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TCVN TIU CHUN VIT NAM

TCVN . - 1-1 : 2008 EN 1996 - 1 - 1:2005

Bin son ln 1

THIT K KT CU XY PHN 1-1: QUY TC CHUNG CHO KT CU XY

KHNG C CT THP V C CT THP

Design of masonry structures. Part 1-1: General rules for reinforced and unreinforced masonry structures

H Ni - 2008

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Li ni u

TCVN *-1-1 :2008 (EN 1996-1-1 :2005) Thit k kt cu xy: Phn 1 - Quy tc chung cho kt cu xy khng c ct thp v c ct thp c bin son trn c s chp nhn tiu chun EN 1996-1-1 :2005 Eurocode 6 : Design of masonry structures Part 1 General rules for reinforced and unreinforced masonry structures.

Eurocode 6 c 4 phn

- EN 1996 - 1 - 1: Quy tc chung i vi khi xy khng c ct thp v c ct thp

- EN 1996 - 1 - 2: Quy tc chung- thit k chu la cho kt cu.

- EN 1996 - 2: Cn nhc thit k, la chn vt liu v thi cng khi xy.

- EN 1996 - 3: Phng php tnh n gin ho i vi kt cu xy khng c ct thp.

Tiu chun Thit k kt cu xy c bin son ln ny gm 3 phn (phn 1-1, 1-2 v phn 2). Phn 3 s c bin son sau.

Ph lc quc gia cho EN 1996-1-1

Cc chn la quc gia cho php trong EN 1996-1-1 c nu cc iu:

- 2.4.3(1)P Trng thi cc hn;

- 2.4.4(1) Trng thi gii hn s dng;

- 3.2.2(1) Quy nh v va xy;

- 3.6.1.2(1) Cng nn c trng ca khi xy khc vi khi xy m thnh;

- 3.6.2.(3), (4) v (6) Cng ct c trng ca khi xy;

- 3.6.3(3) Cng un c trng ca khi xy;

- 3.7.2(2) M un n hi;

- 3.7.4(2)T bin, dn hoc co do m v dn n nhit;

- 4.3.3(3) v (4) Ct thp;

- 5.5.1.3(3) Chiu dy hiu dng ca tng xy;

- 6.1.2.2(2) Gi tr mnh c m thp hn n th t bin c th b qua; - 8.1.2(2) Chiu dy ti thiu ca tng;

- 8.5.2.2(2) Tng rng;

- 8.5.2.3(3) Tng kp;

- 8.6.2(1) Rnh tng v hc tng thng ng;

- 8.6.3(1) Rnh ngang v nghing

Hin ti do cha c c s d liu phc v cho vic bin son ph lc quc gia ca Vit Nam nn cc gi tr quy nh trong ph lc quc gia ca Vng Quc Anh cho cc iu trn c nu Ph lc K tham kho. Khi thit k, c th p dng cc gi tr khuyn co nu trong ni dung tiu chun ny hoc p dng cc gi tr nu Ph lc K nhng phi m bo tnh ng b (ch p dng cc gi tr nu phn ni dung tiu chun hoc ch p dng cc gi tr nu Ph lc K).

TCVN - 1 - 1 : 2008 c B Khoa hc cng ngh ban hnh theo Quyt nh s ngy ..thngnm..

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Mc lc

1 Tng qut........................................................................................................................... 1

1.1 Phm vi p dng ...................................................................................................... 1

1.2 Ti liu vin dn....................................................................................................... 2

1.3 Cc gi thit ............................................................................................................. 4

1.4 Phn bit gia nguyn tc v cc quy tc p dng ................................................. 4

1.5 Thut ng v nh ngha.......................................................................................... 4

1.6 K hiu ..................................................................................................................... 9

2 C s thit k ................................................................................................................... 13

2.1 Yu cu c bn...................................................................................................... 13

2.2 Nguyn tc thit k theo trng thi gii hn .......................................................... 14

2.3 Cc bin c bn..................................................................................................... 14

2.4 Kim tra theo phng php h s ring ................................................................ 14

2.5 Thit k c s tr gip ca th nghim ............................................................ 15

3 Vt liu............................................................................................................................... 15

3.1 Vin xy ................................................................................................................. 15

3.2 Va ........................................................................................................................ 17

3.3 B tng chn.......................................................................................................... 18

3.4 Ct thp ................................................................................................................. 19

3.5 Thp ng sut trc.............................................................................................. 19

3.6 c trng c hc ca khi xy .............................................................................. 19

3.7 c tnh bin dng ca khi xy............................................................................ 26

3.8 Cc thnh phn ph............................................................................................... 28

4 bn lu ......................................................................................................................... 28

4.1 Tng qut............................................................................................................... 28

4.2 Phn cp iu kin mi trng.............................................................................. 28

4.3 bn lu ca khi xy......................................................................................... 29

4.4 Khi xy di t................................................................................................... 31

5 Phn tch kt cu.............................................................................................................. 31

5.1 Tng qut............................................................................................................... 31

5.2 ng x kt cu tnh hung ngu nhin (ngoi ng t v chy) ..................... 32

5.3 S khng hon chnh............................................................................................. 32

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5.4 Hiu ng th cp ................................................................................................... 32

5.5 Phn tch cc cu kin kt cu............................................................................... 33

6. Trng thi cc hn............................................................................................................. 43

6.1 Tng xy khng ct thp ch yu chu ti trng ng......................................... 43

6.2 Tng xy khng c ct thp chu ti trng ct ..................................................... 48

6.3 Tng xy khng ct thp chu ti trng ngang..................................................... 48

6.4 Tng xy khng ct thp chu t hp ti trng ng v ngang ........................... 51

6.5 Thanh ging ........................................................................................................... 51

6.6 Cu kin xy c ct thp chu un, un kt hp vi ti trng dc trc, hoc ti trng dc trc ..................................................................................................................... 52

6.7 Khi xy c ct thp chu ct.................................................................................. 58

6.8 Khi xy ng sut trc......................................................................................... 61

6.9 Khi xy b hn ch bin dng ............................................................................... 62

7 Trng thi gii hn s dng............................................................................................... 62

7.1 Tng qut ............................................................................................................... 62

7.2 Tng xy khng c ct thp ................................................................................ 63

7.3 Cu kin xy c ct thp ........................................................................................ 63

7.4 Cu kin xy ng sut trc.................................................................................. 63

7.5 Cu kin xy b hn ch bin dng ........................................................................ 64

7.6 Tng chu ti trng tp trung................................................................................ 64

8 Cu to ............................................................................................................................... 64

8.1 Chi tit khi xy ...................................................................................................... 64

8.2 Chi tit ct thp ...................................................................................................... 66

8.3 Chi tit ng sut trc ........................................................................................... 71

8.4 Chi tit khi xy b hn ch bin dng.................................................................... 71

8.5 Ni tng ............................................................................................................... 72

8.6 Rnh tng v hc tng...................................................................................... 73

8.7 Lp cch m .......................................................................................................... 75

8.8 Co gin nhit v co gin di hn............................................................................ 75

9 Thi cng ............................................................................................................................ 75

9.1 Tng qut ............................................................................................................... 75

9.2 Thit k cc cu kin kt cu................................................................................. 75

9.3 t ti ln khi xy ................................................................................................. 75

Ph lc A (Tham kho) S cn nhc cc h s ring c lin quan n thi cng ........... 76

Ph lc B (Tham kho) Phng php tnh lch tm ca li n nh ............................. 77

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Ph lc C (Tham kho) Phng php n gin ha tnh lch tm ngoi mt phng ca ti trng tc ng ln tng .................................................................................................. 79

Ph lc D (Tham kho) Xc nh 3 v 4 ....................................................................... 83 Ph lc E (Tham kho) H s m men un, 1, trong tm tng mt lp, cht ti ngang c chiu dy nh hn hoc bng 250 mm ................................................................................. 84

Ph lc F (Tham kho) Gii hn ca t s chiu cao v chiu di vi b dy i vi tng theo trng thi gii hn s dng............................................................................................ 89

Ph lc G (Tham kho) H s gim mnh v lch tm ........................................ 91

Ph lc H (Tham kho) H s tng nu trong 6.1.3 ....................................................... 93

Ph lc I (Tham kho) iu chnh ti trng ngang cho tng ta trn ba hoc bn cnh chu ti trng ngang ngoi mt phng v ti trng ng ....................................................... 94

Ph lc J (Tham kho) Cu kin xy c ct chu ti trng ct - s tng ca vd................ 95 Ph lc K (Tham kho) Ph lc quc gia ca Vng Quc Anh ................................... 96

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TIU CHUN VIT NAM TCVN - 1 - 1:2008 Bin son ln 1

Thit k kt cu xy. Phn 1-1: Quy tc chung cho kt cu xy khng c ct thp v c ct thp Design of masonry structures. Part 1-1: General rules for reinforced and unreinforced masonry structures

1 Tng qut

1.1 Phm vi p dng 1.1.1 Phm vi p dng ca tiu chun Thit k kt cu xy

(1)P Tiu chun Thit k kt cu xy p dng thit k nh v cc cng trnh xy dng hoc cc b phn ca chng bng khi xy khng c ct thp, khi xy c ct thp, khi xy ng sut trc v khi xy b hn ch bin dng.

(2)P Tiu chun Thit k kt cu xy ch cp n cc yu cu v bn, tnh kh dng v bn lu ca kt cu. Nhng yu cu khc (v d, lin quan ti cch nhit hoc cch m) khng c xem xt.

(3)P Kha cnh thi cng ch c cp mt mc cn thit ch ra cht lng ca vt liu v sn phm xy dng cn s dng v tiu chun tay ngh trn cng trng cn t c tun th cc gi thit dng trong cc quy tc thit k.

(4)P Tiu chun Thit k kt cu xy khng cp n cc yu cu c bit ca thit k khng chn. Cc iu khon lin quan n cc yu cu c cho trong Eurocode 8, n b sung v ph hp vi tiu chun ny.

(5)P Cc gi tr bng s ca cc tc ng ln nh v cng trnh xy dng a vo tnh ton trong thit k khng c cho trong tiu chun Thit k kt cu xy. Chng c cho trong Eurocode 1.

1.1.2 Phm vi p dng ca phn 1-1

(1)P Phn 1-1 nu c s thit k nh v cng trnh xy dng th xy, p dng cho khi xy khng c ct thp v khi xy c ct thp, ct thp c thm vo to do, cng hoc ci thin tnh kh dng. Phn ny c a ra cc nguyn tc thit k khi xy ng sut trc v khi xy b hn ch bin dng nhng khng c cc quy tc p dng. Khng p dng cho khi xy c din tch mt bng t hn 0,04m2.

(2) C th p dng cc nguyn tc v cc quy tc p dng nu trong tiu chun ny i vi nhng dng kt cu cha cp ht, i vi vic s dng kt cu mi vi cc vt liu nh, i vi cc vt liu mi hoc kt cu chu cc tc ng v cc nh hng khc cha c kinh nghim, tuy nhin c th cn ti cc iu khon b sung.

(3) Phn 1-1 a ra cc quy tc chi tit ch yu p dng cho cc nh thng thng. Kh nng p dng ca cc quy tc ny c th b hn ch v cc l do thc hnh hoc do vic n gin ho; mi gii hn p dng c cho trong tiu chun v tr cn thit.

(4)P Cc vn sau y c cp n trong Phn 1-1:

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- 1: Tng qut;

- 2: C s thit k;

- 3: Vt liu;

- 4: bn lu;

- 5: Phn tch kt cu;

- 6: Trng thi cc hn;

- 7: Trng thi gii hn s dng;

- 8: Cu to;

- 9: Thi cng;

(5)P Phn 1-1 khng bao hm:

- tnh chu la (c cp n trong phn 1-2);

- cc kha cnh c th ca cc loi nh c bit (th d cc hiu ng ng lc hc nh cao);

- cc kha cnh c th ca cc loi cng trnh xy dng c bit (nh cu, p, ng khi hoc kt cu cha cht lng bng th xy);

- cc kha cnh c th ca cc loi kt cu c bit (nh cun hoc vm);

- khi xy dng va thch cao c hoc khng c xi mng;

- khi xy c vin xy khng c t thnh hng u n (khi xy hc);

- khi xy c gia cng bng cc vt liu khc vi thp.

1.1.3 Cc phn khc ca tiu chun Thit k kt cu xy

(1) Cc phn khc ca tiu chun Thit k kt cu xy b sung cho Phn 1-1 bao gm:

- Phn 1-2: Quy tc chung - thit k chu la cho kt cu.

- Phn 2: Thit k, la chn vt liu v thi cng khi xy.

- Phn 3: Phng php tnh n gin ho kt cu xy khng c ct thp.

1.2 Ti liu vin dn 1.2.1 Tng qut

Tiu chun ny a vo, di hnh thc c hoc khng ghi r thi im, nhng iu khon t cc n phm khc. Cc ti liu vin dn c trch dn ti nhng v tr thch hp trong ni dung tiu chun v cc n phm c lit k di y. i vi trch dn c ghi r thi im, nhng sa i b sung sau ngy xut bn ch c p dng cho tiu chun khi tiu chun ny c sa i, b sung. i vi trch dn khng ghi r thi im th dng cc phin bn mi nht ca chng (bao gm cc sa i).

