Effect of Concrete Release Strength on the Development Length and Flexural Capacity of Members Made With Different Prestressing Wires Commonly Used in Pretensioned Concrete Railroad Ties

2015 ◽  
Author(s):  
Amir Farid Momeni ◽  
Robert J. Peterman ◽  
B. Terry Beck ◽  
Chih-Hang John Wu ◽  
Naga Narendra B. Bodapati
Keyword(s):  
Compressive Strength ◽  
Prestressed Concrete ◽  
Loading Rate ◽  
Test Results ◽  
Development Length ◽  
Concrete Compressive Strength ◽  
Flexural Capacity ◽  
Pretensioned Concrete ◽  
Embedment Length ◽  
Bond Characteristics

A study was conducted to determine the effect of concrete release strength on the development length and flexural capacity of members utilizing five different 5.32-mm-diameter prestressing wires that are commonly used in the manufacture of prestressed concrete railroad ties worldwide. These included two chevron-indented wires with different indent depths, one spiral-indented wire, one dot-indented wire, and one smooth wire (with no surface indentation). A consistent concrete mixture was used for the manufacture of all test specimens, and the different release strengths were obtained by allowing the specimens to cure for different amounts of time prior to de-tensioning. Each prismatic specimen (prism) had a 3.5″ (88.9 mm) × 3.5″ (88.9 mm) square cross section with four wires arranged symmetrically. The prisms were identical except for the wire type and the compressive strength at the time of de-tensioning. All four wires were each initially tensioned to 7000 pounds (31.14 KN) and then de-tensioned gradually when the concrete compressive strength reached 3500 (24.13 MPa), 4500 (31.03 MPa) and 6000 (41.37 MPa) psi. Precise de-tensioning strengths were ensured by testing 4-in.-diameter (101.6 mm) × 8-in.-long (203.2 mm) compression strength cylinders that were temperature match-cured. The prisms were loaded in 3-point-bending to determine the ultimate bond characteristics of each reinforcement type for the different concrete release strengths. A loading rate of 300 lb/min (1334 N/min) was applied at mid-span and the maximum sustained moment was calculated for each test. Two 69-in.-long (175.26 cm) prisms, each having different concrete release strength, were tested with each of the 5 wire types. These prisms were tested at both ends, with a different embedment length assessed at each end. Thus, for each wire type and concrete release strength evaluated, a total of 4 tests were conducted for a total of 60 tests (5 wire types × 3 release strengths × 4 tested embedment lengths). Test results indicate that the concrete compressive strength at de-tensioning can have a direct impact on the ultimate flexural capacity of the members, and this has significant design implications for pretensioned concrete railroad ties. Results are discussed and recommendations made.

Effect of Concrete Release Strength on the Development Length and Flexural Capacity of Members Made With Different Prestressing Strands

2016 ◽  
Author(s):  
Amir Farid Momeni ◽  
Robert J. Peterman ◽  
B. Terry Beck ◽  
Chih-Hang John Wu ◽  
Naga Narendra B. Bodapati
Keyword(s):  
Compressive Strength ◽  
Cross Section ◽  
Loading Rate ◽  
Test Results ◽  
Development Length ◽  
Concrete Compressive Strength ◽  
Flexural Capacity ◽  
Pretensioned Concrete ◽  
Load Tests ◽  
Bond Characteristics

