twenty four concrete construction: shear & deflection Shear in Concrete Beams ACI Shear Values ACI Shear Values

Transcription

1 FOUNDAIONS SRUCURES: FORM, BEHAVIOR, AND DESIGN DR. ANNE NICHOS FA 0 leture twent four Shear n Conrete Beam flexure omne wth hear to form agonal rak horzontal renforement oen t help trrup = vertal renforement onrete ontruton: hear & efleton Coprght Krk Martn Conrete Shear F009an Conrete Shear ACI Shear Value V u at tane from fae of upport hear apat: V where w mean thkne of we at n.a. w ACI Shear Value hear tre (eam) f = 0.75 for hear V f f n p hear trength: V V V u w V trength from trrup renforement Conrete Shear Conrete Shear 4

2 Strrup Renforement hear apat: V A v f Requre Strrup Renforement pang lmt A v = area n all leg of trrup = pang of trrup ma nee trrup when onrete ha enough trength! 0.75 Conrete Shear 5 Conrete Shear 6 oronal Stre & Stran an ee toronal tree & twtng of ax-mmetral ro eton torque reman plane untorte rotate not true for quare eton... Shear Stre Dtruton epen on the eformaton = angle of twt meaure an prove planar eton oen t tort Conrete Shear 7 Conrete Shear 8

3 Shearng Stran relate to the raal tane from the entro to the pont uner tran hear tran vare lnearl along the rau: at outer ameter oronal Stre - Stran know o f v G G an where G the Shear Moulu Conrete Shear 9 Conrete Shear 0 oronal Stre - Stran from an erve where J the polar moment of nerta elat range ( ) A J J Shear Stre happen at outer ameter omne hear an axal tree mum hear tre at 45 twte plane Conrete Shear Conrete Shear

4 Shear Stran knowng olve: G JG ompote haft: an J G J Nonrular Shape toron epen on J plane eton on t reman plane tll at outer ameter a where a longer e (> ) a G Conrete Shear Conrete Shear 4 Open hn-walle Seton wth ver large a/ rato: Conrete Shear 5 a a G Shear Flow n Cloe Seton q the nternal hear fore/unt length a the area oune the enterlne the length egment, t the thkne Conrete Shear 6 ta a 4t t 4

5 Shear Flow n Open Seton eah egment ha proporton of wth repet to toronal rgt, t total angle of twt: I eam - we thker, o n we Conrete Shear 7 t G t oronal Shear Stre twtng moment an eam hear Conrete Shear 8 oronal Shear Renforement loe trrup more longtunal renforement Development ength requre to allow teel to el (f ) tanar hook moment at eam en area enloe hear flow ple lappe mehanal onnetor Conrete Shear 9 Conrete Shear 0 5

6 Development ength l, emement requre oth e proper over, pang: No. 6 or maller No. 7 or larger Conrete Shear l l 5 F F f or n. mnmum 0 f or n. mnmum Conrete Shear Development ength hook en an extenon mnmum l h 00 f Development ength ar n ompreon 0. 0 F l f ple tenon mnmum funton of l an ple lafaton ompreon mnmum funton of an F F Conrete Defleton elat range I tranforme E (wth f n p) normal weght onrete (~ 45 l/ft ) onrete etween 90 an 60 l/ft rake I rake E ajute Conrete Shear Conrete Shear 4 6

7 Defleton mt relate to whether or not eam upport or attahe to a amageale nontrutural element nee to hek erve lve loa an long term efleton agant thee /80 /40 /60 /480 roof tem (tpal) lve floor tem (tpal) lve + long term upportng plater lve upportng maonr lve + long term Conrete Shear 5 7