Transfer length in pretensioned prestressed concrete structures composed of high performance lightweight and normal-weight concrete

2013 ◽  
Vol 56 ◽  
pp. 983-992 ◽  
Author(s):  
Cristina Vázquez-Herrero ◽  
Isabel Martínez-Lage ◽  
Fernando Martínez-Abella
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
Concrete Structures ◽  
Normal Weight ◽  
Transfer Length ◽  
Normal Weight Concrete

New Trends in Prestressed Concrete Bridges

2000 ◽  
Vol 1696 (1) ◽  
pp. 238-272
Author(s):  
Michel Virlogeux
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Concrete Bridges ◽  
Prestressed Concrete Bridges ◽  
External Prestressing ◽  
Different Types ◽  
Composite Bridges ◽  
Cable Stayed Bridges

An overview of the recent evolution in the design and construction of prestressed concrete bridges worldwide is provided. Several major trends are evidenced. Certainly those trends that have had greater influences on the industry because of their wide applications are the development of external prestressing, which is now systematically used in some countries for medium-span bridges; the emergence of high-performance concrete, which extends the possibilities at the same time as it improves the durability of concrete structures; and the more frequent association of steel and concrete for composite bridges of different types and composite elements in bridges, allowing the construction of many innovative structures. For more specific applications, cable-stayed bridges, for which interesting developments have been seen in the last 10 years, and the more extensive use of heavy prefabrication in large projects, with elements up to several thousands of metric tons, are also described. Bridge architecture is also discussed in terms of the fact that good structural designs can produce elegant prestressed concrete bridges.

scholarly journals Experimental Evaluation of Shrinkage, Creep and Prestress Losses in Lightweight Aggregate Concrete with Sintered Fly Ash

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3895
Author(s):  
Rafał Stanisław Szydłowski ◽  
Barbara Łabuzek
Keyword(s):  
Fly Ash ◽  
Prestressed Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Lightweight Aggregate Concrete ◽  
Clear Correlation ◽  
Aggregate Concrete ◽  
Normal Weight Concrete ◽  
Creep Coefficient ◽  
Shrinkage And Creep

The paper presents the experimental results of shrinkage, creep, and prestress loss in concrete with lightweight aggregate obtained by sintering of fly ash. Two concrete mixtures with different proportions of components were tested. Concrete with a density of 1810 and 1820 kg/m3, and a 28-day strength of 56.9 and 58.4 MPa was obtained. Shrinkage and creep were tested on 150 × 250 × 1000 mm3 beams. Creep was tested under prestressing load for 539 days and concrete shrinkage for 900 days. The measurement results were compared with the calculations carried out according to the Eurocode 2 as well as with the results of other research. A very low creep coefficient and lower shrinkage in relation to the calculation results and the results of other research were found. It was also revealed that there is a clear correlation between shrinkage and creep, and the amount of water in the concrete. The value of the creep coefficient during the load holding period was 0.610 and 0.537, which is 56.0 and 49.3% of the value determined from the standard. The prestressing losses in the analyzed period amounted to an average of 13.0%. Based on the obtained test results, it was found that the tested lightweight aggregate concrete is well suited for prestressed concrete structures. Shrinkage was not greater than that calculated for normal weight concrete of a similar strength class, which will not result in increased loss of prestress. Low creep guarantees low deflection increments over time.

Risk of Thermal Cracking from Use of Lightweight Aggregate in Mass Concrete

2017 ◽  
Vol 2629 (1) ◽  
pp. 42-50 ◽  
Author(s):  
Aravind Tankasala ◽  
Anton K. Schindler ◽  
Kyle A. Riding
Keyword(s):  
Cross Sections ◽  
Lightweight Concrete ◽  
Coefficient Of Thermal Expansion ◽  
Concrete Structures ◽  
Lightweight Aggregate ◽  
Thermal Cracking ◽  
Normal Weight ◽  
Mass Concrete ◽  
Normal Weight Concrete ◽  
Cracking Risk

