Structural Performances of Concrete Composite Members: Experimental, Theoretical, Numerical Approaches

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Environmental Sciences".

Deadline for manuscript submissions: closed (30 April 2020) | Viewed by 97543

Special Issue Editors


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Guest Editor
Department of Architectural Engineering, University of Seoul, Seoul 02504, Korea
Interests: structural analysis and design of reinforced concrete (RC) and prestressed concrete (PSC) structures; application of composite members; remaining service life of concrete structures; finite element analysis; large-scale testing
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Guest Editor
School of Urban and Environmental Eng., Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
Interests: seismic design; tall buildings; sustainable materials; ultrasonic technology
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Guest Editor
Department of Architectural Engineering, Kongju National University, Chungnam 31080, Korea
Interests: application of new materials for building structures; development of hybrid materials for building structures; seismic-resistant design and retrofitting of building structures; structural reliability
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Recently, composite materials such as steel–concrete, FRP, and polypropylene or steel fibers have been widely applied to concrete members for enhancement of their flexural or shear performances, crack or deflection controllability, etc. In addition to composite materials, precast prestressed concrete members are also used to construct long-span structures, underground parking lots, large logistics warehouses, and other special structures, because of their excellent structural performances and efficient applicability. In this regard, this Special Issue invites original research articles dealing with experiments and theoretical or numerical modeling of structural behavior of concrete composite members that contribute to our understanding on their performances in more detail.

The scope of this Special Issue, “Structural Performances of Concrete Composite Members: Experimental, Theoretical, Numerical Approaches, covers every aspect of concrete composite members, including: The structural behavior of reinforced concrete members with FRP, polypropylene or steel fibers, steel–concrete composite members, precast/prestressed concrete members, composite behavior between precast concrete and cast-in-place concrete, etc.

Prof. Dr. Kang Su Kim
Dr. Myoungsu (James) Shin
Prof. Dr. Kil-Hee Kim
Guest Editors

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Keywords

  • Composite material
  • FRP
  • Fiber
  • Steel–concrete composite member
  • Precast concrete
  • Prestressed concrete
  • Structural analysis
  • Numerical modelling
  • Experiment
  • Strengthening method

Published Papers (26 papers)

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Research

13 pages, 5017 KiB  
Article
Evaluation of Bond Properties of a Fabric-Reinforced Cementitious Matrix for Strengthening of Concrete Structures
by Min-Jun Kim, Hyeong-Gook Kim, Yong-Jun Lee, Dong-Hwan Kim, Min-Su Jo and Kil-Hee Kim
Appl. Sci. 2020, 10(11), 3767; https://doi.org/10.3390/app10113767 - 29 May 2020
Cited by 5 | Viewed by 2147
Abstract
In the present study, pull-out and pull-off tests were conducted to examine the bond strength between an inorganic cement adhesive (hereinafter referred to as the “matrix”) and a textile, which composed a fabric-reinforced cementitious matrix (FRCM). The matrix was developed by mixing slag [...] Read more.
In the present study, pull-out and pull-off tests were conducted to examine the bond strength between an inorganic cement adhesive (hereinafter referred to as the “matrix”) and a textile, which composed a fabric-reinforced cementitious matrix (FRCM). The matrix was developed by mixing slag and short fibers in an attempt to improve the alkali resistance and compressive strength. The developed matrix was examined with regard to its alkali resistance, water resistance, and void distribution. Bond tests were conducted in two parts: a pull-out series and pull-off series. The type of textile (carbon or basalt) and the weaving methods were selected as test parameters. These tests were performed in accordance with the methods described in ISO10406-1 (pull-out) and ASTM C1583 (pull-off). The test results showed that the developed matrix was superior to existing mortar methods in terms of alkali resistance, water resistance, and compressive strength. Additionally, the FRCM in which carbon textiles were used exhibited excellent bond performance. Full article
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17 pages, 7348 KiB  
Article
Cyclic Testing of a Composite Joint between a Reinforced Concrete Column and a Steel Beam
by Dang Dung Le, Xuan-Huy Nguyen and Quang-Huy Nguyen
Appl. Sci. 2020, 10(7), 2385; https://doi.org/10.3390/app10072385 - 31 Mar 2020
Cited by 8 | Viewed by 12424
Abstract
This paper presents an experimental study on the seismic performance of a novel composite joint between reinforced concrete columns and steel beams (RCSs) for frame structures. In the proposed RCS joint, an H steel profile totally embedded inside an RC column is directly [...] Read more.
This paper presents an experimental study on the seismic performance of a novel composite joint between reinforced concrete columns and steel beams (RCSs) for frame structures. In the proposed RCS joint, an H steel profile totally embedded inside an RC column is directly welded to the steel beam. The H steel profile was covered by two supplementary plates to avoid the stirrups resisting the shear in the connection region. Two full-scale joints were built and tested under reversed-cyclic loading at the University of Transport and Communications of Vietnam. Seismic performance in terms of load-bearing capacity, story drift capacity, energy dissipation, and stiffness degradation were evaluated. The test specimen showed a good response to cyclic load reversals. Full article
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17 pages, 6197 KiB  
Article
Experimental Study on Stress Corrosion Index Governing Time-Dependent Degradation of Rock Strength
by Tae Young Ko and Sean Seungwon Lee
Appl. Sci. 2020, 10(6), 2175; https://doi.org/10.3390/app10062175 - 23 Mar 2020
Cited by 5 | Viewed by 2589
Abstract
Rock fractures in geological conditions are caused not only by applied stress, but also by stress corrosion. Stress corrosion is an environmentally activated chemical process, associated with the fluid-assisted crack growth. Crack growth due to stress corrosion is related to the time-dependent behaviours [...] Read more.
