sixteen wood construction: column design Compression Members (revisited) Critical Stresses (revisited) Effect of Length (revisited)

Transcription

1 ARCHITECTURAL STRUCTURES: ORM, BEHAVIOR, AND DESIGN DR. ANNE NICHOLS ALL 016 ltur sixtn wood onstrution: olumn dsign Comrssion Mmbrs (rvisitd) dsignd for strngth & strsss dsignd for srviability & dfltion nd to dsign for stability ability to suort a sifid load without suddn or unatabl dformations Wood Columns 1 Arhittural Struturs 009abn Wood Columns Efft of Lngth (rvisitd) long & slndr short & stubby Critial Strsss (rvisitd) whn a olumn gts stubby, rushing will limit th load ral world has loads with ntriity Wood Columns 3 Wood Columns 4 Elmnts of Arhittural Struturs ARCH 614 S009abn 1

2 Braing (rvisitd) Wood Columns braing affts sha of bukl in on dirtion both should b hkd! Wood Columns 5 slndrnss ratio = L/d min d 1 = smallst dimnsion l /d 50 (max) whr is th allowabl omrssiv strngth aralll to th grain braing ommon osts, round, built-u Wood Columns 6 f P A Elmnts of Arhittural Struturs ARCH 614 S009abn Allowabl Wood Strss C C C C C whr: = omrssiv strngth aralll to grain C D = load duration fator C M = wt srvi fator (1.0 dry) C t = tmratur fator C = siz fator C = olumn stability fator D M t (Tabl 10.3) Strngth ators wood rortis and load duration, C D short duration highr loads normal duration > 10 yars stability, C ombination urv - tabls C C htt:// D C Wood Columns 7 Wood Columns 8

3 C Charts Chatr 9, g 478 Tabl Emin E l d ( = 0.8 sawn, = 0.9 glulam) Column Charts Not in Andix Wood Columns 9 Wood Columns 10 Produr for Analysis 1. alulat L /d min KL/d ah axis, hoos largst. obtain omut 0.8E K E min E E (K E =0.3 sawn) l l (K E d d = glu-lam) E min Emin ( CM )( Ct )( CT )( Ci ) Produr for Analysis (ont d) 6. omut P allowabl = A or find f atual = P/A 7. is P P allowabl? (or f atual?) ys: OK no: ovrstrssd & no good 3. omut C D 4. alulat E / and gt C (Tabl 9.3) 5. alulat = C Wood Columns 11 Wood Columns 1 3

4 Produr for Dsign 1. guss a siz (ik a stion). alulat L /d min KL/d ah axis, hoos largst 3. obtain omut 0.8E K E min E E K E =0.3 sawn l l K E d d = glu-lam E min Emin ( CM )( Ct )( CT )( Ci ) Produr for Dsign (ont d) 6. omut C 7. omut P allowabl = A or find f atual = P/A 8. is P P allowabl? (or f atual?) ys: OK no: ik a biggr stion and go bak to st. 4. omut C D 5. alulat E / and gt C (Tabl 9.3) Wood Columns 13 Wood Columns 14 Timbr Constrution by Cod light-fram light loads x s floor joists x6, x8, x10, x1 tyial at saings of 1, 16, 4 normal sans of 0-5 ft or m lywood sans btwn joists stud or load-baring masonry walls limitd to around 3 storis fir safty Dsign of Columns with Bnding satisfy strngth stability ik stion Wood Columns 15 Wood Columns 16 4

5 Dsign Wood f fbx f bx 1 Ex 1.0 [ ] trm magnifiation fator for P- bx allowabl bnding strngth Dsign Sts Knowing Loads 1. assum limiting strss bukling, axial strss, ombind strss. solv for r, A or S 3. ik trial stion 4. analyz strsss 5. stion ok? 6. sto whn stion is ok Wood Columns 17 Wood Columns 18 Laminatd Timbr Arhs two & thr hingd arhs bnt to wid rang of urvs bnding and omrssion rsidual strss from laminating, C Laminatd Arh Dsign radius of urvatur, R, limitd by lam thiknss, t R = 100t southrn in & hardwoods R = 15t softwood r = radius to insid fa of laminations t CC r b = b (C C ) Wood Columns 19 Wood Columns 0 5