1.2.2 Cc tiu chun tham kho

- EN 206-1, Concrete - Part 1: Specification, performance, production and conformity (B tng - Phn 1: Ch dn, thc hnh, sn phm v s ph hp)

- EN 771-1, Specification for masonry units - Part 1: Clay masonry units (Yu cu k thut vin xy - Phn 1: Vin xy t st)

- EN 771-2, Specification for masonry units - Part 2: Calcium silicate masonry units (Yu cu k thut vin xy- Phn 2: Vin xy silict canxi)

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- EN 771-3, Specification for masonry units - Part 3: Aggregate concrete masonry units (Dense and light-weight aggregates) (Yu cu k thut vin xy - Phn 3, Vin xy b tng c ct liu (ct liu c chc v ct liu nh))

- EN 771-4, Specification for masonry units - Part 4: Autoclaved aerated concrete masonry units (Yu cu k thut vin xy - Phn 4: Vin xy b tng xp hp hi)

- EN 771-5, Specification for masonry units - Part 5: Manufactured stone masonry units (Yu cu k thut vin xy - Phn 5: Vin xy ch tc)

- EN 771-6, Specification for masonry units - Part 6: Natural stone masonry units (Yu cu k thut vin xy - Phn 6: Vin xy thin nhin)

- EN 772-1, Methods of test for masonry units - Part 1: Determination of compressive strength (Phng php th vin xy - Phn 1: Xc nh cng nn)

- EN 845-1, Specification for ancillary components for masonry - Part 1: Ties, tension straps, hangers and brackets (Yu cu k thut i vi cc thnh phn ph ca khi xy - Phn 1: Thanh ging , bn ging chu ko, mc v gi)

- EN 845-2, Specification for ancillary components for masonry - Part 2: Lintels (Yu cu k thut i vi cc thnh phn ph ca khi xy - Phn 2: Lanh t)

- EN 845-3, Specification for ancillary components for masonry - Part 3: Bed joint reinforcement of steel meshwork (Yu cu k thut i vi cc thnh phn ph ca khi xy - Phn 3: Li ct thp t trong mch ngang)

- EN 846-2, Methods of test for ancillary components for masonry - Part 2: Determination of bond strength of prefabricated bed joint reinforcement in mortar joints (Phng php th cc thnh phn ph ca khi xy - Phn 2: Xc nh cng bm dnh ca ct thp, ch sn dng cho mch ngang, trong mch va)

- EN 998-1, Specification for mortar for masonry - Part 1: Rendering and plastering mortar (Yu cu k thut va xy - Phn 1: Va lt v va trt)

- EN 998-2, Specification for mortar for masonry - Part 2: Masonry mortar (Yu cu k thut va xy Phn 2: Va xy)

- EN 1015-11, Methods of test for mortar for masonry - Part 11: Determination of flexural and compressive strength of hardened mortar (Cc phng php th va xy - Phn 11- Xc nh cng nn v cng un ca va ng rn)

- EN 1052-1, Methods of test for masonry - Part 1: Determination of compressive strength (Phng php th khi xy - Phn 1: Xc nh cng nn)

- EN 1052-2, Methods of test for masonry - Part 2: Determination of flexural strength (Phng php th khi xy - Phn 2: Xc nh cng un)

- EN 1052-3, Methods of test for masonry - Part 3: Determination of initial shear strength (Phng php th khi xy - Phn 3: Xc nh cng ct ban u)

- EN 1052-4, Methods of test for masonry - Part 4: Determination of shear strength including damp proof course (Phng php th khi xy - Phn 4: Xc nh cng ct bao gm lp cch m)

- EN 1052-5, Methods of test for masonry - Part 5: Determination of bond strength by bond wrench method (Phng php th khi xy - Phn 5: Xc nh cng bm dnh theo phng php wrench)

- EN 1990, Basis of structural design (C s thit k kt cu)

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- EN 1991, Actions on structures (Tc ng ln kt cu)

- EN 1992, Design of concrete structures; (Thit k kt cu b tng)

- EN 1993, Design of steel structures (Thit k kt cu thp)

- EN 1994, Design of composite steel and concrete structures (Thit k kt cu hn hp b tng v thp)

- EN 1995, Design of timber structures (Thit k kt cu g)

- EN 1996 -2, Design, selection of materials and execution of masonry (Cn nhc thit k, chn la vt liu v thi cng khi xy)

- EN 1997, Geotechnical design (Thit k a k thut)

- EN 1999, Design of aluminium structures (Thit k kt cu nhm)

- EN 10080, Steel for the reinforcement of concrete - Weldable reinforcing steel (Thp ct b tng - Tnh hn ca ct thp)

- EN 10138, Prestressing steels (Thp ng sut trc)

- EN ISO 1461, Hot dip galvanized coatings on fabricated iron and steel articles Specifications and test methods (Lp ph nhng vo km nng cho cc vt ch sn bng kim loi v thp - Ch dn v phng php th)

1.3 Cc gi thit

(1)P Cc gi thit trong 1.3 ca EN 1990:2002 p dng cho tiu chun ny.

1.4 Phn bit gia nguyn tc v cc quy tc p dng

(1)P Cc quy tc trong 1.4 ca EN 1990:2002 p dng cho tiu chun ny.

1.5 Thut ng v nh ngha

1.5.1 Tng qut

(1) Cc thut ng v nh ngha nu trong 1.5 ca EN 1990:2002 p dng cho tiu chun ny.

(2) Cc iu t 1.5.2 n 1.5.11 nu nhng thut ng v nh ngha b sung ca tiu chun ny.

1.5.2 Thut ng lin quan n khi xy

1.5.2.1 Khi xy (masonry)

Mt h c cc vin xy t theo mt kiu xy nht nh v c lin kt vi nhau bng va

1.5.2.2 Khi xy khng c ct thp (unreinforced masonry)

Khi xy khng c ct thp mc c coi l khi xy c ct thp

1.5.2.3 Khi xy c ct thp (reinforced masonry)

Khi xy c cc thanh thp hoc li thp t trong va hoc b tng sao cho tt c cc vt liu cng tham gia chu lc

1.5.2.4 Khi xy ng sut trc (prestressed masonry)

Khi xy c ng sut nn bn trong c ch ng to ra nh ct thp c ko cng

1.5.2.5 Khi xy b hn ch bin dng (confined masonry)

Khi xy c cc cu kin hn ch bin dng bng b tng ct thp hoc bng khi xy c ct thp chn theo phng thng ng v nm ngang

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1.5.2.6 Kiu xy (masonry bond)

S sp t cc vin xy trong khi xy theo mt kiu c quy c t c tc dng chung

1.5.3 Thut ng lin quan n cng ca khi xy

1.5.3.1 Cng c trng ca khi xy (characteristic strength of masonry)

Gi tr cng ca khi xy c xc sut d kin l 5% khng t trong s cc php th gi thit l v hn. Gi tr ny tng ng vi lch l thuyt ca phn b thng k cc c tnh ring ca vt liu v sn phm trong mt t th nghim. Gi tr danh nh c dng lm gi tr c trng trong mt s trng hp.

1.5.3.2 Cng nn ca khi xy (compressive strength of masonry)

Cng ca khi xy chu nn khng chu nh hng cn tr ca tm m, ca mnh hoc lch tm ca ti trng

1.5.3.3 Cng ct ca khi xy (shear strength of masonry)

Cng ca khi xy chu lc ct

1.5.3.4 Cng un ca khi xy (flexural strength of masonry)

Cng ca khi xy khi un

1.5.3.5 Cng bm dnh ca neo (anchorage bond strength)

Cng bm dnh, trn mt n v din tch b mt, gia ct thp v b tng hoc va, khi ct thp chu lc ko hoc nn

1.5.3.6 S bm dnh (adhesion)

nh hng ca va gy ra sc chu ko v chu ct b mt tip xc ca vin xy

1.5.4 Thut ng lin quan n vin xy

1.5.4.1 Vin xy (masonry unit)

Thnh phn c ch sn dng trong thi cng khi xy

1.5.4.2 Cc nhm vin xy 1,2,3 v 4 (group 1, 2, 3 and 4 masonry units)

Tn nhm vin xy theo t l phn trm v kch thc v hng l rng trong vin xy khi t

1.5.4.3 Mt ngang (bed face)

Mt trn hoc mt di ca vin xy khi t theo d nh

1.5.4.4 Vt lm (frog)

Ch lm, c to thnh trong qu trnh sn xut, trn mt mt hoc hai mt ngang ca vin xy

1.5.4.5 L (hole)

Phn rng c hnh thnh c th xuyn hoc khng xuyn qua vin xy

1.5.4.6 L kp (griphole)

Khong trng to hnh vin xy d nm cht v nng ln bng mt hoc hai tay hoc bng my

1.5.4.7 Vch ngn (web)

Vt liu c gia cc l rng trong vin xy

1.5.4.8 Thnh ngoi (shell)

Vt liu bin gia l rng v b mt vin xy

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1.5.4.9 Tng din tch (gross area)

Din tch ca mt ct ngang vin xy cha tr i din tch l, ch trng v ch lm

1.5.4.10 Cng nn ca vin xy (compressive strength of masonry units)

Cng nn trung bnh ca mt s lng quy nh cc vin xy (xem EN 771-1 n EN 771-6)

1.5.4.11 Cng nn chun ho ca vin xy (normalized compressive strength of masonry units)

Cng nn ca vin xy i v cng nn ca mt vin xy tng ng chiu rng 100mm x chiu cao 100mm c lm kh trong khng kh (xem EN 771-1 n EN 771-6)

1.5.5 Thut ng lin quan n va

1.5.5.1 Va xy (masonry mortar)

Hn hp mt hoc nhiu cht kt dnh v c vi ct liu v nc, i khi c ph gia hay cht n lm lp m, trit mch v mit mch cho khi xy

1.5.5.2 Va xy thng thng (general purpose masonry mortar)

Va xy khng c tnh cht c bit

1.5.5.3 Va xy mch mng (thin layer masonry mortar)

Va xy c thit k vi c ct liu ln nht nh hn hoc bng quy nh

CH THCH xem ch thch 3.6.1.2 (2)

1.5.5.4 Va xy nh (lightweight masonry mortar)

Va xy c thit k vi t trng khi ng rn v kh thp hn s liu quy nh trong EN 998-2

1.5.5.5 Va xy c thit k (designed masonry mortar)

Va c thnh phn v phng php sn xut c la chn t c c tnh quy nh (khi nim tnh nng)

1.5.5.6 Va xy quy nh (prescribed masonry mortar)

Va c ch to theo t l nh trc, cc tnh cht ca chng c gi thit t cc thnh phn cng b ca hn hp (khi nim cng thc)

1.5.5.7 Va xy ch to nh my (factory made masonry mortar)

Va c cn ong v trn nh my

1.5.5.8 Va xy ch to nh my dng bn thnh phm (semi-finished factory made masonry mortar)

Va xy cn ong trc hoc va xy vi ct trn sn

1.5.5.9 Va xy cn ong trc (prebatched masonry mortar)

Va xy c thnh phn c cn ong hon ton trong nh my, cung cp n cng trng xy dng v c trn theo ch dn v cc iu kin ca nh sn xut

1.5.5.10 Va xy vi ct trn sn (premixed lime and sand masonry mortar)

Va c thnh phn c cn ong v trn hon ton trong nh my, cung cp n cng trng xy dng, y cc thnh phn khc do nh my ch nh v cung cp c thm vo (v d xi mng) v c trn vi vi ct

1.5.5.11 Va ch to ti cng trng (site-made mortar)

Va gm cc thnh phn ring r c cn ong v trn cng trng xy dng

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1.5.5.12 Cng nn ca va (compressive strength of mortar)

Cng nn trung bnh ca mt s lng cc mu va theo quy nh sau khi dng h 28 ngy

1.5.6 Thut ng lin quan n b tng chn

1.5.6.1 B tng chn (concrete infill)

B tng dng lp cc l rng hoc khong trng cha sn trong khi xy

1.5.7 Thut ng lin quan n ct thp

1.5.7.1 Thp ct (reinforcing steel)

Ct thp dng trong khi xy

1.5.7.2 Ct thp mch ngang (bed joint reinforcement)

Thp ct gia cng sn t vo mch ngang

1.5.7.3 Thp ng sut trc (prestressing steel)

Si, thanh hoc b thp dng trong khi xy

1.5.8 Thut ng lin quan n cc thnh phn ph

1.5.8.1 Lp cch m (damp proof course)

Lp dng tm, vin xy hoc vt liu khc dng trong khi xy cn nc i qua

1.5.8.2 Thanh ging tng (wall tie)

B phn ni lp ny ca tng rng qua khe rng n lp kia hoc n kt cu khung hay tng pha sau

1.5.8.3 Bn ging (strap)

B phn ni cc cu kin xy n cc b phn khc tip gip nh sn v mi

1.5.9 Thut ng lin quan n mch va

1.5.9.1 Mch ngang (bed joint)

Lp va gia cc mt ngang ca cc vin xy

1.5.9.2 Mch ng - mch u (perpend joint head joint)

Mch va vung gc vi mch ngang v vi b mt tng

1.5.9.3 Mch dc (longitudinal joint)

Mch va ng trong chiu dy ca tng v song song vi b mt tng

1.5.9.4 Mch mng (thin layer joint)

Mch to thnh bi lp va mng

1.5.9.5 Mit mch (jointing)

Qu trnh hon thin mch va

1.5.9.6 Trit mch (pointing)

Qu trnh lp v hon thin mch va c b mt b co ra hoc trng

1.5.10 Thut ng lin quan n cc loi tng

1.5.10.1 Tng chu lc (load-bearing wall)

Tng c thit k ch yu chu ti trng tc dng cng vi ti trng bn thn ca n

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1.5.10.2 Tng n (single-leaf wall)

Tng khng c khe rng hoc mch va lin tc thng ng trong mt phng ca n

1.5.10.3 Tng rng (cavity wall)

Tng gm hai tng n song song, ni vi nhau cht ch bng thanh ging tng hoc ct thp trong mch ngang. Khng gian gia cc lp c cha li di dng mt khe rng lin tc hoc c lp kn hoc lp mt phn bng vt liu cch nhit khng chu lc

CH THCH Mt bc tng gm c hai lp phn ly bng khe rng, trong mt lp khng ng gp vo cng hoc cng ca lp kia th c xem l tng trang tr.