Rock fractures in geological conditions are caused not only by applied stress, but also by stress corrosion. Stress corrosion is an environmentally activated chemical process, associated with the fluid-assisted crack growth. Crack growth due to stress corrosion is related to the time-dependent behaviours of rocks and is a crucial factor in determining the stability of underground structures over the long period of time. In this study, constant stress-rate tests including Brazilian tension and three-point flexural tests for the tensile strength, short-beam compression and single-shear tests for the in-plane shear strength, and a torsion test of rectangular section specimens and a circumferentially notched cylindrical specimen test for the out-of-plane shear strength were conducted at a different loading rate from 0.01 to 10 MPa/s using Coconino sandstone. The results show that the rock strength was proportional to the 1/(n+1)th power of the loading rate, where the parameter n indicates the stress corrosion index. The stress corrosion index (n) ranged from 34 to 38, with an average value of 36. The stress corrosion indices (n) were similar, irrespective of the loading configuration and specimen geometry. The stress corrosion index (n) can, therefore, be regarded as a material constant of rocks. Full article
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18 pages, 7666 KiB  
Article
Experimental Study of the Temperature Distribution in CRTS-II Ballastless Tracks on a High-Speed Railway Bridge
by Lei Zhao, Ling-Yu Zhou, Guang-Chao Zhang, Tian-Yu Wei, Akim D. Mahunon, Li-Qiang Jiang and Ying-Ying Zhang
Appl. Sci. 2020, 10(6), 1980; https://doi.org/10.3390/app10061980 - 13 Mar 2020
Cited by 33 | Viewed by 2752
Abstract
To study the temperature distribution in the China Railway Track System Type II ballastless slab track on a high-speed railway (HSR) bridge, a 1:4 scaled specimen of a simply-supported concrete box girder bridge with a ballastless track was constructed in laboratory. Through a [...] Read more.
To study the temperature distribution in the China Railway Track System Type II ballastless slab track on a high-speed railway (HSR) bridge, a 1:4 scaled specimen of a simply-supported concrete box girder bridge with a ballastless track was constructed in laboratory. Through a rapid, extreme high temperature test in winter and a conventional high temperature test in summer, the temperature distribution laws in the track on the HSR bridge were studied, and the vertical and transverse temperature distribution trend was suggested for the track. Firstly, the extreme high temperature test results showed that the vertical temperature and the vertical temperature difference distribution in the track on HSR bridge were all nonlinear with three stages. Secondly, the extreme high temperature test showed that the transverse temperature distribution in the track was of quadratic parabolic nonlinear form, and the transverse temperature gradient in the bottom base was significantly higher than that of the other layers of the track. Thirdly, the three-dimensional temperature distribution in the track on HSR bridge was a nonlinear, three-stage surface. Furthermore, similar regularities were also obtained in the conventional high temperature test, in which the temperature span ranges were different from those of the extreme high temperature test. In addition, the conventional high temperature test also showed that under the natural environment conditions, the internal temperature gradient in the track layers changed periodically (over a period of 24 h). Full article
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26 pages, 8984 KiB  
Article
Seismic Performance Assessments of RC Frame Structures Strengthened by External Precast Wall Panel
by Seung-Ho Choi, Jin-Ha Hwang, Sun-Jin Han, Hyo-Eun Joo, Hyun-Do Yun and Kang Su Kim
Appl. Sci. 2020, 10(5), 1749; https://doi.org/10.3390/app10051749 - 04 Mar 2020
Cited by 5 | Viewed by 2731
Abstract
In recent years, a variety of strengthening methods have been developed to improve the seismic performance of reinforced concrete (RC) frame structures with non-seismic details. In this regard, this study proposes a new type of seismic strengthening method that compresses prefabricated precast concrete [...] Read more.
In recent years, a variety of strengthening methods have been developed to improve the seismic performance of reinforced concrete (RC) frame structures with non-seismic details. In this regard, this study proposes a new type of seismic strengthening method that compresses prefabricated precast concrete (PC) walls from the outside of a building. In order to verify the proposed method, a RC frame structure strengthened with precast walls was fabricated, and cyclic loading tests were performed. The results showed that specimens strengthened using the proposed method exhibited further improvements in strength, stiffness and energy dissipation capacity, compared to RC frame structures with non-seismic details. In addition, a nonlinear analysis method, capable of considering the flexural compression and shear behaviors of the walls, was suggested to analytically evaluate the structural behavior of the frame structures strengthened by the proposed method. Using this, an analysis model for frame structures strengthened with precast walls was proposed. Through the proposed model, the analysis and test results were compared in relation to stiffness, strength, and energy dissipation capacity. Then, the failure mode of the column was evaluated based on the pushover analysis. In addition, this study proposed a simplified analysis model that considered the placement of longitudinal reinforcements in shear walls. Full article
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17 pages, 4999 KiB  
Article
Shear Tests of Deep Hollow Core Slabs Strengthened by Core-Filling
by Hyo-Eun Joo, Sun-Jin Han, Min-Kook Park and Kang Su Kim
Appl. Sci. 2020, 10(5), 1709; https://doi.org/10.3390/app10051709 - 02 Mar 2020
Cited by 11 | Viewed by 4160
Abstract
Prestressed hollow core slabs (PHCSs) have commonly been applied to long-span structures, due to their excellent flexural capacity and deflection control performance. However, in quite a few cases, the web-shear strength at member ends subjected to high shear forces is insufficient, because the [...] Read more.
