摘要:

A review of recent developments in the formulation of a design approach for ductile earthquake resisting reinforced concrete frames is presented. In particular the concepts of a deterministic design procedure, termed "capacity design," the advantages of moment redistribution, and the effects of gravity load dominance are discussed. In capacity design (a detailed definition of the term is given in Sect. 2.1) the designer attempts to enforce the development of a unique and desirable pattern of plastic hinges when these are required to dissipate significant amounts of energy to ensure the necessary hysteretic damping. The application of a capacity design procedure in determining the design actions for columns of multistorey frames is examined. Some issues relevant to instability during the inelastic dynamic response of frames are also discussed. Using recent experimental evidence, the inelastic behaviour of reinforced concrete columns, shear effects on potential plastic hinges, and special features of the behaviour of beam–column joints, when these are subjected to severe earthquake simulating reversed cyclic loading, are briefly described. Conclusions drawn from these recent experimental studies, which are being considered for incorporation into the new New Zealand concrete design code of practice, are also reported.

ISSN:0315-1468    

DOI:10.1139/l81-016

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A knowledge of future lake levels is helpful in the stormwater management of a lake district with respect to flood control measures, land use measures around the lake, etc. The planning of strategies to achieve management objectives often receives wide attention; however, little or no mention is usually made of prediction of future events, e.g., lake water levels, upon which the strategies are based. These future events are of major importance as they determine the type of objectives and hence the strategies that management will have to develop and follow in the future.In the present study, the available data on monthly lake water levels are examined utilizing two statistical methods, namely, the Box-Jenkins time series analysis and harmonic analysis. The statistical models are then used to predict future lake levels; the predictions are compared with actual observations. It has been found that the predictions made by the Box-Jenkins model are closer to the recorded observations. The results from the two independent methods are combined to yield a composite forecast, which gives results that are slightly better than those given by either of the independent methods.

ISSN:0315-1468    

DOI:10.1139/l81-017

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Post-tensioned continuous voided concrete bridge decks are widely used in the Province of Ontario. These bridge deck designs are generally based on one-dimensional analysis. The longitudinal moments are usually calculated by considering the deck as a wide beam, and the transverse moments in midspan and at the intermediate supports are evaluated by treating those portions of the bridge as a transverse beam and a frame respectively.To examine more precisely this two-dimensional structural behavior under various loading conditions, the recently designed Highway 403 underpass at Winston Churchill Boulevard in Mississauga, Ontario, was analyzed using the readily available ICES STRUDL-II finite element program.This paper describes the ICES STRUDL-II finite element modelling and analysis procedures, the results obtained, and the comparisons with conventional calculations.

ISSN:0315-1468    

DOI:10.1139/l81-018

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Comparisons are made between results of 81 recent tests on beam columns subjected to unsymmetrical and biaxially eccentric loads and the capacities predicted by design equations recommended by CSA standard S16.1-M78 — Steel Structures for Buildings — Limit States Design. It is concluded that the general provisions of the standard lead to satisfactory designs whereas the detailed procedure given in the Appendix of the standard may lead to a higher proportion of unsafe results.

ISSN:0315-1468    

DOI:10.1139/l81-019

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The two-stage stilling basin is a design sometimes used for high head energy dissipating structures. The distinguishing feature of the design is that essentially two hydraulic jumps occur in series in the same structure. The tailwater depth for the first jump is created by a fixed weir. Tailwater for the second jump is due to the natural tailwater available in the downstream channel. Since most of the energy of flow is dissipated in the first jump, the required tailwater depth to produce a jump in the second basin is considerably decreased, with the result that the entire stilling basin floor may be placed at a higher elevation than for a single basin. This can be advantageous in certain situations.In this paper the results of hydraulic model tests for a two-stage stilling basin are reported. The characteristics of the basin first were studied two-dimensionally using a parallel sided flume. A design criterion was established and this was subsequently verified on a three-dimensional model.

ISSN:0315-1468    

DOI:10.1139/l81-020

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

In the past decade structural research has concentrated on the design of tall buildings, and has resulted in more rational and economical design procedures for such structures. In contrast, research related specifically to the design of low buildings has lagged somewhat, even though these buildings form a large portion of the market for the steel industry. This paper is a state-of-the-art paper for light industrial buildings in structural steel. Topics covered are loads, economics of different layouts and framing schemes, design of flexural members, design of compression members, and resistance to lateral loads.

ISSN:0315-1468    

DOI:10.1139/l81-021

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

This paper describes a study of the values of longitudinal moments/stresses and their distribution at sections over the supports of continuous box-girder bridges. A series of continuous box-girder bridges are analyzed using the finite element method. Results from the finite element analysis are compared with the classical beam theory which is commonly used in the design office for this type of bridge. It is found that the use of the classical beam theory assuming knife-edge supports usually results in an overestimation of the support moments. A modified beam-type equation for the support moments is proposed here for the design of continuous box-girder bridges.

ISSN:0315-1468    

DOI:10.1139/l81-022

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The chemical characterization and algal bioassay were used in order to study the eutrophication potential of an urban drain (Saw Mill Creek) on the Rideau River in Ottawa. Samples were collected during 8 different peak storm flow conditions.Although nutrient concentrations were observed to increase during storm flows, peak flow concentrations for total phosphorus and nitrogen averaged only 0.190 mg/L and 2.5 mg/L respectively. These concentrations of nutrients did not significantly stimulate algal growth at the 5% addition level. However, at the 10 and 20% addition levels, bioassays produced on the average 0.96 and 1.96 mg/L of algal standing biomass (measured as chlorophyll-a) respectively. These values were significantly different (at 95% confidence level) from the average biomass of 0.50 mg/L produced by the Rideau samples. In the analysis, a linear relationship between algal biomass and nutrient addition was assumed.Alum treatment of Saw Mill Creek, simulated by the jar test, was generally unable to reduce the algal growth when compared with that at any of the addition levels. Thus it was concluded that treatment would have no significant effect on algal growth at low flows of Saw Mill Creek.However, a reduction in the volume of storm flow of the Saw Mill Creek could have a significant effect on algal growth in the Rideau River.

ISSN:0315-1468    

DOI:10.1139/l81-023

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A theoretical methodology is proposed to establish a relationship between the rainfall at a fixed point and the associated mean rainfall over a geographically fixed area. The distribution relation for mean rainfall over a specific area was derived using an exponential distribution function for hourly point rainfall. Values of the areal correction factor were estimated at equal levels of exceedance probability for point and areal mean rainfalls. Contrary to previous indications for a moving point, it was found that the areal correction factor for a fixed point and fixed area was not always equal to or less than unity. Furthermore, the areal correction factor was found to vary with the return period.

ISSN:0315-1468    

DOI:10.1139/l81-024

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Three types of analogous frames for the stress and deflection analysis of tall shear walls are presented. They are similar to the wide column analogous frame in having horizontal flexurally rigid arms; however, they avoid the coupling of the shear and contraflexural behaviour inherent in the single column of the wide column analogy. The new analogous frames are suitable for the detailed analysis of individual shear walls or of walls connected by beams to other components. In such combined structures a frame model may be more convenient than a mixture of finite elements and frame elements.

ISSN:0315-1468    

DOI:10.1139/l81-025

出版商:NRC Research Press    

年代:1981

数据来源: NRC