1.5.10.4 Tng kp (double-leaf wall)

Tng gm hai lp song song c mch dc gia c nhi cht va v lin kt cht ch vi nhau bng thanh ging tng sao cho cng tham gia chu ti trng

1.5.10.5 Tng rng nhi (grouted cavity wall)

Tng gm hai lp song song c khe rng c lp bng b tng hoc va lng v lin kt cht ch vi nhau bng thanh ging tng hoc ct thp trong mch ngang sao cho cng tham gia chu lc

1.5.10.6 Tng mt (faced wall)

Tng c cc vin mt lin kt vo vin pha sau sao cho cng tham gia chu lc

1.5.10.7 Tng m thnh (shell bedded wall)

Tng c vin xy c xy trn hai di va tr ln, trong c hai di nm mp ngoi mt ngang ca vin xy

1.5.10.8 Tng trang tr (veneer wall)

Tng dng lm tng mt nhng khng lin kt hoc ng gp vo bn ca tng pha sau hoc kt cu khung

1.5.10.9 Tng ct (shear wall)

Tng chu lc ngang trong mt phng ca n

1.5.10.10 Tng tng cng (stiffening wall)

Tng t vung gc vi tng khc to ra ch da cho n chng li cc lc ngang hoc chng on v cng to n nh cho cng trnh

1.5.10.11 Tng khng chu lc (non-loadbearing wall)

Tng khng c xem l chu lc, c th b i m khng lm tn hi n tnh ton vn ca kt cu cn li

1.5.11 Cc thut ng khc

1.5.11.1 Rnh (chase)

ng soi c to thnh trn khi xy

1.5.11.2 Hc (recess)

Ch lm c to thnh trn mt tng

1.5.11.3 Va lng (grout)

Hn hp xi mng, ct, v nc c th rt lp nhng ch rng hoc khng gian nh

1.5.11.4 Khe co gin (movement joint)

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Khe cho php co gin t do trong mt phng tng

1.6 K hiu

(1) Cc k hiu khng ph thuc vt liu cho trong 1.6 ca EN 1990.

(2) Cc k hiu ph thuc vt liu dng trong tiu chun ny l:

Ch La tinh

al khong cch t ch kt thc ca tng n cnh gn nht ca vng t ti trng;

ax khong cch t b mt ca gi ta n mt ct ngang ang xt;

A din tch mt ct ngang ton b theo phng ngang c cht ti ca tng;

Aef din tch hiu dng chu lc;

As din tch mt ct ngang ca ct thp;

Asw din tch ca ct thp chu ct;

B chiu rng ca mt ct;

bc chiu rng ca mt chu nn gia hai v tr c nh;

bef chiu rng hiu dng ca cu kin c cnh;

bef.l chiu dy hiu dng ca cu kin c cnh;

bef.t chiu dy hiu dng ca cu kin c cnh;

cnom lp b tng bo v danh ngha;

D chiu cao hiu dng ca dm;

da vng ca vm di ti trng ngang thit k;

dc kch thc ln nht ca mt ct li theo hng un;

ec lch tm ph;

ehe lch tm nh hoc chn tng do ti trng ngang;

ehm lch tm on gia tng do ti trng ngang;

ei lch tm nh hoc y tng;

einit lch tm ban u

ek lch tm do t bin;

em lch tm do ti trng;

emk lch tm on gia ca tng;

E m un n hi ct tuyn ngn hn ca khi xy;

Elongterm m un n hi di hn ca khi xy;

En m un n hi ca cu kin n;

b cng nn trung bnh chun ho ca vin xy;

bod cng neo thit k ca ct thp;

bok cng neo c trng;

ck cng nn c trng ca b tng chn;

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cvk cng ct c trng ca b tng chn;

d cng nn thit k ca khi xy theo hng ang xt;

k cng nn c trng ca khi xy;

m cng nn ca va xy;

vd cng ct thit k ca khi xy;

vk cng ct c trng ca khi xy;

vko cng ct ban u c trng ca khi xy, di ng sut nn bng khng;

vlt gii hn gi tr ca vk ;

xd cng un thit k thch hp vi mt phng un;

xdl cng un thit k ca khi xy c mt phng ph hu song song vi mch ngang;

xdl.app cng un thit k biu kin ca khi xy c mt phng ph hu song song vi mch ngang;

xkl cng un c trng ca khi xy c mt phng ph hu song song vi mch ngang;

xd2 cng un thit k ca khi xy c mt phng ph hu vung gc vi mch ngang;

xd2,app cng un thit k biu kin ca khi xy c mt phng ph hu vung gc vi mch ngang;

xk2 cng un c trng ca khi xy c mt phng ph hu vung gc vi mch ngang;

yd cng thit k ca ct thp;

yk cng c trng ca ct thp;

Fd bn nn hoc ko thit k ca thanh ging tng;

g tng chiu rng ca cc di va;

G m un trt ca khi xy;

H chiu cao thng thu ca tng xy;

hi chiu cao thng thu ca tng xy th i;

hef chiu cao hiu dng ca tng;

htot tng chiu cao ca kt cu, ca tng hoc li tnh t mt mng;

hc chiu cao ca tng tnh n cao trnh ca ti trng;

Ij mmen qun tnh ca tit din cu kin;

k t s gia kh nng mang ti ngang ca tng c nhp theo phng ng vi kh nng mang ti ngang ca din tch tng thc t, c tnh n kh nng cnh c c nh;

km t s gia cng ca sn vi cng ca tng;

kr cng xoay ca ngm;

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K hng s dng tnh cng nn ca khi xy;

L chiu di ca tng (gia cc tng khc, gia mt tng v mt l ca, hoc gia hai l ca);

lb chiu di neo thng;

lc chiu di phn b nn ca tng;

lcl chiu di thng thu ca l ca;

lef nhp hiu dng ca dm xy;

lefm chiu di hiu dng ca mt gi gia cao tng;

lr khong cch thng thu gia cc ngm ngang;

la chiu di hoc chiu cao ca tng gia cc gi ta c kh nng chu lc y ca vm;

Mad mmen thit k ph;

Md mmen un thit k y li;

Mi mmen im cui nt i;

Mid gi tr thit k ca mmen un nh hoc chn tng;

Mmd gi tr thit k mmen ln nht gia chiu cao tng;

MRd gi tr thit k ca mmen khng;

MEd gi tr thit k ca mmen tc dng;

MEdu gi tr thit k ca mmen trn sn;

MEdf gi tr thit k ca mmen di sn;

n s tng;

ni h s cng ca cu kin;

nt s thanh ging tng hoc chi tit ni trn mt m2 tng;

ntmin s ti thiu cc thanh ging tng hoc chi tit ni trn mt m2 tng;

N tng s cc tc ng thng ng thit k ln cng trnh;

Nad lc y thit k ln nht ca vm trn mt n v chiu di ca tng;

Nid gi tr thit k ca ti trng ng nh hoc chn tng hoc ct;

Nmd gi tr thit k ca ti trng ng gia chiu cao ca tng hoc ct;

NRd gi tr thit k kh nng chu lc ca tng xy hoc ct xy theo phng ng;

NRdc gi tr thit k kh nng chu lc tp trung ca tng theo phng ng;

NEd gi tr thit k ca ti trng ng;

NEdf gi tr thit k ca ti trng ngoi sn;

NEdu gi tr thit k ca ti trnh trn sn;

NEl ti trng do sn tc dng;

NEdc gi tr thit k ti trng ng tp trung;

qlat,d cng ngang thit k trn mt n v din tch ca tng;

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Qd gi tr thit k ca tng ti trng ng phn cng trnh c n nh bng li;

R vng ca vm;

Rc ng sut chy ca thp;

S khong cch cc ct thp chu ct;

Ed gi tr thit k ca ti trng tc dng vo cu kin xy c ct thp;

T chiu dy ca tng;

tch,v chiu su ti a ca rnh ng hoc ca hc m khng tnh ton;

tch,h chiu su ti a ca rnh ngang hoc rnh xin;

ti chiu dy ca tng i;

tmin chiu dy ti thiu ca tng;

tef chiu dy hiu dng ca tng;

tf chiu dy ca cnh;

tri chiu dy ca sn i;

VEd gi tr thit k ca ti trng ct;

VRd gi tr thit k ca sc khng ct;

wi ti trng thit k phn b u i;

WEd ti trng ngang thit k trn mt n v din tch;

X chiu su ca trc trung ho;

z cnh tay n;

Z m un ct tuyn n hi ca mt n v chiu cao hoc chiu di ca tng;

Ch Hy lp

gc ca ct thp chu ct n trc dm; t h s gin n nhit ca khi xy; 1,2 h s m men un; h s tng i vi ti trng tp trung; h s phng i bn chu ct ca tng c ct thp; h s dng xc nh cng nn trung bnh chun ho ca vin xy;

c bin dng t bin cui cng ca khi xy; el bin dng n hi ca khi xy; mu gii hn bin dng nn trong khi xy; sy bin dng chy ca ct thp;

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ng knh hiu dng ca ct thp; h s t bin cui cng ca khi xy; h s gim; fl h s gim c xt ti nh hng ca cng un; i h s gim nh hoc chn tng; m h s gim trong phm vi gia chiu cao tng; M h s ring ca vt liu bao hm tnh bt nh v hnh hc v m hnh; h s dng tnh ton lch tm ngoi mt phng ca ti trng t ln tng;

x chiu cao vng nn ca dm khi dng biu ng sut hnh ch nht; c gi tr ca mnh m nu nh hn n th c th b qua lch tm do t bin;

h s trc giao ca cng un ca khi xy; h s phng i cng xoay ca ngm ca phn t kt cu ang xt; d t trng kh; n h s gim; t h s cng; d ng sut nn thit k; gc nghing so vi phng thng ng ca kt cu.

2 C s thit k

2.1 Yu cu c bn 2.1.1 Tng qut

(1)P Thit k kt cu xy phi ph hp vi cc quy tc chung trong EN 1990.

(2)P Mc ny nu nhng iu khon ring phi p dng i vi kt cu xy.

(3) C th coi l khi xy tho mn cc yu cu c bn ca EN 1990 mc 2 nu p dng:

thit k trng thi gii hn kt hp vi phng php h s ring quy nh trong EN 1990; tc ng c cho trong EN 1991; quy tc t hp c cho trong EN 1990; cc nguyn tc v quy tc p dng c cho trong tiu chun ny. 2.1.2 tin cy

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(1)P Kt cu xy s t c tin cy yu cu khi thit k theo tiu chun ny.

2.1.3 Tui th thit k v bn lu

(1) xem xt bn lu phi thc hin theo mc 4.

2.2 Nguyn tc thit k theo trng thi gii hn (1)P Cc trng thi gii hn, c th ch lin quan n khi xy hoc cc vt liu khc dng cho cc b phn ca kt cu, phi la chn da vo cc phn c lin quan ca EN 1992, EN 1993, EN 1994, EN 1995 v EN 1999.

(2)P i vi kt cu xy, trng thi cc hn v trng thi gii hn s dng phi c xem xt trn mi kha cnh ca kt cu, bao gm cc thnh phn ph trong khi xy.

(3)P i vi kt cu xy, mi gii php thit k c lin quan bao gm c cc giai on c lin quan trong qu trnh thi cng cn phi c cn nhc.

2.3 Cc bin c bn 2.3.1 Tc ng

(1)P Tc ng phi ly theo cc phn c lin quan ca EN 1991.

2.3.2 Gi tr thit k ca tc ng

(1)P H s ring i vi tc ng phi ly theo EN 1990.

(2) H s ring i vi t bin v co ngt ca cu kin b tng trong kt cu xy phi ly theo EN 1992-1-1.

(3) i vi trng thi gii hn s dng, bin dng cng bc phi c a vo di dng gi tr (trung bnh) d tnh.

2.3.3 Cc c tnh ca vt liu v sn phm

(1) c tnh ca vt liu v sn phm xy dng v d liu hnh hc dng cho thit k phi tun theo quy nh trong cc tiu chun c lin quan ca EN, hEN hoc ETA tr khi c ch nh khc trong tiu chun ny.

2.4 Kim tra theo phng php h s ring 2.4.1 Gi tr thit k ca c tnh vt liu

(1)P Gi tr thit k i vi mt c tnh vt liu bng gi tr c trng ca n chia cho h s an ton v vt liu c lin quan, M. 2.4.2 T hp tc ng

(1)P T hp tc ng phi ph hp vi cc quy tc chung trong EN 1990.

