scholarly journals Flexural Strength Estimation for Hollow Cross-Section Simply Supported UHPC Beams

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nasser Hakeem Tu’ma ◽  
Mohammed Naji Hammood ◽  
Rasool Dakhil Mohsin
Keyword(s):  
Flexural Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Bottom Flange ◽  
Structural Elements ◽  
Ultra High Performance Concrete ◽  
Aspect Ratios ◽  
Flange Thickness ◽  
Strength Based ◽  
Reinforced Steel

Abstract The hollow structural elements occupy a great deal of researchers’ interest due to the possibility of losing their weights and maintaining or developing their resistances especially when increasing both compressive and tensile strength of modern materials. The flexural strength based on the forces balance and stain compatibility was derived. Nine beams of Ultra High Performance concrete (UHPC) and conventional reinforced steel bars were casted. Several parameters were taken which are the thickness of the concrete top flange, thickness of the concrete bottom flange, depth of the longitudinal hollow and the ratio of the longitudinal reinforcing steel. By comp aring the practical and theoretical results, the proposed flexural strength provided a safety factor of one-fifth against the experimental collected data. The ultimate flexural force developed up 260 % when increasing the reinforced steel area 4.6 times and 230 % comparing with the solid beam. Many aspect ratios were also mentioned that keep the strength in developing.

Evaluation of Fundamental UHPC Properties According to the Shape of Steel Fiber

2010 ◽  
Vol 452-453 ◽  
pp. 717-720 ◽  
Author(s):  
Gum Sung Ryu ◽  
Su Tae Kang ◽  
Jung Jun Park ◽  
Kyung Taek Koh ◽  
Sung Wook Kim
Keyword(s):  
Aspect Ratio ◽  
Flexural Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Flexural Behavior ◽  
Ultra High Performance Concrete ◽  
Aspect Ratios ◽  
Strength Tests ◽  
Shaped Fibers

This paper intends to examine the effects if the length and shape of steel fibers on the mechanical characteristics of ultra-high performance concrete (UHPC). Accordingly, the length (l) of the steel fibers with diameter (d) of 0.2 mm is varied as 13 mm, 16.3 mm and 19.5 mm and their corresponding aspect ratios (l/d) are 65, 82 and 98. Straight and wave-shaped fibers are adopted to manufacture UHPC. Thereafter, the effects of the aspect ratio and characteristics of the wave-shape of the steel fibers on the strength characteristics of UHPC are examined through compressive and flexural strength tests. The results showed small differences in the workability and compressive behavior but revealed that changing the length of the fibers and increasing the aspect ratio are improving the flexural behavior of UHPC. Specifically, the flexural strength was enhanced by 25% and the flexural toughness by 30%. Compared to rectilinear fibers, the adoption of wave-shaped fibers is seen to degrade the flexural behavior regardless of the aspect ratio. Consequently, using straight steel fibers and adopting larger aspect ratio seems advisable to improve the toughness of UHPC.

Prestressed I-Beams Made of Ultra-High Performance Concrete for Construction of Railway Bridges

2014 ◽  
Vol 578-579 ◽  
pp. 776-778
Author(s):  
Petr Tej ◽  
Jiří Kolísko ◽  
Petr Bouška ◽  
Miroslav Vokáč ◽  
Jindřich Čech
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Load Test ◽  
Bottom Flange ◽  
Structural Elements ◽  
Ultra High Performance Concrete ◽  
Actual Structure ◽  
Railway Bridges ◽  
Four Point Bending

This paper focuses on research into prestressed I-beams made of ultra-high-performance concrete, which are designed to be structural elements in small and medium span railway bridges. Prestressed concrete I-beams are designed with ten prestressing cables in the bottom flange. The prestressed beams are laid close together in the actual structure with panels inserted between them. The entire structure will subsequently become monolithic. At the present time, I-beams made of rolled steel are commonly used as structural elements in this type of structure. The advantage of these types of structures lies in their having a low construction height. This paper presents a computer and experimental analysis of the loading of UHPC prestressed I-beams. For the purpose of the experiments, several specimens of 7 m span were made. The specimens were subsequently tested in the laboratory in four-point bending tests. The paper presents the process and results of the experiments. Simultaneously with the experiments, computer analyses were created in which optimization of the material and geometric parameters of the beams were carried out. The paper demonstrates the correspondence of the experimental and computer-simulated load test results.

