摘要:

The use of stone arches for bridge construction has generally ceased, but since these structures still exist in modern road systems, their structural integrity is of current concern. This paper presents an analysis technique suited for the thick jointed heritage stone arch bridges found in Canada. The effect of increased mortar joint size on structural response is investigated. The response of a section to eccentric thrust is postulated and the effective section properties are derived. Structural behaviour proceeds from a fixed arch to a two-hinge, a three-hinge, and finally a five-hinge failure mode for a symmetrical arch with midspan loading. A typical load–deflection curve is developed, suitably adjusted for secondary effects due to changes in geometry and material nonlinearity. Stone arch bridges in Canada were constructed with thick mortar joints, which exhibit significant deterioration of stiffness with load eccentricity and, therefore, significant secondary effects; as thickness increases, ultimate strength decreases. A suitable limit states prediction for the load capacity of old stone arches is proposed.Key words: arch, bridge, heritage, limit states, stone, structural analysis.

ISSN:0315-1468    

DOI:10.1139/l89-122

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Studies were conducted to evaluate the adsorption–desorption isotherms of a common dry cleaning solvent, perchloroethylene (PCE), in soils, peat moss, and granular activated carbon. The results obtained followed the Freundlich Isotherm, and the organic carbon content of the media was the most significant controlling factor in the adsorption–desorption process. The peat moss exhibited the highest residual saturation concentration for pure PCE amongst all the media tested. The desorption studies indicated that PCE had medium mobility in soil and was not significantly affected by moderate changes in pH.Key words: adsorption, desorption, Freundlich Isotherm, granular activated carbon, peat moss, perchloroethylene, soils.

ISSN:0315-1468    

DOI:10.1139/l89-123

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Results are reported of tests to failure on six full-scale unbonded post-tensioned prestressed concrete slab–edge column specimens. The objective is to study experimentally the strength and behaviour of this type of connections. The variables are quantity and distribution of stud shear reinforcement and length of overhang. The relevant design equations suggested by Dilger and Ghali as well as several models by others for predicting the strength of prestressed concrete slab–edge column connections are compared with test results. It is concluded that the ACI and CSA provisions for predicting the strength of such connections are conservative, and that the presence of stud shear reinforcement is a good means of increasing the strength and ductility of this type of connections.Key words: shear strength, flat slabs, prestressed concrete, unbonded tendons, shear reinforcement, design, ductility.

ISSN:0315-1468    

DOI:10.1139/l89-124

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

To evaluate the performance of the biological activated carbon filters at the Sainte-Rose water treatment plant in Ville de Laval (Québec), water and carbon samples were taken over a period of 150 days. Sampling began 1 year after filter start-up. The filters were then in a pseudo-equilibrium state.During winter, the removal rate of organic material is reduced because of lower water temperatures which affect bacterial activity. Bacterial density in the upper layers of the filter is influenced by temperature variations. During the warm season, bacteria counts are higher in the upper layer of the carbon, in the filter effluent, and in the backwash water. For equal carbon masses, bituminous carbon and peat-based extruded carbon have similar removal rates. However, for equal volumes, bituminous carbon is more efficient.Key words: biological activated carbon, adsorption, filtration, drinking water, organic matter.

ISSN:0315-1468    

DOI:10.1139/l89-125

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

This paper is devoted to the computational analysis of three-dimensional free surface flows. The model solves the Navier-Stokes equations without anya priorirestriction on the pressure distribution. The variational formulation along with the solution algorithm are presented. Finally, the model is used to study the hydrodynamic regime in the vicinity of a projected harbor installation.Key words: free surface flows, three-dimensional flows, finite element method.

ISSN:0315-1468    

DOI:10.1139/l89-126

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

One-seventh scale direct models of single-cell and two-cell prestressed concrete box girder bridges, tested to destruction at McGill University, are analyzed by the nonlinear finite element technique. The nonlinear program NONLACS, utilized in the analysis, is described in detail together with the material models employed. The objective of the current study is to demonstrate the capabilities of the finite element program NONLACS in predicting the ultimate strength and complete response of prestressed concrete box girder bridges at all stages of loading up to the ultimate load. The load–deflection curves, concrete and steel stresses, and deflected shapes of the bridges at different load levels are compared with the corresponding experimental data. The results verify the applicability of the nonlinear finite element method as an economical and expedient alternative, in some cases, to expensive experimental work aimed at the investigation of the complete response of complex structures to applied loads.Key words: box girder bridges, concrete, concrete and steel strains, experimental data, finite element, load–deflection characteristics, nonlinear analysis, prestressing.