CH THCH 1 Trong kt cu nh v vn phng, thng c th n gin ho cc t hp ti trng cho trong EN 1990.

CH THCH 2 Trong kt cu nh v vn phng, ti trng tm thi cho trong b tiu chun EN 1991 c th c x l nh mt tc ng bin i c c nh (tc l, cht ti u trn ton khu , hoc bng khng, tu trng hp), h s gim c cho trong EN 1991-1.

2.4.3 Trng thi cc hn

(1)P Cc gi tr c lin quan ca h s an ton v vt liu M c dng cho trng thi cc hn i vi cc trng hp thng thng v ngu nhin. Khi phn tch kt cu chu cc tc ng ngu nhin, phi tnh n xc sut ca tc ng ngu nhin ang hin din.

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CH THCH C th s dng gi tr kin ngh cho M trong bng di y, cho theo cp lin quan ti vic kim sot thi cng (xem thm ph lc A), hoc s dng cc gi tr nu trong Ph lc J.

M Cp Vt liu

1 2 3 4 5

Khi xy xy bng

A Vin xy loi I, va thit k a 1,5 1,7 2,0 2,2 2,5

B Vin xy loi I, va quy nh b 1,7 2,0 2,2 2,5 2,7

C Vin xy loi II,va bt k a,b,e 2,0 2,2 2,5 2,7 3,0

D Neo ct thp 1,7 2,0 2,2 2,5 2,7

E Ct thp v thp ng sut trc 1,15

F Cc thnh phn ph c,d 1,7 2,0 2,2 2,5 2,7

G Lanh t theo EN 945-2 1,5 n 2,5

a Yu cu i vi va thit k c cho trong EN 998-2 v EN1996-2.

b Yu cu i vi va quy nh c cho trong EN 998-2 v TCVN *-2:2008.

c Cc gi tr cng b l cc gi tr trung bnh.

d Lp cch m c xem l mt phn ca khi xy M. e Khi h s bin ng cho vin xy loi II khng ln hn 25%.

2.4.4 Trng thi gii hn s dng

(1) Khi cc quy tc n gin ho, c cho trong cc iu c lin quan, cp n trng thi gii hn s dng th vic tnh ton chi tit khng yu cu dng t hp tc ng. Khi cn thit, h s ring cho vt liu, i vi trng thi gii hn s dng l M. CH THCH Gi tr M kin ngh i vi tt c cc c tnh vt liu khi phn tch trng thi gii hn s dng l 1,0.

2.5 Thit k c s tr gip ca th nghim (1) Cc c tnh kt cu ca khi xy c th xc nh bng th nghim.

CH THCH Ph lc D (tham kho) ca EN 1990 a ra cc kin ngh cho thit k c s tr gip ca th nghim.

3 Vt liu

3.1 Vin xy

3.1.1 Loi v chia nhm vin xy

(1)P Cc vin xy phi tun theo mt trong cc loi sau:

vin t st ph hp vi EN 771-1.

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vin silict canxi ph hp vi EN 771-2. vin b tng (ct liu nng v nh) ph hp vi EN 771-3. vin b tng xp hp hi ph hp vi EN 771-4. vin ch tc ph hp vi EN 771-5. vin thin nhin c kch thc ph hp vi EN 771-6. (2) Vin xy c th l loi I hoc loi II.

CH THCH nh ngha loi I v loi II c nu trong EN 771-1 6 (3) Cc vin xy phi c nhm li thnh Nhm 1, Nhm 2, Nhm 3 hoc Nhm 4, dng phng trnh v cc gi tr bng s khc cho trong 3.6.1.2 (2). (3), (4), (5) v (6), v 3.6.1.3 v khi vic lp nhm c tham chiu ti nhng iu khc.

CH THCH Thng thng nh sn xut cng b nhm cc vin xy ca h.

(4) Cc vin b tng xp hp hi, vin ch tc v vin thin nhin c quy cch c xp vo Nhm 1. Cc yu cu hnh hc dng phn nhm vin xy t st, silict canxi v vin b tng c cho trong Bng 3.1

Bng 3.1- Cc yu cu hnh hc i vi nhm vin xy

Vt liu v gii hn i vi vin xy

Nhm 2 Nhm 3 Nhm 4

Nhm 1 (mi vt

liu) Vin L rng ng L rng ngang

t st 25; 55 25; 55 25; 70

silict canxi 25; 55 Khng dng Khng dng

Th tch tt c cc l (% tng th tch) 25

b tng b 25; 60 25; 70 25; 50

t st tng l 2

tng cc l kp n 12,5

tng l 2

tng cc l kp n 12,5

tng l 30

silict canxi

tng l 15

tng cc l kp n 30

Khng dng Khng dng Th tch l bt k (% tng th tch) 12,5

b tng b tng l 30

tng cc l kp n 30

tng l 30

tng cc l kp n 12,5

tng l 25

vch ngn thnh ngoi

vch ngn

thnh ngoi

vch ngn

thnh ngoi

t st 5 8 3 6 5 6

silict canxi 5 10 khng dng khng dng

Gi tr cng b v chiu dy vch ngn v thnh ngoi (mm)

Khng yu cu

b tng b 14 18 15 15 20 20

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t st 16 12 12

silict canxi 20 khng dng khng dng

Gi tr cng b v chiu dy gp vch ngn v thnh ngoi (% ton b chiu rng)

khng yu cu

b tng b 18 15 45

aChiu dy gp l chiu dy ca vch ngn v ca thnh ngoi, c o theo phng ngang theo hng c lin quan. Vic kim tra cn c xem l mt php th nghim thu v ch lp li trong trng hp thay i kch thc thit k vin xy v mt nguyn tc . bTrong trng hp l hnh nn, hoc l hnh t ong, dng gi tr trung bnh chiu dy ca vch ngn v ca thnh ngoi.

3.1.2 Cc c tnh vin xy cng nn

(1)P Cng nn ca vin xy dng trong thit k l cng nn chun ho trung bnh, b. CH THCH Trong b EN 771, cng nn chun ho trung bnh:

hoc c nh sn xut cng b; hoc dng EN 772-1, ph lc A chuyn i t cng nn (chuyn i cng nn vin xy v cng

nn trung bnh chun ho).

(2) Khi nh sn xut cng b cng nn chun ho ca vin xy l cng c trng th cng ny phi c quy i v cng trung bnh tng ng thng qua mt h s da trn h s bin ng ca vin xy.

3.2 Va

3.2.1 Cc loi va xy

(1) Va xy gm c va thng thng, va lp mng hoc va nh tu theo cu to ca n.

(2) Va xy c xem l va thit k hay va quy nh tu theo phng php xc nh thnh phn ca n.

(3) Va xy c th c sn xut trong nh my (cn ong trc hay trn trc), sn xut dng bn thnh phm trong nh my hoc sn xut ti cng trng tu theo phng php ch to.

(4)P Cc loi va xy sn xut trong nh my v va sn xut dng bn thnh phm trong nh my cn ph hp vi EN 998-2. Va xy sn xut ti cng trng cn ph hp vi TCVN *-2:2008, Va xy vi ct trn trc cn ph hp vi EN 998-2 v s dng ph hp vi EN 998-2.

3.2.2 Quy nh v va xy

(1) Va phi c phn mc theo cng nn ca chng, biu din bng ch M tip theo l cng nn tnh bng N/mm2 , th d M5. Va xy quy nh sau M v s cng nn s l m t thnh phn quy nh ca n, v d 1:1:5 xi mng: vi: ct theo th tch.

CH THCH C th tham kho ph lc K v cc hn hp va xy quy nh.

(2) Va xy thng thng c th l va thit k ph hp vi EN 998-2 hoc va xy quy nh ph hp vi EN 998-2.

(3) Va xy mch mng v va nh phi l va thit k ph hp vi EN 998-2.

3.2.3 Cc c tnh ca va

3.2.3.1 Cng nn ca va xy

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(1)P Cng nn ca va xy, fm, phi c xc nh theo EN 1015-11.

(2) Va xy s dng trong khi xy c ct, tr khi xy c ct thp mch ngang, khng nn c cng nn, fm, nh hn 4 N/mm2, v s dng trong khi xy c ct thp mch ngang th khng nh hn 2 N/mm2.

3.2.3.2 S dnh kt gia vin xy v va

(1)P S dnh kt gia va v cc vin xy phi ph hp vi mc ch s dng.

CH THCH 1 S dnh kt ph hp s ph thuc vo loi va v cc vin xy c s dng.

CH THCH 2 EN 1052-3 lin quan ti vic xc nh cng ct ban u ca khi xy v EN 1052-5 cp ti vic xc nh cng dnh kt khi chu un.

3.3 B tng chn 3.3.1 Tng qut

(1)P B tng chn phi ph hp vi EN 206.

(2) B tng chn c quy nh bi cng nn c trng, fck, (cp cng b tng) lin quan ti cng mu tr/lp phng tui 28 ngy, ph hp vi EN 206.

3.3.2 Quy nh i vi b tng chn

(1) Cp cng , nh xc nh trong EN 206-1, ca b tng chn khng c nh hn C12/15.

(2) B tng c th c thit k hoc quy nh v cn cha mt lng nc va t cng quy nh v linh ng ph hp.

(3)P linh ng ca b tng chn cn m bo cc l rng s hon ton b lp kn khi b tng theo TCVN *-2:2008.

(4) Cp st S3 n S5 hoc cp chy F4 n F6, ph hp vi EN 206-1, l t yu cu trong hu ht cc trng hp. Cc l c kch thc nh nht nh hn 85mm cn s dng st S5 hoc S6. Trng hp s dng b tng c st cao th cn c bin php gim co ngt ln ca b tng.

(5) Kch thc ct liu ln nht ca b tng chn khng c vt qu 20mm. Khi b tng chn s dng trong cc l rng c kch thc nh hn 100mm hoc khi lp bo v ct thp nh hn 25mm, th kch thc ct liu ln nht khng c vt qu 10mm.

3.3.3 Cc c tnh ca b tng chn

(1)P Cng nn v cng ct c trng ca b tng chn phi c xc nh t cc php th mu b tng.

CH THCH Cc kt qu th nghim c th ly t cc php th c thc hin cho d n hoc t cc c s d liu.

(2) Trong trng hp khng c sn cc s liu th nghim, cng nn c trng, fck, v cng ct c trng, fcvk, ca b tng chn c th ly t bng 3.2.

Bng 3.2 - Cng c trng ca b tng chn

Cp cng b tng C12/15 C16/20 C20/25

C25/30 hoc ln hn

fck (N/mm2) 12 16 20 25

fcvk (N/mm2) 0,27 0,33 0,39 0,45

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3.4 Ct thp 3.4.1 Tng qut

(1)P Ct thp cc-bon phi c quy nh l ph hp vi EN 10080. Thp khng g v thp m c bit phi c quy nh ring.

(2)P Cc yu cu i vi cc tnh cht c l ca ct thp l dnh cho loi thp t trong khi xy hoc b tng chn ng rn. Cn trnh cc thao tc thc hin ti cng trng hay trong qu trnh sn xut c nh hng ti cc tnh cht ca thp.

CH THCH EN 10080 cp ti ng sut chy Re , bao gm cc gi tr c trng, nh nht v ln nht da trn cht lng di hn ca sn phm. Ngc li, fyk l ng sut chy c trng ch da vo yu cu v ct thp i vi kt cu. Khng c quan h trc tip gia fyk v Re c trng. Tuy nhin, cc phng php nh gi v thm tra cng chy cho trong EN 10080 quy nh vic kim tra c c fyk.

(3) Ct thp c th l thp cc-bon hoc thp khng g austenitic. Ct thp c th trn hoc c g (bm dnh cao) v c th hn c.

(4) Thng tin chi tit v cc c tnh ca ct thp tham kho trong EN 1992-1-1.

3.4.2 c tnh ca cc thanh ct thp

(1)P Cng c trng ca thanh ct thp, fyk , phi ph hp vi Ph lc C ca EN 1992-1-1.

(1) H s gin n nhit c th ly bng 12 10-6K-1. CH THCH Thng thng c th b qua s khc nhau gia h s gin n nhit ca ct thp v ca khi xy hoc b tng bao quanh.

3.4.3 c tnh ca ct thp ch sn dng cho mch ngang

(1)P Ct thp ch sn dng cho mch ngang phi ph hp vi EN 845-3.

3.5 Thp ng sut trc

(1)P Thp ng sut trc phi ph hp vi EN 10138 hoc Ph duyt k thut Chu u thch hp.

(2) Cc c tnh ca thp ng sut trc ly theo EN 1992-1-1.

3.6 c trng c hc ca khi xy 3.6.1 Cng nn c trng ca khi xy

3.6.1.1 Tng qut

(1)P Cng nn c trng ca khi xy , fk, phi c xc nh t cc kt qu th nghim trn mu khi xy.

CH THCH Cc kt qu th nghim c th ly t cc php th thc hin cho d n, hoc c sn t c s d liu.

