An analytical approach towards determining the strength of FRP-reinforced/prestressed concrete beams

2002 ◽  
Vol 29 (2) ◽  
pp. 301-315 ◽  
Author(s):  
Sameh R Salib ◽  
George Abdel-Sayed ◽  
Nabil Grace
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Research Work ◽  
Longitudinal Direction ◽  
Design Guidelines ◽  
Fiber Reinforced Polymers ◽  
Experimental Program ◽  
Premature Failure ◽  
Mode Of Failure

Non-corrosive fiber-reinforced polymers (FRP) are becoming a desirable replacement to steel bars in reinforcing/prestressing concrete structures. However, the difference between the two materials is not only related to the properties in the longitudinal direction of the bars as most of the current research work and design guidelines are concerned with. The properties in the transverse direction of the bars have basic differences, which may influence the beam strength and its mode of failure. This paper presents a comprehensive analytical modeling for evaluating the strength of concrete beams reinforced and (or) prestressed with FRP bars and the corresponding mode of failure. It takes into account significant parameters such as the crack path geometry, the crack width, and the properties of the bars in both longitudinal and transverse directions. The proposed analysis identifies any premature failure of beam due to the dowel failure of FRP reinforcement and determines the contribution of stirrups, if any, based on the number and actual tensile strain of the stirrups crossing the failure crack. A good agreement has been observed between the results of the developed model and the results of an experimental program conducted at the University of Windsor, as well as other published experimental programs.Key words: ACM, FRP, cracks, dowel action, reinforced concrete, strength.

scholarly journals Experimental Study on the Torsional Behaviour of Prestressed HSC Hollow Beams

2020 ◽  
Vol 10 (2) ◽  
pp. 642 ◽  
Author(s):  
Luís Bernardo ◽  
Sérgio Lopes ◽  
Mafalda Teixeira
Keyword(s):  
Experimental Study ◽  
High Strength Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
High Strength ◽  
Experimental Program ◽  
Pure Torsion ◽  
Strength Concrete ◽  
Hollow Beams

This article describes an experimental program developed to study the influence of longitudinal prestress on the behaviour of high-strength concrete hollow beams under pure torsion. The pre-cracking, the post-cracking and the ultimate behaviour are analysed. Three tests were carried out on large hollow high-strength concrete beams with similar concrete strength. The variable studied was the level of longitudinal uniform prestress. Some important conclusions on different aspects of the beams’ behaviour are presented. These conclusions, considered important for the design of box bridges, include the influence of the level of prestress in the cracking and ultimate behaviour.

EFFECT OF CORROSION LONGITUDINAL STEEL BARS ON THE FLEXURAL STRENGTH OF RC BEAMS

2021 ◽  
Vol 28 (2) ◽  
pp. 44-53
Author(s):  
Noor Mahmood ◽  
Assim Lateef
Keyword(s):  
Concrete Beams ◽  
Concrete Strength ◽  
Corrosion Process ◽  
Rc Beams ◽  
Cross Sectional ◽  
Flexural Failure ◽  
Steel Bars ◽  
Major Parameter ◽  
Mode Of Failure ◽  
Concentrated Loading

The main objective of this research is to investigate the effect of corroded steel bars on the ultimate flexural capacity of reinforcement concrete beams. The experimental work consists of four RC beams with dimensions (150×200×1200) mm tested under two-point concentrated loading. The major parameter of the current research is corrosion period (5,10,20) days. The amount of longitudinal and transverse reinforcement, concrete strength and, the other parameters were kept constant for all samples. The comparisons between specimens are based on the visual cracking loads, ultimate loads, deflection, cracks pattern and mode of failure. Results showed that visual first cracking load, and ultimate loads of corroded RC beams were decreased with increase corrosion durations relative to the control beam as a result of the corrosion process. The mode of failure was flexural failure for all specimens. Corrosion caused decreasing percentage in weight of steel bars and cross-sectional area of longitudinal steel bars. This percent increased as exposure time to corrosion process increased by 8.5% and 28.39% for 20 days respectively.

