPFRC compared to conventional RC can be effectively overcome by partially strengthening impact-sensitive RC members with HPFRC. To study the feasibility of this technique, HPFRC was applied as a tensile layer at the bottom of RC beams. Drop weight impact tests were carried out on beams with two values (35 and 55 mm) of HPFRC thickness, in addition to companion RC beams. Results show that the impact response can be divided into two stages: a first stage governed by local effects and shear plug formation at midspan, and a second stage governed by global beam behavior with formation of shear web cracks. A new resisting mechanism was observed for beams strengthened with HPFRC, as the strengthening layer worked similarly to a stress ribbon retaining the damaged RC and reducing fragmentation-induced debris. Such mechanism was fully achieved by the specimens with 35 mm HPFRC layer but was limited for the specimens with 55 mm HPFRC layer due to impact-induced interface debonding. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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15 pages, 4127 KiB

Open AccessArticle

Testing of a Dual-Steel-Plate-Confined High-Performance Concrete Composite Shaft Lining Structure and Its Application

by Zhishu Yao, Ping Zhang, Hua Cheng, Weipei Xue and Xiang Li

Appl. Sci. 2020, 10(8), 2938; https://doi.org/10.3390/app10082938 - 23 Apr 2020

Cited by 5 | Viewed by 1996

Abstract

To address the support problem of large-diameter drilling shafts in the west area of Zhangji coal mine, a thinner shaft lining structure composed of double layers of steel plate and high-performance concrete is proposed herein. Firstly, a series of tests of high-performance concrete [...] Read more.

To address the support problem of large-diameter drilling shafts in the west area of Zhangji coal mine, a thinner shaft lining structure composed of double layers of steel plate and high-performance concrete is proposed herein. Firstly, a series of tests of high-performance concrete preparation were carried out, and the optimized mix ratio of pumping concrete with 60–70 MPa strength for shaft lining of the drilled shaft was obtained. Then, shaft lining models were designed according to the similarity theory, and the mechanical properties of the shaft lining were experimentally studied by loading test. The test results showed that the stress state of concrete in the shaft was obviously improved, and the compressive strength of concrete was increased by 1.97–2.52 times. Finally, the results of the study were applied to a shaft in the control strata of the inlet shaft in the west area of Zhangji coal mine, which made it possible to use the drilling method to construct the shaft. The following field measurement showed that the annular strain of the shaft lining concrete was −487 με, which is far less than the ultimate strain value of C65 concrete, and the shaft lining structure was kept safe and reliable. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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31 pages, 12943 KiB

Open AccessArticle

Experimental Investigation of Stochastic Mechanical Behavior of Cement Emulsified Asphalt Mortar under Monotonic Compression

by Xiao Li, Zhiwu Yu, Peng Liu, Zhi Shan and Zilong Meng

Appl. Sci. 2020, 10(8), 2860; https://doi.org/10.3390/app10082860 - 20 Apr 2020

Cited by 5 | Viewed by 1858

Abstract

Experimental investigation on cement emulsified asphalt mortar (CA mortar) under uniaxial monotonic compression by taking into account the stochastic properties were investigated. An analytical constitutive model based on the statistic damage approach capable of mimicking the stochastic mechanical responses of CA mortar under [...] Read more.

Experimental investigation on cement emulsified asphalt mortar (CA mortar) under uniaxial monotonic compression by taking into account the stochastic properties were investigated. An analytical constitutive model based on the statistic damage approach capable of mimicking the stochastic mechanical responses of CA mortar under uniaxial compression was proposed. The comparison between the experimental results and the predictions demonstrated that the proposed model was able to characterize the salient features for CA mortar under uniaxial monotonic compression. Furthermore, the compressive stochastic evolution (SE) of CA mortar tested in this work and comparative analyses among typical China Railway Track System-I (CRTS-I) type CA mortar and concrete in several aspects were examined and performed; it was revealed that the Lognormal distribution density function can well represent the damage probability density for CA mortar, and its stochastic constitutive relationship can be reflected by a media process of transition from microscale to macroscale. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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17 pages, 4362 KiB

Open AccessArticle

Multi-Step Prestressing with Hybrid SMA Wires

by Chi-Young Jung, Tae-Ryeon Woo and Jong-Han Lee

Appl. Sci. 2020, 10(8), 2842; https://doi.org/10.3390/app10082842 - 20 Apr 2020

Cited by 3 | Viewed by 2329

Abstract

Prestressing force is induced in reinforced concrete (RC) structures to improve their load-carrying capacity. Generally, the prestressing strand of an RC structure is tensioned using a hydraulic jack, which decreases its workability. In this study, we evaluate the application of prestressing force by [...] Read more.