3.6.1.2 Cng nn c trng ca khi xy khng phi l khi xy m thnh

(1) Cng nn c trng ca khi xy c xc nh t:

(i) Cc kt qu th nghim (thc hin cho d n hoc c sn t c s d liu) ph hp vi EN-1052; cc kt qu th nghim cn c th hin di dng bng biu hoc di dng phng trnh (3.1).

fk = K fb fm (3.1)

trong :

fk l cng nn c trng ca khi xy, N/mm2

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K l hng s, trong trng hp nht nh c iu chnh theo 3.6.1.2.(3) v/hoc 3.6.1.2(6)

, l cc hng s fb l cng nn trung bnh chun ho ca vin xy theo hng ca lc tc dng, N/mm2

fm l cng nn ca va, N/mm2

Gii hn s dng phng trnh (3.1) cn c cho theo fm, fb, h s bin ng ca kt qu th nghim v phn nhm ca cc vin xy.

hoc

(ii) t (2) v (3) di y.

CH THCH C th tham kho cc gi tr tra bng dng trong phng trnh (3.1) v nhng gii hn, tham chiu vic Lp nhm trong Bng 3.1 Ph lc K nu s dng la chn (i).

(2) Quan h gia cng nn c trng ca khi xy, fk, cng nn trung bnh chun ho ca vin xy, fb, v cng va, fm, c th xc nh t:

phng trnh (3.2), i vi khi xy bng va thng thng v va nh;

phng trnh (3.3), i vi khi xy dng va lp mng, cc mch ngang c chiu dy t 0,5mm ti 3mm v cc vin xy t st thuc Nhm 1 v 4, vin silict canxi, cc vin b tng v vin b tng xp hp hi;

phng trnh (3.4), i vi khi xy dng va lp mng, cc mch ngang c chiu dy t 0,5mm n 3mm v cc vin xy t st thuc Nhm 2 v 3.

CH THCH EN 998-2 khng a ra gii hn no v chiu dy ca mch va mng, gii hn v chu dy ca mch ngang t 0,5 ti 3mm l m bo rng va lp mng c c tnh cao c tha nhn tn ti lm cho cc phng trnh (3.3) v (3.4) c ngha. Khng cn s dng cng va, fm, trong cc phng trnh (3.3) v (3.4).

fk = K . fb0,7. fm0,3 (3.2)

fk = K . fb0,85 (3.3)

fk = K . fb0,7 (3.4)

trong :

K l mt hng s theo bng 3.3, v trong trng hp nht nh c iu chnh theo 3.6.1.2(3) v /hoc 3.6.1.2(6)

vi iu kin cc yu cu sau y c tho mn:

khi xy c cu to ph hp vi mc 8 ca tiu chun ny;

ton b cc mch va tho mn cc yu cu ca 8.1.5 (1) v (3) n mc c coi l chn;

fb khng c ly ln hn 75 N/mm2 khi cc vin xy c xy bng va thng thng;

fb khng c ly ln hn 50 N/mm2 khi cc vin xy c xy bng va lp mng;

fm khng c ly ln hn 20 N/mm2 hoc ln hn 2fb khi cc vin xy c xy bng va thng thng;

fm khng c ly ln hn 10 N/mm2 khi cc vin xy c xy bng va nh;

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chiu dy ca khi xy bng chiu rng hoc chiu di ca vin xy khng c mch va song song vi mt tng trn mt on hoc sut chiu di ca tng;

h s bin ng v cng ca cc vin xy khng ln hn 25%.

(3) Trong trng hp hng tc ng song song vi hng ca cc mch ngang, cng nn c trng c th c xc nh t cc phng trnh (3.2), (3.3) v (3.4), s dng cng nn chun ho ca vin xy, fb, xc nh t cc php th m hng gia ti ln mu th trng vi hng ca tc ng trong khi xy, nhng vi h s cho trong EN 772-1, khng c ly ln hn 1. i vi cc vin xy Nhm 2 v 3 th K c nhn vi 0,5.

(4) i vi khi xy bng va thng thng v vin xy b tng thuc Nhm 2 v Nhm 3 c k rng ng c chn y bng b tng, ly gi tr fb bng cch coi cc vin xy l Nhm 1 vi cng nn ph hp vi cng nn ca cc vin xy hoc ca b tng chn, ly gi tr nh hn.

(5) Khi cc mch ng khng c chn, c th dng cc phng trnh (3.2), (3.3) hoc (3.4), c xt ti bt c tc ng ngang no c th tc ng vo khi xy hoc c truyn qua khi xy. Xem thm 3.6.2 (4).

(6) i vi khi xy c xy bng va thng thng, trong trng hp c mch va song song vi mt tng trn ton b hoc mt phn ca chiu di tng th c th ly gi tr K bng cch nhn cc gi tr cho trong Bng 3.3 vi 0.8.

Bng 3.3 Cc gi tr ca K dng vi va thng thng, va lp mng v va nh.

Va nh c khi lng th tch

Vin xy

Va thng thng

Va lp mng (mch ngang

0,5mm v 3mm)

600 d 800 kg/m3

800 d 1300 kg/m3

Nhm 1 0,55 0,75 0,30 0,40

Nhm 2 0,45 0,70 0,25 0,30

Nhm 3 0,35 0,50 0,20 0,25 t st

Nhm 4 0,35 0,35 0,20 0,25

Nhm 1 0,55 0,80 Silict canxi

Nhm 2 0,45 0,65

Nhm 1 0,55 0,80 0,45 0,45

Nhm 2 0,45 0,65 0,45 0,45

Nhm 3 0,40 0,50

B tng

Nhm 4 0,35

B tng xp hp hi Nhm 1 0,55 0,80 0,45 0,45

ch tc Nhm 1 0,45 0,75

thin nhin c quy cch Nhm 1 0,45

Khng c gi tr do t hp va xy/vin xy khng thng dng.

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3.6.1.3 Cng nn c trng ca khi xy m thnh

(1) Cng nn c trng ca khi xy m thnh, xy bng cc vin xy thuc Nhm 1 v Nhm 4 c th ly theo 3.6.1.2, min sao:

chiu rng ca tng di va t 30mm tr ln;

chiu dy ca khi xy bng chiu rng hoc chiu di ca vin xy khng c mch dc no xuyn sut chiu di hoc mt phn ca tng;

t l g/t khng nh hn 0,4;

K c ly theo 3.6.1.2 khi g/t = 1 hoc K c ly bng na cc gi tr khi g/t = 0,4, vi cc gi tr trung gian th p dng ni suy tuyn tnh.

trong :

g l tng chiu rng ca cc di va;

t chiu dy ca tng.

(2) Cng nn c trng ca khi xy m thnh xy bng vin xy Nhm 2 v Nhm 3, c th ly theo 3.6.1.2, min sao cng nn trung bnh chun ho ca vin xy, fb, c s dng trong phng trnh l cng xc nh t cc kt qu th nghim trn cc vin xy c th nghim ph hp vi EN 772-1 i vi cc vin xy m thnh.

3.6.2 Cng ct c trng ca khi xy

(1)P Cng ct c trng ca khi xy, fvk, phi c xc nh t cc kt qu th nghim trn khi xy.

CH THCH Cc kt qu th nghim c th ly t cc php th c tin hnh cho d n hoc c sn trong c s d liu.

(2) Cng ct ban u c trng, fvko, phi c xc nh t cc php th ph hp vi EN 1052-3 hoc EN 1052-4

(3) Cng ct c trng ca khi xy, fvk, dng va xy ph thng ph hp vi 3.2.2 (2) hoc va lp mng cc mch ngang c chiu dy 0,5mm n 3mm, ph hp vi 3.2.2 (3) hoc va nh ph hp vi 3.2.2 (4) vi tt c cc mch tho mn cc yu cu ca 8.1.5, c coi l chn y, c th xc nh t phng trnh (3.5)

fvk = fvko + 0,4 d (3.5) nhng khng ln hn 0,065 fb hoc fvlt

trong :

fvko l cng ct ban u c trng, khi ng sut nn bng 0;

d l ng sut nn thit k vung gc vi lc ct trong cu kin cao trnh ang xt, s dng t hp ti trng thch hp da trn ng sut thng ng trung bnh trn min nn ca tng ni to ra sc khng ct;

fb l cng nn chun ho ca vin xy nh m t trong 3.1.2.1, i vi hng gia ti ln cc mu th vung gc vi b mt ca mch ngang.

CH THCH S dng gii hn 0,065 fb nu p dng Ph lc K.

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(4) Cng ct c trng ca khi xy, s dng va xy thng thng ph hp vi 3.2.2 (2) hoc va lp mng ph hp vi 3.2.2 (3) cc mch ngang c chiu dy 0,5mm n 3mm, hoc va nh ph hp vi 3.2.2 (4) v c cc mch ng cha chn nhng vi cc b mt tip gip ca cc vin xy gi gn nhau, c th xc nh t phng trnh (3.6)

fvk = 0,5. fvko + 0,4 d (3.6) nhng khng ln hn: 0,045 fb hoc fvlt

trong : fvko, d v fb nh nh ngha trong (3) trn CH THCH S dng gii hn 0,045 fb nu p dng Ph lc K.

(5) khi xy m thnh khi cc vin xy c t trn 2 hoc nhiu di va thng thng bng nhau, mi di rng ti thiu 30mm, th fvk c th xc nh t phng trnh (3.7)

fvk = (g/t). fvko + 0,4 d (3.7) nhng khng ln hn gi tr ly theo (4) trn

trong :

fvk , v fb nh c nh ngha trong (3) trn v : g l tng chiu rng ca cc di va ;

t l chiu dy tng.

(6) Cng ct ban u c trng ca khi xy, fvko , c th c xc nh t:

nh gi c s d liu cc kt qu th nghim v cng ct ban u ca khi xy;

t cc gi tr cho trong bng 3.4, min sao va thng thng c trn ph hp vi TCVN *-2:2008 khng cha cc ph gia hoc cc cht n.

CH THCH C th tham kho Ph lc K i vi gi tr fvko.

(7) Sc khng ct theo phng ng ca ch ni hai tng xy c th xc nh t cc php th ph hp i vi mt d n c th hoc c th xc nh t vic nh gi cc s liu th nghim. Khi khng c nhng s liu nh vy, sc khng ct c trng c th da vo fvko , trong fvko l cng ct c trng khi chu ng sut nn bng khng, nh cho trong 3.6.2 (2) v (6), min sao s lin kt gia cc bc tng ph hp vi 8.5.2.1.

Bng 3.4 Cc gi tr ca cng ct ban u c trng ca khi xy, fvko

fvko (N/mm2)

Vin xy Va thng thng vi cp cng cho

trc

Va lp mng (mch ngang

0,5mm v 3mm)

Va nh

M10-M20 0,30

M2,5-M9 0,20 t st

M1-M2 0,10

0,30 0,15

M10-M20 0,20

M2,5-M9 0,15 Silict canxi

M1-M2 0,10

0,40 0,15

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B tng ct liu M10-M20 0,20

B tng xp hp hi M2,5-M9 0,15

thin nhin c quy cch v ch tc M1-M2 0,10

0,30 0,15

3.6.3 Cng un c trng ca khi xy

(1) Trng hp un ngoi mt phng, cn xem xt cc tnh hung sau: cng un c mt phng ph hu song song vi cc mch ngang, fxk1; cng un c mt phng ph hu vung gc vi cc mch ngang, fxk2 (xem hnh 3.1)

a) mt phng ph hu song song vi cc mch ngang, fxk1

b) mt phng ph hu vung gc vi cc mch ngang, fxk2

Hnh 3.1- Cc mt phng ph hu khi xy khi un

(2)P Cng un c trng ca khi xy, fxk1 v fxk2 phi c xc nh t cc kt qu th nghim khi xy.

CH THCH Cc kt qu th nghim c th ly t cc php th tin hnh cho d n hoc t c s d liu.

(3) Cng un c trng ca khi xy c th xc nh bi cc php th ph hp vi EN 1052, hoc c th c thit lp t nh gi cc s liu th nghim da trn cng un ca khi xy xc nh t t hp thch hp ca vin xy v va xy.

CH THCH 1 C th tham kho Ph lc K v cc gi tr fxk1 v fxk2.

CH THCH 2 Trong trng hp cc s liu th nghim khng c sn, cc gi tr cng un c trng ca khi xy bng va thng thng, va lp mng hoc va nh c th ly t cc bng trong ti liu ny, min sao va lp mng v va nh c mc M5 hoc cao hn.

CH THCH 3 i vi khi xy bng vin b tng xp hp hi lin kt bng va lp mng th cc gi tr fxk1 v fxk2 c th ly t cc bng trong ti liu ny hoc t cc phng trnh sau:

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fxk1 = 0,035 fb vi cc mch ng c chn v khng chn

fxk2 = 0,035 fb vi cc mch ng c chn hoc 0,025 fb vi mch ng khng chn

Cc gi tr ca fxk1 i vi mt phng ph hu song song vi cc mch ngang

fxk1 (N/mm2)

Va thng thng Vin xy

fm < 5N/mm2 fm 5N/mm2 Va lp mng

Va nh

t st 0,10 0,10 0,15 0,1

Silict canxi 0,05 0,10 0,20 khng dng

B tng ct liu 0,05 0,10 0,20 khng dng

B tng xp hp hi 0,05 0,10 0,15 0,10

ch tc 0,05 0,10 khng dng khng dng

thin nhin c quy cch 0,05 0,10 0,15 khng dng

Cc gi tr ca fxk2 i vi mt phng ph hu vung gc vi cc mch ngang

fxk2 (N/mm2)

Va thng thng Vin xy

fm < 5N/mm2

fm 5N/mm2

Va lp mng Va nh

t st 0,20 0,40 0,15 0,10

Silict canxi 0,20 0,40 0,30 khng dng

B tng ct liu 0,20 0,40 0,30 khng dng

< 400 kg/m3

0,20 0,20 0,20 0,15 B tng xp hp hi

400 kg/m3

0,20 0,40 0,30 0,45

ch tc 0,20 0,40 khng dng khng dng

thin nhin c quy cch 0,20 0,40 0,15 khng dng

CH THCH 4 fxk2 khng nn ly ln hn cng un ca vin xy

3.6.4 Cng neo c trng ca ct thp

(1)P Cng neo c trng ca ct thp t trong va hoc b tng phi c xc nh t cc kt qu th nghim.

