scholarly journals STUDY ON THE ANCHORAGE ZONE PROBLEMS OF PRESTRESSED CONCRETE MEMBERS : Part 2 : Stress distribution in the anchorage zone subjectted to three dimensional by concentrated load

1974 ◽  
Vol 223 (0) ◽  
pp. 9-16,69
Author(s):  
SHIN OKAMOTO
Keyword(s):  
Stress Distribution ◽  
Prestressed Concrete ◽  
Three Dimensional ◽  
Concentrated Load ◽  
Concrete Members

Structural behavior of cable anchorage zones in prestressed concrete cable-stayed bridge

2002 ◽  
Vol 29 (1) ◽  
pp. 171-180 ◽  
Author(s):  
Byung-Wan Jo ◽  
Yunn-Ju Byun ◽  
Ghi-Ho Tae
Keyword(s):  
Stress Distribution ◽  
Prestressed Concrete ◽  
Three Dimensional ◽  
Stress Distributions ◽  
Anchor Plate ◽  
Element Analysis ◽  
Cable Stayed Bridge ◽  
Local Modeling ◽  
Actual Design ◽  
Tendon Force

Since the cable anchorage zone in a prestressed concrete cable-stayed bridge is subjected to a large amount of concentrated tendon force, it shows very complicated stress distributions which can cause serious local cracks. Accordingly, it is necessary to investigate the parameters affecting the stress distribution, such as the cable inclination, the position of the anchor plate, the modeling method, and three-dimensional effects. The tensile stress distribution in the anchorage zone is compared to the actual design condition by varing the stiffness of spring elements in the local modeling, and an appropriate position for the anchor plate is determined. The results provide elementary data for the stress state in the anchorage zones and encourage more efficient designs.Key words: finite element analysis, bursting stress, spalling stress, cable anchorage zone, cable-stayed bridge.

scholarly journals A comparative finite analysis of the mechanical behavior of ProTaper NEXT and WaveOne rotary files

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Nada Omar ◽  
Amira Galal Ismail ◽  
Manar Galal ◽  
Mohamed H. Zaazou ◽  
Mohamed Abdullah Mohamed
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Mechanical Behavior ◽  
Computer Aided Design ◽  
Software Package ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Concentrated Load

Abstract Finite element analysis was used to evaluate the stress distribution, estimate the residual stresses, bending, and amount of displacement of two nickel-titanium instruments manufactured by the same M-wire technology but with different cross-section. Materials and methods Two brands of Ni-Ti instruments ProTaper NEXT (Dentsply Maillefer), and WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) were scanned with stereomicroscope to produce a two-dimensional model for each file using computer-aided design programs (CAD) (SolidWorks software package), which then was converted into stereolithographic extension to be readable by programming software (MATLAB software) to produce three-dimensional models. The mathematical analysis of files was performed on SolidWorks software package. The mechanical behavior of the two files was analyzed numerically in a SolidWorks package to simulate and measure torsion, bending, and file displacement. Application of a shear moment (torsion) 2.5 N/mm moment of force was applied to the shaft in a clockwise direction, while the last 4 mm of the tip was rigidly constrained to evaluate the stress distribution on each file. As for Cantilever bending, a concentrated load of 1 N at the tip of the file with its shaft rigidly held in place was applied for the finite element models. The vertical displacement was measured and the von Mises stress distribution was evaluated. Results The WaveOne file showed higher torsional stresses accumulation than those accumulated in the ProTaper NEXT. While the ProTaper NEXT showed more bending and file displacement than those showed by WaveOne file. Conclusions The two files rotary models highlighted the different mechanical properties of the files although they share the same manufactured technology M-wire. The ProTaper NEXT showed less torsional stress accumulation and more bending properties.

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.

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