Glulam – Primary structures
Pitched cambered beams
with straight bottom flange

Glulam – Primary structures
Pitched cambered beams
with straight bottom flange

Glulam – Primary structures
Pitched cambered beams
with raised lower chord

Glulam – Primary structures
Pitched cambered beams
with raised lower chord

Pitched cambered beams
with straight bottom flange

Pitched cambered beams with a straight bottom chord represent an extremely economical variant due to the girder geometry adapted to the course of forces and the roof pitch. The top edge of the beams runs according to the minimum roof pitch of 2 – 5° required to drain the water. At the point of highest bending stress in the centre of the panel, the required cross-sectional area for absorbing the bending moment results from the specified inclination.
The design with a cantilever arm on one or both sides increases the economic efficiency, as this optimises the moment distribution. It should be taken into account that the length of the cantilever arm should usually not exceed 25% of the field length. The resulting canopies can be used as covered temporary storage or also as a shelter for motor vehicles. Saddle roof beams are used in industrial construction as well as in sports and leisure construction. When choosing the roof covering, cold and warm roofs can be used. Here, the profiles are either laid from truss to truss in the longitudinal direction of the hall without an additional secondary supporting structure or from the ridge to the eaves via purlin systems. The structure is supported on supports made of wood, concrete or steel, which should be clamped at least on one side to dissipate the wind forces.
Openings and recesses for piping (heating, sprinkler system, etc.) are reinforced by planking on the outside. When dimensioning, a width to height ratio of 1:10 must be taken into account. Furthermore, care must be taken to ensure appropriate tilt bracing of the beams by means of bracing or roof panels.

Technical
Data

Span 10 – 50 m
Roof pitch 2 – 5°
Usual beam spacing (other dimensions possible) 5 – 7 m
Beam width (2 cm preferred dimensions each) 10 to 26 cm
Cantilevers yes
Height of components (for structural design) h1 = l/16 ; h2 = l/25 to l/30
Possible fire resistance classes R 30 > without problems
R 60 > with additional costs
Preferred strength classes GL 24h/c, GL 28c, GL 30c

Pitched cambered beams
with raised lower chord

This type of girder offers similar advantages as the gable roof girder described above, but here the roof pitch can be set at up to 20°. This means that roof coverings, e.g. tile coverings, which require a steeper roof slope for drainage, can also be implemented.
The transverse tensile stresses in the middle beam area that occur with greater roof pitches must be absorbed by additional transverse tensile restraints, glued-in threaded rods or external planking. The measures should be explicitly listed in the tender. The ridge saddle of these trusses is usually not statically stressed and can also be replaced by an elevation. If a continuous rooflight is installed in the ridge area, this can be omitted completely.
When planning, it is essential to keep the question of transport in mind due to the greater roof pitch. Transport widths of up to approx. 3.50 m are common. When dimensioning, a width to height ratio of 1:10 must be maintained. The tilt bracing of the girders by bracing or roof panes is to be taken into account in the tender.

Technical
Data

Span 10 – 40 m
Roof pitch 5 – 20°
Usual beam spacing (other dimensions possible) 5 – 7 m
Beam width (2 cm preferred dimensions each) 10 to 26 cm
Cantilevers yes
Height of components (for structural design) h1 = l/14 – l/16; h2 = l/20 – l/24
Possible fire resistance classes R 30 > without problems
R 60 > with additional costs
Preferred strength classes GL 24h/c, GL 28c, GL 30c

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