CH THCH Cc kt qu th nghim c th ly t cc php th c tin hnh cho d n hoc sn c t c s d liu.

(2) Cng neo c trng ca ct thp c th c thit lp t vic nh gi cc s liu th nghim.

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(3) Khi khng c s liu th nghim, i vi ct thp t trong cc tit din b tng vi kch thc ln hn hoc bng 150mm, hoc trng hp b tng chn bao quanh ct thp c chn bi cc vin xy, n mc ct thp c th c coi l b hn ch bin dng, th cng neo c trng, fbok, c cho trong bng 3.5.

(4) i vi ct thp t trong va hoc trong cc tit din b tng c kch thc nh hn 150mm hoc trng hp b tng chn quanh ct thp khng b chn bn trong cc vin xy, mc c th coi ct thp khng b hn ch bin dng, th cng neo c trng, fbok, c cho trong bng 3.6.

(5) i vi ct thp ch sn mch ngang, cng neo c trng cn c xc nh bng cc php th ph hp vi EN 846-2 hoc s dng cng dnh kt ca ring cc si dc.

Bng 3.5 - Cng neo c trng ca ct thp trong b tng chn b hn ch bin dng

Cp cng b tng C12/15 C16/20 C20/25 C25/30 hoc cao hn

fbok i vi ct thp cc-bon thng (N/mm2) 1,3 1,5 1,6 1,8

fbok i vi ct thp cc-bon v thp khng g bm dnh cao (N/mm2)

2,4 3,0 3,4 4,1

Bng 3.6 - Cng neo c trng ca ct thp, trong va hoc b tng khng b hn ch bin dng, trong cc vin xy

Va M2-M5 M5-M9 M10-M14 M15-M19 M20 Cp cng

B tng khng dng C12/15 C16/20 C20/25 C25/30 hoc

cao hn

fbok i vi ct thp cc-bon thng (N/mm2) 0,5 0,7 1,2 1,4 1,4

fbok i vi ct thp cc-bon v thp khng g bm dnh cao (N/mm2) 0,5 1,0 1,5 2,0 3,4

3.7 c tnh bin dng ca khi xy 3.7.1 Quan h ng sut - bin dng

(1)P Quan h ng sut bin dng ca khi xy khi nn l phi tuyn. C th coi quan h ny l tuyn tnh, parabol, ch nht-parabol (xem hnh 3.2) hoc l ch nht khi thit k tit din khi xy (xem 6.6.1(1)P).

CH THCH Hnh 3.2 l s xp x v khng th ph hp cho tt c cc loi vin xy.

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1) in hnh

2) biu l tng ho

(parabolic-ch nht)

3) biu thit k

Hnh 3.2- Quan h ng sut- bin dng ca khi xy khi nn

3.7.2 M un n hi

(1)P M un n hi ct tuyn ngn hn, E, phi c xc nh bng cc php th ph hp vi EN 1052-1.

CH THCH Cc kt qu th nghim c th ly t cc php th cho d n hoc sn c t c s d liu.

(2) Khi khng c gi tr c xc nh bng cc php th ph hp vi EN 1052-1, m un n hi ct tuyn ca khi xy, E, dng trong tnh ton kt cu c th ly bng KE fk.

CH THCH Gi tr KE c th ly bng 1 000.

(3) M un di hn cn da trn gi tr ct tuyn ngn hn, c gim bt c tnh n hiu ng t bin, (xem 3.7.4) nh sau:

+= 1

EElongterm (3.8)

trong :

h s t bin cui cng 3.7.3 M un ct

(1) M un ct G c th ly bng 40% m un n hi E.

3.7.4 T bin, gin m hoc co ngt v gin n nhit

(1)P Cc h s t bin, gin m hoc co ngt v gin n nhit phi c xc nh bng th nghim.

CH THCH 1 Cc kt qu th nghim c th ly t cc php th cho d n hoc t c s d liu c sn.

CH THCH 2 Hin ti khng c phng php th no ca Chu u xc nh t bin hoc gin m.

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(2) H s t bin cui cng, , h s gin m hoc co ngt di hn, hoc h s gin n nhit, t , cn xc nh t vic nh gi cc s liu th nghim.

CH THCH Cc min gi tr i vi tnh cht bin dng ca khi xy cho trong bng di y. C th tham kho Ph lc K v cc h s ny.

Cc min h s t bin, h s co gin do m v cc tnh cht nhit ca khi xy

Loi vin xy H s t bin cui cnga

Co gin di hn do mb, mm/m

H s gin n nhit t, 10-6/K

t st 0,5-1,5 -0,2 n +1,0 4-8

Silict canxi 1,0-2,0 -0,4 n -0,1 7-11

B tng ct liu nng v ch tc 1,0-2,0 -0,6 n -0,1 6-12

B tng ct liu nh 1,0-3,0 -1,0 n -0,2 6-12

B tng xp hp hi 0,5-1,5 -0,4 n +0,2 7-9

Mc ma 5-9

Trm tch 2-7 thin nhin

Bin cht

c -0,4 n +0,7

1-18 a H s t bin cui cng = c / el , trong c l bin dng t bin cui cng v el = /E b Gi tr di hn ca co gin do m l s m, ch hin tng co, l s dng, ch hin tng gin c Cc gi tr ny thng rt thp

3.8 Cc thnh phn ph 3.8.1. Lp cch m

(1)P Cc lp cch m phi ngn c nc (mao dn) xuyn qua.

3.8.2. Thanh ging tng

(1)P Thanh ging tng phi ph hp vi EN 845-1.

3.8.3 Bn ging, mc v gi

(1)P Bn ging, mc v gi phi ph hp vi EN 845-1.

3.8.4 Lanh t ch sn

(1)P Lanh t ch sn phi ph hp vi EN 845-2.

3.8.5 Dng c ng sut trc

(1)P Neo, b ni, ng v v bc ngoi phi ph hp vi cc yu cu ca EN 1992-1.

4 bn lu

4.1 Tng qut

(1) Khi xy phi c thit k c bn lu cn thit theo mc ch s dng, c xt ti cc iu kin mi trng c lin quan.

4.2 Phn cp iu kin mi trng

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(1) Vic phn cp iu kin mi trng phi ph hp vi TCVN *-2:2008.

4.3 bn lu ca khi xy

4.3.1 Vin xy

(1)P Cc vin xy phi bn lu chu c cc iu kin tip xc trong sut thi gian s dng d kin ca cng trnh.

CH THCH Ch dn v thit k v xy dng nhm to ra bn lu thch hp cho trong TCVN *-2:2008.

4.3.2 Va xy

(1)P Va trong khi xy phi bn lu chu c cc iu kin tip xc trong sut thi gian s dng d kin ca cng trnh v khng c cha cc thnh phn c th c nh hng bt li n cc c tnh hoc bn lu ca va hoc cc vt liu tip gip.

CH THCH Ch dn v thit k v xy dng t c bn lu thch hp ca cc mch va cho trong mc 8 ca tiu chun ny v trong TCVN *-2:2008.

4.3.3 Ct thp

(1)P Ct thp phi bn lu, hoc bn thn n khng n mn hoc c bo v tt khi t thp theo cc nguyn tc p dng trong mc 8, n s chu c cc iu kin tip xc cc b trong sut thi gian s dng d kin ca cng trnh.

(2) Cn phi c bin php bo v trong trng hp dng thp cc-bon to ra bn lu cn thit, n phi c m km ph hp vi EN ISO 1461 sao cho lp km m khng mng hn so vi yu cu to ra bn lu cn thit (xem (3) di y) hoc thp phi c lp bo v tng ng, v d nh bt epoxy dnh kt bng nng chy.

(3) Loi ct thp v mc bo v ti thiu i vi ct thp cn phi c la chn theo cp tip xc c lin quan ca ni s dng.

CH THCH C th tham kho Ph lc K hoc bng di y v vic la chn ct thp p ng yu cu bn lu:

La chn ct thp v bn lu

Mc bo v ti thiu i vi ct thp

Cp tip xc a Nm trong va

Nm trong b tng vi lp bo v nh hn yu cu theo (4)

MX1 Thp cc-bon khng c bo v b Thp cc-bon khng bo v

Thp cc-bon, m dy hoc c lp bo v tng ng c

MX2 Thp cc-bon khng bo v, trong khi xy vi lp va lt mt l d

Thp cc-bon khng c bo v hoc, trng hp va xy dng chn l rng, thp cc-bon, m dy hoc c lp bo v tng ng c

Thp khng g auxtenite AISI 316 hoc 304

MX3 Thp cc-bon khng bo v, trong khi xy vi lp va lt b mt l d

Thp cc-bon, m dy hoc c lp bo v tng ng

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MX4

Thp khng g auxtenite AISI 316, thp cc-bon m dy hoc vi lp bo v tng ng b vi lp va lt b mt l

Thp khng g auxtenite AISI 316

MX5 Thp khng g auxtenite AISI 316 hoc 304 e

Thp khng g auxtenite AISI 316 hoc 304 e

a Xem TCVN *-2:2008 b i vi lp trong ca tng rng ngoi c kh nng b m th cn s dng thp cc-bon, m dy hoc lp bo v tng ng nh (c). c Thp cc-bon cn c m vi khi lng lp m km ti thiu l 900g/m2 hoc m vi khi lng ti thiu ca lp m km l 60g/m2 v c lp epoxy dnh kt vi chiu dy ti thiu l 80 m, trung bnh l 100 m. Xem 3.4. d Va xy phi l va thng thng hoc va lp mng, khng nh hn M4, lp bo v bn trong hnh 8.2 phi tng ln 30mm v khi xy cn c trt bng va trt ph hp vi EN 998-1. e Thp khng g auxtenite c th vn khng ph hp vi tt c cc mi trng xm thc, v iu cn c xem xt c th cho tng cng trnh

(4) Trng hp dng thp cc-bon khng c bo v th cn phi c lp b tng bo v ct thp c chiu dy cnom

CH THCH C th tham kho Ph lc K hoc bng di y v cc gi tr kin ngh cho lp b tng bo v ti thiu cnom i vi ct thp cc-bon

Cc gi tr kin ngh cho lp b tng bo v ti thiu cnom i vi ct thp cc-bon

Hm lng xi mng ti thiu a (kg/m3)

275 300 325 350 400

T l nc/xi mng ti a

0,65 0,60 0,55 0,50 0,45

Cp tip xc

Chiu dy ti thiu ca lp bo v (mm)

MX1b 20 20 20c 20c 20c

MX2 --- 35 30 25 20

MX3 --- --- 40 30 25

MX4 v MX5 --- --- --- 60d 50

a Tt c cc hn hp s dng ct liu thng c kch thc ti a danh ngha l 20 mm. Trng hp dng cc loi ct liu khc, hm lng xi mng cn phi c iu chnh tng thm 20% cho ct liu 14 mm v tng thm 40% cho ct liu 10 mm. b Cch khc l s dng t l 1:0 ti :3:2 (ximng: vi: ct: ct liu 10 mm danh ngha, t l trn theo th tch) p ng iu kin tip xc MX1, khi lp bo v ct thp ti thiu l 15 mm.

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c Nhng lp bo v ny c th gim xung chiu dy ti thiu l 15mm min sao kch thc danh ngha ln nht ca ct liu khng vt qu 10 mm d Trng hp b tng chn c th phi chu bng gi trong khi vn cn t th nn s dng b tng chu lnh.

(5) Trng hp bo v bng cch m km th ct thp cn c m sau khi un to hnh.

(6) EN 845-3 lit k cc h bo v i vi ct thp mch ngang ch sn nh sn xut cn cng b.

4.3.4 Thp ng sut trc

(1)P Thp ng sut trc phi bn lu, khi lp t ph hp vi cc quy tc p dng trong mc 8, chng li nhng iu kin tip xc cc b c lin quan trong sut thi gian s dng d kin ca cng trnh.

(2) Khi thp ng sut trc phi m th n phi c thnh phn cu to sao cho khng b nh hng bt li ca qu trnh m.

4.3.5 Dng c ng sut trc

(1)P Cc neo, ng ni, ng v v bc phi c sc khng n mn trong iu kin mi trng chng c s dng.

4.3.6 Thnh phn ph v cc gc

(1) TCVN *-2:2008 c nhng yu cu v bn lu ca cc thnh phn ph (cc lp cch m, thanh ging tng, bn ging, mc v gi, v cc gc ).

4.4 Khi xy di t

(1)P Khi xy di t phi m bo khng b nh hng bt li ca cc iu kin t hoc phi c bo v mt cch thch hp khi cc tc ng .

(2) Cn phi c cc bin php bo v khi xy trnh b ph hoi bi cc tc ng ca m khi tip xc vi t.

