scholarly journals Experimental Study on Improving the Compressive Strength of UHPC Turntable

2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Jiawei Wang ◽  
Quansheng Sun
Keyword(s):  
Compressive Strength ◽  
Failure Mechanism ◽  
Structural Reliability ◽  
Steel Fiber ◽  
Mechanical Performance ◽  
Frictional Resistance ◽  
Steel Tube ◽  
Manufacturing Cost ◽  
Loading Effect ◽  
Spherical Hinge

Purpose. In the recent years, horizontal rotation methods have been widely used for bridge construction, particularly for constructing overpass bridges on highways, railways, and shipping. However, bridges constructed using the swivel construction method bear several types of loads during the rotation process. Furthermore, the bridge turntable, which is the core force-bearing component of the structure, bears considerably large vertical pressure and horizontal frictional resistance. The present research proposes three strengthening methods when applying ultrahigh performance concrete (UHPC) materials to the turntable of a spherical hinge to improve structural reliability. Furthermore, the mechanical properties of the structure are evaluated using a unidirectional compressive strength test to provide a theoretical and experimental basis for the application of the UHPC material. Design/Methodology/Approach. To evaluate the mechanical performance of the turntable of a spherical hinge, scale models of six sets of UHPC turntables—steel tube-UHPC, stirrup-UHPC, and directional steel fiber UHPC—were constructed in the study. The compressive strengths of the turntable specimens were calculated after theoretical analysis. After obtaining the load-displacement curves of the cube specimens, the force characteristics of the turntable and the failure mechanism of the structure were analyzed by observing the failure mode of the specimens. Findings. The compressive strength of the steel tube-UHPC turntable was 207 MPa, which can completely replace the traditional steel turntable. In addition, the stirrup-UHPC turntable demonstrated a significant loading effect. However, the effect of the restraint radius of the stirrup needs to be considered during the design; otherwise, the loading effect is poor. Furthermore, a directional steel fiber UHPC turntable can improve the compressive strength to a certain extent. We summarize the failure mechanism of the spherical hinge turntable specimens that are expected to play a role in UHPC spherical hinge in engineering applications and construction monitoring. Originality/Value. To the best of our knowledge, this study is the first to employ the UHPC, steel tube-UHPC, stirrup-UHPC, and directional steel fiber spherical hinge turntables in the swivel construction of bridges. The compressive strength and mechanical characteristics of the UHPC structure meet the requirements of the turntable, and more importantly, the manufacturing process (on-site pouring) of the aforementioned UHPC turntable structures is relatively simple. Finally, the manufacturing cost of the turntables is expected to be reduced by more than 50% compared to those of traditional turntables.

Experimental research on compressive strength of UHPC spherical hinge

2019 ◽  
Vol 11 (2) ◽  
pp. 354-378
Author(s):  
Wang Jiawei ◽  
Sun Quansheng
Keyword(s):  
Compressive Strength ◽  
Mechanical Behavior ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Testing Machine ◽  
Manufacturing Cost ◽  
Displacement Curve ◽  
Content Type ◽  
Spherical Hinge ◽  
The Impact

Purpose In order to reduce the impact of bridge construction on traffic under the bridge, the construction of bridges for some important traffic nodes usually adopts the swivel construction method. The spherical hinge is a rotating mechanism located between the bottom of the pier and the bridge cap, and is subjected to tremendous vertical pressure. According to the mechanical characteristics of the spherical hinges, this paper applies the ultra-high performance concrete (UHPC) material to the spherical hinge. The spherical hinge is subjected to a compression test to test its mechanical behavior. This paper aims to discuss this issue. Design/methodology/approach In order to test the mechanical behavior of the UHPC spherical hinge, multiple sets of 100 mm UHPC spherical hinge specimens were prefabricated. Through the universal testing machine to measure the compressive strength of specimens, draw the force-displacement curve to analyze the failure mechanism and establish the stress calculation formula of the spherical hinge at each point along the radial direction. Findings Through the test, the compressive strength of UHPC spherical hinge is obtained, and the influencing factors of UHPC spherical hinge strength are found: reducing water–cement ratio, increasing steel fiber content and length and changing steel fiber arrangement direction can effectively improve the compression strength of UHPC spherical hinge. Originality/value For the first time, UHPC materials were applied to the spherical hinge structure, the UHPC spherical hinge diameter is 1/3 of the diameter of the reinforced concrete spherical hinge, which is equivalent to the diameter of the steel spherical hinge. By applying the UHPC spherical hinge, the manufacturing cost is reduced, the process is simple, and the construction difficulty is reduced.

