Civil Engineering Association

One of the main physical properties of a hollow profile is its optimal efficiency, superior to all other structural elements, in resisting compression. In filling the hollow profile with concrete, one, increase its structural capacity considerably or, potentially, one decreases, for a given load, clutter in reducing the section of a pillar. An excellent resistance to fire is also obtained in this way, without having ecourse to external protection. This aspect is already the object of a precedent dimensioning guide.
This guide is the fifth in the set of works by the CIDECT under the general title "Construction with Hollow Steel Sections". It is destined to help engineers and businessmen anxious to use concrete filled hollow profiles as pillars, as much in buildings as in bridges, under static loads but also under seismic conditions because these profiles behave remarkably in earthquakes.

This sixth manual of the set of works by the CIDECT under the general title "Construction with Hollow Steel Sections" is destined to encourage projects and products engineers, inventors and manufacturers to examine the excellent mechanical, architectural and structural qualities of hollow profiles in steel compared to those of the other open profiles, and to dedicate a little time to study a project or a product to see if the utilisation of hollow profile in steel would improve techniques and, what is probably more important, would lead to savings.
In order to compensate for a specific lack of knowledge in the field of construction in hollow profiles, which is, often the case among mechanical construction engineers, this manual not only offers advice concerning manufacture, assembly and installation, but recommends methods to use for static and fatigue calculations. Above all, this work, contains many examples of constructions in various fields, which will help the reader to understand suitable procedures for the utilisation of these profiles.
Thanks to the international co-ordination of researches and the technical projects of the CIDECT (International Committee for the Development and the survey of the Tubular Construction) unified calculation recommendations have been introduced in the International and European codes of dimensioning of structures in circular hollow and rectangular profiles in steel.

This seventh manual of the CIDECT collection "Construction with Hollow Steel Sections", treats the main aspects of manufacture, assembly and installation of structures in hollow profiles, that must be taken into consideration to obtain a secure, economic and architecturally pleasing construction.
This manual is designed for architects, estimators and manufacturers to give to each of them a preview and an understanding of the necessary requirements for the economic dimensioning of structures using hollow profiles in steel. In all types of constructions, it is essential that these three parties have the same understanding of the whole of the industrial chain.
This manual contains technical information on elementary constructive arrangements, methods, of assembly (welding, bolting etc.), constructive details and their influence on the resistance of the assembly, hot and cold bending, manufacture in factory or on the site, transport, large unit installation. Certain economic aspects which can affect the global cost of the construction are also handled.

Rectangular or circular hollow steel sections are often used in construction because of their structural efficiency and also because of their shape, when a visible architectural expression is required. The surface and profile of hollow steel sections are attractive and their high load bearing capacity leads to slim, economic and elegant constructions with large spans. Unprotected structural hollow sections (SHS) have an inherent fire resistance of some 15 to 30 minutes. Traditionally, it has been assumed that unprotected steel members fail when they reach temperatures of about 450 to 550OC. However, the temperature at which a steel member reaches ultimate limit state, is dependent on the massivity of the section and the actual load level. If the service load level of a column is less than 50°/o of its resistance, the critical temperature rises to more than 650°C, which means for bare steel an increase In failure time of more than 20%. When hollow steel sections are required to withstand extended periods in fire, additional measures, such as the following have to be taken to delay the rise in steel temperature.