(3) Khi t c kh nng cha cc ho cht c hi cho khi xy th khi xy cn phi c xy bng nhng vt liu c kh nng chu cc cht ho hc hoc n cn c bo v theo cch m cc cht ho hc khng th xm nhp vo khi xy.

5 Phn tch kt cu

5.1 Tng qut (1)P kim tra mi trng thi gii hn c lin quan, c th xy dng mt m hnh tnh ton kt cu t:

m t kt cu thch hp, cc vt liu xy dng cng trnh v mi trng ni xy dng cng trnh;

ng x ca ton th hay mt s b phn kt cu c quan h vi trng thi gii hn c lin quan;

cc tc ng v cch thc tc ng.

(2)P B tr tng th ca kt cu v s tng tc cng s lin kt ca cc b phn khc nhau ca kt cu phi m bo to ra s n nh thch hp v vng chc trong qu trnh xy dng v s dng.

(3) Cc m hnh tnh ton c th da trn tng b phn kt cu ring bit (nh tng) min sao tho mn 5.1(2)P.

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CH THCH Trong trng hp kt cu c xy dng t cc thnh phn c thit k ring bit th phi m bo s n nh v vng chc tng th.

(4) H qu ca tc ng ln kt cu phi c tnh ton bng mt trong hai cch sau:

l thuyt phi tuyn, tha nhn mt mi quan h c th gia ng sut v bin dng (xem 3.7.1);

l thuyt n hi tuyn tnh, tha nhn quan h tuyn tnh gia ng sut v bin dng vi dc bng m un n hi ct tuyn ngn hn (xem 3.7.2).

(5) Cc kt qu thu c t phn tch cc m hnh tnh ton cn a ra cu kin bt k:

ti trng dc trc do tc ng ngang v ng;

ti trng ct do cc tc ng ngang v/hoc ng;

m men un do cc tc ng ngang v/hoc ng;

m men xon nu c.

(1)P Cc cu kin kt cu phi c kim tra v trng thi cc hn v trng thi gii hn s dng da trn cc tc ng, l cc kt qu c c t phn tch.

(7) Cc quy tc thit k kim tra trng thi cc hn v trng thi gii hn s dng c cho trong mc 6 v mc 7.

5.2 ng x kt cu tnh hung ngu nhin (ngoi ng t v chy) (1)P Ngoi vic thit k kt cu chu cc ti trng s dng thng thng, cn phi m bo vi mt xc sut hp l l kt cu khng b h hi do b s dng sai hoc b nh hng bi tc ng ngu nhin vi mt mc nht nh so vi tc ng ban u.

CH THCH Khng c kt cu no c th chu cc ti trng hoc lc qu ln, hoc b tn tht cu kin chu lc hoc cc phn ca n do mt nguyn nhn cc oan. V d: trong mt ngi nh nh, mt h hng chnh c th gy ra s ph hu ton b.

(2) ng x kt cu cc tnh hung ngu nhin cn xem xt theo mt trong cc phng php sau:

cc cu kin c thit k chu cc tc ng ngu nhin cho trong EN 1991-1-7;

gi nh loi b ln lt cc cu kin chu ti ch yu;

dng mt h thng ging;

gim nguy c ca cc tc ng ngu nhin nh s dng hng ro ngn xe c m vo.

5.3 S khng hon chnh (1)P S khng hon chnh phi c xt n trong thit k.

(1) Cc nh hng c th ca s khng hon chnh cn c tnh n bng cch gi nh rng kt

cu b nghing mt gc = )h( tot100

1 radian theo phng ng.

trong :

htot l tng chiu cao ca kt cu tnh bng m.

Cn b sung tc ng ngang do nghing ny vo cc tc ng khc.

5.4 Hiu ng th cp

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(1)P Cc kt cu c tng xy c thit k theo tiu chun ny phi c cc b phn c ging vi nhau mt cch tho ng sao cho khng xut hin nghing lch kt cu hoc c nghing lch theo tnh ton.

(2) Khng cn tnh n nghing lch ca kt cu nu cu kin tng cng theo phng ng tho mn phng trnh (5.1) trong hng un thch hp ti chn cng trnh:

0,6 i vi n 4 EINh Edtot

0,2 + 0,1n vi 1 n 4 (5.1)

trong :

htot l tng chiu cao ca kt cu tnh t mt mng;

NEd l gi tr thit k ca ti trng ng (ti chn cng trnh);

EI l tng cng un ca tt c cc cu kin ng lm cng cng trnh hng c lin quan.

CH THCH: C th b qua cc l m, cc cu kin tng cng theo phng ng, nh hn 2 m2 vi chiu cao khng ln hn 0,6h.

n l s tng.

(3) Khi cc cu kin tng cng khng tho mn 5.4 (2) th cn tnh ton kim tra chu nghing lch.

CH THCH: Phng php tnh ton lch tm ca li n nh do nghing cho trong Ph Lc B.

5.5 Phn tch cc cu kin kt cu 5.5.1 Tng xy chu ti trng ng

5.5.1.1 Tng qut

(1) Khi phn tch tng chu ti trng ng, trong thit k cn xt ti nhng vn sau:

cc ti trng ng tc dng trc tip vo tng; cc hiu ng th cp;

lch tm tnh ton t bn v mt bng ca tng, tc ng tng h gia cc sn tng v cc tng tng cng;

lch tm do sai lch khi thi cng v s khc nhau v c tnh vt liu ca cc thnh phn ring l.

CH THCH: Xem TCVN *-2:2008 v lch cho php khi thi cng.

(2) M men un c th c tnh ton theo cc c tnh vt liu cho trong mc 3, s lm vic ca mch va v theo cc nguyn tc ca c hc kt cu.

CH THCH: Ph lc C a ra mt phng php n gin tnh ton cc m men un tng do ti trng ng gy ra. Ph lc C(4), C(5) c th dng vi bt c tnh ton no, k c l thuyt n hi tuyn tnh.

(3)P lch tm ban u, einit, c p dng cho ton b chiu cao tng tnh n nhng sai st khi thi cng.

(4) lch tm ban u, einit, c th gi thit bng hef/450, trong hef l chiu cao hiu dng ca tng, tnh ton theo 5.5.1.2.

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5.5.1.2 Chiu cao hiu dng ca tng xy

(1)P Chiu cao hiu dng ca tng chu lc c nh gi da trn cng tng i ca cc cu kin kt cu lin kt vi tng v hiu qu ca cc lin kt .

(2) Tng c th c tng cng bi sn hoc mi, bi b tr cc tng ngang mt cch thch hp hoc bt k cu kin kt cu cng tng t khc lin kt vi tng.

(3) Tng c xem l cng ti cnh ng nu:

khng c vt nt gia tng v tng tng cng, ngha l c hai tng u c lm bng vt liu c bin dng tng t nhau, u chu ti tng i ng u, c xy ng thi v lin kt vi nhau v khng xy ra nhng chuyn v khc nhau gia hai tng do co ngt, do ti trng v.v..

hoc

lin kt gia tng v tng tng cng c th khng li cc lc ko nn bi cc neo hoc thanh ging hoc cc bin php thch hp khc.

(4) Tng tng cng phi c chiu di t nht l 1/5 chiu cao thng thu v c chiu dy t nht l 0,3 ln chiu dy hiu dng ca tng c tng cng.

(5) Nu tng tng cng c cc l m th chiu di ti thiu ca tng gia cc l m, bao gm tng cng nh gii thiu trong hnh 5.1, v tng tng cng cn ko di mt khong t nht bng 1/5 chiu cao tng ngoi phm vi mi l m.

1

h >h/5 h

5 2 >t

h

t1)

2)

4)

3)

h12

2

21(h +h )

K HIU 1) Tng c tng cng 2) Tng tng cng 3) h2 (ca s) 4) h2 (ca i)

Hnh 5.1- Chiu di ti thiu ca tng tng cng c l m

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(6) Tng c th c tng cng bng cc cu kin khng phi l tng xy min sao cc cu kin c cng tng ng tng xy tng cng, c m t trong (4) trn, v chng lin kt vi tng c tng cng bng cc neo hoc thanh ging c thit k khng cc lc ko v nn.

(7) Tng c tng cng hai cnh ng vi l 30 t (hoc tng c tng cng 1 cnh vi l 15 t), trong l l chiu di ca tng gia cc tng tng cng hoc 1 cnh v t l chiu dy ca tng cng, cn c x l nh tng ch c lin kt ti nh v chn tng.

(8) Nu tng c tng cng b gim yu do cc rnh ng v/hoc cc hc ngoi nhng iu c php theo 6.1.2.1(7) th cn dng chiu dy gim yu ca tng thay cho t, hoc phi gi thit cnh t do ti v tr ca cc rnh hoc hc ng. Bao gi cng phi gi thit l cnh t do khi chiu dy tng cn li sau khi to rnh hoc hc nh hn mt na chiu dy tng.

(9) Tng c cc l m c chiu cao thng thy ln hn 1/4 chiu cao thng thy ca tng hoc chiu rng thng thy ln hn 1/4 chiu di tng hoc din tch ln hn 1/10 ca tng din tch tng s c xem l c cnh t do ti cnh ca l m xc nh chiu cao hiu dng.

(10) Chiu cao hiu dng ca tng c tnh nh sau:

hef = n.h (5.2) trong :

hef l chiu cao hiu dng ca tng;

h l chiu cao thng thy ca tng;

n l h s gim vi n = 2, 3 hoc 4 ph thuc vo lin kt ti cnh hoc vo s tng cng ca tng.

(11) H s gim, n, c th c gi thit nh sau: (i) i vi tng c nh ti nh v chn tng bng sn hoc mi b tng ct thp m rng ra c hai bn cng mt cao trnh hoc bng sn b tng ct thp ch m rng ra mt bn v c gi ta ti thiu bng 2/3 chiu dy tng:

2 = 0,75 (5.3) tr phi lch tm ca ti trng ti nh tng ln hn 0,25 ln chiu dy tng, trong trng hp

2 = 1,0 (5.4) (ii) i vi tng c nh ti nh v chn tng bng sn g hoc mi g m rng ra c hai bn cng mt cao trnh hoc bng sn g m rng ra mt bn, c gi ta ti thiu bng 2/3 chiu dy tng nhng khng nh hn 85 mm:

2 = 1,0 (5.5) (iii) i vi tng c nh ti nh v chn tng v c tng cng mt cnh ng (cnh ng cn li t do):

khi h 3,5 l,

222

3

31

1

+

=lh

(5.6)

vi 2 t (i) hoc (ii), ly gi tr no thch hp, hoc

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khi h > 3,5 l,

3,05,13 = hl (5.7)

trong :

l l chiu di tng.

CH THCH: Cc gi tr ca 3 cho di dng biu Ph Lc D (iv) i vi tng c nh ti nh v chn tng v c tng cng hai cnh ng:

khi h 1,15 l, vi 2 t (i) hoc (ii), ly gi tr no thch hp, 22

24

1

1

+=

lh

(5.8)

hoc

khi h > 1,15l,

hl5,0

4 = (5.9) trong :

l l chiu di tng.

CH THCH: Cc gi tr ca 4 cho trong dng biu Ph Lc D. 5.5.1.3 Chiu dy hiu dng ca tng xy

(1) Chiu dy hiu dng, tef, ca tng mt lp, tng hai lp, tng mt, tng m thnh v tng rng nhi nh nh ngha trong 1.5.10 cn c ly bng chiu dy thc t ca tng, t.

(2) Chiu dy hiu dng ca tng c tng cng bng b tr xc nh t phng trnh (5.10):

tef = t.t (5.10) trong :

tef l chiu dy hiu dng;

t l h s ly t bng 5.1; t l chiu dy tng.

Bng 5.1 - H s cng, t, i vi tng c tng cng bng b tr, xem hnh 5.2 T s ca chiu dy tr v chiu dy thc t ca tng lin

kt vi tr T s ca khong cch tr (t tm

n tm) v chiu rng tr

1 2 3

6 1,0 1,4 2,0

10 1,0 1,2 1,4

20 1,0 1,0 1,0

CH THCH c php ni suy gia cc gi tr cho trong bng.

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2)

4)

1)

3)

K HIU 1)Khong cch tr 2) Chiu su tr 3) Chiu dy tng 4) Chiu rng tr

Hnh 5.2- Minh ho cc nh ngha dng trong bng 5.1

(3) Chiu dy hiu dng, tef, ca tng rng m 2 lp c lin kt bng thanh ging tng ph hp vi 6.5 c xc nh bng phng trnh (5.11):

3 32

31tefef ttkt += (5.11)

trong :

t1, t2 l chiu dy thc t ca cc lp hoc chiu dy hiu dng ca chng c tnh t phng trnh (5.10), trong trng hp thch hp, t1 l chiu dy ca lp ngoi hoc lp khng chu ti v t2 l chiu dy lp trong hoc lp chu ti;

ktef l h s tnh n cc gi tr E lin quan ca hai lp t1 v t2.

CH THCH: C th ly gi tr ktef (tnh bng E1/E2) bng 1.

(4) Khi ch c mt lp ca tng rng chu ti, c th dng phng trnh (5.11) tnh chiu dy hiu dng min sao cc thanh ging tng mm lp chu ti khng b nh hng bt li ca lp khng chu ti. Khi tnh ton chiu dy hiu dng, chiu dy ca lp khng chu ti khng c ly ln hn chiu dy ca lp chu ti.

