摘要:

This paper describes the behaviour of two full-scale models of a portion of highway bridge slab reinforced with fibre reinforced polymer (FRP) reinforcement. The first slab was reinforced totally with carbon FRP (CFRP), and the second slab was reinforced with hybrid glass FRP (GFRP) and steel reinforcement. The models were tested under static loading up to failure using a concentrated load acting on each span of the continuous slab and the two cantilevers to simulate the effect of a truck wheel load. Load-deflection behaviour, crack patterns, strain distribution, and failure mode are reported. The measured values are compared to values calculated using nonlinear finite element analysis model. The accuracy of the nonlinear finite element analysis is demonstrated using independent test results conducted by others. The analytical model is used to examine the influence of various parameters, including the type of reinforcement, boundary conditions, and reinforcement ratio. Based on serviceability and ultimate capacity requirements, reinforcement ratios for using CFRP and GFRP reinforcement for typical bridge deck slabs are recommended.Key words: bridges, deflection, FRP, reinforcement, concrete, punching, slabs, shear, finite element model, strain.

ISSN:0315-1468    

DOI:10.1139/l99-098

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

An extensive research project is currently being carried out at The University of Manitoba, Canada, to develop lightweight glass fiber reinforced plastic (GFRP) poles for use in transmission and distribution networks. In this paper, results from tests involving full-scale tapered GFRP poles with a hollow circular cross section subjected to cantilever bending are presented. The filament winding process was employed to produce the poles using polyester resin reinforced with E-glass fibers. Cantilever bending tests were conducted on twelve full-scale poles up to failure. Test parameters included fiber orientation and number of layers. Extensive theoretical work preceded the test program and a theoretical model was developed for evaluating the failure load. The results to date indicate that the developed theoretical model can predict quite well the ultimate capacity and behavior performance of GFRP poles. This theoretical model was used in this investigation to determine the optimum cross-sectional dimensions for 6.1 m (20 ft) and 18.3 m (60 ft) Class 1 GFRP poles.Key words: transmission and distribution poles, filament winding, fiber-reinforced plastics.

ISSN:0315-1468    

DOI:10.1139/l99-089

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

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.

ISSN:0315-1468    

DOI:10.1139/l00-004

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

Strain sensors are a valuable tool for assessing the health of structures. The University of New Brunswick, in conjunction with ISIS Canada, is developing a distributed fibre optic strain sensor based on Brillouin scattering. This sensor can provide a virtually unlimited number of measurement points using a single optical fibre. A description of the operating principles of the system is given, along with a summary of laboratory test results. Strain measurement accuracy as high as approximately ±11 µ&egr; has been demonstrated at 1 m spatial resolution. Spatial resolutions as short as 100 mm can be used, although with decreased strain measurement accuracy. Future development of the technology will include an enhancement allowing both strain and temperature to be measured simultaneously.Key words: strain sensor, fibre optics, distributed sensing, structural monitoring, Brillouin scattering.

ISSN:0315-1468    

DOI:10.1139/l00-006

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

This paper presents an overview of the development and application of ISIS fibre optic sensor (FOS) technology by the University of Toronto Institute for Aerospace Studies and Department of Electrical and Computer Engineering. The primary focus of this technology has involved the use of fibre Bragg gratings (FBGs) to measure strain and temperature in concrete structures and fibre reinforced plastic (FRP) overwraps applied to concrete structures. A brief review of existing fibre optic sensor configurations and the advantages of using FOS compared to other strain sensors is first presented. Subsequently, the development of new sensor concepts such as a long gauge of arbitrary length, a distributed gauge for measuring local strain gradients, and multiple FBGs on a single fibre optic cable are discussed, with examples of their application to civil engineering structures. In addition, the specialized instruments under development that are essential for obtaining strain information from these sensors are also described. Finally, the issue of wireless remote monitoring of FOS systems is addressed.Key words: fibre optic sensors, Bragg gratings, civil engineering structures, instrumentation.

ISSN:0315-1468    

DOI:10.1139/l00-010

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

This paper presents the results of an experimental investigation of the long-term deflection behaviour of concrete shallow beams reinforced with glass fibre reinforced polymer (GFRP) bars. The long-term deflections of the GFRP-reinforced beams are compared to deflections of identical beams reinforced with steel bars. All beams were under sustained loading for approximately 8 months. The variables were the level of sustained loading and the reinforcement materials: steel or GFRP. The experimental immediate and long-term deflections of both the steel- and the GFRP-reinforced beams were compared to calculated deflections using the CEB-FIP Model Code 1990, and the ACI 318-95 code using the recommendations of ACI Committee 209; these references are for steel reinforced concrete members. The test results indicate that under similar loading conditions and the same reinforcement ratio, the GFRP-reinforced beams had long-term deflections, due to creep and shrinkage, 1.7 times greater than those of the steel-reinforced beams. A comparison of the theoretical and experimental immediate and long-term deflections indicates that the CEB-FIP Model Code 1990 gives reasonable predictions for all beams, and that the ACI 318-95 code, using the ACI Committee 209 recommendations, overestimates the deflections due to the combined effects of creep and shrinkage.Key words: glass fibre reinforced polymer (GFRP), steel, reinforced concrete, long-term, deflections, flexure, elastic modulus.

