Behaviour of Prestressed Ultra-High Performance Concrete I-Beams Subjected to Shear and Flexure (original) (raw)
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Structural Design with Ultra-High Performance Concrete
Structural Design with Ultra-High Performance Concrete, 2023
UHPC is a structural material that exhibits compelling structural behaviors. These behaviors are distinct from those exhibited by other more common materials used in the civil infrastructure, such as conventional concrete or steel. In comparison to conventional concrete, UHPC offers sustained postcracking tensile resistance, along with an increased compressive strength, an increased elastic modulus, and a decreased susceptibility to liquid permeation. To effectively engage the enhanced behaviors of UHPC, structural design guidance must rationally and conservatively provide a framework within which designers can appropriately conceive UHPC structures and proportion UHPC elements. With a look toward the future, UHPC can most likely allow for the design of novel structures whose composition is efficient, whose functionality is improved, and whose lifespan is extended. Until now, there has not been any formal design guidance in the United States for structural design with UHPC. Recent research and development-based advancements related to UHPC, and a growing interest from bridge owners in the possibilities presented by this material, have provided an opportunity for the bridge engineering community to consider and potentially adopt formal structural design guidance for UHPC structural elements. The main body of the report provides an overview of UHPC in the context of structural design. The report also contains three appendices. The first, Appendix A—Guide Specification for Structural Design with Ultra-High Performance Concrete, contains a draft structural design framework developed for consideration by AASHTO and presented in the format commonly used for AASHTO guide specifications. Section 1 of Appendix A focuses on structural design guidance, while Section 2 focuses material conformance guidance. To assist readers in understanding the potential application of the proposed structural design framework, a pair of design examples has been developed to demonstrate some of the basic concepts embedded in the framework. The first example focuses on using the methods in the design framework to analyze the behavior of a rectangular beam. This example can be found in Appendix B—Analysis of a Rectangular, Mild Steel Reinforced UHPC Beam. The second example demonstrates the design of a slab-on-stringer bridge superstructure using pretensioned girders. This example can be found in Appendix C—Design Example of a Pretensioned UHPC I-Beam Bridge with a Conventional Concrete Deck.
Acta Polytechnica CTU Proceedings
With the aim to reduce the environmental footprint of buildings, this paper presents an original structural system concept for two-way slabs in residential and office buildings. The proposed system extends the best practice in terms of modularity, versatility, demountability, reusability, and durability. A finite set of elements can be used to form the main load-bearing system of multiple successively constructed buildings having different and unpredicted layouts and static systems. Ultra-High Performance Concrete (UHPC) was identified as one of the most promising materials for this application because of its high strength, extreme durability and the opportunities it opens for shape optimization and material consumption reduction. In the first part of this contribution, the main features of the new structural system and preliminary design assumptions for UHPC modules are briefly outlined. Then, the authors present and discuss the results of an experimental campaign on prestressed UH...
Experimental Study of Structural Behaviour of Beam using Ultra High Performance Concrete I
JETIR, 2018
UHPC (ultra-high performance concrete) is a relatively new type of concrete that exhibits mechanical properties that are far superior to those of conventional concrete and high performance concrete. The main characteristics that distinguish UHPC from conventional reinforced concrete are the improved compressive strength, the tensile strength, the addition of steel fibres, and the resistance to corrosion and degradation. The mechanical properties of UHPC allow for smaller, thinner, lighter sections to be designed while strength is maintained or improved. The use of UHPC has been limited to a few structure applications due to the high cost of the materials and the lack of established design guidelines. As the construction of superhigh structures and long span structures increases all over the world, strength and stiffness of structures are being improved by applying Ultra-high strength concrete. With such trends, demands to use 100Mpa or Ultrahigh strength concrete more than that are anticipated to spread out. Reinforced concrete is being used extensively in the construction industry all over the world. The use of Ultra high strength concrete has increased due to its obvious advantages like increased modulus of elasticity, chemical resistance, freeze thaw resistance, lower creep shrinkage and lower permeability.
BEHAVIOR OF ULTRA HIGH PERFORMANCE CONCRETE STRUCTURES
A study has been made through this investigation to understand the behavior of UHPC members with steel fibers by using two approaches: experimental investigation of concrete mixes and simulation of the problem studied by other researchers using finite elements. Experimental investigation is carried out to obtain the mechanical properties for two types of UHPC mixes, namely, the type of pozzolanic admixture (Silica Fume and High Reactivity Metakaolin) in addition to use three different values of steel fibers volume fraction (1%, 1.5% and 2%). The finite element method through the ANSYS computer program is used. The eight node brick element is used to model the UHPC beams with embedded steel fibers. The stress-strain curve in compression for the UHPC with steel fibers is simulated by a nonlinear elasto-plastic model which is terminated at the onset the crushing. In tension, a smeared crack model with fix orthogonal cracks has been used. The experimental data obtained from other researchers is compared with the finite element solution and good agreement between the results is obtained. Parametric studies are carried out to investigate the effects of type of pozzolanic admixture, volume fraction of steel fibers and other solution parameters. Higher values of compressive strength have been achieved using UHPC mixes with Silica Fume in comparison with UHPC mix with High Reactivity Metakaolin.