Prestressed hollow core slabs (PHCSs) have commonly been applied to long-span structures, due to their excellent flexural capacity and deflection control performance. However, in quite a few cases, the web-shear strength at member ends subjected to high shear forces is insufficient, because the web of the PHCS is very thin, making it difficult to place shear reinforcement, and the prestress is not fully effective in transfer length regions. Accordingly, a variety of shear strengthening methods have been proposed to improve the web-shear strength of PHCS ends. In this study, experimental research was conducted to investigate the shear resistance mechanism of PHCS strengthened by core-filling method, which has been most widely used in the construction field. The number of filled cores and the shear reinforcement ratio were set as the main test variables, and the patterns and angles of shear cracks that occurred in the PHCS units and filled cores, respectively, and the strain behavior of the shear reinforcement, were measured and analyzed in detail. This study also analyzed the test results based on the current design codes, and proposed a modified shear strength equation that can be applied to the core-filled PHCS. Full article
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15 pages, 4238 KiB  
Article
Shear Performance for Prestressed Concrete Hollow Core Slabs
by Yong-Jun Lee, Hyeong-Gook Kim, Min-Jun Kim, Dong-Hwan Kim and Kil-Hee Kim
Appl. Sci. 2020, 10(5), 1636; https://doi.org/10.3390/app10051636 - 29 Feb 2020
Cited by 15 | Viewed by 3454
Abstract
This study evaluated the shear performance of prestressed concrete hollow core slabs (HCS), which are convenient to use as floor structures of flexible spaces. A total of 18 specimens, with cross-sectional height and presence of topping concrete as variables, were fabricated by extrusion. [...] Read more.
This study evaluated the shear performance of prestressed concrete hollow core slabs (HCS), which are convenient to use as floor structures of flexible spaces. A total of 18 specimens, with cross-sectional height and presence of topping concrete as variables, were fabricated by extrusion. A four-point loading test was conducted using simply supported beams. The results showed that shear performance satisfied the requirements of ACI 318-19 regardless of cross-sectional height or presence of topping concrete. Through comparison with past studies, the web-shear strength of HCS was found to be influenced by compressive stress due to prestress at the centroid, compressive strength of concrete, and shear span-to-depth ratio. Full article
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14 pages, 2466 KiB  
Article
Effect of Fiber Reinforced Polymer Tubes Filled with Recycled Materials and Concrete on Structural Capacity of Pile Foundations
by Visar Farhangi and Moses Karakouzian
Appl. Sci. 2020, 10(5), 1554; https://doi.org/10.3390/app10051554 - 25 Feb 2020
Cited by 83 | Viewed by 7589
Abstract
This paper deals with analyzing the structural responses of glass-fiber-reinforced polymer (GFRP) tubes filled with recycled and concrete material for developing composite piles, as an alternative to traditional steel reinforced piles in bridge foundations. The full-scale GFRP composite piles included three structural layers, [...] Read more.
This paper deals with analyzing the structural responses of glass-fiber-reinforced polymer (GFRP) tubes filled with recycled and concrete material for developing composite piles, as an alternative to traditional steel reinforced piles in bridge foundations. The full-scale GFRP composite piles included three structural layers, using a fiber-oriented material that was inclined longitudinally. Almost 60% of the fibers were orientated at 35° from the longitudinal direction of the pile and the rest 40 percent were oriented at 86° from the horizontal axis. The segment between the inner and outer layers was inclined 3° from the hoop direction in the tube. The behavior of the filled GFRP tubes was semi-linear and resulted in increasing the total ductility and strength of the piles. Adjusting the material’s properties, such as the EAxial, EHoop, and Poisson ratios, optimized the results. The lateral strength of the GFRP composite pile and pre-stressed piles are investigated under both axial compression and bending moment loads. Based on the conducted parametric study, the required axial and bending capacities of piles in different ranges of eccentricities can be reached using the combination of tube wall thickness and GFRP fiber percentages. Full article
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21 pages, 13700 KiB  
Article
Characteristics of Crack Growth in Rock-Like Materials under Monotonic and Cyclic Loading Conditions
by Tae Young Ko and Sean Seungwon Lee
Appl. Sci. 2020, 10(2), 719; https://doi.org/10.3390/app10020719 - 20 Jan 2020
Cited by 10 | Viewed by 2916
Abstract
Experiments with gypsum as a model rock material were conducted to investigate the characteristics of crack growth under monotonic and cyclic loading. The specimens had two pre-existing flaws that were placed at different inclination angle, spacing and continuity. Tensile or wing cracks and [...] Read more.
Experiments with gypsum as a model rock material were conducted to investigate the characteristics of crack growth under monotonic and cyclic loading. The specimens had two pre-existing flaws that were placed at different inclination angle, spacing and continuity. Tensile or wing cracks and secondary or shear cracks were observed in both the monotonic and cyclic tests. Wing cracks or tensile cracks initiated at (or near) the tips of flaws and grew parallel to the loading direction. Secondary or shear cracks occurred after initiation of the wing crack and culminated in a final failure. Secondary cracks started at the tips of flaws and propagated in the colinear direction of flaws or perpendicular to loading. Six types of coalescence were observed. Both the monotonic and cyclic tests showed almost identical coalescence types. Coalescence occurred due to the internal shear cracks in specimens containing colinear flaws, while it occurred through combinations of internal shear cracks, internal wing cracks and tension cracks in specimens with non-colinear flaws. Fatigue cracks occurred in tests under cyclic loads. Finally, the subcritical crack growth parameters under monotonic and cyclic loading were determined. Although there were variations in the parameters, the parameter “n” showed similar values. Full article
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20 pages, 8528 KiB  
Article
Experimental Study of the Influence of Extremely Repeated Thermal Loading on a Ballastless Slab Track-Bridge Structure
by Lingyu Zhou, Tianyu Wei, Guangchao Zhang, Yingying Zhang, Mahunon Akim Djibril Gildas, Lei Zhao and Wei Guo
Appl. Sci. 2020, 10(2), 461; https://doi.org/10.3390/app10020461 - 08 Jan 2020
Cited by 27 | Viewed by 2028
Abstract
To study the initiation and expansion of the interlayer gap of the China Railway Track System Type II (CRTS-II) ballastless slab track structure under the action of repeated thermal loading as well as the influence of the interlayer gap on the displacement, strain [...] Read more.