ISSN:0315-1468    

DOI:10.1139/l00-009

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

A promising use for high performance composite materials is to reinforce timber beams. The present paper studies the use of carbon and glass fibres to reinforce sawn timber sections. Consideration is given to strength phenomena of commercial timber alone and in reinforced sections in bending and shear. Anchorage length considerations for composite strips applied to the underside of simple beams are discussed. Experimental results are presented for three geometries of reinforcement using matched samples of 25 pairs of beams, reinforced and not. Results establish that the wood itself in the composite section shows strength increase, and that the increase in moment resistance of the reinforced beams is far greater than that predicted by simple models.Key words: composite material, timber, reinforcement, bending, shear.

ISSN:0315-1468    

DOI:10.1139/l00-017

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

The use of fibre-reinforced polymers for repair and retrofit is growing at an unprecedented rate. This technique has been used for strengthening and rehabilitation of columns, beams, masonry, joints, etc. and has also found significant suitability for seismic applications. All research to date has focused, however, on wraps and jackets with continuous, unidirectional fibres. Within the auspices of Network of Centers of Excellence on Intelligent Sensing for Innovative Structures (ISIS) program, an entirely new method of fibre reinforced polymer coating is being developed. In this method, the composite with short, randomly distributed fibres is sprayed on the surface of concrete to be repaired. Composite gets pneumatically compacted on the application surface and develops a strong bond with concrete during the hardening process. In this paper, the effectiveness of the spray technique is compared with wraps carrying continuous fibres when applied to concrete cylinders under compression. To assess size effects, a companion test series involving larger cylinders was carried out. It was found that sprayed composites with randomly distributed short fibres performed equally well as or even better than wraps with continuous fibres. Within the continuous fibre wraps, those with a 0-90° fibre orientation are far more effective than those with a ±45° orientation.Key words: concrete, repair, glass fibre, polymer matrix, spray, wraps, deformability, size effect

ISSN:0315-1468    

DOI:10.1139/l00-027

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

An experimental research project was undertaken to evaluate the need to strengthen existing reinforced concrete bridges belonging to the Ministère des Transports du Québec. A typical bridge consisting of a single-span bridge with T-shaped sections was identified. Evaluation of the bridge showed that an increase in bending strength and shear strength would be necessary to satisfy current loading conditions and code requirements. The increase in bending strength was obtained by bonding carbon-reinforced composite materials to the underface of the beams, with fibres in the longitudinal direction. External U-shaped stirrups made of glass-reinforced composite materials were installed on the outside faces of the beams in order to increase their shear strength. This paper presents a selection of experimental results initially obtained on T-section beams, scaled 1:3 with respect to the bridge under consideration. The actual reinforcement scheme selected for the bridge is then presented, accompanied by comments on the construction process. Conventional instrumentation and fibre optic sensors were incorporated to the repair work in order to evaluate the behaviour of the bridge, before and after strengthening. Initial results of this ongoing evaluation are presented here.Key words: bridge strengthening, FRP, composite materials, instrumentation, field testin

ISSN:0315-1468    

DOI:10.1139/l00-028

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

The use of corrosion free fibre reinforced polymer (FRP) composites as reinforcement to concrete is currently being seen as a promising option to generate durable concrete structures. However, there exists very little credible information about its field application and performance. This paper describes the Joffre Bridge project, in Sherbrooke (Québec, Canada), over the St-François River, where Carbon Fibre Reinforced Polymer (CFRP) was used as reinforcement for a portion of the concrete deck slab. The bridge consists of five longitudinal spans with lengths varying from 26 to 37 m. Each span has a concrete deck supported by five steel girders at 3.7 m. A part of the concrete deck slab (7.3 × 11.5 m) and a portion of the traffic barrier and the sidewalk were reinforced with Carbon (CFRP) and Glass Fibre Reinforced Polymer (GFRP) reinforcement. The bridge was extensively instrumented with many different types of gauges, including integrated fibre optic sensors (FOS) into FRP reinforcement. The performance of the bridge had been assessed under static and dynamic loading using calibrated heavy trucks. Moreover, structural design and construction details of the bridge and instrumentation were performed. The results from calibrated field tests on the bridge are presented in this paper.Key words: concrete bridge deck, FRP reinforcement, fibre optic sensors (FOS), field calibrated tests, performance monitori

ISSN:0315-1468    

DOI:10.1139/l00-029

出版商:NRC Research Press    

年代:2000

数据来源: NRC