Structural Concrete, 2020
The increasing demands of sustainable design and construction with economical sections, reduced cover, and more efficient time schedule require more flexibility in the design methodologies. The development of ultra-high performance concrete (UHPC) have gained increasing interests as an attractive option for structural members with lightweight and superior performances. Concrete members reinforced with steel bars and fibers, generally known as hybrid reinforced concrete (HRC), offer a feasible solution in terms of reducing reinforcing materials and achieving desired structural performance. This paper proposes an analytical model to predict the flexural behavior of hybrid reinforced UHPC with steel reinforcements. Moment-curvature solutions are derived for reinforced sections based on parameterized tension-compression constitutive models. The approach is applicable to customized cross section and derivation of T-section is demonstrated. The moment-curvature response is further simplified as a tri-linear model, which is used for the development of full-range displacement solutions in analytical form. The proposed model is validated with the experimental data from literature covering a range of materials and member sizes. The full-range solutions may provide insights into the serviceability design approach based on the criterion of maximum crack width or allowable deflection.
Structural Concrete, 2020
The increasing demands of sustainable design and construction with economical sections, reduced cover, and more efficient time schedule require more flexibility in the design methodologies. The development of ultra‐high performance concrete (UHPC) have gained increasing interests as an attractive option for structural members with lightweight and superior performances. Concrete members reinforced with steel bars and fibers, generally known as hybrid reinforced concrete (HRC), offer a feasible solution in terms of reducing reinforcing materials and achieving desired structural performance. This paper proposes an analytical model to predict the flexural behavior of hybrid reinforced UHPC with steel reinforcements. Moment–curvature solutions are derived for reinforced sections based on parameterized tension‐compression constitutive models. The approach is applicable to customized cross section and derivation of T‐section is demonstrated. The moment–curvature response is further simplif...
Revista IBRACON de Estruturas e Materiais, 2017
This paper does a review of the recent achievements on the knowledge of UHPFRC properties and in the development of design procedures. UHPFRC is defined as a new material, with unique properties (high ductility, low permeability, very high strength capacity in compression, higher toughness) in comparison to conventional concrete. It is important to know both material and mechanical properties to fully take advantage of its outstanding properties for structural applications. However, since this is a new material, the current design codes are not well suited and should be reviewed before being applied to UHPFRC. In the first part, the following material properties are addressed: hydration process; permeability; fibers role; mix design; fiber-matrix bond properties workability; mixing procedure; and curing. In the second part, the mechanical properties of the material are discussed, together with some design recommendations. The aspects herein examined are: size effect; compressive and flexural strength; tensile stress-strain relation; shear and punching shear capacity; creep and shrinkage; fracture energy; steel bars anchorage and adherence. Besides, the tensile mechanical characterization is described using inverse analysis based on bending tests data. In the last part, material behavior at high temperature is discussed, including physical-chemical transformations of the concrete, spalling effect, and transient creep. In the latter case, a new Load Induced Thermal Strain (LITS) semi-empirical model is described and compared with UHPC experimental results.
Strength Iso-Responses of Shear-Deficient Ultra-High Performance Fiber Reinforced Concrete Beams
Sustainability
The development of sustainable construction methods can be achieved by improving the performance of reinforced concrete elements, resulting in an increase in structural life expectancy. This paper presents a study of the structural performance of shear-deficient ultrahigh-performance concrete (UHPC) concrete beams to produce sustainable construction materials. In the first phase of the experimental campaign, performance-based optimizations were implemented for UHPC. The characteristic compressive strength of all mixes was kept at 130 ± 10 MPa. The elastic modulus of plain UHPC was obtained at 8 GPa, and for the fiber-reinforced one was 40 GPa. Additionally, 18 sets of reinforced UHPC beams were investigated for their structural behavior based on the overall depth, reinforcement ratio (ρ), and the shear-span-to-depth ratio (λ) as key variables. Here, λ was varied between 1 and 2 and ρ was varied between 0.56% and 3.15%. The experimental study determined the lowest shear strength as 4...
Structural performance of ultra-high-performance fiber-reinforced concrete beams
Structural Concrete, 2017
Ultra-high performance fibre reinforced concrete (UHPFRC) is a relatively new construction material. In comparison with conventional high strength concrete UHPFRC usually does not contain coarse aggregates larger than 6-7 mm in size. This paper presents the outcomes of an experimental study of UHPFRC beams subjected to four-point loading. The effect of two parameters was studied, namely the fibre content and the temperature of curing water. Eight UHPFRC beams comprising 6 beams reinforced with rebars and two beams without rebars were tested. Three fibre contents were investigated in this study (1%, 2% and 4% in volume). The study investigated two curing temperatures of water which are 20°C and 90°C. The results presented in this paper include deflections, toughness energy and moment capacity and also includes a comparison with calculations according to EC2 provisions. A minor difference was observed in the deformation and flexural behaviour of beams with fibre contents of 1% and 2%