To study the initiation and expansion of the interlayer gap of the China Railway Track System Type II (CRTS-II) ballastless slab track structure under the action of repeated thermal loading as well as the influence of the interlayer gap on the displacement, strain and stiffness of the track structure, a 1/4 scale three-span ballastless slab track simply supported bridge structural system specimen was developed and 18 cycles of extremely thermal loading tests were carried out. Static loading tests were carried out before and after the repeated thermal loading test and the effects of the repeated temperature loading on the mechanical properties of the structural system were analyzed. The test results show that under repeated temperature loading, there is a gap between the track slab and cement emulsified asphalt (CA) mortar near the fixed end section of the beam (close to the shear slots). The interlayer gap gradually expands to the mid-span section in a “stepped” shape in three stages: initiation, expansion and stabilization. Under the same temperature load, the camber of the concrete box beam decreases gradually while that of the track structure increases gradually with the increase of the interlayer gap length. During the three stages of interlayer gap development, the track structure stiffness degrades gradually, and the fastest reduction rate during the expansion stage. At the end of the 18th cycle of thermal loading, a degradation of 14.96% and 2.52% is observed in the stiffness of the track structure and that of the ballastless track-bridge structural system, respectively. Full article
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11 pages, 1741 KiB  
Article
Strengthening of Reinforced Concrete Slab-Column Connections with Carbon Fiber Reinforced Polymer Laminates
by Cheng-Chih Chen and Shun-Long Chen
Appl. Sci. 2020, 10(1), 265; https://doi.org/10.3390/app10010265 - 30 Dec 2019
Cited by 18 | Viewed by 5618
Abstract
This study presents the structural behavior and punching shear strength of the concrete slab-column connections strengthened with carbon fiber reinforced polymer (CFRP) laminates. The variables considered for the twelve specimens included the compressive strength of the concrete, the ratio of the tensile steel [...] Read more.
This study presents the structural behavior and punching shear strength of the concrete slab-column connections strengthened with carbon fiber reinforced polymer (CFRP) laminates. The variables considered for the twelve specimens included the compressive strength of the concrete, the ratio of the tensile steel reinforcement, and the amount of the CFRP laminates. Square concrete slabs were simply supported along four edges. During the test, monotonically concentrated load was applied to the stub column located at the center of the slab. The punching shear strength, stiffness, and mode of failure were investigated. Test results demonstrated that increasing the compressive strength of concrete, ratio of the steel reinforcement, and amount of the CFRP laminates led to an increase in the punching shear strength of the slabs. Moreover, the CFRP laminates were effective in appreciably increasing the punching shear strength of the slab-column connections. An analytical approach was conducted to calculate the punching shear strength of the slab-column connections strengthened with CFRP laminates. Based on the theory of reinforced concrete members, the application of the CFRP laminates increased the flexural strength of the slab and resulted in an increase of the effective depth of the slab section. Consequently, the punching shear strength was increased. The results of the analytical calculation revealed that the analytical work accurately predicted the experimental punching shear strength. Full article
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14 pages, 3863 KiB  
Article
Stressing State Analysis on a Single Tube CFST Arch Under Spatial Loads
by Kangkang Yang, Jian Yuan, Jun Shi, Kaikai Zheng and Jiyang Shen
Appl. Sci. 2019, 9(23), 5039; https://doi.org/10.3390/app9235039 - 22 Nov 2019
Cited by 3 | Viewed by 2895
Abstract
This paper analyzes the stressing state characteristics of a concrete-filled steel tubular (CFST) arch model under spatial loads, using the method of modeling structural stressing state and the thin plate simulating interpolation (TSI) method. Firstly, the parameter-generalized strain energy density (GSED) is applied [...] Read more.
This paper analyzes the stressing state characteristics of a concrete-filled steel tubular (CFST) arch model under spatial loads, using the method of modeling structural stressing state and the thin plate simulating interpolation (TSI) method. Firstly, the parameter-generalized strain energy density (GSED) is applied to model the stressing state of the arch. Then, the normalized GSED sum at each load plots the characteristic curve. The characteristic loads P (66 kN) and Q (85 kN) in the curve are distinguished by the Mann–Kendall (M–K) criterion. To characterize structural axial and bending stressing states, the parameters of the sectional average strain and generalized bending strain are proposed as stressing state submodes. Finally, the TSI method is used to interpolate strain data for deep analysis of internal forces. By modeling the structural stressing state, the working behavior characteristics of arch structures are greatly revealed in a particular view and the results could provide a reference for the development of bridge design. Full article
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11 pages, 3297 KiB  
Communication
Dynamic Behavior of PET FRP and Its Preliminary Application in Impact Strengthening of Concrete Columns
by Yu-Lei Bai, Zhi-Wei Yan, Togay Ozbakkaloglu, Jian-Guo Dai, Jun-Feng Jia and Jun-Bo Jia
Appl. Sci. 2019, 9(23), 4987; https://doi.org/10.3390/app9234987 - 20 Nov 2019
Cited by 18 | Viewed by 2712
Abstract
Polyethylene terephthalate (PET) fiber has attracted significant attention for reinforced concrete (RC) structure rehabilitation due to its large rupture strain (LRS; more than 7%) characteristic and recyclability from waste plastic bottles. This study presents a dynamic tensile test of PET fiber bundles performed [...] Read more.
