LVL Handbook EUROPE

2. LVL STRUCTURES IN FLOORS, WALLS, ROOFS AND IN SPECIAL APPLICATIONS

In roof structures that have higher resistance to fire re-

quirements than the nail plate trusses can achieve, an LVL-P

bottom chord can be designed to carry the loads in the case

of fire as a beam, allowing the rest of the frame to be designed

to normal temperature requirements. Sides are protected with

stone wool insulation and the top edge is supported against

lateral torsional buckling.

When roof trusses are left visible, LVL-P king post or

queen post trusses with dowel type connections are an aes-

thetically pleasing solution. They are the most competitive op-

tion for 15-22 metre spans in cases where double-tapered solid

beams are uneconomical due to the roof slope and where the

fire resistance requirement is R15. With larger trusses, e.g. for

sports halls, LVL can be used for all truss components, as di-

agonals combined with glulam chords, or in hybrid structures

with steel members.

A 3-pin frame structure is a good solution when the interi-

or height of a hall needs to be maximized. The built-up column

part of the frame has two LVL-C panels which are screwed and

glued together with wooden battens to form a box structure.

The intermediate battens are shorter than the LVL-C panels

which creates a space for the rafter part of the 3-pin frame to

sit in. The battens should therefore have the same width as the

rafter. The rafter part of the 3-pin frame is a single LVL-P beam,

box beamor a glulambeam. The moment-rigid corner is a tim-

ber-to-timber connection made with bolt, screw or dowel cir-

cle without separate steel parts. The size and number of fasten-

ers in the corner connection depend on the size of the hall and

the loads. The crosswise veneers in LVL-C panels provide good

connection strength and prevent the risk of corner cracking

To optimize material use, it is recommended to choose

column panel and rafter sizes that fit the LVL panel width when

they are diagonally cut as a single taper. The wider end is at

the moment-rigid corner connection and the narrower end to-

Figure 2.80.

Left: LVL queen post trusses, Fupicsa production hall, Spain. Right: King post trusses, Manese Wassström, Tammisaari, Finland.

Metsä Wood

Stora Enso

Figure 2.81.

LVL roof trusses. Ydalir, France.

wards the pin points: the ridge and foundations. 3-pin frames

are the most competitive when the capacity of a single LVL-P

rafter is adequate for the loads. In areas with high wind loads a

small roof angle is preferable and in areas with high snow load

a larger roof angle is preferable. The economical span range is

10-30 m

19.

Figure 2.82.

Principle of diagonal sawing of LVL panels to produce

single-tapered column and rafter members for 3-pin frames. The

dimensions should be chosen so that the full panel width can be

used.

LVL Handbook Europe