摘要:

This paper summarizes the results of tests performed on 48 push-out specimens to investigate the feasibility of using perfobond rib type shear connectors in composite beams with ribbed metal decks placed parallel to the steel beams. The perfobond rib shear connector is a flat steel plate containing a number of holes. The results indicate that perfobond rib connectors can be effectively used in composite beams with ribbed metal decks placed parallel to the steel beams. An appreciable improvement in performance was observed in test specimens when additional reinforcing bars were passed through the perfobond rib holes. Shank shear was the principal mode of failure in specimens with headed studs. In specimens with perfobond rib, failure was triggered by the longitudinal splitting of the concrete slab, followed by the crushing of concrete in front of the perfobond rib.Key words: composite beam, shear connector, perfobond rib, headed stud, push-out test, metal deck.

ISSN:0315-1468    

DOI:10.1139/l92-001

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

The inelastic seismic response of simple single-story structures, symmetric in plan in the elastic domain but having lateral load resisting structural elements (LLRSEs) of unequal yield strengths, has been studied. When yielding is initiated in such structures, an instantaneous state of torsional coupling in plan induces an additional torsional component to the response of the system. This torsional effect produces, under some circumstances, a magnification of the ductility demand of the LLRSE having lesser strength as compared to what would otherwise be expected of a single-degree-of-freedom. A parametric study has been conducted to investigate the circumstances where this amplification becomes significant, and the results of this research are presented herein. The rotational inertia is shown to have a significant influence on this transient state of inelastic torsional response. A limited investigation of single-story multi-element structures, single-story structures with complex force–displacement relationships, and simple multistory structures demonstrates that the findings and observations noted from the parametric study are equally applicable to more elaborate structures. Implications on Canadian design practice are discussed.Key words: seismic response, torsional coupling, structural symmetry, inelastic response, ductility demand, parametric study, code implications, rotational inertia.

ISSN:0315-1468    

DOI:10.1139/l92-002

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

The improvements in the performance characteristics of cements due to carbon fiber reinforcement are described. In particular, the structure, the physical properties, the mechanical behavior, and the durability aspects of carbon–cement composites using pitch-based fibers are discussed. The various possible applications of these composites in structural and nonstructural applications are enumerated. The future research needs are identified.Key words: cements, carbon fibers, microstructure, strength, toughness, durability, applications.

ISSN:0315-1468    

DOI:10.1139/l92-003

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

The lip dimension of cold formed steel C-sections (channels) is optimized according to the provisions of CSA Standard CAN/CSA-S136-M89 "Cold formed steel structural members." The provisions in the 1989 edition of S136 are compared with those of the 1984 edition. Due to changes in design criteria, previously optimal sections are no longer optimal. The interaction of many of the elements is described and the manner in which the design standard takes the interaction into account is discussed. The lip sizes of C-sections are optimized in order to maximize flexural resistance and minimize cross-sectional area. An optimal C-section is one in which the flange is nearest to being fully effective. The optimal geometry generally has a lip-to-flange ratio of 3/8, which is restricted by a maximum lip flat width of 14 times the steel thickness. An optimal section based on the 1989 edition of S136 has a lower flexural resistance and a longer lip than an optimal C-section based on the 1984 edition of S136. Due to certain changes in the 1989 edition of S136, cold work of forming is now applicable in fewer cases than previously allowed by the 1984 edition of S136.Key words: cold formed steel, effective width, stiffener, lip, C-section, channel, optimization.

ISSN:0315-1468    

DOI:10.1139/l92-004

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Estimates of flows with specified probabilities are required for the design and planning of water resource projects. The design flow required could be a peak flood, a low flow, or other flows, depending on the project. Such flows can be readily estimated when there are adequate data; but this is rarely the case in Canada. A procedure is presented for estimating design flows on the basis of whatever information is available, however inadequate. It is based on the use of a compound probability distribution made up of a weighted combination of underlying distributions. The model can be specified on the basis of regional information alone, and design flows are computed from that. Other data can then be used to update the weights of the component distributions, thereby increasing the accuracy of the estimates. The procedure is illustrated with practical examples.Key words: design flows, flow estimation, floods frequency analysis, Bayesian methods.