Prestressing force is induced in reinforced concrete (RC) structures to improve their load-carrying capacity. Generally, the prestressing strand of an RC structure is tensioned using a hydraulic jack, which decreases its workability. In this study, we evaluate the application of prestressing force by using a shape memory alloy (SMA), as has been actively studied in civil engineering. Experiments were conducted to measure the multi-stepwise prestressing force introduced in a hybrid SMA wire composed of two different types of SMA wires. The experimental parameters were determined based on the combinations of the SMA wires and the heating temperatures. The results of the experiments show that the prestressing force was induced in a sequence. The magnitude of the prestressing force generated by the hybrid SMA wire was equal to the sum of the prestressing forces generated by the NiTi50 and NiTi90 SMA wires. In conclusion, this study verified the applicability of the proposed concept of multi-stepwise prestressing by using hybrid SMA wires. Further research is required to measure the effect of prestressing by locally heating the center of a girder with the aim of expanding the applicability of this concept. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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26 pages, 8582 KiB

Open AccessFeature PaperArticle

Consistent Time-to-Failure Tests and Analyses of Adhesive Anchor Systems

by Krešimir Ninčević, Ioannis Boumakis, Stefan Meissl and Roman Wan-Wendner

Appl. Sci. 2020, 10(4), 1527; https://doi.org/10.3390/app10041527 - 24 Feb 2020

Cited by 13 | Viewed by 2967

Abstract

Motivated by tunnel accidents in the recent past, several investigations into the sustained load behavior of adhesive anchors have been initiated. Nevertheless, the reliable lifetime prediction of bonded anchor systems based on a relatively short testing period still represents an unsolved challenge due [...] Read more.

Motivated by tunnel accidents in the recent past, several investigations into the sustained load behavior of adhesive anchors have been initiated. Nevertheless, the reliable lifetime prediction of bonded anchor systems based on a relatively short testing period still represents an unsolved challenge due to the complex nonlinear viscoelastic behavior of concrete and adhesives alike. This contribution summarizes the results of a comprehensive experimental investigation and systematically carried out time-to-failure analysis performed on bonded anchors under sustained tensile load. Two different adhesive materials that find widespread application in the building industry were used, one epoxy and one vinylester based. Performed experiments include full material characterizations of concrete and the adhesives, bonded anchor pull-out tests at different loading rates, and time-to-failure sustained load tests. All anchor tests are performed in a confined configuration with close support. After a thorough review of available experimental data and analysis methods in the literature, the experimental data are presented with the main goal to (i) provide guidance for the analysis of load versus time-to-failure test data, and (ii) to derive a set of recommendations for efficient time-to-failure tests having in mind the needs associated with different analysis techniques. Finally, a new approach based on a sigmoid function, previously used only for concrete, is for the first time applied to bonded anchors systems and compared to the established regression models. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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14 pages, 13863 KiB

Open AccessArticle

Experimental Investigation of Concrete with Recycled Aggregates for Suitability in Concrete Structures

by Arkadiusz Denisiewicz, Małgorzata Śliwa, Krzysztof Kula and Tomasz Socha

Appl. Sci. 2019, 9(23), 5010; https://doi.org/10.3390/app9235010 - 21 Nov 2019

Cited by 1 | Viewed by 2829

Abstract

This paper presents the experimental tests of concrete made on the recycled aggregates basis. Tests were carried out to determine the concrete suitability for construction purposes. The physical and strength properties were determined for three types of recycling aggregates. The aggregates were obtained [...] Read more.

This paper presents the experimental tests of concrete made on the recycled aggregates basis. Tests were carried out to determine the concrete suitability for construction purposes. The physical and strength properties were determined for three types of recycling aggregates. The aggregates were obtained from sanitary ceramics ‘SC’ (washbasins and toilet bowls), building ceramics ‘BC’ (solid bricks), and concrete rubble ‘CR’. The results obtained in tests of compressive strength, bending tensile strength, water absorption, total shrinkage, watertightness, and frost resistance of concrete made of SC and CR aggregates gave grounds for stating its suitability for structural purposes. Concrete based on the BC aggregates is not recommended for structural applications. Full article

(This article belongs to the Special Issue Recent Advances in Testing and Modelling Reinforced Concrete Structures)

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