Steel Structures for Buildings
This new edition of CSA Standard S16, Steel Structures for Buildings, supersedes previous editions published in 1924, 1930, 1940 and 1954.
In the comparatively short period of six years which has elapsed since the publication of the 1954 edition, the advances in science and technology have been such that the task of revising the Standard proved to be no light one. Techniques and materials, which had received little recognition previously, had developed to a point where they now demanded attention. Formulae which had been suitable when applied to the type of structural steel used almost exclusively heretofore, had to be reviewed in the light of a trend toward improved mechanical properties and a greater number of available steels. Rules which had been framed in the most general terms, had to become more precise. From an ever-growing mass of technical literature, and from data gleaned from the work of other engineering organizations, it has been necessary to extract and apply the salient features which affect this particular branch of engineering.
The size of the Standard has been increased, but every effort has been made to keep 1t as brief as is consistent with adequate coverage and clarity of expression. Repeatedly, the Committee had to admit that complete instructions, free from all possibility 'of misunderstanding, and framed to meet every conceivable eventuality, could be provided only by extending and elaborating the material into a text—book. A tendency in this direction may, in fact, be observed in some of the corresponding European Specifications. It has been avoided as far as possible in this Standard. The aim has been to follow a middle path between the opposing views of those who would assume that the Standard will be used only by experts who hardly need one, and those who feel that guidance should be provided for those who are relatively inexperienced in this field of engineering.
In previous editions of this Standard, reference was made in the prefatory remarks to the advisability of having design work carried out or supervised by competent Professional Engineers. This recommendation must again be repeated. It has been pointed out, above, that complete rules for every phase of design or fabrication could be provided only in a work of text—book proportions. It should also be obvious that mere possession of a. specification or text-book does not confer on the user the ability to design structures of the types therein described. Such ability must come from appropriate technical education and from actual experience. The work of the Committee has proceeded on the assumption that the Standard will be used by those whose technical background will enable them to grasp its intent and avoid misunderstanding.
In comparing this new edition with the preceding 1954 edition, many minor changes and some major ones will be found. Perhaps the most important changes are those in the section on Unit Stresses. It was agreed that the previous formula for compression members, which had the great merit of simplicity, contained features which would be erroneous if a plied to a high-strength steel. These features have been-corrected. The work of the Column Research Council proved very valuable in this regard. Similarly, the work of the Research Council on Riveted and Bolted Structural Joints provided the basis for permitting some increases in bolt and rivet values.
The addition of a section on Plastic Design represents a new departure, considered to be necessary in view of requests received from users of the Standard. Here, again, the aim has been to set forth only the essential rules. The work, gratefully acknowledged, of the American Institute of Steel Construction provided much of this material. To those not yet familiar with this comparatively new design technique, it should be pointed out that reference to a recognized text book or manual is necessary, since the new section in the Standard does not pretend to take the place of either.
The increasing use of perforated plates in lieu of lacing systems has led to the expansion of the relevant material in the Standard. Also, recognizing the fact that battens, which hitherto had been relegated to a secondary role were being used with success by designers particularly in the United Kingdom and in Europe, the Committee has made some corresponding modifications in the provisions for their use.
The Section on Open-Web Steel Joists has been re-written. This type of construction unit, originally a substitute in metal for the ordinary wooden floor joist, has developed into something much more ambitious in scope. The distinction which once could_be drawn between short-span and long-span joists proved to be meaningless in the light of the present overlapping of methods of manufacture. Joists of almost any span
can be found fabricated of either special or standard structural sections, and assembled by either manual or automatic welding processes. The familiar term Open-Web Steel Joist has been re-tained, although it was realized that the term might well be Standardized Truss. It is important that all users should recognize the fact that the Specification does not attempt to cover the design of joists which carry concentrated loads, have cantilever ends, have the function of providing a measure of rigidity in a building frame, or otherwise depart from the definition of a simple joist. Such members must continue to be designed on their merits rather than selected from a catalogue of standard joists
References to turned bolts have been omitted, since it appears that the use of this type of fastener has become a rarity. The explicit references to rib bolts have been changed to read special fasteners, since more than one type of bolt with a ribbed shank can be obtained. In the high—strength field, mention is made of interference body bolts, a tightly fitting high-strength bolt having a knurled shank. The term ordinary bolt has been substituted for unfinished bolt, as being more truly descriptive; for this item the Standard reference now covers the bolt itself, rather than the material from which it is made.
Various opinions were expressed as to suitable wording for some of the Standard clauses and also as to the necessity for certain requirements. Thus the form finally adopted does not necessarily represent in all respects a unanimous decision of the Committee. In spite of every effort shortcomings may appear. Unfortunately, the perfect specification is a goal unattainable because its writing and revision would never be completed. This Standard, like many others, is a compromise between new knowledge and former experience, and between the opinions and personal experiences of the Committee members who without exception have striven to make this new edition as complete and useful as possible.
This Standard was prepared by the Committee for Steel Structures for Buildings under the jurisdiction of the Sectional Committee on Steel Construction and was approved by these Committees and the CSA Technical Council.
This Specification applies to the design, fabrication and erection of the structural steelwork used in the construction of buildings. It is not intended to apply to bridges, transmission towers, radio and television towers, masts, fire-escapes, sign structures, suspended ceilings, skylights, greenhouses, or light-gauge steel construction consisting of members formed from flat—rolled sheet or strip.