scholarly journals Experimental and Numerical Study on the Compression Behavior of Square Concrete-Filled Steel Tube Stub Columns with Steel Fiber-Reinforced High-Strength Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Hyung-Suk Jung ◽  
Baek-Il Bae ◽  
Hyun-Ki Choi ◽  
Joo-Hong Chung ◽  
Chang-Sik Choi ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Yield Strength ◽  
Parametric Study ◽  
High Strength Concrete ◽  
High Performance ◽  
Steel Fiber ◽  
High Strength ◽  
Steel Tube ◽  
Stub Columns ◽  
Strain Increase

This study was conducted to evaluate the applicability of concrete-filled steel tube (CFT) columns made from high-performance construction materials. KBC2016, South Korea’s current building code, limits the maximum compressive strength of concrete at 70 MPa and the maximum yield strength of steel at 650 MPa. Similar restrictions to material properties are imposed on major composite structural design parameters in other countries worldwide. With the recent acceleration of the pace of development in the field of material technology, the compressive strength of commercial concrete has been greatly improved and the problem of low tensile strength, known to be the major limitation of concrete, is being successfully addressed by adding fiber reinforcement to concrete. Therefore, the focus of this study was to experimentally determine the strength and ductility enhancement effects, which depend on material composition. To this end, we performed concentric axial loading tests on CFT stub columns made from steel with a yield strength of 800 MPa and steel fiber-reinforced high-strength concrete. By measuring the strain at the yield point of CFT steel during the test, we could determine whether steel yields earlier than ultimate failure load of the member, which is a key design concept of composite structures. The analysis results revealed that the yield point of steel preceded that of concrete on the stress-strain curve by the concurrent action of the strain increase at the maximum strength, attributable to the high compressive strength and steel fiber reinforcement, and the strain increase induced by the confining stress of the steel tube. Additionally, we performed parametric study using ABAQUS to establish the broad applications of CFT using high-performance materials, with the width-to-thickness ratio as the main parameter. Parametric study was undertaken as experimental investigation was not feasible, and we reviewed the criteria for limiting the width-to-thickness ratio as specified in the current building code.

Research on the Main Mechanical Capability of Steel Fibers Concrete of Deck Pavement

2011 ◽  
Vol 374-377 ◽  
pp. 1619-1622
Author(s):  
Ling Zhang ◽  
Zhi Qiang Shi
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Service Life ◽  
Flexural Strength ◽  
Steel Fiber ◽  
Mechanical Performance ◽  
Volume Ratio ◽  
Steel Fibers ◽  
Fiber Types ◽  
Splitting Strength

In this article, based on a certain actual project, the main physical and mechanical performance including compressive strength, splitting strength, flexural strength and shear strength are studied in detail through the experiments. Different fiber types and volume ratio are chosen in the experiments for the purpose of determining the best quantities and types of steel fiber in concrete to lengthen the service life of deck pavements. It is showed that the research has some referential value for similar projects.

scholarly journals Experimental Research on Reinforced Concrete Columns Strengthened with Steel Jacket and Concrete Infill

2021 ◽  
Vol 11 (9) ◽  
pp. 4043
Author(s):  
Aleksandar Landović ◽  
Miroslav Bešević
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Experimental Research ◽  
Failure Modes ◽  
Steel Tube ◽  
Rc Columns ◽  
Rc Column ◽  
Steel Jacket ◽  
Ductile Behavior

Experimental research on axially compressed columns made from reinforced concrete (RC) and RC columns strengthened with a steel jacket and additional fill concrete is presented in this paper. A premade squared cross-section RC column was placed inside a steel tube, and then the space between the column and the tube was filled with additional concrete. A total of fourteen stub axially compressed columns, including nine strengthened specimens and five plain reinforced concrete specimens, were experimentally tested. The main parameter that was varied in the experiment was the compressive strength of the filler concrete. Three different concrete compression strength classes were used. Test results showed that all three cross-section parts (the core column, the fill, and the steel jacket) worked together in the force-carrying process through all load levels, even if only the basic RC column was loaded. The strengthened columns exhibited pronounced ductile behavior compared to the plain RC columns. The influence of the test parameters on the axial compressive strength was investigated. In addition, the specimen failure modes, strain development, and load vs. deformation relations were registered. The applicability of three different design codes to predict the axial bearing capacity of the strengthened columns was also investigated.

