摘要:

The behavior of a typical connection at the ends of an HSS bracing member was investigated with the finite element method. The connection is effected by means of a gusset plate welded into slots in the HSS member. The paper presents the results of the finite element analyses of 25 connections which differed in the values assigned to the three main parameters that were considered. The finite element results are compared with the provisions of CSA Standard S16.1-M89, and some adjustments to these provisions are recommended.Key words: connections, steel, shear lag, finite element, hollow section, gusset.

ISSN:0315-1468    

DOI:10.1139/l95-077

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Floodplain conveyance in compound channel flows is examined through applications of the dynamic flow routing modelDWOPERto both laboratory and field data sets. Three different approaches regarding the modelling of off-channel storage are considered, namely, the single-channel approach and two interface-plane methods, which artificially separate main channel flows from floodplain flows, using (i) vertical and (ii) diagonal interface planes. The single-channel method, which views composite flow fields as single units without storage, produced significant differences between simulated and observed stage and discharge hydrographs. The vertical interface method gave generally good results in the case of the laboratory data, but was less successful when applied to the field data. The diagonal interface method, which in this instance applied outward-facing diagonal interface planes at the junctions of the main channel and floodplain zones, produced superior results overall.Key words: floodplain, conveyance, unsteady flow, compound channels, off-channel storage, interface planes.

ISSN:0315-1468    

DOI:10.1139/l95-078

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

In Part I of this paper, stress–strain curves for micro-fiber reinforced cement-based composites containing high volume fractions of carbon, steel, and polypropylene fibers were obtained. Considerable strengthening, toughening, and stiffening of the host matrix due to micro-fiber reinforcement under both static and impact conditions were reported. In this paper, composites are characterized under an applied flexural load. Both notched and unnotched specimens were tested in four-point flexure; significant improvements in the flexural behavior due to fiber reinforcement were noted. Notched specimens were tested to study the growth of cracks in these composites and to develop a valid fracture criterion. With this objective, crack growth resistance curves and crack opening resistance curves in terms of the stress intensity factor were constructed. The paper recognizes the potential of these composites in various applications and stresses the need for further research.Key words: Portland cement-based materials, fiber reinforcement, fracture toughness, R-curves.

ISSN:0315-1468    

DOI:10.1139/l95-079

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Ten full-scale specimens consisting of wide-flange beams shear connected by means of tee stubs to hollow structural section (HSS) column faces were tested. Shear–displacement and shear–rotation behaviour were documented and five possible failure modes were identified for this type of connection. In all cases, excessive displacements resulted from yielding of the tee stem, while different ultimate failure modes were observed. Except for bending of the HSS wall, the identified failure modes could be related to well-known limit states. Quantitative evaluations were provided for the remaining failure modes.Key words: connection, steel, HSS, W shape, shear, column, beam, tee stub, experimental.

ISSN:0315-1468    

DOI:10.1139/l95-080

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Many concrete dams and other concrete structures in Canada, and throughout the world, are suffering from deteriorations induced by alkali–aggregate reaction (AAR) that impair the durability and serviceability, and might also affect, in the long term, the safety of the installation. Alkali–aggregate reaction produces concrete expansion, and generally leads to a loss of strength and stiffness (cracking), and generates undesirable deformations and disturbances in the equilibrium of internal forces. The expansion mechanisms in concrete affected by AAR are complex and influenced by a number of factors that are difficult to quantify. Nevertheless, advanced numerical simulation models are generally used in close conjunction with field monitoring of displacements to assist in the structural evaluation and rehabilitation of dams where AAR has been identified. A review of the physical processes that control the structural behaviour of concrete dams suffering from AAR, and numerical simulation procedures to represent AAR concrete expansion by the finite element method, is presented herein. The present state of knowledge to simulate the AAR expansion process has been found to be limited and not yet satisfactorily developed. A methodology to distribute the observed concrete expansion in proportion to the compressive stress state, temperature, moisture, and the reactivity of the concrete constituents is proposed in this paper as a first step to rationalize the numerical modelling of the AAR concrete swelling process in concrete dams.Key words: alkali–aggregate reaction, concrete dams, finite element method, dam safety.

ISSN:0315-1468    

DOI:10.1139/l95-081

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The physical and numerical modelling of a circular cross-section floating breakwater subjected to normal and obliquely incident regular waves is described. The transmission coefficient, breakwater motions, and mooring line forces were measured in two- and three-dimensional laboratory tests for a range of wave conditions and breakwater parameters. The experimental results are compared with results of a numerical model based on linear two-dimensional wave diffraction theory. The performance of the breakwater is summarized and compared with that of a rectangular-section breakwater. Possible modifications to improve the breakwater's performance characteristics are considered.Key words: coastal structures, floating breakwaters, hydrodynamics, moorings, waves.