ISSN:0315-1468    

DOI:10.1139/l89-127

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Nine large-scale concrete masonry infilled panels (3.6 × 2.8 m) were tested to destruction under uniformly distributed lateral pressure applied in small increments. Load–deformation curves of the infills and the enclosing steel frame showed linear elastic behaviour prior to first cracking. Nonlinear behaviour due to cracking and arching action of infill was prominent in the postcracking range. Parameters investigated experimentally included the effects of boundary supports, joint reinforcement, panel thicknesses, panel opening, and characteristics of construction. In parallel with the testing program, computer-aided analytical techniques were developed to predict the first crack and ultimate loads. First crack prediction was based on a finite element analysis for bending of thick plates, while ultimate load prediction was based on a yield-line technique modified to account for the arching action of infill confined within a flexible frame. Having been verified by comparison with test results, the postcracking analysis program was used to conduct a parametric study. It was found that infill compressive strength, panel dimensions, and frame rigidity have significant effect on ultimate loads. While central openings do not affect the ultimate strength, they do, however, reduce postcracking ductility.Key words: masonry, infill panel, steel frame, experimental, out-of-plane, behaviour, strength, arching, yield-line technique, cracking.

ISSN:0315-1468    

DOI:10.1139/l89-128

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Masonry shear panels used as infilling in steel frames are investigated experimentally. Twenty-eight large-scale specimens were tested to ultimate panel strength under in-plane, horizontal loading applied at roof level. Of the parameters varied in the test series, interface conditions between panel edges and frame were found to significantly affect the strength and behaviour. Column-to-panel ties were found to be ineffective in increasing ultimate strength while initial stiffness was only marginally increased. A 20 mm gap between the upper edge of a panel and roof beam was particularly detrimental to the system shear capacity. While panel openings reduced initial major crack load, the same was not necessarily true for their effect on ultimate strength. Reinforced bond beams at one third and two thirds of the panel height forced initial major cracking to occur quite close to ultimate, which itself was only marginally increased. The lowest initial major cracking and ultimate loads were recorded for those specimens consisting of a panel in a hinge frame with a 20 mm gap between the upper edge of the panel and roof beam.Key words: masonry, infilled panel, steel frame, experimental, in-plane, behaviour, strength.

ISSN:0315-1468    

DOI:10.1139/l89-129

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Experimentally determined dynamic responses of ten scale models of masonry infilled steel frames were compared with the results of three simple analytical models. Effects investigated included stiffening and strengthening contribution of the masonry infill, degradation of the system, motion intensity, frame stiffness, and rotational joint rigidity at slab-to-column intersections. Tests on one-third scale models, subjected to sinusoidal motions, revealed that masonry infill markedly increases the dynamic strength and stiffness of the system. At weak-to-moderate motions (below 0.5 g), models exhibited a nonlinear response before the final failure, while strong motions accelerated the system degradation rate. Stiffer frames and rotationally rigid joints resulted in significantly increased system dynamic strength. A braced frame model wherein cross-bracing replaces the panel action adequately predicted linear and lower-region nonlinear responses of infilled frames with flexible column-to-slab rotational conditions. Satisfactory predictions of the linear response of framed walls with rigid column-to-slab rotational conditions were made with a single degree of freedom model. The third analytical model based on an equivalent strut technique was found to be unsatisfactory for predicting dynamic response of masonry infilled frames.Key words: masonry panel, steel frame, shear, dynamic, analytical, experimental.

ISSN:0315-1468    

DOI:10.1139/l89-130

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

An improved instrumentation scheme has been designed and tested for measuring the generalized forces occurring within armour units in a physical model of a breakwater subjected to wave action. The fundamental change is centered around the concept of a load cell. Compared with previous devices developed by the authors, this new unit has improved sensitivity, full protection from all environmental influences, and a wider range of applicability. These improvements were substantiated by a number of static and hydraulic tests.Key words: breakwaters, armour, model, analysis, instrumentation.

ISSN:0315-1468    

DOI:10.1139/l89-131

出版商:NRC Research Press    

年代:1989

数据来源: NRC