scholarly journals Effects of Steel Fiber Percentage and Aspect Ratios on Fresh and Harden Properties of Ultra-High Performance Fiber

2021 ◽  
Vol 2 (3) ◽  
pp. 501-515
Author(s):  
Rajib Kumar Biswas ◽  
Farabi Bin Ahmed ◽  
Md. Ehsanul Haque ◽  
Afra Anam Provasha ◽  
Zahid Hasan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
High Performance ◽  
Steel Fiber ◽  
Setting Time ◽  
Fiber Reinforced Concrete ◽  
Future Research ◽  
Manufacturing Cost ◽  
Aspect Ratios ◽  
High Performance Fiber

Steel fibers and their aspect ratios are important parameters that have significant influence on the mechanical properties of ultrahigh-performance fiber-reinforced concrete (UHPFRC). Steel fiber dosage also significantly contributes to the initial manufacturing cost of UHPFRC. This study presents a comprehensive literature review of the effects of steel fiber percentages and aspect ratios on the setting time, workability, and mechanical properties of UHPFRC. It was evident that (1) an increase in steel fiber dosage and aspect ratio negatively impacted workability, owing to the interlocking between fibers; (2) compressive strength was positively influenced by the steel fiber dosage and aspect ratio; and (3) a faster loading rate significantly improved the mechanical properties. There were also some shortcomings in the measurement method for setting time. Lastly, this research highlights current issues for future research. The findings of the study are useful for practicing engineers to understand the distinctive characteristics of UHPFRC.

Shear response of steel fiber reinforced recycled concrete-filled steel tube columns

2021 ◽  
pp. 136943322110093
Author(s):  
Zhenzhen Liu ◽  
Yiyan Lu ◽  
Shan Li ◽  
Jiancong Liao
Keyword(s):  
Axial Compression ◽  
Steel Fiber ◽  
Steel Tube ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Superposition Method ◽  
Fiber Reinforced ◽  
Concrete Filled Steel Tube ◽  
Shear Span

A comprehensive study of the shear characteristics of steel fiber reinforced recycled concrete-filled steel tube (SRCFST) columns is conducted. 50 CFST stub columns are tested with the variables of steel tube diameter-thickness ratio ( D/t), shear span-to-depth ratio (λ), axial compression ratio ( n), and concrete mix. Two types of cements, three recycled aggregate percentages, three water-cement ratios, and three steel fiber contents are considered in design of concrete mixes. The experimental results show that SRCFST columns present the coincident shear behavior of the ordinary CFST columns. As λ is increased, shear resistance shows a downtrend, while the flexural strength presents an increasing trend. Imposing axial compression or thickening steel tube contributes to an adequate safety margin in plastic period. Based on the contributions superposition method, a predicted model of the shear capacity of SRCFST columns is proposed in consideration of shear-span ratio, axial compression, and self-stress.

scholarly journals Insight into the Mechanical Performance of the UHPC Repaired Cementitious Composite System after Exposure to High Temperatures

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4095
Author(s):  
Qing Chen ◽  
Zhiyuan Zhu ◽  
Rui Ma ◽  
Zhengwu Jiang ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
High Temperatures ◽  
Bonding Strength ◽  
Composite System ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Interfacial Structure ◽  
Cementitious Composite ◽  
Average Percentage

In this paper, the mechanical performance of an ultra-high-performance concrete (UHPC) repaired cementitious composite system, including the old matrix and the new reinforcement (UHPC), under various high temperature levels (20 °C, 100 °C, 300 °C, and 500 °C) was studied. In this system, UHPC reinforced with different contents of steel fibers and polypropylene (PP) fibers was utilized. Moreover, the physical, compressive, bonding, and flexural behaviors of the UHPC repaired system after being exposed to different high temperatures were investigated. Meanwhile, X-ray diffraction (XRD), baseline evaluation test (BET), and scanning electron microscope (SEM) tests were conducted to analyze the effect of high temperature on the microstructural changes in a UHPC repaired cementitious composite system. Results indicate that the appearance of the bonded system changed, and its mass decreased slightly. The average percentage of residual mass of the system was 99.5%, 96%, and 94–95% at 100 °C, 300 °C, and 500 °C, respectively. The residual compressive strength, bonding strength, and flexural performance improved first and then deteriorated with the increase of temperature. When the temperature reached 500 °C, the compressive strength, bonding strength, and flexural strength decreased by about 20%, 30%, and 15% for the UHPC bonded system, respectively. Under high temperature, the original components of UHPC decreased and the pore structure deteriorated. The cumulative pore volume at 500 °C could reach more than three times that at room temperature (about 20 °C). The bonding showed obvious deterioration, and the interfacial structure became looser after exposure to high temperature.