ISSN:0315-1468    

DOI:10.1139/l92-005

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Between 1967 and 1982, depths and specific gravities of snow were recorded on 44 single- and multi-level flat-roofed buildings between Halifax and Edmonton. The average density of snow in the drifts where the roofs change elevation was about 3.0 kN/m3, the value used consequently in the 1990 National Building Code of Canada (NBC). This is some 25% higher than the value used in the 1985 NBC. Data on drift geometry and maximum loads in the drifts are presented and compared with provisions in the 1990 NBC. As well, the paper presents measured values of average and maximum roof-to-ground load ratios for upper level roofs and for lower roofs away from the drifts. These compare favourably with those recommended in the 1985 and 1990 NBC. The statistical variabilities of snow loads and densities are given, since these are required to establish load factors used for limit states design in the NBC. Further research needs are identified.Key words: snow loads, snow drifts, uniform snow, flat roofs, snow density, snow load variability, snow load survey.

ISSN:0315-1468    

DOI:10.1139/l92-006

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Successful use of high performance composite materials was first made in the aircraft industry and, to a lesser extent, in the automobile industry. The use of these materials in civil engineering is now a reality, particularly for prestressing applications. This state-of-the-art paper deals with composite materials used for cables. It describes the composition of fiber prestressing cables and presents their mechanical properties. The anchorages, the advantages and disadvantages of these cables, their field of applications, and three successful applications in structural engineering are also discussed.Key words: composite materials, prestressing, fiber cables, concrete.

ISSN:0315-1468    

DOI:10.1139/l92-007

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

This paper presents the results of a numerical model study of the St. Lawrence River flow from the Beauharnois–Les Cèdres and Carillon hydroelectric complexes, just upstream from the Montreal Archipelago, to the city of Québec. The main factors affecting the water levels in the river under free water surface conditions, and their degree of influence, were estimated. In particular, the effects of the flows, local inflows, flow variations, and tide on the water levels along the St. Lawrence maritime channel were analyzed. The daily average flows are of utmost importance, other parameters being adjusting factors.Key words: St. Lawrence River, water level prediction, numerical model.

ISSN:0315-1468    

DOI:10.1139/l92-008

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

A limit states criterion of ductility is described for nonlinear behaviour of structural members in flexure. Experimental results and theoretical models are reported for the behaviour of steel and composite continuous beams, portal frames, and continuous steel pipes. The ductility criterion is used to identify the basis for analyzing the load effects and resistances of these elements.Key words: limit states, ductility, analysis, design, beams, pipes, steel, composite, resistance.

ISSN:0315-1468    

DOI:10.1139/l92-009

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

The results of monotonic and cyclic nail connection lateral tests are presented. The tests are part of an extensive experimental and analytical study to investigate the behaviour of timber shear walls subjected to earthquakes. The results from the nail connection tests were used in a larger study of timber shear walls. The nonlinear load–deflection curves were used for modelling the nail connection between the sheathing and the framing of the shear walls. The dependency of the nail connection on the grain orientation of the timber materials is investigated along with the evidence that the material properties of the nails are the primary parameters for the load–displacement characteristics of the connection made with hot-dipped, galvanized common nails. Both the monotonic and cyclic lateral behaviours of the connections are established. The premise that the hysteresis for the nail connection is contained within an envelope defined by the monotonic load–displacement curve is confirmed. These connection characteristics translate into similar behaviour in nailed timber shear walls. Therefore, an improved undertanding of the principal connection used in the construction of shear walls will also improve the understanding of the behaviour of shear walls.Key words: connections, nails, plywood, waferboard, monotonic, cyclic, shear wall.

ISSN:0315-1468    

DOI:10.1139/l92-010

出版商:NRC Research Press    

年代:1992

数据来源: NRC