Chuong 3 - Dam Thep

CHNG 3DM THPCh yu chu M v VChia 2 loi: dm hnh v dm t hp.

Nhng K trong thit k dmTha K chu lc ti tit din nguy him.Bn bng, bn cnh tha iu kin chu lc cc b v lc tp trung.Tha K vng.Tha K n nh tng th.Tha K cu to v kh thi.

Thit k dm thp hnhChn tit dinKim tra bnKim tra n nh tng thCu to v tnh ton cc chi tit

Chn tit din dm hnhTheo s kt cu, xc nh M v VXc nh moment khng un yu cu:

Tra bng quy cch thp cn nng, chn li dm hnh tha:

Kim tra K bn v unXc nh li M c k trng lng bn thn dm.Kim tra theo cng thc:

Kim tra K bn chu ctXc nh li V c k trng lng bn thn dm.Kim tra theo cng thc Jurapski:

Kim tra bn bng chu ng sut cc b

Kim tra bn bng chu ng sut cc b (tt)

Kim tra tit din chu ng thi , v c

Kim tra vng dmVi dm n gin, nhp L chu ti trng phn b u:

Kim tra n nh tng th dm

THIT K DM T HPCng trnh chu ti trng ln (q>20kN/m).Nhp ln (L>12m).Trnh t: chn tit din, kim tra bn, bin dng, n nh, cu to v tnh ton cc chi tit.

hmin h hkt (hmax)Chn chiu cao dm

Xc nh chiu dy bn bngCoi nh bn bng ch chu lc ct Vmax

Xc nh chiu dy bn bng (tt)

Xc nh kch thc cnh

Xc nh kch thc cnh (tt)

Kim tra bnTheo K chu un:

Theo K chu ct:

Ti tit din chu ng thi M v V:

Kim tra bn chu ng sut cc b bn bng Khi bn bng khng c sn gia cng:

Kim tra dm chu , v c:

Kim tra vngKhi chn h hmin th khng cn kim tra vng.

Nu khng th kim tra vng:

KiM TRA N NH TNG TH

tnh b cn theo trnh t: tnh , tra bng 3.4 tm , tnh 1, tnh b Ch : s dng cho dm I n gin

Cc trng hp khng cn kim tra n nh tng thC bn sn thp hoc BTCT.Khi tha iu kin:

Cc bin php tng cng n nh tng thXem xt vic s dng bn sn.iu chnh t s bf/tf hay bf/hf tha mn biu thc trn.Gim nhp tnh ton ngoi mt phng cho cnh nn dm (b tr thm h ging, thanh chng ngang).

n nh cc b bn cnh

n nh cc b bn cnh (tt)ng sut ti hn:

Quan nim mt n nh khi cr = f

n nh cc b bn bngDo ng sut tip (do V):

Cho cr = fv, suy ra:

Ch : ti trng tnh tc dng

n nh cc b bn bng (tt)Khi th tha iu kin n nh bn bng.Ngc li phi gia cng sn ngang.

n nh cc b bn bng (tt)Khi b tr sn ngang nh trn th mnh quy c thay i nh sau:Nu lc ny th bn bng t K n nh

n nh cc b bn bng (tt)

Do ng sut php:

n nh cc b bn bng (tt)iu kin khng ch:

Khi t s hw/tw vt qu gi tr trn th bn bng b mt n nh cc b.Cn phi gia cng sn dc.

n nh cc b bn bng (tt)Do tc dng ng thi ca ng sut php v ng sut tip:Trng hp th 1: khi khng c ti trng tp trung (c = 0) v

n nh cc b bn bng (tt)Trng hp th 2: khi c ti trng tp trung (c 0) v

CU TO V TNH TON CC CHI TiT DM HNHLin kt bn bng v cnh:

Cu to mi ni dm

Cu to mi ni dm (tt)

TNH TON MI NI DM T HP

Dng lin kt bulong ni dm

Dng lin kt bulong ni dm (tt)Tng din tch cc bn ni khng nh hn din tch thp c bn.Khi ni cnh: nu l bulong chim 15% din tch bn ni th ly tit din thc ca bn ni ( tr i tit din gim yu do l khot).

Dng lin kt bulong ni dm (tt)Moment un tc dng ti mi ni:

Dng lin kt bulong ni dm (tt)Trnh t tnh ton: Chn trc ng knh bulong v kch thc bn ghp.Tnh ton kim tra mi ni bng: chn trc s hng bulong nw cho 1 bn mi ni (chn theo khong cch min), tnh ton theo cng thc (khi ch c M):

Dng lin kt bulong ni dm (tt)

Dng lin kt bulong ni dm (tt)Khi c M v V tc dng ng thi (V ch do bn bng chu):

Dng lin kt bulong ni dm (tt)Kim tra mi ni cnh: S bulong mt bn mi ni:

CHNG 4: CT C CHU NN NG TM V LCH TMS tnh u ct: ngang khp c nh, dc ngm trt.Chn ct: khp, ngm.Khung: u ct lin kt cng.Ct chu nn ng tm: u ct LK khp.Chiu di tnh ton: L0 = .L: h s chiu di tnh ton (ph thuc s tnh), tra bng 4.1

mnh ca ct

CT C CHU NN NG TM

Tnh ton ct c chu nn ng tmTnh ton v bn:

Tnh ton n nh tng th:

min tra bng II.1 ph lc II ty theo max

Tnh ton ct c chu nn ng tm (tt)Tnh ton n nh cc b: xt mnh ca tng bn bng hay bn cnh.

Tnh ton ct c chu nn ng tm (tt)Tnh ton v bn:

Tnh n nh tng th:

Tnh ton ct c chu nn ng tm (tt)Tnh ton n nh cc b:

Tnh ton ct c chu nn ng tm (tt)

Xc nh tit din ct c chu nn ng tm

Xc nh tit din ct c chu nn ng tm (tt)

Xc nh tit din ct c chu nn lch tm, nn un

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Chuong 3 - Dam Thep