scholarly journals Service load analysis of unbonded partially prestressed concrete members

2005 ◽  
Vol 57 (4) ◽  
pp. 199-209 ◽  
Author(s):  
F. T. K. Au ◽  
J. S. Du ◽  
Y. K. Cheung
Keyword(s):  
Prestressed Concrete ◽  
Concrete Members ◽  
Service Load ◽  
Load Analysis

scholarly journals Studi Mengenai Analisis Penampang Balok Prategang Parsial pada Beban Kerja. (Hal. 83-95)

2019 ◽  
Vol 5 (2) ◽  
pp. 83
Author(s):  
Dally Margan ◽  
Priyanto Saelan
Keyword(s):  
Prestressed Concrete ◽  
Failure Load ◽  
Analysis Method ◽  
Study Results ◽  
Service Load ◽  
Building Safety ◽  
Load Analysis ◽  
Beam Section ◽  
Prestressed Beam

ABSTRAKPenampang balok prategang parsial dapat dirancang dengan dua metode analisis yaitu metode analisis terhadap beban runtuh dan metode analisis terhadap beban kerja. Perancangan penampang balok prategang parsial pada umumnya dilakukan dengan menggunakan metode analisis terhadap beban runtuh yang telah ditetapkan dalam SNI 03-2847-2002, namun perancangan menggunakan pendekatan beban kerja tidak dicantumkan. Oleh karena itu dilakukan studi analisis untuk mengetahui sejauh mana metode analisis terhadap beban kerja dapat diaplikasikan dalam perancangan penampang balok prategang parsial. Studi kasus ini dilakukan dengan persentase 60, 70, 80, dan 90. Dari hasil studi kasus didapatkan bahwa dengan menggunakan metode analisis terhadap beban kerja dapat dilakukan namun dengan batasan persentase prategang yang beragam yaitu 90, 95, dan 99. Metode analisis terhadap beban kerja dapat dilakukan pada kasus-kasus tertentu dan menggunakan beton dan tendon dengan mutu tinggi untuk faktor keamanan bangunan.Kata kunci: beton prategang parsial, pendekatan beban kerja, persentase prategang, lebar retak ABSTRACTPartial prestressed beam section can be designed with two analysis methods are failure load analysis method and service load analysis method. The design of the partial prestressed beam section generally is using the failure load analysis method which has been specified in SNI 03-2847-2002, but the design with the analytical method of service load is not included. Therefore an analytical study was conducted to determine the extent to which the service load analysis method can be applied for the design of a partial prestressed beam section. This case study was carried out at 60, 70, 80, and 90 prestressed percentages. From the case study results it was found that using the analysis method of service load can be done but with variations of a limited percentage are 90, 95, and 99. The method of analysis of workload can be done in certain cases and using high-quality concrete and tendons for building safety factor.Keywords: partial prestressed concrete, service load analysis method, prestressed percentage, crack width

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.

Evaluation of the expansion attained to date by concrete affected by alkali–silica reaction. Part III: Application to existing structures

2005 ◽  
Vol 32 (3) ◽  
pp. 463-479 ◽  
Author(s):  
Marc-André Bérubé ◽  
Nizar Smaoui ◽  
Benoit Fournier ◽  
Benoit Bissonnette ◽  
Benoit Durand
Keyword(s):  
Prestressed Concrete ◽  
Alkali Silica Reaction ◽  
Existing Structures ◽  
Concrete Members ◽  
Crack Widths ◽  
Concrete Petrography ◽  
Made In

The expansion attained by a concrete affected by alkali-silica reaction (ASR) is an important parameter in the evaluation of the corresponding structure. In part I, relationships were established in the laboratory between the ASR expansion and the stiffness damage test (SDT), the damage rating index (DRI), and the cumulated width of cracks observed at the surface of concrete specimens made with various types of reactive aggregates. In part II, these relationships were verified in the case of specimens made in laboratory but exposed outdoors. In part III, the aforementioned methods were applied to three ASR-affected structures. The measurement of crack widths at the surface of the affected members allowed a rather good estimation of the concrete expansion, provided the measurements were taken on the most severely exposed sections of these members. The DRI did not allow differentiating the most visually and mechanically affected concretes from the least affected concretes. The SDT proved to be the most interesting method to date for evaluating the expansion of ASR-affected concrete; however, it seemed to underestimate the expansion of the prestressed concrete members investigated.Key words: aggregates, alkali–silica reaction, concrete, petrography, expansion, stiffness, cracking.

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