Losses in partially prestressed concrete

1988 ◽  
Vol 15 (5) ◽  
pp. 890-899
Author(s):  
B. DeV. Batchelor ◽  
Jayanth Srinivasan ◽  
Mark F. Green
Keyword(s):  
Key Words ◽  
Prestressed Concrete ◽  
Effective Modulus ◽  
Highway Bridge ◽  
Design Code ◽  
Bridge Design ◽  
Prestress Losses ◽  
Concrete Members ◽  
Modulus Method

The calculation of prestress losses by the age-adjusted effective modulus method is analyzed and compared with the Ontario highway bridge design code predictions for partially prestressed concrete. Specifically, the effect of nonprestressed reinforcement on prestress losses is studied. The age-adjusted effective modulus method for calculating prestress losses is outlined, and plots of prestress losses versus partial prestressing ratio are presented and analyzed. It is shown that prestress losses decrease with increasing amounts of nonprestressed reinforcement. Also, the Ontario highway bridge design code expressions, which are intended for use with fully prestressed sections, are not suitable for use in the design of partially prestressed concrete members. Key words: concrete (prestress), design, partial prestressing, prestress losses.

New Canadian Highway Bridge Design Code design provisions for fibre-reinforced structures

2007 ◽  
Vol 34 (3) ◽  
pp. 267-283 ◽  
Author(s):  
A A Mufti ◽  
B Bakht ◽  
N Banthia ◽  
B Benmokrane ◽  
G Desgagné ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Highway Bridge ◽  
Code Design ◽  
Design Code ◽  
Bridge Design ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Deck Slabs ◽  
Fibre Reinforced Polymer ◽  
Precast Construction

This paper presents a synthesis of the design provisions of the second edition of the Canadian Highway Bridge Design Code (CHBDC) for fibre-reinforced structures. New design provisions for applications not covered by the first edition of the CHBDC and the rationale for those that remain unchanged from the first edition are given. Among the new design provisions are those for glass-fibre-reinforced polymer as both primary reinforcement and tendons in concrete; and for the rehabilitation of concrete and timber structures with externally bonded fibre-reinforced-polymer (FRP) systems or near-surface-mounted reinforcement. The provisions for fibre-reinforced concrete deck slabs in the first edition have been reorganized in the second edition to explicitly include deck slabs of both cast-in-place and precast construction and are now referred to as externally restrained deck slabs, whereas deck slabs containing internal FRP reinforcement are referred to as internally restrained deck slabs. Resistance factors in the second edition have been recast from those in the first edition and depend on the condition of use, with a further distinction made between factory- and field-produced FRP. In the second edition, the deformability requirements for FRP-reinforced and FRP-prestressed concrete beams and slabs of the first edition have been split into three subclauses covering the design for deformability, minimum flexural resistance, and crack-control reinforcement. The effect of sustained loads on the strength of FRPs is accounted for in the second edition by limits on stresses in FRP at the serviceability limit state.Key words: beams, bridges, concrete, decks, fibre-reinforced-polymer reinforcement, fibre-reinforced-polymer sheets, prestressing, repair, strengthening, wood.

Calibration of the Ontario Highway Bridge Design Code 1991 edition

1994 ◽  
Vol 21 (1) ◽  
pp. 25-35 ◽  
Author(s):  
Andrzej S. Nowak ◽  
Hid N. Grouni
Keyword(s):  
Reinforced Concrete ◽  
Reliability Analysis ◽  
Prestressed Concrete ◽  
Highway Bridge ◽  
Live Load ◽  
Design Code ◽  
Reliability Indices ◽  
Resistance Factors ◽  
Load And Resistance Factors ◽  
Selection Of

The paper describes the calculation of load and resistance factors for the Ontario Highway Bridge Design Code (OHBDC) 1991 edition. The work involved the development of load and resistance models, the selection of the reliability analysis method, and the calculation of the reliability indices. The statistical models for load and resistance are reviewed. The considered load components include dead load, live load, and dynamic load. Resistance models are developed for girder bridges (steel, reinforced concrete, and prestressed concrete). A reliability analysis is performed for selected representative structures. Reliability indices are calculated using an iterative procedure. The calculations are performed for bridge girders designed using OHBDC 1983 edition. The resulting reliability indices are between 3 and 4 for steel girders and reinforced concrete T-beams, and between 3.5 and 5 for prestressed concrete girders. Lower values are observed for shorter spans (up to 30–40 m). The acceptance criterion in the selection of load and resistance factors is closeness to the target reliability level. The analysis confirmed the need to increase the design live load for shorter spans. Partial resistance factors are considered for steel and concrete. The criteria for the evaluation of existing bridges are based on the reliability analysis and economic considerations. Key words: bridge code, calibration, load factor, resistance factor, reliability index.