Polyethylene terephthalate (PET) fiber has attracted significant attention for reinforced concrete (RC) structure rehabilitation due to its large rupture strain (LRS; more than 7%) characteristic and recyclability from waste plastic bottles. This study presents a dynamic tensile test of PET fiber bundles performed using a drop-weight impact system. Results showed that the tensile strength and the elastic modulus of the PET fiber bundles increased, whereas the failure strain and the toughness decreased with the increasing strain rate from 1/600 to 160 s−1. In addition, the performance of concrete confined with the PET fiber-reinforced polymer (FRP) under impact loading was investigated based on a 75 mm-diameter split Hopkinson pressure bar (SHPB) device and a drop-weight apparatus. For the SHPB test, owing to the large rupture strain property of PET FRP, the PET FRP-confined concrete exhibited significantly better performance under impact loading compared to its counterpart confined with carbon FRPs (CFRPs). During the drop-weight test, the confinement of the PET FRP composites to the concrete columns as external jackets not only improved the peak impact force, but also prolonged the impact process. Full article
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38 pages, 4001 KiB  
Article
Shear Strength Prediction Equations and Experimental Study of High Strength Steel Fiber-Reinforced Concrete Beams with Different Shear Span-to-Depth Ratios
by Wisena Perceka, Wen-Cheng Liao and Yung-Fu Wu
Appl. Sci. 2019, 9(22), 4790; https://doi.org/10.3390/app9224790 - 09 Nov 2019
Cited by 15 | Viewed by 7582
Abstract
Conducting research on steel fiber-reinforced concrete (SFRC) beams without stirrups, particularly the SFRC beams with high-strength concrete (HSC) and high-strength steel (HSS) reinforcing bars is essential due to the limitation of test results of high strength SFRC beams with high strength steel reinforcing [...] Read more.
Conducting research on steel fiber-reinforced concrete (SFRC) beams without stirrups, particularly the SFRC beams with high-strength concrete (HSC) and high-strength steel (HSS) reinforcing bars is essential due to the limitation of test results of high strength SFRC beams with high strength steel reinforcing bars. Eight shear strength prediction equations for analysis and design of the SFRC beam derived by different researchers are summarized. A database was constructed from 236 beams. Accordingly, the previous shear strength equations can be evaluated. Ten high-strength SFRC beams subjected to monotonic loading were prepared to verify the existing shear strength prediction equations. The equations for predicting shear strength of the SFRC beam are proposed on the basis of observations from the test results and evaluation results of the previous shear strength equations. The proposed shear strength equation possesses a reasonable result. For alternative analysis and design of the SFRC beams, ACI 318-19 shear strength equation is modified to consider steel fiber parameters. Full article
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17 pages, 7211 KiB  
Article
Temperature Distributions inside Concrete Sections of Renewable Energy Storage Pile Foundations
by Dichuan Zhang, Zhamilya Mamesh, Dilnura Sailauova, Chang-Seon Shon, Deuckhang Lee and Jong R. Kim
Appl. Sci. 2019, 9(22), 4776; https://doi.org/10.3390/app9224776 - 08 Nov 2019
Cited by 6 | Viewed by 2384
Abstract
A new pile foundation system is being developed for renewable energy storage through a multi-disciplinary research project. This system utilizes the compressed air technology to store renewable energy inside the reinforced concrete pile foundation configured with hollowed sections. The compressed air can result [...] Read more.
A new pile foundation system is being developed for renewable energy storage through a multi-disciplinary research project. This system utilizes the compressed air technology to store renewable energy inside the reinforced concrete pile foundation configured with hollowed sections. The compressed air can result in high air pressure to which the structural response of the pile foundation subjected has been studied. However, the temperature in the pile foundation can be affected by the compressed air if sufficient cooling is not provided. The temperature change can generate thermal stresses and affect the structural safety of the pile foundation. As a first step to investigate this thermal effect, this paper studies temperature distributions inside the concrete section for the pile foundation through non-steady state heat transfer analyses. Several parameters were considered in the study, including thermal conductivities of the concrete, specific heat capacities of the concrete, and dimensions of the pile foundation. It has been found that the temperature distribution along the concrete section varies significantly during a daily energy storage cycle as well as subsequent cycles due to the cumulative effect of residual temperatures at the end of each cycle. The temperature distribution is largely affected by the thermal conductivity of the concrete and the geometry of the pile foundation. The obtained temperature distribution can be used for investigation of the thermal stress inside the foundation and surrounding soil. Full article
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25 pages, 6872 KiB  
Article
Axial Compressive Behavior of Steel-Damping-Concrete Composite Wall
by Chunwei Zhang, Dong An and Limeng Zhu
Appl. Sci. 2019, 9(21), 4679; https://doi.org/10.3390/app9214679 - 02 Nov 2019
Cited by 9 | Viewed by 3475
Abstract
This paper presents a novel steel-damping-concrete (SDC) composite wall as a vertical element for high-rise buildings and nuclear power plants etc. In an SDC composite wall, a damping layer is sandwiched between the concrete core and steel plates to reduce structural response based [...] Read more.
This paper presents a novel steel-damping-concrete (SDC) composite wall as a vertical element for high-rise buildings and nuclear power plants etc. In an SDC composite wall, a damping layer is sandwiched between the concrete core and steel plates to reduce structural response based on its damping characteristics under axial and seismic loads. To ensure that an SDC composite wall exhibits a comparable compressive resistance as a steel-concrete-steel (SCS) composite wall, two types of reinforcing approaches including steel sheets and sleeves are utilized to enhance the weakness of the damping layer on the concrete core. The compressive performance of the reinforced SDC composite wall is numerically and analytically investigated using finite element (FE) simulations by ABAQUS. The influences of several key parameters including the type of reinforcement, the thickness of the damping layer, steel plates, and concrete core, the binding bar spacing as well as the diameter of steel sheets on the compressive performance of the composite walls are investigated through numerical analyses. The results show that while only embedding the rubber interlayer in the composite wall leads to the decrease of compressive resistance of the composite wall, the steel sheets and sleeves can provide the confinement effect on concrete core efficiently and improve the compressive resistance and ductility of walls. Based on the available methods in the current design codes such as Eurocode 4, AISC-360, a theoretical model is developed to predict the ultimate compressive resistance of SDC walls. The predictions show a reasonable correlation when compared with the numerical results. Full article
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15 pages, 2880 KiB  
Article
Improved Shear Strength Equation for Concrete Wide Beams
by Min Sook Kim, Joowon Kang and Young Hak Lee
Appl. Sci. 2019, 9(21), 4513; https://doi.org/10.3390/app9214513 - 24 Oct 2019
Cited by 6 | Viewed by 3076
Abstract
An improved shear strength equation is proposed that considers transverse reinforcement spacing and support conditions for concrete wide beams. Eighteen specimens were fabricated to examine the influence of transverse reinforcement spacing, the number of transverse shear reinforcement, and support width on shear capacity. [...] Read more.
