Info

u fin.G — 14.82 mm u fin. q — 9.51 mm U net. fin — 24.33 mm

Example 6.7.4 A curved glulam beam with a constant cross-section, 175 mm wide, having a profile as shown in Figure E6.7.4, and with an effective span of 18.0 m is to be used in the construction of the roof for a school hall. The beam will be laterally supported along the full length of the compression edge and there will be no load sharing between glulam beams. It is strength class GL 32h in accordance with BE EN 1194:1999, made from 30-mm-thick laminations, and will function in service class 2 conditions. For the design loading condition given below, which includes an allowance for the self-weight of the beam, ignoring SLS requirements, confirm that the beam will comply with the design rules in EC5. The design loading arises from a combination of permanent and short-term variable loading.

1. Glulam beam geometric properties

Breadth of each beam, b b = 175 mm

Depth of the beam at the apex, hap hap = 960 mm

Effective span of beam, I I = 18.0m

Bearing length at each end of the beam, ¿b = 200 mm

Design action = 6 kN/m iiiiiiiiiiiiiiiiiiiiiiiiiiiiiii

Straight section

Bearing length at each end = 200 mm

Straight section

Bearing length at each end = 200 mm

Effective span =18 m

Effective span =18 m

Angle of slope of the straight member lengths of the beam, p

Inner radius of the curved beam section, rin = 18 m rin

Thickness of laminations in the beam, t t = 30 mm

Section modulus of the beam about the y-y axis at the apex, Wy

2. Glulam properties

Table 6.2, homogeneous grade GL 32h

Characteristic bending strength, /m.g.k Characteristic shear strength, /v.g k Characteristic bearing strength, /c.90.g.k Characteristic compressive strength,

Characteristic tensile strength perpendicular to the grain, /t,9o.g.k b-h ap2

/m.g.k = 32N/mm2 /v.g.k = 3.8N/mm2 /c.90.g.k = 3.3N/mm2 /c.o.g.k = 29 N/mm2

3. Partial safety factors

Table 2.8 (UKNA to BS EN 1990:2002, Table NA.A1.2(B))) for the ULS

Permanent actions, yg Yg = 1.35

Variable actions, yq Yq = 1.5 Table 2.6 (UKNA to EC5, Table NA.3):

Material factor for glulam at ULS, yM YM = 1.25

0 0

Post a comment