Load tests were conducted on pretensioned members made with five different strands (three 7-wire strands and two 3-wire strands) to determine the effect of concrete release strength on the development length and flexural capacity of members. Strands named generically SA, SC, SD, SE and SF and they were all indented except SA (no surface indentation). All strands had diameter of 3/8″ (9.52 mm) except SC which had diameter of 5/16″ (7.94 mm). Among all types of strands used in manufacturing of test prisms, SC and SF were 3-wire strands, while SA, SD and SE were 7-wire strands. A consistent concrete mixture was used for the manufacture of all test specimens, and the different release strengths were obtained by allowing the specimens to cure for different amounts of time prior to de-tensioning. For SA, SD, SE and SF strands, each prismatic specimen (prism) had a 5.5″ (139.7 mm) × 5.5″ (139.7 mm) square cross section with four strands arranged symmetrically. However, prisms made with SC strand had 4.5″ (114.3 mm) × 4.5″ (114.3 mm) square cross section with four strands arranged symmetrically. The prisms were identical except for the strand type and the compressive strength at the time of de-tensioning. All four strands were pulled and de-tensioned gradually when the concrete compressive strength reached 3500 (24.13 MPa), 4500 (31.03 MPa) and 6000 (41.37 MPa) psi. Precise de-tensioning strengths were ensured by testing 4-in.-diameter (101.6 mm) × 8-in.-long (203.2 mm) compression strength cylinders that were temperature match-cured. The prisms were loaded in 3-point-bending to determine the ultimate bond characteristics of each reinforcement type for the different concrete release strengths. A loading rate of 900 lb/min (4003 N/min) for 5.5″ (139.7 mm) × 5.5″ (139.7 mm) prisms was applied at mid-span and the maximum sustained moment was calculated for each. Same procedure with loading rate of 500 lb/min (2224 N/min) was applied to 4.5″ (114.3 mm) × 4.5″ (114.3 mm) prisms. Three 69-in.-long (175.26 cm) prisms, each having different concrete release strength, were tested with each of the 5 strand types. Two out of three testing prisms were tested at only one end and one was tested at its both ends. Thus, for each strand type and concrete release strength evaluated, a total of 4 tests were conducted for a total of 60 tests (5 strand types × 3 release strengths × 4 tested embedment lengths). Test results indicate that the concrete compressive strength at de-tensioning can have a direct impact on the ultimate flexural capacity of the members, and this has significant design implications for pretensioned concrete railroad ties. Results are discussed and recommendations made.

Variasi Penambahan Sika Cim Dan Fiber Kawat Pada Beton Mutu Fc’ 30 Mpa

2018 ◽  
Vol 9 (2) ◽  
pp. 67-73
Author(s):  
M Zainul Arifin
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Curing Temperature ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Normal Concrete ◽  
Astm Method ◽  
Additive Type ◽  
Composition Variation ◽  
Compressive Strength Of Concrete

This research was conducted to determine the value of the highest compressive strength from the ratio of normal concrete to normal concrete plus additive types of Sika Cim with a composition variation of 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1 , 50% and 1.75% of the weight of cement besides that in this study also aims to find the highest tensile strength from the ratio of normal concrete to normal concrete in the mixture of sika cim composition at the highest compressive strength above and after that added fiber wire with a size diameter of 1 mm in length 100 mm with a ratio of 1% of material weight. The concrete mix plan was calculated using the ASTM method, the matrial composition of the normal concrete mixture as follows, 314 kg / m3 cement, 789 kg / m3 sand, 1125 kg / m3 gravel and 189 liters / m3 of water at 10 cm slump, then normal concrete added variations of the composition of sika cim 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1.5%, 1.75% by weight of cement and fiber, the tests carried out were compressive strength of concrete and tensile strength of concrete, normal maintenance is soaked in fresh water for 28 days at 30oC. From the test results it was found that the normal concrete compressive strength at the age of 28 days was fc1 30 Mpa, the variation in the addition of the sika cim additive type mineral was achieved in composition 0.75% of the cement weight of fc1 40.2 Mpa 30C. Besides that the tensile strength test results were 28 days old with the addition of 1% fiber wire mineral to the weight of the material at a curing temperature of 30oC of 7.5%.

