Use of span tables for pre-dimensioning sandwich panels

To enable practical pre-dimensioning of sandwich panels, the manufacturers have compiled span/dimensioning tables and summarised these for their product ranges. These tables can be quickly and easily consulted for

- max. bolt distances (for wall panels)
- and the max. permissible snow loading (in the case of roof panels) with preset purlin distances.

To explain the span tables and their application, an example is taken from the product range of GALILEO member Hoesch Siegerlandwerke GmbH for the Hoesch isowand LL 60 (see page 8.2.2).

Explanations of the span table

Corner area: An increased wind load must be allowed for in the corner areas of the building (2.00 m from the corners on both sides).

Height above ground: The wind loads change with the height of the building, as per DIN 1055-4.

Building shape:BTo determine the wind pull, the dynamic pressure is multiplied by a pressure correction value c_p, dependent on the building shape. The h/a factor is determined for this purpose. If the determined factor is

<= 0,25 table —> column 0,25 >= 0,50 table —> column 0,50

Fig. 8.2.1 The span table on page 8.2.2 refers to installation-ready sandwich panels for walls with lined facings - Hoesch isowand System - type LL 60

Fig. 8.2.2 Dynamic pressure q dependent on the building height
bis = to; Staudruck = Dynamic pressure; Gebaudehoehe =Building height

Span table for pre-dimensioning sandwich panels

Static System

Fig. 8.2.3 Static system

Colour groups

The colour of the outer shell and thus the temperature is of considerable importance in the design of sandwich panels. The table on page 8.2.4 divides the common colour shades into colour groups I to III. The colour group dictates which line should be referred to in the span table.

Further important information

The tables only apply for identical spans (see also the following example).

Example:
Read value of triple beam - 4.00 mm means that the distances between bolts must not exceed 4.00 m.
In the case of different spans, e.g. 4.00 m / 2.50 m / 4.00 m, pressure can result in the maximum crush tension across the middle bearings being exceeded. One effect of this can be creases in the facing.

The span is the centre distance of the bearings.

The span table is designed so that deflection max. f: l/100, i.e. does not exceed 1/100 of the span.

The span table does not apply for buildings with unusual temperatures, e.g. cold stores.

The span table on page 8.2.2 includes verification of the bearing compression and of the fasteners.

Span tables serve for pre-dimensioning and do not replace the required static dimensioning.

Colours according to RAL CLASSIC with colour groups and brightness values for sandwich panels

*) The colour samples in this table in accordance with RYB values (Red-Yellow-Blue values) may differ from the original, depending on monitor, graphics card or printer, and are only intended as orientation aids.

Author: Karl-Heinz Wickel