An improved shear strength equation is proposed that considers transverse reinforcement spacing and support conditions for concrete wide beams. Eighteen specimens were fabricated to examine the influence of transverse reinforcement spacing, the number of transverse shear reinforcement, and support width on shear capacity. From the test results, a shear strength equation is proposed and used to evaluate the shear strength of 23 specimens from previous studies and 18 from this study. For the 41 specimens, the proposed shear strength equation results had a mean of 1.16 and a standard deviation of 0.16. It showed that the proposed shear strength equation can predict shear strength reasonably well for concrete wide beams. Full article
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18 pages, 7697 KiB  
Article
Stressing State Analysis of CFST Arch Supports in Deep Roadway Based on NSF Method
by Jiyang Shen, Wen Huang, Xiaocong Yang, Jun Shi and Kaikai Zheng
Appl. Sci. 2019, 9(20), 4238; https://doi.org/10.3390/app9204238 - 10 Oct 2019
Cited by 10 | Viewed by 1892
Abstract
This paper experimentally analyzes the working behavior characteristics of five concrete-filled steel tube (CFST) arch supports in deep roadway based on the numerical shape function (NSF) method and structural stressing state theory. First, the measured strain data are expanded by the NSF method [...] Read more.
This paper experimentally analyzes the working behavior characteristics of five concrete-filled steel tube (CFST) arch supports in deep roadway based on the numerical shape function (NSF) method and structural stressing state theory. First, the measured strain data are expanded by the NSF method and modeled as generalized strain energy density (GSED) to characterize the stressing state of the supports. Then, one of the supports is taken as an example and the Mann-Kendall (M-K) criterion is adopted to detect the mutation characteristics of the support, which derives the new definition of structural failure load. Correspondingly, the stressing state modes as well as strain and stress fields for the support are proposed to verify their mutation characteristics. Finally, the common and different characteristics of stressing state, damage development and internal forces for different supports are also summarized. The analytical results of the supports explore a new analysis method for underground structures and the unseen knowledge provides a reference to more rational future design. Full article
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14 pages, 5293 KiB  
Article
Experimental Research on the Properties of Rock-Filled Concrete
by Hai Wei, Guohui Zhang, Fanfan Sun, Mingming Wang, Wenhai Li and Juncai Xu
Appl. Sci. 2019, 9(18), 3767; https://doi.org/10.3390/app9183767 - 09 Sep 2019
Cited by 4 | Viewed by 2200
Abstract
In order to comprehensively evaluate the properties of rock-filled concrete (RFC) with the strength of C15, lab experimental test and in-situ test are applied to explore the mechanical, hydraulic, ultrasonic characteristics of RFC in Hantang reservoir dam. Four types of defects within RFC [...] Read more.
In order to comprehensively evaluate the properties of rock-filled concrete (RFC) with the strength of C15, lab experimental test and in-situ test are applied to explore the mechanical, hydraulic, ultrasonic characteristics of RFC in Hantang reservoir dam. Four types of defects within RFC are shown from the appearance of borehole cores specimens: (1) large sized voids existing in interfacial transition zone (ITZ) between self-compacting concrete (SCC) and rock block (RB); (2) bad cohesion in ITZ; (3) joints within rock block; (4) voids within SCC. For hydraulic aspects, the average porosity of RFC is 14.10%; the permeability rate of RFC ranges from 2.41 Lu to 10.41 Lu, with the average of 11.32 Lu, occasionally more than 25.52 Lu due to interconnected defects. For ultrasonic aspects, the ultrasonic velocity of RFC conforms to lognormal distribution, with the average of 2993.3 m/s and standard deviation of 650.5 m/s. For mechanical aspects, the average cubic compressive strength of RFC is 22.55 Mpa, with the standard deviation of 4.09 Mp. Thus the data shows a relatively great dispersion due to uneven distribution of some defects in RFC, which deteriorate the quality of RFC. Through the experimental investigation, it is shown that the quality of massive RFC in the Hantang dam is obviously non-homogeneous, mainly influenced by construction technology. Full article
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21 pages, 3945 KiB  
Article
Investigation of the Fatigue Behaviour of a Ballastless Slab Track–Bridge Structural System under Train Load
by Lingyu Zhou, Linqi Yang, Zhi Shan, Xiusheng Peng and Akim D. Mahunon
Appl. Sci. 2019, 9(17), 3625; https://doi.org/10.3390/app9173625 - 03 Sep 2019
Cited by 28 | Viewed by 3044
Abstract
To probe into the time-dependent behaviour of the ballastless track–bridge structural system under train load, based on the import of the static and fatigue damage constitutive model of materials to simulate damage deterioration of the structural system and interface cohesive zone model to [...] Read more.