Equivalent area of voided slabs

1998 ◽  
Vol 25 (4) ◽  
pp. 797-801 ◽  
Author(s):  
Leslie G Jaeger ◽  
Baidar Bakht ◽  
Gamil Tadros
Keyword(s):  
Simple Expression ◽  
Technical Note ◽  
Axial Stiffness ◽  
Highway Bridge ◽  
Slab Thickness ◽  
Design Code ◽  
Bridge Design ◽  
Equivalent Thickness ◽  
Simple Alternative ◽  
Equivalent Area

In order to calculate prestress losses in the transverse prestressing of voided concrete slabs, it is sometimes convenient to estimate the thickness of an equivalent solid slab. The Ontario Highway Bridge Design Code, as well as the forthcoming Canadian Highway Bridge Design Code, specifies a simple expression for calculating this equivalent thickness. This expression is reviewed in this technical note, and a simple alternative expression, believed to be more accurate, is proposed, along with its derivation. It is shown that the equivalent solid slab thickness obtained from consideration of in-plane forces is also applicable to transverse shear deformations, provided that the usual approximations of elementary strength of materials are used in both cases.Key words: axial stiffness, equivalent area, shear deformation, transverse prestressing, voided slab, slab.

scholarly journals DEFORMATIONAL ANALYSIS OF PRESTRESSED HIGH‐STRENGTH CONCRETE MEMBERS USING FLEXURAL CONSTITUTIVE MODEL

2005 ◽  
Vol 11 (2) ◽  
pp. 145-151
Author(s):  
Renata Zamblauskaitė ◽  
Gintaris Kaklauskas ◽  
Darius Bačinskas
Keyword(s):  
Constitutive Model ◽  
Prestressed Concrete ◽  
Linear Time ◽  
High Strength ◽  
Concrete Members ◽  
Calculation Technique ◽  
Short And Long Term ◽  
Modulus Method ◽  
Creep And Shrinkage

In this paper, an attempt has been made to extend application of the recently proposed Flexural constitutive model to short‐ and long‐term deformational analysis of flexural partially prestressed concrete members. The effect of tension stiffening and non‐linear time effects of creep and shrinkage are taken into account. Effective modulus method is used for modelling long‐term deformations. The proposed calculation technique is based on the layered approach and use of material stress‐strain relationships. Curvatures prediction results were tested against experimental data of partially prestressed concrete beams reported in literature.

scholarly journals LONG‐TERM DEFORMATION ANALYSIS OF NON‐CRACKED PC MEMBERS USING FLEXURAL CONSTITUTIVE MODEL AND DESIGN METHODS

2006 ◽  
Vol 12 (2) ◽  
pp. 124-133
Author(s):  
Renata Zamblauskaite ◽  
Gintaris Kaklauskas ◽  
Povilas Vainiūnas
Keyword(s):  
Constitutive Model ◽  
Prestressed Concrete ◽  
Linear Time ◽  
Deformation Analysis ◽  
Stress And Strain ◽  
Concrete Members ◽  
Calculation Technique ◽  
Modulus Method ◽  
Creep And Shrinkage

In this paper, an attempt has been made to extend application of the recently proposed Flexural constitutive model to long‐term deformation analysis of prestressed concrete members. The effect of non‐linear time effects of creep and shrinkage are taken into account. Effective modulus method is used for modeling of long‐term deformations. The proposed calculation technique is based on the layered approach and use of material stress and strain relationships. Curvatures and deflections prediction results were tested against experimental data of prestressed concrete beams reported in the literature.

Dynamic loading and testing of bridges in Ontario

1984 ◽  
Vol 11 (4) ◽  
pp. 833-843 ◽  
Author(s):  
J. R. Billing
Keyword(s):  
Dynamic Load ◽  
Dynamic Testing ◽  
Highway Bridge ◽  
Vibration Modes ◽  
Design Codes ◽  
Test Results ◽  
Design Code ◽  
Bridge Design ◽  
Strain Measurements ◽  
Bridge Testing

The Ontario Highway Bridge Design Code (OHBDC) contains provisions on dynamic load and vibration that are substantially different from other codes. Dynamic testing of 27 bridges of various configurations, of steel, timber, and concrete construction, and with spans from 5 to 122 m was therefore undertaken to obtain comprehensive data to support OHBDC provisions. Standardized instrumentation, data acquisition, and test and data processing procedures were used for all bridge tests. Data was gathered from passing trucks, and scheduled runs by test vehicles of various weights. Accelerometer responses were used to determine bridge vibration modes, and dynamic amplifications were obtained from displacement or strain measurements. The form of the provisions adopted for dynamic load and vibration was confirmed by the test results, subject to minor adjustment of values. Observations on the distribution of dynamic load, and its relationship to span length and vehicle weight, may provide a basis for future refinement of the dynamic load provisions. If the stiffness of curbs and barrier walls is not included in deflection calculations, bridges designed by deflection could be penalized. Key words: bridges, vibration, bridge testing, bridge design codes.

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