Electromagnetic Wave Absorbing and Mechanical Properties of Cement-Based Composite Panel with Different Nanomaterials

2017 ◽  
Vol 26 (1) ◽  
pp. 096369351702600
Author(s):  
Sun Yafei ◽  
Gao Peiwei ◽  
Peng Hailong ◽  
Liu Hongwei ◽  
Lu Xiaolin ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Electromagnetic Wave ◽  
Double Layer ◽  
Mechanical Performance ◽  
Interface Structure ◽  
Composite Panel ◽  
Effective Bandwidth ◽  
Composite Panels ◽  
Frequency Range ◽  
Triple Layer

This paper presents the microstructures and mechanical and absorbing properties of double and triple layer, cement-based, composite panels. The results obtained show that the frequency range in 2-18GHz had less than −10dB effective bandwidth, which correlates with 3.7and 10.8GHz in double and triple layer cement-based composite panels. Furthermore, the double layer panel's compressive strength at 7 and 28 days was 40.2 and 61.2MPa, respectively. For the triple layer panel, the strength values were 35.6MPa and 49.2MPa. The triple layer panel's electromagnetic wave (EMW) absorbing properties were superior compared to the properties of the double layer panel. However, the triple layer panel's mechanical performance was inferior to that of the double layer panel. This study proposes that carbon nanotubes can effectively improve the compressive strength and interface structure of cement-based composite panels.

scholarly journals Experimental Study on Deformation Behavior and Compressive Strength of Concrete Cast in Steel Tube Arches under Low-Temperature Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Tuo Shi ◽  
Nianchun Deng ◽  
Xiao Guo ◽  
Wen Xu ◽  
Shi Wang
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
Performance Test ◽  
Large Diameter ◽  
Test Site ◽  
Steel Tube ◽  
Design Strength ◽  
Curing Conditions ◽  
Expansive Agent ◽  
Arch Bridges

Taking the construction of a concrete-filled steel tube (CFST) arch bridge (part of the Sichuan-Tibet Railway) in low temperatures as the test site, firstly the deformation performance test of concrete was carried out. Following this initial testing, measurement of compressive strength and shrinkage performance was conducted in large-diameter CFSTs under a variety of curing conditions. Experimental results showed that the expansion effect of Ca-Mg composite expansive agent in concrete was better than that of other expansive agents at any stage. Under low-temperature curing (0°C), the sampling strength of the large-diameter CFSTs reached 73.5% of the design strength at 28 d in the presence of a nonthermal curing system. The design strength itself was reached, when a curing system involving a thermal insulation film was applied, and use of this film also led to improvements in concrete shrinkage. The results suggested that a Ca-Mg composite expansive agent, combined with an insulation film curing system, should be the technique selected for concrete pumping construction of CFST arch bridges in Tibet.

Tests on Mechanical Properties and Anti-Penetration Performance of Steel-Fiber Reactive Powder Concrete

2013 ◽  
Vol 671-674 ◽  
pp. 1761-1765
Author(s):  
Yong Liu ◽  
Chun Ming Song ◽  
Song Lin Yue
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Steel Fiber ◽  
Reactive Powder Concrete ◽  
Calculation Results ◽  
Reactive Powder ◽  
Penetration Tests

In order to get mechanical properties ,some RPC samples with 5% steel fiber are tested, many groups data were obtained such as compressive strength, shear strength and fracture toughness. And a group of tests on RPC with 5% steel-fiber under penetration were also conducted to validate the performance to impact. The penetration tests are carried out by the semi-AP projectiles with the diameter of 57 mm and earth penetrators with the diameter of 80 mm, and velocities of the two kinds of projectiles are 300～600 m/s and 800～900 m/s, respectively. By contrast between the experimental data and the calculation results of C30 reinforced concrete by using experiential formula under penetration, it shows that the resistance of steel-fiber RPC to penetration is 3 times as that of general C30 reinforced concrete.

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