To probe into the time-dependent behaviour of the ballastless track–bridge structural system under train load, based on the import of the static and fatigue damage constitutive model of materials to simulate damage deterioration of the structural system and interface cohesive zone model to the interface layer, a three-dimensional nonlinear finite element model of the China Railway Track System Type II (CRTS II) ballastless track–bridge structural system was established using the equivalent static method. Then, using this model, we developed the numerical simulation analysis of the influence law of material damage deterioration on structural system performance under train load and revealed the fatigue evolution of the structural system. The results show that the beam remains in compressed status for the whole process, the track is in compression in the midspan and in tension at the beam end, and the tensile stress is larger near the shear groove under the double-track static load. Under the fatigue load, stiffness degradation of the structural system is not obvious, and integral rigidity of the structural system is dependent on the rigidity of the beam. Strength reduction of the materials caused stress redistribution of the structural system and had a larger effect on the stress of each layer of track structure than on the stress on the beam. The fatigue degradation of the cement-emulsified asphalt (CA) mortar layer material has a significant impact on the structural system, which directly affects structural layer stress variation with the fatigue loading cycle. Full article
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16 pages, 5722 KiB  
Article
Fatigue Cracking Resistance of Engineered Cementitious Composites (ECC) under Working Condition of Orthotropic Steel Bridge Decks Pavement
by Yanjing Zhao, Jiwang Jiang, Fujian Ni and Lan Zhou
Appl. Sci. 2019, 9(17), 3577; https://doi.org/10.3390/app9173577 - 01 Sep 2019
Cited by 15 | Viewed by 2810
Abstract
In order to investigate the fatigue cracking resistance of engineered cementitious composites (ECC) used in in total life pavement, the semi-circular bending (SCB) test and improved three-point bending fatigue test (ITBF) were utilized in this study. The digital image correlation (DIC) method was [...] Read more.
In order to investigate the fatigue cracking resistance of engineered cementitious composites (ECC) used in in total life pavement, the semi-circular bending (SCB) test and improved three-point bending fatigue test (ITBF) were utilized in this study. The digital image correlation (DIC) method was also utilized to track the surface strain fields of specimens during the SCB test. X-ray computed tomography (CT) and digital image processing (DIP) technologies were applied to measure the internal-crack distribution of the ITBF specimen. The results of the SCB test showed that the fatigue cracking damage process of ECC can be divided into three stages and that the cracking stable propagating stages occupied the main part, which indicates that ECC has excellent ductility and toughness and could work very well with existing cracks. The ITBF results showed that the fatigue cracking resistance of ECC was better than epoxy asphalt concrete (EAC). In addition, the internal-crack distribution along the depth direction of the ITBF specimen could be presented well by the image pixel statistical (IPS) method based on CT scanning of image slices. It could be found that multiple cracks propagate simultaneously in ECC, instead of a single crack, under the OSBD pavement working condition. Full article
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20 pages, 3805 KiB  
Article
Nonlinear Finite Element Analysis Formulation for Shear in Reinforced Concrete Beams
by Sang-Ho Kim, Sun-Jin Han and Kang Su Kim
Appl. Sci. 2019, 9(17), 3503; https://doi.org/10.3390/app9173503 - 25 Aug 2019
Cited by 3 | Viewed by 2879
Abstract
This study suggests a novel beam-column element formulation that utilizes an equilibrium-driven shear stress function. The beam shear is obtained from the bi-axial states of micro-planes, through matrix condensation and zero vertical traction assumptions. This properly remedies the shear stiffening of a one-dimensional [...] Read more.
This study suggests a novel beam-column element formulation that utilizes an equilibrium-driven shear stress function. The beam shear is obtained from the bi-axial states of micro-planes, through matrix condensation and zero vertical traction assumptions. This properly remedies the shear stiffening of a one-dimensional beam-column element, keeping its degrees of freedom to a minimum. For verification of the proposed method, a total of seven shear test results of reinforced concrete (RC) beams were collected from the literature, in which the key variables were the reinforcement ratio, the presence of shear reinforcement, and section shape. The advantages are clearly shown in the shear stresses distributions being accurately described and the global load-displacement relations being successfully obtained and matching well with various test results. The proposed model shows satisfactory descriptions of the monotonic load-displacement response of the RC beams failing in multiple modes that vary from diagonal-tension to flexural-compression. In addition, more accurate and reliable information of sectional responses including sectional shear deformation and stresses is collected, leading to better prediction of a potential shear failure mode. Finally, the advantages of the proposed model are demonstrated by comparing the analysis results of an RCT-beam by using the different shear assumptions that include the constant and parabolic shear strains, constant shear flow, and the proposed shear stress function. Full article
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20 pages, 8923 KiB  
Article
Assessment of Performance of Fiber Reinforced Geopolymer Composites by Experiment and Simulation Analysis
by Khoa V. A. Pham, Tan Khoa Nguyen, Tuan Anh Le, Sang Whan Han, Gayoon Lee and Kihak Lee
Appl. Sci. 2019, 9(16), 3424; https://doi.org/10.3390/app9163424 - 20 Aug 2019
Cited by 30 | Viewed by 3794
Abstract
In this work, the experimental and simulation analysis of the performance of geopolymer composites reinforced with steel fiber and polypropylene fiber is investigated. By embedding hooked end steel fiber and polypropylene fiber with various volume fractions of 0%, 0.5%, 1%, 1.5% to the [...] Read more.
