Structural Eurocodes EN 1995 Design of Timber Structures

Transcription

1 Structural Eurocoes EN 995 Design o Tiber Structures John J Murph Chartere Engineer EN Design o Tiber Structures General Coon Rules an Rules or Builings Liit state esign Tiber Properties IS-EN 338: 003 Table. Values are ith percentile characteristic values erive ro tests o ive inutes uration. Values or tension an bening relate to sections o epth 50. W, W : Elastic oulus Clause.3..3 Service Classes Table. Loa-uration classes Peranent (> 0 ears) Long-ter (6 onths 0 ears) Meiu-ter ( wee 6 onths) Short-ter (< wee) Instantaneous sel weight storage loaing ipose loor loaing snow; aintenance win 3 Internal Col roos, external walls External (ull expose) c < % % - 0% > 0% < 65% < 85% Table.3 γ M.3 (partial actor o saet or a aterial propert or soli tiber) rh

2 Service class Peran ent Long -ter Meiu -ter Shortter Table 3. o (soli tiber) Instantane ous.. Table 3. e : eoration actor e 0.6 (Service class ); e 0.8 (Service class ) Clause.4.() X o (X /γ M ) X : characteristic value o strength propert X : esign value o strength propert Clause.4.3() R o (R /γ M ) R : characteristic value o resistance (loa carring capacit) R : esign value o resistance (loa carring capacit) o : Moiication actor or loa uration an oisture content When loas are, or exaple, a cobination o Peranent an Meiu ter use o or Meiu ter. However, epening on agnitue o loas, it a be necessar to consier Peranent loa alone with o or Peranent. (3..3 ()) : strength propert : applie stress 3. (3): Depth actor h in {(50/h) 0.,.3} when h < 50 h is applie to an t,0, Clause 6.6 ss. (loa sharing)..3 Serviceabilit liit states () Mean values o ouli (5) u in,g u inst,g ( e ) u in,q u inst,q ( ψ, e ) ψ, : EC0 Table NA ( 0.3 or resiential, oice) e aes an allowance or creep (u: eoration) Clause 6..5 Copression perpenicular to the grain 90, 90 90, ( 90, 90, * o * ss / γ M ) 90, F 90, /A e (Eective bearing length actual bearing length ax. 30 on both sies) Clause 6..5 (4) 90.5 (soli tiber)

3 Clause 6..6 Bening about one axis ( * o * ss * crit * h / γ M ) (Eq 6. when, 0) : actor that aes allowance or re-istribution o bening stresses in a section ( 0.7 or soli tiber) Clause 6..7 () Shear τ v, ( * o * ss / γ M ) () b e cr * b cr 0.67 or soli tiber (to account or cracing o lexural ebers) Concentrate shear orce within epth o eber ro ace o support can be ignore () Meber with notch vertical notch at ege o support; soli tiber τ.5v/bh e v v, v Min. h n.5.i h x α( α ) 0,8 α h α Vertical notch at ege o support; soli tiber For 50 eep notch in 5 joist (length 50 ): v For 5 eep notch in 5 joist (length 50 ): v BS values: 0.78, 0.89, Cobine bening an axial copression Table 7. Liiting election (w inst : l/300 - l/500) (w in : l/50 - l/300) (w net,in : l/50 - l/350) (5) Lateral stabilit: crit.0 when copression ege is hel in place an torsional rotation at supports is prevente.,,,, when, or soli tiber o rectangular section 3

4 6.3 Stabilit o ebers 6.3. Coluns subjecte to either copression or cobine copression an bening λ λ π λ λ rel, π E E λ λ I λ an λ 0.3, stabilit is not an issue; Eq s 6.9 an 6.0 to be satisie 0.5( β ( λ 0.3) λ c ) 6.7,, ( β ( λ 0.3) λ c ) 6.8,, 6.4 For stu bening about axis: Beas subjecte to either bening or cobine bening an copression an bening M π E I G crit tor, crit W lew crit I 0.78b E hl e , λ crit 6.30 crit : (λ 0.75) λ (0.75 < λ.4) / λ (λ >.4)

5 7.3 Vibrations (3) Moal aping ratio ζ (eta) 0.0 ( 0.0) Eect o vibrations epens on huan sensitivit I < 8 H; ore etaile analsis require vibration acceleration is critical in ters o huan sensitivit. I > 8 H; vibration velocit is critical in ters o huan sensitivit. Assessent thereore requires consieration o: Natural requenc Delection ue to a vertical static loa ( N) Velocit ue to unit ipulse ( Ns) Resiential loors () Funaental requenc > 8 H π l ( EI ) l 7.5 w/f a /N 7.3 UK National Annex:- w inst,q (Fl 3 /48EI l )( ist * ap ) F N ap.05 or sipl supporte tiber joists (to account or shear election) ist ax (0.3, strut * ( * ln (4 * EI b /s 4 )) (to account or loa sharing ) strut.97 when strutting provie; otherwise v b ( ς ) /(Ns ) 7.4 Section 8 Connections with etal asteners 40 n 40 v b l 4 40 ( n ) bl 00 (a, b: Figure 7.) 4 ( EI ) l ( EI ) b UK NA Table 5: a.8 (l < 4000 ); 6500/l. (l > 4000 ) b 80 60a (a ); 60 40a (a > ) Clause 8. Lateral loa-carring capacit o etal owel-tpe asteners 8.3 Naile connections spacings, characteristic values etc. 8.5 Bolte connections - spacings, characteristic values etc. Design tables provie in Manual or the esign o tiber builing structures to Eurocoe 5 (TRADA, IStructE) This anual also provies useul inoration on Initial Design 5

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