Fibre reinforced polymer shear reinforcement for concrete members: behaviour and design guidelines

2000 ◽  
Vol 27 (5) ◽  
pp. 859-872 ◽  
Author(s):  
Emile Shehata ◽  
Ryan Morphy ◽  
Sami Rizkalla
Keyword(s):  
Large Scale ◽  
Concrete Beams ◽  
Shear Crack ◽  
Design Guidelines ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Shear Reinforcement ◽  
Material Type ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer

This paper describes an experimental program conducted to examine the structural performance of fibre reinforced polymer (FRP) stirrups as shear reinforcement for concrete structures. A total of ten large-scale reinforced concrete beams were tested to investigate the contribution of the FRP stirrups in a beam mechanism. The ten beams included four beams reinforced with carbon fibre reinforced polymer (CFRP) stirrups, four beams reinforced with glass fibre reinforced polymer (GFRP) stirrups, one beam reinforced with steel stirrups, and one control beam without shear reinforcement. The variables were the material type of stirrups, the material type of the flexural reinforcement, and the stirrup spacing. Due to the unidirectional characteristics of FRP, significant reduction in the strength of the stirrup relative to the tensile strength parallel to the fibres is introduced by bending FRP bars into a stirrup configuration and by the kinking action due to inclination of the diagonal shear crack with respect to the direction of the stirrups. A total of 52 specially designed panel specimens were tested to investigate the bend and kinking effect on the capacity of FRP stirrups, along with two control specimens reinforced with steel stirrups. The variables considered in the panel specimens are the material type of the stirrups, the bar diameter, the bend radius, the configuration of the stirrup anchorage, the tail length beyond the bend portion, and the angle of the stirrups. Based on the findings of this investigation, shear design equations for concrete beams reinforced with FRP, appropriate for the Canadian Standards Association (CSA) code, are proposed. The reliability of the proposed equations is evaluated using test results of 118 beams tested by others.Key words: shear, fibre-reinforced polymers, CFRP, cracks, GFRP, kink, stirrups, bend capacity.

Low temperature behaviour of CFRP prestressed concrete beams

1996 ◽  
Vol 23 (2) ◽  
pp. 464-470 ◽  
Author(s):  
Paul E. Bryan ◽  
Mark F. Green
Keyword(s):  
Low Temperature ◽  
Carbon Fibre ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
High Strength ◽  
Experimental Program ◽  
Short Term ◽  
Cold Regions ◽  
Reinforced Plastic ◽  
Short Term Exposure

The corrosion of steel prestressing tendons exposed to deicing salts is increasingly becoming a significant problem in Canada. New fibre reinforced plastic (FRP) materials with high strength-to-weight ratios and noncorrosive characteristics are strong alternatives to solve this problem. Carbon fibre reinforced plastic (CFRP) is one of the most promising among available FRPs. Nevertheless, for CFRP rods to gain acceptance in Canada and other cold regions, their behaviour at low temperatures must be investigated. This paper describes an investigation of the feasibility of using CFRP LEADLINE rods to prestress concrete beams. The results of an experimental program on the short-term behaviour of CFRP prestressed concrete beams at low temperature (−27 °C) are discussed. A simple analytical model is used to predict the flexural response of CFRP beams at low temperature. The experimental results agree well with the analytical predictions. The behaviour of the CFRP tendons is shown to be unaffected by short-term exposure to this low temperature. Key words: carbon fibre, fibre reinforced plastic (FRP), advanced composite materials, prestressed concrete, low temperature, cold regions.