5.5.1.4 mnh ca tng xy

(1)P mnh ca tng xy bng gi tr ca chiu cao hiu dng, hef, chia cho gi tr ca chiu dy hiu dng, tef.

(2) mnh ca tng xy khng c ln hn 27 khi chu ti trng ng l ch yu.

5.5.2 Cu kin xy c ct thp chu ti trng ng

5.5.2.1 mnh

(1) mnh ca cc cu kin xy c ct thp chu ti ng trong mt phng ca cu kin cn c xc nh ph hp vi 5.5.1.4.

(2) Khi tnh ton mnh ca tng rng nhi, chiu dy ca tng khng c da vo rng khe rng ln hn 100 mm.

(3) mnh ca cc cu kin khng c ln hn 27.

5.5.2.2 Nhp hiu dng ca dm xy

(1) Nhp hiu dng, lef, ca dm xy n gin hoc lin tc, khng k dm su, c th ly gi tr nh hn trong hai gi tr di y (xem hnh 5.3):

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khong cch gia cc tm gi ta;

khong cch thng thu gia cc gi ta cng vi chiu su hiu dng, d.

2) 3)

l

t

1)

ef

1 2

d

t

K HIU

1) Ct thp

2) t1/2 hoc d/2 ly gi tr nh


Hnh 5.3- Nhp hiu dng ca dm xy n gin hoc dm lin tc

(2) Nhp hiu dng, lef, ca cng xon xy c th ly gi tr nh hn trong hai gi tr di y: (xem hnh 5.4):

khong cch gia u cng xon v tm gi ta ca n;

khong cch gia u cng xon v mt gi ta cng vi na chiu su hiu dng ca n, d.

d

2)

1)

t

lef

K HIU

1) Ct thp


Hnh 5.4- Nhp hiu dng ca cng xon xy

(3) Nhp hiu dng ca dm su xy c th xc nh theo 5.5.2.3.

5.5.2.3 Dm su xy chu ti trng ng

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(1) Dm su xy l tng hoc cc phn ca tng chu ti trng ng, bc qua l m sao cho t s ca chiu cao ton b tng trn l m vi nhp hiu dng ca l m t nht l 0,5. Nhp hiu dng ca dm su c th c ly bng:

lef = 1,15 lcl (5.12)

trong :

lcl l chiu rng thng thu ca l m, xem hnh 5.5.

(2) Cn a vo tnh ton ton b cc ti trng ng tc ng ln phn tng nm pha trn nhp hiu dng, tr phi ti trng c th do cc b phn khc chu, v d, do cc sn pha trn lm vic nh ging.

(3) Khi xc nh cc m men un, dm su c th c xem l dm c gi ta n gin nh trong hnh 5.5

h> l /2

l

l

1)

ef

cl

ef

K HIU

1) Ct thp

Hnh 5.5- Phn tch dm su xy

5.5.2.4 S phn phi li ni lc

(1) Trong cc cu kin xy c ct thp, s phn phi ni lc n hi tuyn tnh c th c thay i, gi thit cn bng lc, nu cc cu kin c do, c th c chp nhn nu t s ca chiu su trc trung ho, x, v chiu su hu hiu, d, khng vt qu 0,4 trc khi phn phi li mmen. nh hng ti ton b thit k t bt c s phn phi li mmen no cn c a vo tnh ton theo EN 1992-1-1.

5.5.2.5 Nhp gii hn ca cc cu kin xy c ct thp chu un

(1) Nhp ca cc cu kin xy c ct thp cn phi gii hn gi tr thch hp ly theo bng 5.2.

Bng 5.2 Cc t s gii hn ca nhp hiu dng vi chiu su hiu dng i vi tng chu un ngoi mt phng v i vi dm

T s ca nhp hiu dng vi chiu su hiu dng (lef/d) hoc chiu dy hiu dng (lef/tef)

Tng chu un ngoi mt phng Dm

Gi ta n gin 35 20

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Lin tc 45 26

Un theo hai chiu 45 -

Cng xon 18 7

CH THCH: i vi tng ng t do khng to thnh mt phn ca cng trnh v ch yu chu ti trng gi, cc t s trn c th tng thm 30% min sao cc tng nh vy khng c lp hon thin c th b h hi do vng.

(2) cc cu kin gi ta n gin hoc lin tc, khong cch thng thy gia cc lin kt ngang, lr, phi m bo cc yu cu sau:

lr 60 bc hoc (5.13)

2250

cr bdl , ly gi tr nh hn (5.14)

trong :

d l chiu su hiu dng ca tit din cu kin;

bc l chiu rng ca mt chu nn gia cc lin kt.

(3) i vi cng xon vi lin kt ngang ch c ti gi ta, khong cch thng thy t u cng xon ti mt gi ta, lr, khng c vt qu:

lr 25 bc hoc (5.15) 2100cc bd

l , ly gi tr nh hn; (5.16) trong :

bc c ly ti b mt gi ta.

5.5.3 Tng xy chu ct

(1) Khi phn tch tng xy chu ct, cng n hi ca tng, bao gm cc cnh, c s dng lm cng ca tng. i vi tng c chiu cao ln hn hai ln chiu di th c th b qua nh hng ca bin dng do ct ln cng.

(2) Tng giao hoc mt phn ca n c th xem l mt cnh i vi tng chu ct min sao s lin kt ca tng ct vi cnh c th chu cc tc ng ct tng ng v cnh khng b mt n nh trong phm vi chiu di gi nh.

(3) Chiu di ca bt c tng giao no c xem l cnh (xem hnh 5.6), l chiu dy ca tng ct cng vi gi tr nh nht di y (v mi pha ca n):

htot/5, trong htot l ton b chiu cao ca tng ct;

mt na khong cch gia cc tng ct (ls) khi c lin kt vi tng giao;

khong cch ti u tng;

na chiu cao thng thu (h);

6 ln chiu dy ca tng giao, t.

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(4) cc tng giao, cc l m c kch thc nh hn h/4 hoc l/4 c th b qua. Cc l m vi kch thc ln hn h/4 hoc l/4 cn c xem l ch kt thc ca tng.

1)

l

2)

3) s

K HIU 1) Gi tr nh nht

Hnh 5.6- Chiu rng cnh i vi tng ct

(5) Nu sn c th l tng ho l ming cng th lc ngang c th c phn phi ti cc tng ct theo t l cng ca chng.

(6)P Khi b tr tng ct trn mt bng khng i xng, hoc v bt c l do no m lc ngang lch tm so vi tm cng tng th ca kt cu th cn xt n nh hng ca tc ng xoay trn tng bc tng (hiu ng xon).

(7) Nu cc sn khng cng c coi l cc ming cng (v d, cc cu kin b tng c sn khng c lin kt vi nhau) th cc lc ngang do cc tng ct chu cn ly t cc sn m chng trc tip lin kt, tr khi thc hin phn tch bn cng.

(8) Lc ngang ln nht tc dng ln mt tng ct c th gim ti 15% min sao ti trng tc dng ln cc tng ct song song vi n tng ln mt cch tng ng.

(9) Khi xc nh ti trng thit k c lin quan h tr kh nng khng ct, ti trng ng tc dng ln cc sn lm vic theo hai phng c th c phn b u ln cc tng ; trong trng hp cc tm sn hoc mi lm vic theo mt phng, c th xem xt s truyn ti trng theo gc 450 t ti trng dc trc, ti cc tng thp hn, ln cc bc tng khng c gia ti trc tip.

(10) S phn b ng sut ct dc theo vng nn ca tng c th gi thit l khng i.

5.5.4 Cc cu kin xy c ct thp chu ti trng ct

(1) Khi tnh ton ti trng ct thit k trong cc cu kin xy chu ti phn b u, c th gi thit rng ti trng ct ln nht xy ra khong cch d/2 tnh t mt gi ta, trong d l chiu su hiu dng ca tit din cu kin.

(2) Khi ly ti trng ct ln nht ti d/2 tnh t mt gi ta, cn tho mn cc iu kin sau:

ti trng v phn lc gi ta phi gy ra nn theo ng cho trong cu kin (gi ta trc tip);

gi ta ngoi cng, ct thp chu ko khong cch 2,5 d tnh t mt gi ta phi c neo vo gi ta;

gi trung gian, ct thp chu ko ti mt gi ta cn ko di mt khong t nht 2,5d, cng thm chiu di neo, vo gia nhp.

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5.5.5 Tng xy chu ti trng ngang

(1) Khi phn tch tng xy chu ti trng ngang, cn tnh n trong thit k nhng vn sau:

nh hng ca cc lp cch m;

cc iu kin gi ta v tnh lin tc qua cc gi ta.

(2) Tng mt cn c phn tch nh tng n c xy hon ton bng cc vin xy c cng chu un thp.

(3) Khe co gin trong tng c coi l ni m men v lc ct khng th truyn qua.

CH THCH: Mt s neo c bit c thit k truyn mmen v/hoc lc ct qua khe co gin; vic s dng chng khng thuc phm vi ca tiu chun ny.

(4) Phn lc dc theo mt cnh tng do ti trng tc dng c th c gi thit l phn b u khi thit k cc bin php ta. Lin kt c nh gi ta c th c to ra bng cc thanh ging, bng cc phn tht vo ca khi xy c xy ghp hoc bi sn hoc mi.

(5) Trng hp tng chu ti trng ngang c lin kt (xem 8.1.4) vi tng chu ti trng ng, hoc sn b tng ct thp ln chng, gi ta c th c xem l lin tc. Lp cch m cn c xem l to ra gi ta n gin. Trng hp tng lin kt vi tng chu lc ng hoc vi kt cu thch hp khc bng cc thanh ging ti cnh ng, th c th gi thit tnh lin tc mt phn m men ti cc cnh thng ng ca tng nu cng ca cc thanh ging c kim tra l .

(6) Trong trng hp tng rng, c th gi thit hon ton lin tc thm ch ch mt lp c lin kt lin tc qua gi ta, min l tng rng c cc thanh ging ph hp vi 6.3.3. Ti trng truyn t tng xung gi ta ca n c th c thc hin bng cc thanh ging vo ch mt lp tng, min l c s lin kt chc chn gia hai lp tng (xem 6.3.3) t bit ti cc cnh ng ca tng. Trong cc trng hp khc c th gi thit lin tc mt phn.

(7) Khi tng c dc theo 3 hoc 4 cnh, vic tnh ton m men tc dng, MEdi, c th ly nh sau:

khi mt phng ph hu song song vi cc mch ngang, ngha l theo hng fxk1:

MEd1 = 1.WEd. l2 trn mt n v chiu di ca tng (5.17) hoc

khi mt phng ph hu vung gc vi mch ngang, ngha l theo hng fxk2:

MEd2 = 1.WEd. l2 trn mt n v chiu di ca tng (5.18) trong :

1, 2 l cc h s mmen un k n mc ngm ti cc cnh ca tng, t s chiu cao/chiu di ca tng; chng c th c tnh ton t l thuyt;

l l chiu di ca tng;

WEd l ti trng ngang thit k trn mt n v din tch.

CH THCH: Cc gi tr ca h s mmen 1 v 2 c th ly t Ph lc E cho cc tng mt lp vi chiu dy nh hn hoc bng 250mm, trong 1 = 2 trong :

l t s trc giao ca cc cng un thit k ca khi xy, fxd1/fxd2, xem 3.6.3 hoc fxd1,app/fxd2 xem 6.3.1(4) hoc fxd1/fxd2,app xem 6.5.2(9);

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(8) H s mmen un lp cch m c th c ly nh i vi mt cnh hon ton lin tc khi ng sut thng ng thit k trn lp cch m bng hoc ln hn ng sut ko thit k gy ra bi mmen sinh ra do tc ng.

(9) Khi tng ch ta dc theo cnh chn tng v cnh nh tng, mmen c th tnh ton theo cc nguyn tc thit k thng thng, c xt ti bt c s lin tc no.

(10) Tm tng chu ti trng ngang hoc tng ng t do xy bng vin xy vi va mc M2 n M20 v thit k theo 6.3, cc kch thc cn c gii hn theo mc ra trong Ph lc F trnh cc mmen qu ln do vng, t bin, co ngt, hiu ng nhit v nt gy ra.

(11) Khi phn tch cc loi tng c hnh dng khng u n hoc tng c din tch l m ln th c th s dng phng php c cng nhn tnh mmen trong cc tm phng, chng hn nh phng php phn t hu hn hoc phng php tng t ng bin dng, c xt n tnh bt ng hng ca khi xy trong trng hp thch hp.

6. Trng thi cc hn

6.1 Tng xy khng ct thp ch yu chu ti trng ng 6.1.1 Tng qut

(1)P Kh nng chu ti trng ng ca tng xy cn da trn kch thc ca tng, nh hng ca lch tm v c tnh vt liu ca khi xy.

(2) Khi tnh ton kh nng chu ti trng ng ca tng xy, c th gi thit:

tit din phng duy tr phng; cng chu ko ca khi xy vung gc vi mch ngang bng khng. 6.1.2 Kim tra tng xy khng c ct thp ch yu chu ti trng ng

6.1.2.1 Tng qut

(1)P trng thi cc hn, gi tr thit k ca ti trng ng tc dng ln tng xy, NEd, phi nh hn hoc bng gi tr thit k v kh nng chu lc the

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