scholarly journals Bond Modelling for the Assessment of Transmission Length in Prestressed-Concrete Members

CivilEng ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 75-92 ◽  
Author(s):  
Nicola Fabris ◽  
Flora Faleschini ◽  
Carlo Pellegrino
Keyword(s):  
Prestressed Concrete ◽  
Local Behaviour ◽  
Material Models ◽  
Experimental Database ◽  
Concrete Members ◽  
Adequate Knowledge ◽  
Prestressing Force ◽  
Transmission Length ◽  
Data Points ◽  
Concrete Interface

Transmission of the prestressing force to concrete by prestressing tendons is a topic of discussion within the fib Task Group 2.5: Bond and Material Models. Particularly, the extensive use of pretensioned prestressed-concrete (PC) requires adequate knowledge of bond development at the steel–concrete interface after prestress release. The transmission length, representing the distance from the free-end of the beam necessary to transmit the fully effective prestressing-force to the surrounding concrete, is a design parameter of paramount importance for PC members detailing. This contribution presents the analytical modelling of the transmission length based on the thick-walled cylinders (TWC) theory, considering anisotropic behaviour of the concrete. To derive the optimal friction coefficient between steel and concrete, the theoretical model has been calibrated according to an experimental database of transmission lengths collected from the literature, encompassing 130 data points from 7 different campaigns. Additionally, local behaviour has been analysed by assessing radial cracking and bond stress development along the transmission length.

Study of Accelerated Production of Prestressed Concrete Sleepers Using Strut-and-Tie Model

2014 ◽  
Vol 1054 ◽  
pp. 122-127
Author(s):  
Patarapol Tantipidok ◽  
Dinara McLaughin ◽  
Petr Štemberk
Keyword(s):  
Prestressed Concrete ◽  
Large Scale ◽  
Design Method ◽  
Substantial Reduction ◽  
Model Code ◽  
Strut And Tie ◽  
Prestressing Force ◽  
Model Code 2010 ◽  
Transmission Length ◽  
Strut And Tie Model

When designing the technological process for producing prestressed concrete sleepers on a large scale, it is especially important to achieve substantial reduction of production time due to the economic aspect. In this study, an estimation of the earliest possible time to release prestressing force from the wire with respect to bond development is presented, thus, allowing earlier removal and reuse of a prestressed concrete sleeper formwork. Time-dependent development of concrete compressive and tensile strength is defined according to fib Model Code 2010. A Strut-and-Tie Model has been adapted as a design method for establishing the transmission length required for anchoring prestressed wires in a prestressed concrete sleeper in accordance with the bond stress. Additional calculations have established that the method is consistent with the Eurocode approach.

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.

scholarly journals Smart Sensing of PSC Girders Using a PC Strand with a Built-in Optical Fiber Sensor

2021 ◽  
Vol 11 (1) ◽  
pp. 359
Author(s):  
Sung Tae Kim ◽  
Hyejin Yoon ◽  
Young-Hwan Park ◽  
Seung-Seop Jin ◽  
Soobong Shin ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Prestressed Concrete ◽  
Steel Wire ◽  
Optical Fiber Sensor ◽  
Fiber Reinforced Polymer ◽  
Bridge Structure ◽  
Fbg Sensor ◽  
Prestressing Force ◽  
Reinforced Polymer ◽  
Loading Tests

This paper presents a multi-functional strand capable of introducing prestressing force in prestressed concrete (PSC) girders and sensing their static and dynamic behavior as well. This innovative strand is developed by replacing the core steel wire of the strand used in PSC structures with a carbon fiber-reinforced polymer (CFRP) wire with a built-in optical Fiber Bragg Grating (FBG) sensor. A full-scale girder specimen was fabricated by applying this multi-function strand to check the possibility of tracking the change of prestressing force at each construction stage. Moreover, dynamic data could be secured during dynamic loading tests without installing accelerometers and made it possible to obtain the natural frequencies of the structure. The results verified the capability to effectively manage the prestressing force in the PSC bridge structure by applying the PC strand with a built-in optical sensor known for its outstanding practicability and durability.

Evaluation of the expansion attained to date by concrete affected by alkali–silica reaction. Part III: Application to existing structures

2005 ◽  
Vol 32 (3) ◽  
pp. 463-479 ◽  
Author(s):  
Marc-André Bérubé ◽  
Nizar Smaoui ◽  
Benoit Fournier ◽  
Benoit Bissonnette ◽  
Benoit Durand
Keyword(s):  
Prestressed Concrete ◽  
Alkali Silica Reaction ◽  
Existing Structures ◽  
Concrete Members ◽  
Crack Widths ◽  
Concrete Petrography ◽  
Made In

The expansion attained by a concrete affected by alkali-silica reaction (ASR) is an important parameter in the evaluation of the corresponding structure. In part I, relationships were established in the laboratory between the ASR expansion and the stiffness damage test (SDT), the damage rating index (DRI), and the cumulated width of cracks observed at the surface of concrete specimens made with various types of reactive aggregates. In part II, these relationships were verified in the case of specimens made in laboratory but exposed outdoors. In part III, the aforementioned methods were applied to three ASR-affected structures. The measurement of crack widths at the surface of the affected members allowed a rather good estimation of the concrete expansion, provided the measurements were taken on the most severely exposed sections of these members. The DRI did not allow differentiating the most visually and mechanically affected concretes from the least affected concretes. The SDT proved to be the most interesting method to date for evaluating the expansion of ASR-affected concrete; however, it seemed to underestimate the expansion of the prestressed concrete members investigated.Key words: aggregates, alkali–silica reaction, concrete, petrography, expansion, stiffness, cracking.

Thin-Walled Prestressed Concrete Members under Combined Loading

1996 ◽  
Vol 122 (3) ◽  
pp. 291-297 ◽  
Author(s):  
B. M. Luccioni ◽  
J. C. Reimundín ◽  
R. Danesi
Keyword(s):  
Prestressed Concrete ◽  
Combined Loading ◽  
Concrete Members ◽  
Thin Walled
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