PENGKAJIAN KEKUATAN BETON STRUKTUR JEMBATAN PASCA KEBAKARAN

2013 ◽  
Vol 12 (3) ◽  
Author(s):  
Sudarmadi Sudarmadi
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Strength Assessment ◽  
Concrete Testing

In this paper a case study about concrete strength assessment of bridge structure experiencing fire is discussed. Assessment methods include activities of visual inspection, concrete testing by Hammer Test, Ultrasonic Pulse Velocity Test, and Core Test. Then, test results are compared with the requirement of RSNI T-12-2004. Test results show that surface concrete at the location of fire deteriorates so that its quality is decreased into the category of Very Poor with ultrasonic pulse velocity ranges between 1,14 – 1,74 km/s. From test results also it can be known that concrete compressive strength of inner part of bridge pier ranges about 267 – 274 kg/cm2 and concrete compressive strength of beam and plate experiencing fire directly is about 173 kg/cm2 and 159 kg/cm2. It can be concluded that surface concrete strength at the location of fire does not meet the requirement of RSNI T-12-2004. So, repair on surface concrete of pier, beam, and plate at the location of fire is required.

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 of Splice Connections for Precast Concrete Structures

2014 ◽  
Vol 980 ◽  
pp. 132-136 ◽  
Author(s):  
Ahmad Baharuddin Abd Rahman ◽  
Jen Hua Ling ◽  
Zuhairi Abd Hamid ◽  
Mohd Hanim Osman ◽  
Shahrin Mohammad ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Failure Modes ◽  
Ultimate Load ◽  
Precast Concrete ◽  
Tensile Load ◽  
Test Results ◽  
Steel Bars ◽  
Embedment Length ◽  
Bar Diameter

This paper presents the test results of proposed grouted sleeve connections under increasing tensile load. The objective of this research was to investigate splice connections that could provide tensile strength similar to the full tensile strength of the connected rebars. The parameters varied were splice types, splice length and rebar embedment length. The performance of the splice connection was evaluated based on the load-displacement, ultimate load, displacements and failure modes. The results show that the strength of splice connection depends on the bond strength between sleeve-to-grout and grout-to-rebar; the tensile strength of spliced steel bars and also the tensile strength of sleeve. It is observed that when the grout compressive strength is more than 60N/mm2and bar embedded length is at least 10 bar diameter, the splice connection in BS series is able to provide full tensile strength of the connected rebars.

Assessment of the Concrete Compressive Strength in Existing Structures Based on Core Test Results

2018 ◽  
Vol 272 ◽  
pp. 238-243 ◽  
Author(s):  
Viktar V. Tur ◽  
Stanislav S. Derechennik
Keyword(s):  
Monte Carlo Simulation ◽  
Quality Control ◽  
Compressive Strength ◽  
Structural Reliability ◽  
Reliability Estimation ◽  
Control Procedure ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Existing Structures

Evaluation of the concrete compressive strength in existing structures is an important problem, which is associated with structural reliability estimation as well as a quality control procedure. In accordance with a new concept of EN 13791, reported by T.A.Harrison, one of the main targets of the standard is to determine not a class, but in-situ characteristic concrete compressive strength. Hereby proposed criterion for the estimation of the in-situ characteristic concrete compressive strength is based on the non-parametric confidence interval for quantile. This criterion was verified by the both Monte Carlo simulation and test results under the real concrete structures.

Study on the Compressive Strength and Mixing of Ultra-High Performance Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 825-828
Author(s):  
Su Li Feng ◽  
Peng Zhao
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Strength Properties ◽  
Test Method ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Ultra High Performance Concrete ◽  
Mixture Ratio

The test in order to obtain liquidity, higher intensity ultra-high performance concrete(UHPC), in the course of preparation, high intensity quartz sand to replace the ordinary sand,reasonable mixture ratio control low water-cement ratio,the incorporation of part of the test piece ofsteel fibers, produced eight specimens . In the ordinary molding and the standard conservation 28d thecase, the ultra-high-performance concrete compressive strength of more than 170MPa.Thepreparation of the test method and test results will provide the basis for further study of the law of themechanical properties of ultra high strength properties of concrete.

scholarly journals A Study on Ductility of Prestressed Concrete Pier Based on Response Surface Methodology

2016 ◽  
Vol 6 (6) ◽  
pp. 1253-1257
Author(s):  
H. Wang ◽  
Y. Zhang ◽  
S. Qin
Keyword(s):  
Compressive Strength ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Prestressed Concrete ◽  
Reinforcement Ratio ◽  
Longitudinal Reinforcement ◽  
Shear Reinforcement ◽  
Concrete Compressive Strength ◽  
Curvature Ductility ◽  
The Relationship