Prestressed I-Beams of 12 m Span Made of Ultra-High Performance Concrete for Construction of Railway Bridges

2014 ◽  
Vol 587-589 ◽  
pp. 1593-1596
Author(s):  
Petr Tej ◽  
Jiří Kolísko ◽  
Petr Bouška ◽  
Miroslav Vokáč ◽  
Jindřich Čech
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Load Test ◽  
Bottom Flange ◽  
Structural Elements ◽  
Ultra High Performance Concrete ◽  
Actual Structure ◽  
Railway Bridges ◽  
Four Point Bending

This paper focuses on research of prestressed I-beams made of ultra-high performance concrete (UHPC), which are designed to be structural elements in small and medium span railway bridges. Prestressed concrete I-beams are designed with ten prestressing cables in the bottom flange. The prestressed beams are laid close together in the actual structure, with panels inserted between them. The entire structure will subsequently become monolithic. At the present time, I-beams made of rolled steel are commonly used as structural elements in this type of structure. The advantage of these types of structures lies in their having low construction height. This paper presents a computer and experimental analysis of loading of UHPC prestressed I-beams. For the purpose of the experiments, three specimens of 12 m span were made. The specimens were subsequently tested in the laboratory in four-point bending tests. The paper presents the process and results of the experiments. Simultaneously with the experiments, computer analyses were created in which optimization of the material and geometric parameters of the beams were carried out. The paper demonstrates the correspondence of the experimental and computer-simulated load test results.

scholarly journals Flexural Strength Evaluation of Reinforced Concrete Members with Ultra High Performance Concrete

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Baek-Il Bae ◽  
Hyun-Ki Choi ◽  
Chang-Sik Choi
Keyword(s):  
Flexural Strength ◽  
High Performance ◽  
Strain Softening ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
High Strength ◽  
Tension Stress ◽  
Compression Stress ◽  
Ultra High Performance Concrete ◽  
Stress Block

Flexural strength evaluation models for steel fiber reinforced ultra high strength concrete were suggested and evaluated with test results. Suggested flexural strength models were composed of compression stress blocks and tension stress blocks. Rectangular stress block, triangular stress block, and real distribution shape of stress were used on compression side. Under tension, rectangular stress block distributed to whole area of tension side and partial area of tension side was used. The last model for tension side is realistic stress distribution. All these models were verified with test result which was carried out in this study. Test was conducted by four-point loading with 2,000 kN actuator for slender beam specimen. Additional verifications were carried out with previous researches on flexural strength of steel fiber reinforced concrete or ultra high strength concrete. Total of 21 test specimens were evaluated. As a result of comparison for flexural strength of section, neutral axis depth at ultimate state, models with triangular compression stress block, and strain-softening type tension stress block can be used as exact solution for ultra high performance concrete. For the conservative and convenient design of section, modified rectangular stress block model can be used with strain softening type tension stress block.

Evaluation of Flexural Performance in UHPC(Ultra High Performance Concrete) According to Placement Methods

2009 ◽  
Vol 417-418 ◽  
pp. 581-584 ◽  
Author(s):  
Gum Sung Ryu ◽  
Su Tae Kang ◽  
Jung Jun Park ◽  
Gyung Taek Koh
Keyword(s):  
Flexural Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Initial Crack ◽  
Ultra High Performance Concrete ◽  
Remarkable Feature ◽  
Flexural Performance ◽  
Placement Method ◽  
Compaction Properties ◽  
And Diffusion

Apart from its high compressive, tensile and flexural strengths reaching approximately 200MPa, 15MPa and 35MPa, respectively, Ultra High Performance Concrete (UHPC) is characterized by its high resistance against degrading factors that can delay their penetration and diffusion speeds down to 1/20 to maximum 1/10,000 compared to ordinary concrete. UHPC also exhibits self-compaction properties with a slump flow of about 220mm. Furthermore, the most remarkable feature of UHPC is the improvement of its flexural strength and toughness through the admixing of steel fiber. Accordingly, this study evaluates the effects of the placement method on the flexural performance of UHPC. As a result, the flexural strength of UHPC appears to be extremely dependent on the placement method with variation of the maximum flexural strength up to 2 to 3 times while poor influence is observed on the initial crack strength.

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