Investigation of Five Synthetic Fibers as Potential Replacements of Steel Fibers in Ultrahigh-Performance Concrete

Epackachi

2022

Structural Concrete

Self Cite

Ultra‐high performance concrete (UHPC) is an emerging class of cementitious materials with the strength and durability characteristics that far exceed those of normal‐strength concrete (NSC). While the use of UHPC in bridge structures has significantly advanced, the same cannot be stated for building structures. Among possible building applications, this study focuses on the use of UHPC in shear walls, where a significant loading demand is anticipated from the lateral loads due to wind and/or earthquake events. Upon validating a set of finite‐element models with the experimental test results, a holistic investigation has been performed in the current study to evaluate a variety of UHPC shear walls. In particular, the main structural response measures, including initial stiffness, force‐displacement relationship, and strength loss under cyclic lateral loads, have been extracted and compared. The study has been then extended to systematically investigate the effects of key design variables, such as wall thickness, aspect ratio, axial force, steel reinforcement, presence of boundary elements, and strength of embedded steel bars. The outcome of this study provides the building sector with firsthand information regarding the possibility of replacing NSC with UHPC in shear walls. This will be an important step forward to improve the safety and performance of building structures, especially where they are exposed to a high risk of wind and/or earthquake hazards.

Section: Uhpc Shear Walls Under Lateral Loadsmentioning

confidence: 99%

Section: Uhpc Shear Walls Under Lateral Loadsmentioning

confidence: 99%

Structural response assessment of ultra‐high performance concrete shear walls under cyclic lateral loads

Kulkarni

Epackachi

2022

Structural Concrete

Self Cite

“…A detailed review of the existing literature indicates that most of the past studies were focused on normal‐strength concrete (NSC) and high‐strength concrete (HSC). In recent years, advanced cementitious composite materials, such as ultra‐high‐performance fiber‐reinforced concrete (UHPFRC), have received attention, mainly because of their outstanding strength and durability 14–19 . With significantly high compressive and tensile strengths (compared to NSC and HSC), UHPFRC is a promising alternative to replace NSC conventionally used in CFSTs.…”

Section: Introductionmentioning

confidence: 99%

Synergistic use of ultra‐high‐performance fiber‐reinforced concrete (UHPFRC) and carbon fiber‐reinforced polymer (CFRP) for improving the impact resistance of concrete‐filled steel tubes

Saini

Structural Design Tall Build

2023

Self Cite

Concrete-filled steel tubes (CFSTs) have received growing attention, owing to their rapid construction, reduced labor requirement, and reasonable material cost. While in service, the CFSTs can be subjected to unexpected impact loads, originating from vehicle and vessel collision, as well as water-and wind-borne debris impact. Such extreme loading events often cause a partial or complete failure of conventional CFSTs, risking the safety and performance of the entire structural systems that rely on them. To address this issue, the current study explores how two advanced composite materials, including ultra-high-performance fiber-reinforced concrete (UHPFRC) and carbon fiber-reinforced polymer (CFRP), can be utilized to provide superior mechanical properties and minimize the vulnerability of CFSTs to impact loads. The composite materials under consideration are appropriate for both new and existing structures, in which normal-strength concrete can be replaced with UHPFRC, while CFRP sheets can further strengthen the CFSTs. For obtaining in-depth insights, a computational framework validated with the experimental tests was developed in the current study. Using a set of representative impact scenarios, various response measures, such as internal forces and deflections, as well as the energy absorbed by the CFSTs, were recorded during impact simulations. The investigations were then further extended to capture the influence of the main design parameters related to concrete, CFRP, and steel tube. From the conducted investigations, an energy absorption index was introduced, as a measure to evaluate the performance of CFSTs under impact loads.

“…This is critical, especially for plastic shrinkage, during which concrete is still in the fresh state and has not gained an adequate strength 11–16 . On the other hand, macrofibers are most beneficial in enhancing the concrete's postpeak strength properties through bridging macrocracks and enabling the concrete matrix to offer enhanced ductility and impact resistance 17–24 . Given the complementary contributions of micro and macrofibers to concrete, a transition to hybrid fiber‐reinforced concrete (FRC) mixtures, which contain both micro and macrofibers, has received growing attention 25–28 …”

Section: Introductionmentioning

confidence: 99%

“…[11][12][13][14][15][16] On the other hand, macrofibers are most beneficial in enhancing the concrete's postpeak strength properties through bridging macrocracks and enabling the concrete matrix to offer enhanced ductility and impact resistance. [17][18][19][20][21][22][23][24] Given the complementary contributions of micro and macrofibers to concrete, a transition to hybrid fiberreinforced concrete (FRC) mixtures, which contain both micro and macrofibers, has received growing attention. [25][26][27][28] Focusing on the development of hybrid FRC with synthetic fibers, Ahmed and Mihashi 29 investigated a set of FRC mixtures that contained micro and macro polyvinyl alcohol (PVA) fibers with a dosage from 1.0% to as high as 3.0% of the concrete's volume.…”

mentioning

confidence: 99%

Mechanical properties of hybrid fiber‐reinforced concretes made with low dosages of synthetic fibers

Kazemian

2022

Structural Concrete

Self Cite

Recent advances made in concrete fibers have made them one of the concrete's recommended ingredients, mainly to eliminate the drawbacks associated with the weakness of cementitious materials, such as concrete, in tension. The addition of fibers, however, introduces extra cost and labor requirements, while selecting an appropriate choice and dosage of fibers has still remained a standing question. To address the outlined issues, the current study investigates the development of fiber‐reinforced concrete (FRC) mixtures with a focus on achieving superior mechanical properties with a low dosage of synthetic fibers. For this purpose, three choices of macrofibers were examined. The investigations spanned four dosages of each macrofiber mixed with three dosages of a microfiber included to ensure adequate resistance to early‐age, shrinkage‐induced strains. The experiments conducted on the developed hybrid FRC mixtures systematically measured workability, as well as compressive, splitting tensile, and flexural strength properties. The test results were then paired with the micro‐scale monitoring of the bond between individual macrofibers and the concrete matrix through scanning electron microscope images. The outcome shed light on how each of the macrofibers of choice contributed to improving the FRC's mechanical properties. This paved the way to benefit from a minimum dosage of them to achieve the expected structural response, while avoiding crack formation and propagation in various applications.