The ductility of prestressed concrete pier is studied based on response surface methodology. Referring to the pervious prestressed concrete pier, based on Box-Behnken design, the ductility of 25 prestressed concrete piers is calculated by numerical method. The relationship between longitudinal reinforcement ratio, shear reinforcement ratio, prestressed tendon quantity, concrete compressive strength and ductility factor is gotten. The influence of the longitudinal reinforcement ratio, the shear reinforcement ratio, the prestressed tendon quantity and concrete compressive strength to curvature ductility is discussed. Then the ductility regression equation is deduced. The result showed that the influence of the prestressed tendon quantity to the ductility of prestressed concrete pier is significant. With the increasing of the prestressed tendon quantity, the curvature ductility curved reduces. With the increasing of shear reinforcement ratio and compressive strength of concrete, the curvature ductility increases linearly. And the influence of the longitudinal reinforcement ratio to ductility of the prestressed concrete pier is insignificant. 

Effective Strategies for Improving Camber Predictions in Precast, Prestressed Concrete Bridge Girders

2019 ◽  
Vol 2673 (3) ◽  
pp. 342-354
Author(s):  
David M. Mante ◽  
Robert W. Barnes ◽  
Levent Isbiliroglu ◽  
Andric Hofrichter ◽  
Anton K. Schindler
Keyword(s):  
Compressive Strength ◽  
Prestressed Concrete ◽  
Modulus Of Elasticity ◽  
Prediction Models ◽  
Bridge Girders ◽  
Concrete Compressive Strength ◽  
Time Step ◽  
Production Cycles ◽  
Precast Prestressed Concrete ◽  
Creep And Shrinkage

In order to limit construction conflicts in bridges with precast, prestressed concrete girders, it is essential that designers are able to predict midspan girder camber with sufficient accuracy at key stages. This paper describes a study of the effectiveness of various strategies for improving camber predictions when compared with field-measured values from actual bridge girders produced in the southeastern United States. The study also incorporated concrete materials data from nearly 2000 girder production cycles among four regional producers, in addition to a laboratory study of mechanical and time-dependent properties of representative concrete mixtures. A standard incremental time-step analysis software was developed and utilized for the parametric study included in this work. For the girder production cycles monitored in this study, the use of regionally calibrated prediction models for material properties (concrete compressive strength, modulus of elasticity, creep, and shrinkage) resulted in the elimination of approximately 80% of the prediction error associated with current camber prediction practices within the region. As compared with a mean overprediction error of 68% for current design practice, implementation of calibrated prediction models reduced the mean overprediction to approximately 10%. The most effective prediction improvement techniques were determined to be reliance on expected rather than specified concrete compressive strength, the use of an appropriate aggregate correction factor for modulus of elasticity computations, and the use of an incremental time-step analysis method incorporating AASHTO Load and Resistance Factor Design (LRFD) or International Federation for Structural Concrete ( fib) Model Code 2010 creep and shrinkage prediction equations.

Proposition of a New Conformity Criterion for the Assessment of the Concrete Compressive Strength

2017 ◽  
Vol 259 ◽  
pp. 106-110
Author(s):  
Elżbieta Szczygielska ◽  
Viktar V. Tur
Keyword(s):  
Monte Carlo Simulation ◽  
Compressive Strength ◽  
Monte Carlo ◽  
Standard Deviation ◽  
Probability Density Function ◽  
Concrete Strength ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Strength Assessment ◽  
Probability Density Function Pdf

A new conformity criterion for concrete strength assessment that could be used at the initial production stage, is proposed. As an innovative conformity criterion was evaluated based on Order Statistics Theory, it is independent from the type probability density function (PDF) in population, estimation of the standard deviation, shape of the specimen and the level of autocorrelation of the test results. Proposed criterion was evaluated and positively verified both AOQL-concept using Monte Carlo simulation and the test results obtained under real production.

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