In this work, the experimental and simulation analysis of the performance of geopolymer composites reinforced with steel fiber and polypropylene fiber is investigated. By embedding hooked end steel fiber and polypropylene fiber with various volume fractions of 0%, 0.5%, 1%, 1.5% to the geopolymer concrete mixture, the mechanical behavior was enhanced significantly through experimental results. The compressive strength was improved 26% with 0.5% of polypropylene fiber and 46% with 1% of hooked end steel fiber while the increment of splitting tensile strength was 12% and 28%, respectively. The flexural strength of specimens using two fiber types was also improved when compared with the non-fiber geopolymer concrete. The highest increment obtained with 1.5% of fiber volume content was from 26% to 42%. The compressive performance and flexural performance of fiber-reinforced geopolymer concrete were also better than specimens without fiber, with a higher load carrying capacity, higher stress, higher toughness and smaller strain. Using hooked end steel fiber resulted in better mechanical strength than using polypropylene fiber, and the presence of fibers is an important factor related to the strength improvements. A finite element analysis was modeled by the ANSYS program, and this showed that the load–deflection response and crack patterns also agreed quite well with experimental results. Full article
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18 pages, 8469 KiB  
Article
Effect of Harsh Conditions on the Tensile Behaviour of Lap-Spliced Carbon Fiber Textile-Reinforced Mortar (TRM) with Different Surface Treatment Methods
by Hai Van Tran, Gia Toai Truong and Kyoung-Kyu Choi
Appl. Sci. 2019, 9(15), 3087; https://doi.org/10.3390/app9153087 - 31 Jul 2019
Cited by 6 | Viewed by 2842
Abstract
In the present study, the effect of harsh conditions on the tensile behavior of lap-spliced carbon fiber textile-reinforced mortar (TRM) with different surface treatment methods was investigated through the direct tensile test. The TRM coupons were exposed to three different harsh conditions: a [...] Read more.
In the present study, the effect of harsh conditions on the tensile behavior of lap-spliced carbon fiber textile-reinforced mortar (TRM) with different surface treatment methods was investigated through the direct tensile test. The TRM coupons were exposed to three different harsh conditions: a chloride environment of 3.5 wt.% sodium chloride, a high temperature and humidity environment (50 °C and 95% relative humidity), and sustained load of 30% of the tensile strength during 60 days. In addition, two different surface treatment methods of the lap-spliced region of TRM coupons were used: carbon fiber textile impregnated by epoxy resin, and carbon fiber textile covered with aluminum oxide (Al2O3) powder after epoxy resin impregnation. The tensile characteristics of TRM coupons were investigated in terms of the cracking strength, ultimate strength, initial stiffness, and ultimate strain, to evaluate the influence of different surface treatment methods on the tensile behaviors of TRM coupons after exposure to various types of harsh conditions. Additionally, the test results were compared to the previous test results of TRM coupons that were not subjected to harsh conditions. Full article
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25 pages, 5731 KiB  
Article
Behavior of Fiber-Reinforced Polymer-Confined High-Strength Concrete under Split-Hopkinson Pressure Bar (SHPB) Impact Compression
by Zhihong Xie, Zhijian Duan, Yongchang Guo, Xiang Li and Junjie Zeng
Appl. Sci. 2019, 9(14), 2830; https://doi.org/10.3390/app9142830 - 16 Jul 2019
Cited by 14 | Viewed by 3133
Abstract
Fiber-reinforced polymer (FRP) has become increasingly popular in repairing existing steel-reinforced concrete (RC) members or constructing new structures. Although the quasi-static axial compression performance of FRP-confined concrete (FCC) has been comprehensively studied, its dynamic compression performance is not well understood, especially the dynamic [...] Read more.
Fiber-reinforced polymer (FRP) has become increasingly popular in repairing existing steel-reinforced concrete (RC) members or constructing new structures. Although the quasi-static axial compression performance of FRP-confined concrete (FCC) has been comprehensively studied, its dynamic compression performance is not well understood, especially the dynamic compressive behavior of FRP-confined high-strength concrete (FCHC). This paper presents an experimental program that consists of quasi-static compression tests and Split-Hopkinson Pressure Bar (SHPB) impact tests on FRP-confined high-strength concrete. The effects of the FRP types, FRP confinement stiffness, and strain rate on the impact resistance of FCHC are carefully studied. The experimental results show that the strain rate effect is evident for FRP-confined high-strength concrete and the existence of the FRP greatly improves the dynamic compressive strength of high-strength concrete. An existing strength model is modified for impact strength of FCHC and the predicted results are compared with the test results. The results and discussions show that the proposed model is accurate and superior to the existing models. Full article
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17 pages, 8780 KiB  
Article
Experimental Study on Dynamic Response Characteristics of RPC and RC Micro Piles in SAJBs
by Junfeng Cheng, Xiaoyong Luo, Yizhou Zhuang, Liang Xu and Xiaoye Luo
Appl. Sci. 2019, 9(13), 2644; https://doi.org/10.3390/app9132644 - 29 Jun 2019
Cited by 9 | Viewed by 3311
Abstract
The pile foundations below approach slab in a semi-integral abutment jointless bridge (SAJB) that requires high flexibility to accommodate the horizontal cyclic deformation of approach slab generated by the girder’s thermal expansion and contraction as well as earthquake action. In this paper, reactive [...] Read more.
The pile foundations below approach slab in a semi-integral abutment jointless bridge (SAJB) that requires high flexibility to accommodate the horizontal cyclic deformation of approach slab generated by the girder’s thermal expansion and contraction as well as earthquake action. In this paper, reactive powder concrete (RPC) and reinforce concrete (RC) micro piles were designed and fabricated. The shaking table tests on dynamic response of micro piles-soil interaction were conducted to investigate the dynamic response characteristics such as the strain time history of pile-soil system, the bending moment, and the deformation of piles. The maximum strain response of piles was observed at the buried depth of 4.2 D (D is the diameter of pile). Meanwhile, the maximum bending moments of RPC and RC piles appear at the depth of 0.64 D and 0.42 D, respectively, under the dynamic load excitation, and the peak horizontal deformation of piles were observed at pile head. It is found that the bending moment and the strain response of the RPC pile are larger than that of the RC micro pile, and increased by 40% and 98%, respectively. The RPC micro pile has better crack resistance, higher ductility, and flexural rigidity than that of the RC pile, and it can be widely used as pile foundations in SAJBs for the earthquake area. Full article
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