ISSN:0315-1468    

DOI:10.1139/l95-082

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

LG-1 hydroelectric project, part of La Grande Complex in northern Quebec, required the construction of a 2444 m long dyke on the north bank. The presence of sensitive marine clay, with deltaic and river sand and silt deposits on top of the clay in the central terrace, called for special design features. These included the construction of a dyke with side berms in a depression to ensure stability and the construction of a cement–bentonite cutoff through the sand and silt deposits of the terrace. This paper describes the different phases of dyke construction with emphasis on foundation treatment and construction techniques.Key words: bentonite, cement, clay, construction, cutoff, dyke, excavation, foundation, slurry, trench.

ISSN:0315-1468    

DOI:10.1139/l95-083

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Test results are presented for single fastener glass-fibre-reinforced plastic (GFRP) members connected with GFRP threaded rods, steel threaded rods, and steel bolts. Twenty-eight joints were tested in tension and thirty-five were tested in compression. For some of the tests, a GFRP pipe was used as a protective sleeve for the threads of the steel and GFRP threaded rods. The effect of fastener strength and stiffness on the load carrying capacity of the joints is reported. The major findings for both the tension and compression tests were that joints constructed with a GFRP threaded rod had approximately half the strength of joints constructed with a steel threaded rod. Also, joints constructed with a GFRP threaded rod and GFRP pipe sleeve were at least a third stronger than joints constructed with a GFRP threaded rod alone. The GFRP members used consisted of a pultruded glass fibre sheet, which was composed of symmetrically stacked, alternating layers of identically orientated unidirectional E-glass fibres and randomly orientated E-glass continuous strand mat. The maximum load carrying capacity decreased with increasing angle of loading with respect to the unidirectional fibres, but this was more pronounced for the tension tests than for the compression tests. For the tests performed, it was sufficient to finger tighten end nuts; indeed, tightening end nuts by a half turn-of-the-nut slightly decreased the strength of the joints.Key words: glass-fibre-reinforced plastic, connections, fibreglass bolts, experimental.

ISSN:0315-1468    

DOI:10.1139/l95-084

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Current seismic provisions require that shear links in eccentrically braced frames be fully welded to the column flanges at the link-column joint. Since field welding may have its disadvantages, the use of bolted extended end-plate connection is examined. An experimental program is conducted to assess the response of extended end-plate connections of link-column joints in eccentrically braced frames. Six link-column joint specimens are tested using a cyclic load that represents the severe load reversals that the frame may be subjected to during strong earthquakes. The specimens are selected on the basis of different connection designs. Measurements of forces, strains, and displacements are made. Interaction curves relating the shear force and moment acting on links with semirigid connections are developed. The slip tendency and energy dissipation capacity of the different specimens are compared. On the basis of the test results, a design procedure is developed for the bolted extended end-plate link-column connection. It is concluded that bolted extended end-plate connections can be used for link-column joints of eccentrically braced frames. In properly designed connections bolt slippage was not measured even at high shear forces that are characteristic of link-column joint. Existing guidelines for the design of extended end-plate link-column joints are modified to account for the variable shear force and moment associated with links of different lengths.Key words: steel, frame, eccentric, braced, bolted, end plate, link, connection.

ISSN:0315-1468    

DOI:10.1139/l95-085

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Data on beams with tension lap splices tested under static loading at the same institution over the past two decades are correlated with the bond provisions of the Canadian concrete standard CAN/CSA A23.3-94 (detailed design approach), as well as with the recommendations of ACI Committee 408, on which the Canadian standard appears to be largely based. The correlations show that transverse reinforcement is more effective than the new bond provisions allowed in cases where the bond failure is governed by splitting rather than bar pullout. Extending the effective limits for confinement provides a more accurate estimate of the bond resistance available at higher levels of confinement, resulting in a more uniform factor of safety over a wide range of confinements. Lap splices with no transverse confinement showed relatively poorer performance than lap splices with varying degrees of transverse confinement when correlated with resistances predicted on the basis of the new CAN/CSA A23.3-94 provisions. Weaker relative splice performance in the absence of transverse confinement raises a concern for the development lengths required by the CAN/CSA A23.3-94 provisions. With highly stressed lap splices, a class factor of 1.3 is applied to the basic development length to determine the lap length. Published information, on the other hand, has shown that lap splice lengths and development lengths should be the same for transferring or developing the same level of stress in tension reinforcement when the same level of confinement is provided along the anchorage. In contrast, the ACI Committee 408 recommendations use a larger factor of safety on development length and lap splice length, rather than applying class factors for splices only, making splice and development lengths the same for the same confinement and required strength transfer. For the data considered, required lap lengths are similar using both the CSA Standard CAN/CSA A23.3-94 (including the 1.3 class factor) and the ACI 408 recommendations, and only small differences in overall prediction accuracy were found. Differences in the definition of the concrete confinement term for close bar spacing by the two design models, different limits on the total confinement that can be considered effective, as well as a further modification factor for bar size in the CAN/CSA A23.3-94 provisions, result in only small differences in lap length requirements for most of the data considered.Key words: anchorage (structural), bond, confinement, lap splices, reinforced concrete, standards, static loading, tension.

ISSN:0315-1468    

DOI:10.1139/l95-086

出版商:NRC Research Press    

年代:1995

数据来源: NRC