LOADS EVALUATION

Permanent loads

the load given by the roofing including battens and rafters: gp 500N

m2

Snow load

35 r 35 ( )180

0.611 rad

Sok 2kN

m2

ce 1ct 0.951 0.8

2 0.8 0.8

30 1.733

Sk1 Sok 1 ce ct 1.52 103 PaSk2 0.5 Sok 1 ce ct 760PaSk3 Sok 2 ce ct 3.293 103 Pa Sk Sk3

Wind load

qref 0.5kN

m2

I x( )2.35

2.5 lnx0.4

I 10( ) 0.292cg 1 3.5 2 0.303 3.121

cr 0.222 ln10.270.4

2

0.51

ctw 1

ce cg cr ctw 1.591 The coefficient cp is negative so that on the roff side directly exposed to the wind action there is sucction having asdirect effect the derease of loads acting on the frame system.For heavy weight roofs this effect is not taken into account.

cp 0.86w qref ce cp 684.188 Pa

Live load

P 1000Nm

RAFTERS DESIGN

Permanent loads

d1 0.8mbr 15 cm

l2 4.25m hr 15 cmd2 3.5mcos r( ) 0.819sin r( ) 0.574n 1g_pc gp n d1 400 kg

s2

g_pcn g_pc cos r( ) 327.661 kgs2

Snow load

gzc Sk3 d1 2.635 103 kgs2

qzn gzc cos r( )2 1.768 103 kgs2

Wind load is not taken into account since is suction

Live load

Pnc P n 1 103 kgs2

Pncc Pnc cos r( ) 819.152 kg

s2

Loading hypothesis

q1 1.35 g_pcn 1.5 qzn 3.094 103 kgs2

q2 1.35 g_pcn 1.05 qzn 2.299 103 kgs2

q3 1.35 g_pcn 1.5 Pncc 1.05 qzn 3.527 103 kgs2

q4 1.35 g_pcn 1.5 qzn 1.05 Pncc 3.954 103 kgs2

Bending moments computation

M1q1 l228

6.986 103 J

M2q2 l228

5.19 103 J

M3q3 l228

7.964 103 J

M4q4 l228

8.928 103 J Mmax M4 8.928 103 J

Strengt check

W brhr( )2

6 0.563L

0.55 gp 0.65 Sk3

gp Sk3( ) 0.64

Ric 21.68N

mm2 obtained by interpolation between 2 values of

mti 0.9 surgace treated and fireproofed wood

Mr Ric W mti 1.098 104 J Mmax Mr OK

Deflection check

fadml2200

0.0213m

permanent load

gpn gp d1 cos r( ) 327.661 kgs2

snow load

gzn Sk cos r( )( )2 d1 1.768 103 kgs2

live load

Pcn P cos r( ) 819.152 kgs2

deformations due to permanent loads

Ibr hr( )3

124.219 10 5 m4

E 11300N

mm2

Kdef_p 0.5

fp_inst5384

gpn l24E I 2.92 10

3 m

fp_c fp_inst 1 Kdef_p( ) 4.38 10 3 m

deformations due to snow load

Kdef_z 0.25

fz_inst5384

gzn l24E I 0.016m

fz_c fz_inst 1 Kdef_z( ) 0.02m

deformations due to live load

Kdef_l 0

fl_inst5384

Pcn l23 1 mE I 1.718 10

3 m

fl_c fl_inst 1 Kdef_l( ) 1.718 10 3 m

f1 fp_c fz_c 0.024mfl fp_c fl_c 6.097 10 3 m fmax f1 0.024m

fmax fadm

CENTRAL PURLIN DESIGN

Permanent load

bp 25 cmlc 2.55mhp 25 cm

d2 3.5mn 1n1 1.1cos r( ) 0.819 8400

N

m3 acacia( )

qpp gp n d2 1cos r( )

bp hp n1 2.714 103 kgs2

the element is not subjected to biaxial bending as it should be , because wind is in suction and it isnot considered in computation

Snow load

qzp_p Sk d2 1.153 104 kgs2

Live load

Pp P n 1 103 kgs2

Loading hypothesis

q1p 1.35 qpp 1.5 qzp_p 2.095 104 kgs2

q2p 1.35 qpp 1.05 qzp_p 1.577 104 kgs2

q3p 1.35qpp 1.05 Pp 4.714 103 kgs2

q4p 1.35 qpp 1.5 qzp_p 1.05 Pp 2.2 104 kgs2

Bending moments computation

M1p q1p lc( )2 1.363 105 J

M2p q2p lc( )2 1.025 105 J

M3p q3p lc( )2 3.065 104 J

M4p q4p lc( )2 1.431 105 J Mmaxp M4p 1.431 105 J

Strengt check

Wpbp hp( )2

27.813L

0.55 gp 0.65 Sk3

gp Sk3( ) 0.64

Ric 21.68N

mm2 obtained by interpolation between 2 values of

mti 0.9 surgace treated and fireproofed wood

Mrp Ric Wp mti 1.524 105 J Mmax Mr OK

Deflection check

fadmplc200

0.0128m

deformations due to permanent loads

Ipbp hp( )3

123.255 10 4 m4

E 11300N

mm2

Kdef_p 0.5

fp_instp5384

gpn lc4E I 3.784 10

4 m

fp_cp fp_instp 1 Kdef_p( ) 5.676 10 4 m

deformations due to snow load

Kdef_z 0.25

fz_instp5384

gzn lc4E I 2.042 10

3 m

fz_cp fz_instp 1 Kdef_z( ) 2.552 10 3 m

f1 fp_cp fz_cp 3.12 10 3 mfmax f1 3.12 10 3 mfmax fadm

CENTRAL PURLINDESIGN

' Permanent load

15

dp 15 cmhp 2.25mt 2.55 m

Npopgp n

cos r( )d2 t bp hp n1 t dp

24

n1 hp 1.907 10

4 N

Snow load

Nzp Sk d2 t 2.939 104 N

Wind load is not taken into account since it is suction

Live load is not significant compared to the snow load in the case of post design

Loading hypothesis

N1 1.35 Npop 1.5 Nzp 6.983 104 NN2 1.35 Npop 1.05 Nzp 5.661 104 N

Post checking

gperm gp bp hp 1t

dp2

4hp 1

t 1

d2 2.39 103 Pa

p0.8 gperm 0.85 Sk

gperm Sk 0.829

Rcp 11.80N

mm2

Ac dp24

0.018m2

mtc 0.9 surface treted and fire proofed woodi 0.25 dp 0.038m

lf hp 0.75m 1.5m

lfi

40 75

1 0.8

100

2

0.872

Cr Ac Rcp mtc 1.636 105 N N Cr OK