摘要:

Tests on full-scale connections between wide flange beams and rectangular hollow section (RHS) columns reveal various modes of failure as a function of connection geometry. Tension and compression moment plates with web clip angles or tension plates and seat angles welded to doubler plate reinforced RHS walls are investigated. Eight failure modes were identified from an experimental program consisting of ten full-scale specimens. Semi-empirical expressions based on assumed stress distributions predict failure modes and corresponding moment capacities reasonably well for various connection configurations. Further analytical parametric studies showed the importance of tension plate and doubler plate dimensions on joint strength and behaviour.Key words: RHS, W-shape, columns, beams, connections, experimental, analytical, design, steel.

ISSN:0315-1468    

DOI:10.1139/l90-091

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The earthquake that hit the San Francisco area on October 17, 1989, is reviewed with respect to damage to buildings, transportation facilities, and services. The San Francisco experience underlines that soil conditions and inadequate structural integrity are the two most important factors in the seismic risk to a building and its inhabitants. This earthquake is used as a model for the damage prediction in the Greater Vancouver area from a "design earthquake" that is implied in the National Building Code of Canada. In comparable housing density the expected damage would be somewhat greater than that observed in the San Francisco region in October 1989 because of differences in amplitude of ground motions and building design standards. This study is seen as a first step in the detailed assessment of damage potentials for the Vancouver region, or other similar metropolitan areas. Potential shortcomings in the 1985 National Building Code of Canada were identified in the seismic requirements for non-engineered buildings (Part 9) concerning lateral bracing, beam splice ties over supports, and anchorage and reinforcing of chimneys.Key words: earthquake damage, building code, damage prediction.

ISSN:0315-1468    

DOI:10.1139/l90-092

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Damage to building structures during the October 17, 1989, Loma Prieta earthquake prompted site visits by the authors. This paper presents examples of damage to buildings constructed with reinforced concrete, steel, masonry, and timber. The observed damage is used to illustrate some of the seismic design clauses in the 1990 National Building Code of Canada, the 1984 Canadian Standards Association (CSA) Standard for the Design of Concrete Structures for Buildings, and the 1989 CSA Standard for the Limit States Design of Steel Structures. The important roles played by the presence of soft soil, poor structural layouts, inadequate detailing, the lack of reinforcement in masonry, as well as inadequate connections to foundations are highlighted. Examples of the performance of upgraded structures are also given, and the concern over the presence of existing hazardous buildings in significant seismic zones in Canada is emphasized.Key words: seismic design, earthquake, Loma Prieta, structures, codes, concrete, steel, masonry, timber, upgrading.

ISSN:0315-1468    

DOI:10.1139/l90-093

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The present work deals with formulation of theoretical and analytical methods leading to the development of column strength curves. The formulations were developed for both elastic and inelastic behaviour. Two types of reinforcement have been developed for strengthening the W-shape columns under load. Since the column strength curves are based in part on the magnitude and distribution of residual stresses, it is extremely important to consider the new pattern of residual stresses due to welding process. Also, the welding sequence will affect the magnitude and distribution of residual stresses. Theoretical formulations leading to a closed-form solution for the prediction of critical load were developed for two types of strengthening using the superposition of original residual, new welding, and initial loading stresses. A nonlinear finite element analysis based on the large deformation theory of stability was used to predict the strengthened column critical load. It takes into consideration the effect of cooling residual stresses and new welding residual stresses. The formulations were incorporated with gradual penetration of yielding, the spreading of inelastic zones along the member length, the presence of residual stresses, and strain hardening of the material. Experiments were carried out to determine the actual capacity of strengthened columns. Seven specimens were tested using two and four strengthening plates. The welding stresses were measured through a series of experiments, and it was found that the parabolic distribution is a very close approximation to the actual new welding stress distribution.Key words: reinforcement of steel columns, welding stresses, welding sequence, strengthening of existing structures, buckling, steel plating, finite element.

ISSN:0315-1468    

DOI:10.1139/l90-094

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

This paper examines the transient stress analysis of a multilayer pavement structure subjected to heat conduction and associated thermoelastic effects by the cooling of its surface. In particular, the layered structure contains a transverse crack which can be created either during the construction of the pavement or during its service life. The numerical treatment of the transient stress analysis is achieved using a finite element scheme, which models the heat conduction and thermoelasticity of each component in the layered system and the singular stress field at the extremities of a crack. The numerical scheme is applied to examine the manner in which the propagation of an existing crack is influenced by the thermoelastic mismatch between the layers adjacent to the crack location. The analysis also illustrates the influence of the thermoelastic mismatch between a cracked pavement and an overlay, in the suppression of crack propagation.Key words: fracture mechanics, pavement structures, low-temperature fracture, transient thermal effects, finite element modelling, stress intensity factors.

ISSN:0315-1468    

DOI:10.1139/l90-095

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Prestressed and nailed laminated timber bridge decks are made from laminates which, because of their being usually shorter in length than the deck span, are butt-jointed at regular intervals. In calculating deflections of such decks, it is usual to ignore the reduction in flexural rigidity of the deck caused by the presence of the butt joint. The effect of butt joints on the flexural rigidity of the laminated deck is studied analytically, and it is shown that the deflections of a deck having such joints may be significantly larger than those of a deck without them. A simple method is presented to account conservatively for the presence of butt joints in the calculation of the deflections of a prestressed laminated timber deck.Key words: timber bridge, laminated deck, butt joint, prestressed wood deck.

ISSN:0315-1468    

DOI:10.1139/l90-096

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Earlier simplified methods of analyzing elastic cantilever slabs subjected to concentrated loads involve the use of a cosh function along with graphical charts of a coefficient. It is shown that in the simplified methods, the cosh function, which was derived empirically, may be an approximation of a simple algebraic function. An example is presented to compare the results of rigorous analysis with those obtained by simplified methods incorporating the cosh and algebraic functions, respectively.Key words: cantilever slab, concentrated load, cosh function, deck slab overhang, simplified method.

ISSN:0315-1468    

DOI:10.1139/l90-097

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The present investigation deals with the removal of the lower portion of a glued laminated column in an existing uranium industrial processing plant in Saskatchewan, Canada. The lower 8 m of the column was eliminated to avoid transmission of high dynamic magnification forces created from installing a new rod mill in the crushing area of the plant. The construction details of transferring and securing the building column loads to the adjacent concrete wall and new steel trestle are examined. Some design aspects of a new built-up girder and other supporting elements are discussed. A summary of the construction procedure employed is given, which would be extremely valuable in similar structural alteration or rehabilitation jobs for old industrial plants. The construction of a new mill and the structural alterations were carried out during the spring of 1984. Since then, the new mill and the existing structure have performed satisfactorily.Key words: shearing existing column, rod mill, rehabilitation, built-up girder, structural alteration.

ISSN:0315-1468    

DOI:10.1139/l90-098

出版商:NRC Research Press    

年代:1990

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l90-099

出版商:NRC Research Press    

年代:1990

数据来源: NRC