Steel Structures for Buildings
In response to requests received from time to time during 1922-1923, the Main Committee decided in October, 1923, to form a Committee for the purpose of drawing up a Standard Specification for Steel Structures for Buildings, it being intended that this should deal with steel construction for buildings in the same way as that in which the C.E.S.A, Specifications for Railway and Highway Bridges treat of steel bridge construction.
Inquiries showed that such a specification, if available, would be welcomed by fabricators and manufacturers, as well as by engineers and architects. It was felt also that its use- would promote economy and protect the public, especially if employed by local authorities in the formulation of their building by—laws, thus obtaining uniformity of practice throughout the Dominion.
The Committee on Steel Structures for Buildings includes architects; consulting engineers and representatives nominated by the fabricating companies, the inspection companies, and by- the Government Departments concerned.
In preparing the Specification now published, the Committee has carefully considered the work done in the United States and elsewhere along similar lines. It will, however, be noted that no drastic changes in existing practice are recommended for the present. It is considered that further investigations and experimental data are needed in regard to such composite forms of construction as columns encased in reinforced concrete and beam flanges embedded in concrete floor-slabs, before definite means can be specified for talking advantage of the additional stiffness or strength so obtained.
Attention is drawn to the live—loads in Appendix A, recommended for use on work Where no Engineer is engaged, or where the Engineer makes no alternative specification. The Committee recognizes that these recommended loads as given for various classes of buildings do not necessarily represent the maximum that such buildings may ever receive, but it is believed that they do, in normal cases, represent the loads for which it is desirable to limit the unit working stresses to the values specified. Where a building is likely to be subjected on extraordinary occasions to a temporary load somewhat in excess of the tabulated values, it is felt that the normal factor of safety will permit of the steel carrying temporarily a unit stress similarly in excess of the specified value, always provided that: the elastic limit be not reached.
In view of the complex technical problems now recognized as occurring in the construction of important buildings, it is considered essential that the computations involved in the proportioning of their structural steel work be made by, or under the direction of, a competent Professional Engineer.
The Specification was approved by the Committee on Steel Structures for Buildings in May, 1924, by the Sectional Committee on Steel Bridges and Construction in October, and by the Main Committee in November.