This paper describes the results of a numerical investigation of incorporating lightweight aggregate (LWA) in mass concrete structures. Numerical simulation was performed with ConcreteWorks software on three rectangular piers for normal weight concrete, internally cured concrete, sand–lightweight concrete, and all–lightweight concrete. Results show that temperature differences greater than 35°F may not necessarily introduce thermal cracking in mass concrete made with LWA. Maximum core temperatures and temperature differences increased with decreasing concrete density; however, the cracking risk of the mass concrete elements decreased as a greater quantity of LWA was used, regardless of element size. This trend occurred because other properties, such as coefficient of thermal expansion, creep, modulus of elasticity, tensile strength, and geometrical conditions, influenced the risk of thermal cracking. Additionally, the identification of the cross-section locations involved in measuring the critical temperature difference in a mass concrete structure are presented. The results of this work can be helpful in identifying critical stress locations in cross sections and assessing the cracking risk for mass concrete structures. A temperature and stress analysis is recommended before mass concrete construction involving LWA is begun.

scholarly journals Structural Safety Evaluation of Precast, Prestressed Concrete Deck Slabs Cast Using 120-MPa High-Performance Concrete with a Reinforced Joint

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3040 ◽  
Author(s):  
Jae-Hyun Bae ◽  
Hoon-Hee Hwang ◽  
Sung-Yong Park
Keyword(s):  
Reinforced Concrete ◽  
Prestressed Concrete ◽  
High Performance ◽  
Bridge Deck ◽  
Concrete Structures ◽  
Fatigue Performance ◽  
Structural Performance ◽  
Strength Concrete ◽  
Deck Slabs ◽  
Deck Slab

Prestressed concrete structures are used in various fields as they can reduce the cross-sectional area of members compared with reinforced concrete structures. In addition, the use of high-performance and strength concrete can help reduce weight and achieve excellent durability. Recently, structures have increasingly been constructed using high-performance and strength concrete, and therefore, structural verification is required. Thus, this study experimentally evaluated the structural performance of a long-span bridge deck slab joint, regarded as the weak point of structures. The specimens were designed with a 4 m span for application to cable-stayed bridges. To ensure the required load resistance and serviceability, the specimens comprised of 120 MPa high-performance fiber-reinforced concrete and were prestressed. The deck slabs satisfied all static and fatigue performance as well as serviceability requirements, although they were thinner than typical concrete bridge deck slabs. The study also verified whether the deck slabs were suitable to help implement precast segmental construction methods. Finally, the results confirmed that the structural performance of the developed prestressed concrete (PSC) deck slab was sufficient for the intended bridge application as it achieved a sufficiently large safety factor in the static and fatigue performance tests, relative to the design requirement.

Flexural design of precast, prestressed ultra-high-performance concrete members

PCI Journal ◽  
2020 ◽  
Vol 65 (6) ◽  
pp. 35-61
Author(s):  
Chungwook Sim ◽  
Maher Tadros ◽  
David Gee ◽  
Micheal Asaad
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Limit State ◽  
Design Guidelines ◽  
Design Tool ◽  
Supplementary Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Concrete Members ◽  
Cylinder Strength

Ultra-high-performance concrete (UHPC) is a special concrete mixture with outstanding mechanical and durability characteristics. It is a mixture of portland cement, supplementary cementitious materials, sand, and high-strength, high-aspect-ratio microfibers. In this paper, the authors propose flexural design guidelines for precast, prestressed concrete members made with concrete mixtures developed by precasters to meet minimum specific characteristics qualifying it to be called PCI-UHPC. Minimum specified cylinder strength is 10 ksi (69 MPa) at prestress release and 18 ksi (124 MPa) at the time the member is placed in service, typically 28 days. Minimum flexural cracking and tensile strengths of 1.5 and 2 ksi (10 and 14 MPa), respectively, according to ASTM C1609 testing specifications are required. In addition, strain-hardening and ductility requirements are specified. Tensile properties are shown to be more important for structural optimization than cylinder strength. Both building and bridge products are considered because the paper is focused on capacity rather than demand. Both service limit state and strength limit state are covered. When the contribution of fibers to capacity should be included and when they may be ignored is shown. It is further shown that the traditional equivalent rectangular stress block in compression can still be used to produce satisfactory results in prestressed concrete members. A spreadsheet workbook is offered online as a design tool. It is valid for multilayers of concrete of different strengths, rows of reinforcing bars of different grades, and prestressing strands. It produces moment-curvature diagrams and flexural capacity at ultimate strain. A fully worked-out example of a 250 ft (76.2 m) span decked I-beam of optimized shape is given.

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