Subiecte Metale

1. Elements of the transversal frame of a steel industrial building

The transversal frame is the main structure of the building consisting in columns and girders interconnected and its design depends on the dimensions imposed by the technological processes- equipment, devices and various systems for lifting and transportation both horizontally and vertically inside the building. When the transversal frame has more than one span, the slope of the roof has to be small (3 5%) (fig.3 ).

Fig. 3. Sloping the trusses and girders of the transversal frames of industrial buildings

If the roof has two slopes longitudinal skylights are not recommended because of adequate water drainage from the roof (fig.4 ). The most frequent structures have double pitched roofs in the central span and mono-pitched roofs in the lateral span.

The current industrial buildings may be equipped or not with cranes. Also, there may be one crane or two or even more, placed either at the same level or at different levels. Sometimes, the cranes travel in one single span, although the building is made of several spans and on the contrary, sometimes the cranes travel along all the transversal section of the building and special measures must be taken in order to keep the constant level (fig.4.d )

The span of the building is measured between the axes of the crane girders in the case when the runway girders are sustained by columns and respectively, in the axes of the columns at the foundation level in the case when there are not crane girders or when the crane girders are sustained by brackets attached to the columns with constant cross section.

Standard STAS 1686-79 imposes the modulation of the span L and the bay lT of the industrial buildings, the module being 30 M, where the basic module is M=100 mm in construction. However, for steel structures, 60 M or 120 M is preferred. The usual modulation determines spans of: 18, 24, 30, 36 m, in this case the bay being of 6 m. Another modulation imposed by the necessities may be: 9, 15, 21, 27, 33 m, the bays being 15, 18 m.

2. Purlins for industrial buildings: types of sections, connection between the parts of a continuous purlin: welded at site, bolted.

Purlins are beams that sustain the layers of a flat roof or the cladding of a sloping roof to an industrial building. They are made from hot-rolled profiles, the most used sections being universal beams, joists, channels, structural hollow sections also special sections as Castella beams all of them for bays between 6 9 m For bays between 9 15 m the economic solution is the truss made of smaller sections, generally hollow sections fig4

Fig. 2.Connection between the parts of a continuous purlin: a)- welded at site; b)- bolted; c)-distance from the support recommended as joining position; d)- full continuity insured by welded splices on the web and on flanges

3.Details of supports of purlins on trusses –simply supported purlins; continuous purlins