scholarly journals STRUCTURAL TEST OF PRECAST PRESTRESSED CONCRETE BEAMS USING LARGE DIAMETER PRESTRESSING STRANDS WITH PRETENSIONING SYSTEM

2012 ◽  
Vol 77 (672) ◽  
pp. 265-272 ◽  
Author(s):  
Shin-ichi TAKEZAKI ◽  
Takeyoshi KORENAGA ◽  
Hiroshi NOGUCHI
2020 ◽  
Vol 6 (1) ◽  
pp. 130-141
Author(s):  
Amin K Akhnoukh

The objective of this research is to investigate the advantage of using large-diameter 0.7-inch (18 mm) strands in pretention applications. Large-diameter strands are advantageous in bridge construction due to the increased girders capacity required to sustain exponential increase in vehicle numbers, sizes, and weights. In this research, flexure capacity of girders fabricated using 0.7-inch (18 mm) diameter strands will be calculated and compared to bridge capacities constructed using smaller strands. Finally, two similar bridge sections will be designed using 0.6-inch (15 mm) and 0.7-inch (18 mm) diameter strands to quantify the structural advantages of increased strand diameter. The research findings showed that a smaller number of girders is required for bridge construction when larger strands are used. Four girders are required to design the bridge panel using high performance concrete and large diameter strands, as compared to 6 girders required when regular concrete mix designs and normal size strands are used. The advantages of large strands and high-performance concrete mixes include expedited construction, reduced project dead loads, and reduced demand for labor and equipment. Thus, large strands can partially contribute to the improvement of bridge conditions, minimize construction cost, and increase construction site safety.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jakub Kraľovanec ◽  
Martin Moravčík ◽  
Jozef Jošt

Abstract Knowledge of prestressing force’s value is in the case of prestressed concrete structure the most important basis for defining load-carrying capacity and remaining service life. Numbers of prestressed concrete structures are about to reach their limit of service life and they are exhibiting signs of deterioration due to the conceptional errors, inadequate maintenance and environmental distress. All of these factors negatively influence the actual state of prestressing. Thus, it is essential to determine the value of prestressing force considering the degradation of materials, such as corrosion of prestressing strands or wires. While assessing structure in service, it is difficult to apply magnetoelastic sensors or use other direct methods for determining the state of prestressing. Hence, the indirect methods enable to analytically calculate the prestressing force based on the results of measurement, e.g. strain, stress, deflection, or width of the crack. The present paper focuses on numerical analysis of prestressing in a twosome of precast prestressed concrete beams. For the numerical analysis, two indirect methods are applied, specifically Saw-cut method and Crack initiation method. Finally, the results are discussed and recommendations for the experimental campaign are summarized.


2020 ◽  
Author(s):  
Farshad Haddadi

The Florida International University's 2020 Big Beam Team greatly appreciated the opportunity to participate in this competition. The presented report is a step by step design procedure for designing prestressed concrete beams which is expected to perform and fail in a predefined load. The chosen design was a I‐shaped member composed of four straight prestressing strands, and incorporating two compression longitudinal bars. The beam was designed supported span of 18 ft., center-to-center of bearing, and a total length of 19 ft. The loading consists of two point loads as live load and the beam self-weight as dead load. The beam is designed to remain uncracked under the unfactored live load of 20 kips (10 kips at each point) and have capacity of more than factored live load of 32 kips. The final capacity should be less than 40 kips. The team predicted the cracking load, failure load, and ultimate deflection of the beam using a moment‐curvature analysis.


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