A Review of Strand Development Length for Pretensioned Concrete Members

Buckner, C. Dale

doi:10.15554/pcij.03011995.84.105

Cited by 57 publications

(27 citation statements)

References 12 publications

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“…Recently, some novel and interesting approaches have also been adopted to study the transfer length, for example, designated concrete element [60,61], genetic programming [62] and neural network [63,64]. Additional literature reviews can be found in other studies [65][66][67].…”

Section: Composite Beam Theorymentioning

confidence: 99%

Composite beam theory for pretensioned concrete structures with solutions to transfer length and immediate prestress losses

Bai

Davidson

2016

Engineering Structures

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Section: Composite Beam Theorymentioning

confidence: 99%

Composite beam theory for pretensioned concrete structures with solutions to transfer length and immediate prestress losses

Bai

Davidson

2016

Engineering Structures

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“…where kb is a dimensionless factor that reflects the actual value of average flexural bond stress that can be devel oped in particular cases, and Uaye rep resents a basic average value of bond stress of 0.25 ksi (1.72 MPa). Recom mended values of kb are as follows: k,, 8, for piles embedded in a foot ing or a pier cap kb = 4, for slabs and slender mem bers (i.e., the current AASHTO provi sion applies) kb = 2, if the ratio of Ld/h, calculated using kb =4, is equal to or less than 3 Buckner 3 proposed the following development length equation for pre tensioned strands:…”

Section: Modifications To Aashto Provisionsmentioning

confidence: 99%

A Critical Evaluation of the AASHTO Provisions for Strand Development Length of Prestressed Concrete Members

Shahawy¹

2001

pcij

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This paper presents a critical evaluation of recent proposals for calculating the development length of prestressing strands. The results of an extensive testing program on a variety of prestressed concrete members are discussed. An evaluation of the results indicates that there is a direct interaction between shear and bond at the ends of prestressed concrete members. The effect of this interaction on the development length is important yet ignored in all existing proposals. This paper examines the relevance of recently proposed modifications of methods for calculating transfer and development lengths presented in the AASHTO Specifications. It presents proposed modifications based on a number of investigations conducted by the author over the past ten years. The present study offers a new rational approach for estimating the development length and compares it against other proposals. Based on the results, it is recommended that the current AASHTO equation [Eq.(2)] be used to estimate the development length of strands for prestressed concrete members with a depth of 24 in. (610 mm) or less. For deeper members, the simplified equation presented in this paper offers the best correlation with test results.

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“…The ACI transfer length equation was derived from and based on an average transfer bond stress of 2.76 MPa (Tabatabai and Dickson 1993). In addition, several authors (Zia and Mostafa 1977;Shahawy et al 1992;Mitchell et al 1993;Deatherage et al 1994;Buckner 1995;Tadros and Baishya 1996;Mahmoud et al 1999) consider that using term f si (the initial effective stress in a prestressing strand just after the prestress transfer, accounting for losses only by the elastic shortening of concrete) in Eq. (1) is more rational for design purposes than f se by considering that transfer length is established at the release of prestress and that it does not significantly change over time.…”

Section: Introductionmentioning

confidence: 99%

“…(1) is more rational for design purposes than f se by considering that transfer length is established at the release of prestress and that it does not significantly change over time. However, U t = 2.76 MPa is retained in (Shahawy et al 1992;Deatherage et al 1994;Buckner 1995;Tadros and Baishya 1996), resulting in longer transfer lengths when f si is used. …”

Section: Introductionmentioning

confidence: 99%

Time-dependent evolution of strand transfer length in pretensioned prestressed concrete members

Martí‐Vargas

Ros

2012

Mech Time-Depend Mater

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For design purposes, it is generally considered that prestressing strand transfer length does not change with time. However, some experimental studies on the effect of time on transfer lengths show contradictory results. In this paper, an experimental research to study transfer length changes over time is presented. A test procedure based on the ECADA testing technique to measure prestressing strand force variation over time in pretensioned prestressed concrete specimens has been set up. With this test method, an experimental program that varies concrete strength, specimen cross-section, age of release, prestress transfer method, and embedment length has been carried out. Both the initial and long-term transfer lengths of 13-mm prestressing steel strands have been measured. The test results show that transfer length variation exists for some prestressing load conditions, resulting in increased transfer length over time. The applied test method based on prestressing strand force measurements has shown more reliable results than procedures based on measuring free end slips and longitudinal strains of concrete. An additional factor for transfer length models is proposed in order to include the time-dependent evolution of strand transfer length in pretensioned prestressed concrete members.

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A Review of Strand Development Length for Pretensioned Concrete Members

Cited by 57 publications

References 12 publications

Composite beam theory for pretensioned concrete structures with solutions to transfer length and immediate prestress losses

Composite beam theory for pretensioned concrete structures with solutions to transfer length and immediate prestress losses

A Critical Evaluation of the AASHTO Provisions for Strand Development Length of Prestressed Concrete Members

Time-dependent evolution of strand transfer length in pretensioned prestressed concrete members

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