Effect of SCC Mix Proportioning on Transfer and Development Length of Prestressing Strands

2008 ◽  
Author(s):  
Mahmoodul Haq ◽  
Rigoberto Burgueño
Keyword(s):  
Development Length ◽  
Mix Proportioning ◽  
Prestressing Strands

Effect of Strand Indentation Types on the Development Length and Flexural Capacity of Concrete Railroad Ties Made With Different Prestressing Strands

2019 ◽  
Author(s):  
Amir Farid Momeni ◽  
Robert J. Peterman ◽  
B. Terry Beck ◽  
Chih-Hang John Wu
Keyword(s):  
The Other ◽  
Development Length ◽  
Concrete Compressive Strength ◽  
Concentrated Load ◽  
Bonding Performance ◽  
Pretensioned Concrete ◽  
Load Tests ◽  
Prestressing Strands ◽  
Wire Strand ◽  
Prestressing Strand

Pretensioned concrete prisms made with five different prestressing strand types (four 7-wire strands and one 3-wire strand) were load tested to failure to understand the effect of strand indentation types on the development length and bonding performance of these different reinforcements. The prestressing strands were denoted SA, SB, SD, SE and SF. SA was a smooth strand while the other four were indented strands. All strands utilized in manufacturing ofprisms had diameter of 3/8″ (9.52 mm). Among all types of strands, SF was the only 3-wire strand and the remaining strands were all 7-wire strands. For all types of strands, four straight strands were embedded into each concrete prism, which had a 5.5″ (139.7 mm) × 5.5″ (139.7 mm) square cross section. The strands were tensioned to 75 percent of ultimate tensile strength of strands and gradually de-tensioned when the concrete compressive strength reached 4500 psi (31.03 Mpa). A consistent concrete mixture with type III cement, water-cement ratio of 0.32 and a 6-in. slump was used for all prisms. Prisms were load tested in 3-point-bending at different embedment lengths to obtain estimations of the development length of each type of strand. Two out of three identical 69-in.-long (175.26 cm) prisms were load tested at one end and one was tested at both ends for each reinforcement type evaluated. First prisms were tested at 28-in. (71.12 cm) from the end, while second prisms were tested at 20-in. (33.02 cm) from the end. Third prisms were loaded at 16.5-in. (41.9 cm) from one end and 13-in. (33.02 cm) from the other end. Thus, a total of 20 load tests (5 strand types × 4 tests each) were conducted in this study. During each test, a concentrated load with the rate of 900 lb/min (4003 N/min) was applied at mid-span until failure occurred. Values of load, mid-span deflection, and strand endslip were continuously monitored and recorded during each test. Plots of load-vs-deflection were then compared for prisms with each strand type and span, and the maximum sustained moment was also calculated for each test. The load tests revealed that there is a large difference in the development length of the strands based on their indentation type.

Development length of prestressing strands cast in lightweight self-consolidating concrete

2021 ◽  
Vol 226 ◽  
pp. 111393
Author(s):  
Royce W. Floyd ◽  
Jared Bymaster ◽  
Canh N. Dang ◽  
W. Micah Hale
Keyword(s):  
Development Length ◽  
Self Consolidating Concrete ◽  
Prestressing Strands

Effect of Pile Embedment on the Development Length of Prestressing Strands

PCI Journal ◽  
1992 ◽  
Vol 37 (6) ◽  
pp. 44-59 ◽  
Author(s):  
Mohsen A. Shahawy ◽  
Moussa Issa
Keyword(s):  
Development Length ◽  
Prestressing Strands

Development Length of Prestressing Strands

PCI Journal ◽  
1977 ◽  
Vol 22 (5) ◽  
pp. 54-65 ◽  
Author(s):  
Talat Mostafa ◽  
Paul Zia
Keyword(s):  
Development Length ◽  
Prestressing Strands

Theoretical study of the prestressing strand's stress by computer modeling methods

2020 ◽  
Vol 76 (11) ◽  
pp. 1139-1148
Author(s):  
A. G. Korchunov ◽  
E. M. Medvedeva ◽  
E. M. Golubchik
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Steel Microstructure ◽  
Compressive Stresses ◽  
Wide Range ◽  
Prestressing Strands ◽  
Increasing Temperature ◽  
Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

Sign in / Sign up

Export Citation Format

Share Document