Available plastic rotation in continuous high-strength concrete beams

2008 ◽  
Vol 35 (10) ◽  
pp. 1152-1162 ◽  
Author(s):  
Ricardo N.F. do Carmo ◽  
Sérgio M.R. Lopes
Keyword(s):  
High Strength Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
High Strength ◽  
Reinforcement Ratio ◽  
Experimental Program ◽  
Strength Concrete ◽  
Model Code ◽  
Moment Redistribution ◽  
Eurocode 2

An experimental program was formulated to study moment redistribution in continuous high-strength concrete beams. The evaluation of ductility is important for this type of beam as, for high-strength concrete, the ductility decreases as the concrete strength increases. It is therefore necessary to determine whether the critical sections are able to develop appreciable plastic rotations to justify the application of a linear elastic analysis with moment redistribution. This work specifically examined the influence of the tensile reinforcement ratio and the transverse reinforcement ratio on the rotation capacity of plastic hinges. The moment redistribution obtained experimentally is compared with the guidelines recommended in Eurocode 2, CEB-FIP Model Code 1990, and ACI 318. The results show that ACI 318 recommendations for linear analysis with moment redistribution are too conservative and that the predictions, according to Eurocode 2 and CEB-FIP Model Code 1990, agree with experimental evidence.

scholarly journals Flexural and Shear Behavior of FRP Strengthened AASHTO Type Concrete Bridge Girders

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Nur Yazdani ◽  
Farzia Haque ◽  
Istiaque Hasan
Keyword(s):  
Prestressed Concrete ◽  
Failure Modes ◽  
Highway Bridges ◽  
Design Guidelines ◽  
Shear Capacity ◽  
Bridge Girders ◽  
Fiber Reinforced Polymers ◽  
Concrete Bridge ◽  
Prestressing Steel ◽  
Frp Wrapping

Fiber-reinforced polymers (FRP) are being increasingly used for the repair and strengthening of deteriorated or unsafe concrete structures, including structurally deficient concrete highway bridges. The behavior of FRP strengthened concrete bridge girders, including failure modes, failure loads, and deflections, can be determined using an analytical finite element modeling approach, as outlined in this paper. The differences in flexural versus shear FRP strengthening and comparison with available design guidelines are also beneficial to design professionals. In this paper, a common AASHTO type prestressed concrete bridge girder with FRP wrapping was analyzed using the ANSYS FEM software and the ACI analytical approach. Both flexural and shear FRP applications, including vertical and inclined shear strengthening, were examined. Results showed that FRP wrapping can significantly benefit concrete bridge girders in terms of flexure/shear capacity increase, deflection reduction, and crack control. The FRP strength was underutilized in the section selected herein, which could be addressed through decrease of the amount of FRP and prestressing steel used, thereby increasing the section ductility. The ACI approach produced comparable results to the FEM and can be effectively and conveniently used in design.

Torsional strength of reinforced concrete beams

2000 ◽  
Vol 27 (3) ◽  
pp. 445-453 ◽  
Author(s):  
Khaldoun N Rahal
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Pure Shear ◽  
Concrete Strength ◽  
Reinforced Concrete Beams ◽  
Axial Loads ◽  
Simple Method ◽  
Torsional Strength ◽  
Mode Of Failure ◽  
Good Agreement

A simple method for predicting the ultimate strength and mode of failure of reinforced concrete beams subjected to pure torsion is presented. This method is an extension of a recently developed method for predicting the strength of membrane elements subjected to pure shear that was also applied to beams subjected to combined shearing forces, bending moments, and axial loads. The torsional strength is related to the amounts of transverse and longitudinal reinforcement and to the concrete strength. To check the adequacy of this simple method, the calculated strength and mode of failure are checked against the experimental results of 66 beam tests available in the literature, and good agreement is found. The simplicity of the method is illustrated by an example.Key words: beams, building codes, mode of failure, reinforced concrete, shear, strength, torsion.

PRESTRESSED CONCRETE BEAMS WITH A LONGITUDINAL CAVITY

PCI Journal ◽  
1973 ◽  
Vol 18 (1) ◽  
pp. 39-49
Author(s):  
A. A. Hamoudi ◽  
R. A. Bierweiler ◽  
M. K. S. Phang
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams
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