Properties of Materials

Transcription

1 Mechnicl & Therml Proerties o Mterils D. Pinte R. Zhri Universit o Timisor Romni Kliske G. Kklusks D. Bcinsks V. Gribnik Vilnius Gedimins Technicl Universit Lithuni Á. Török M. Hjál Budest tuniversit it o Technolog nd conomics Hungr

2 .3 Design vlues o mteril roerties Mechnicl roerties X d i k X /γ k M i Chrcteristic vlue o mechnicl roert or norml temerture design to N Reduction ctor or mechnicl Check NA! roert with resect to temerture Prtil mteril set (X k / X k ) ctor or ire sitution; 1.0 recommended or therml & Mteril roert mechnicl roerties t elevted temertures Therml roerties X d i X k / γ M i γ X γ M i k i n increse o the roert is vourble or set i n increse o the roert is unvourble or set

3 STL N

4 3. Mteril Proerties Steel Annex A Strinhrdening Crbon steel mbient vlues N Mechnicl roerties Therml roerties Stress-strin reltionshis lstic modulus Yield strength Stinless steel Annex C Therml elongtion Seciic het Therml conductivit

5 3..1 Stress strin reltionshis Stress σ ~ 50 K/min Vlid onl or heting rtes: Tngent modulus t ) ( ) )( ( c c b c + + t n α ) ( ) ( ) ( ) ( c Strin α t u / / ( ) or σ t b b ( ) ( ) ( ) + < < ) )/( ( 1 0 or or σ σ t t t c [ ] < < 0.0 or ) )/( ( 1 or σ σ u t u t u t

6 Reduction ctors Reduction ctor BS (% strin) 0.6 Yield strength k k k Sloe o liner roortionl elstic rnge 0. limit Temerture [ o C]

7 Stress strin curves or S75 ] Stress [N/mm ] Correltion t ll temertures is in good greement. 0 C 00 C 300 C 400 C 500 C 600 C 700 C 800 C Test dt Strin [%]

8 CONCRT 199 1

9 3. Mteril Proerties Concrete N mbient vlues Mechnicl Norml weight roerties concrete + Reinorcing steel Prestressing steel Therml roerties High strength concrete Section 6 Stress-strin reltionshis lstic modulus Yield strength Therml elongtion Seciic het Therml conductivit Lightweight concrete The vlues o mteril roerties given in this section shll be treted s chrcteristic vlues.

10 3...1 Concrete under comression 3 c 3 c1 [ + ( / c1 ) ] σ ( ) Liner or non - liner models Stress σ c 1. Vlid onl or heting rtes: or or c1 c1 < cu1 ~ 50 K/min. The three rmeters c c1 nd cu1 re temerture-deendent c1 Strin cu 1

11 [ C] Concrete comressive strength rmeters Siliceous & clcreous c1 cu Siliceous concrete hs lrger strength reduction thn clcreous concrete. Vrition o strins c1 nd cu1 with temertures re the sme or both concrete tes. Reduction ctor o comressive strength c Siliceous ggregte Clcreous ggregte g Tble Temerture [ o C]

12 3... Concrete under tension Conservtivel tensile strength o concrete should normll be ignored. Reduction ctor o tensile strength I it is necessr to consider the tensile strength In bsence o more ccurte inormtion these vlues should be used Temerture [ o C]

13 Fctors ecting strength o concrete Mix roortions Wter cement rtio Aggregte cement rtio Te o ggregte (Schneider nd Horvth 003)

14 Comrison exer (1 3) redicted (4 9) comressive concrete under ire 1 Concrete strength c / c siliceous ggregtes (1) () (3) (4) (5) (6) 0 (7) (8) (9) 0 Temerture C

15 The strin comonents ( ) ( ) ( ) σ σ + + σ t tot σ th tr cr tot σ th the totl strin the stress relted strin the therml strin tr cr the trnsient cree strin (lod induced therml strin)

16 The therml strin o concrete The therml strin is the ree therml exnsion rom the ire Minl inluenced b the te nd mount o ggregte The corse ggregte ls n imortnt role (Schneider nd Horvth 003)

17 Trnsient cree strin develos during irst heting under lod. It is unique to concrete. Lits is much lrger thn the elstic strin contributes to signiicnt relxtion nd redistribution o therml stresses in heted concrete structures. (Khour 000). ctors ecting the trnsient strin rete o ggregte ggregte/cement rtio curing conditions loding level (Schneider nd Horvth 003). Mthemticl models or trnsient therml strin clcultions re reviewed b Yousse nd Moth (007).

18 Shrinkge strin Could be dded to the eq. o strin However since ll exerimentl high temerture dt re reorted rom unseled test conditions the shrinkge comonent cn be viewed s being included in the therml strin. shrinkge is ssumed to be indeendent o loding (Nielsen et l 004).

19 xlosive slling When the moisture content is less thn 3% b weight exlosive slling is unlikel to occur. Above 3% more ccurte ssessments moisture content te o ggregte ermebilit o concrete nd heting rte should be considered. Slling cn be groued into our ctegories: () ggregte slling; (b) exlosive slling; (c) surce slling; (d) corner/sloughing o slling. The irst three occur during the irst 0 30 min into ire nd re inluenced b the heting rte while the ourth occurs ter min o ire nd is inluenced b the mximum temerture.

20 xlosive slling (contd.) The min rmeters ecting the slling eect re content o moisture in concrete the heting condition comressive stresses thickness o concrete osition o reinorcement mix roortion ibre volume (Schneider nd Horvth 003). ) The rediction o slling is now becoming ossible with the develoment o thermo hdro mechniclhdro mechnicl nonliner inite element models cble o redicting ore ressures (Khour 000).

21 3..3 Reinorcing steel Stress σ ~ 50 K/min Vlid onl or heting rtes: Tngent modulus t ) ( ) )( ( c c b c + + t n α ) ( ) ( ) ( ) ( c Strin α t u / Clss A reinorcement: t 0 05; / ( ) or σ t b b st 0.05; su 0.10 ( ) ( ) ( ) + < < ) )/( ( 1 0 or or σ σ t t t c [ ] < < 0.0 or ) )/( ( 1 or σ σ u t u t u t

22 Reduction ctors Without mteril Clss N steel tests t in ire Reduction ctor s tension rebr (hotrolled) or strin > % 1 s tension rebr (cold worked) or strin > % s comression & tension rebr or strin < % s hot-rolled rebr 3..3 Reinorcing steel Tble s cold worked rebr s hot-rolled rebr s cold worked rebr 0. 0 Clss N Reinorcing Steel Temerture [ o C]

23 1 Reduction ctors Clss X steel Reduction ctor strength tested in ire s tension rebr (hot rolled & cold worked) or strin > % 0.8 s comression & tension rebr (hot rolled & cold worked) or strin < % s hot rolled & cold 0.6 w orked rebr 3..3 Reinorcing steel Tble 3.b 0.4 s hot rolled & cold w orked rebr 0. 0 Clss X Reinorcing Steel Temerture [ o C]

24 Therml Proerties

25 STL

26 Therml elongtion Steel 3.4 Therml roerties The nonliner model incororting the eect o hse chnge in steel crstl structure between 750 C & 860 C. Therml elongtion Δl /l [x10-3 ] 0 16 Phse chnge in crstl structure Temerture [ o C]

27 Seciic het Steel The model incorortes the eect o hse chnge in steel crstl structure t 735 C. Seciic het [J/kg K] 5000 Phse chnge in crstl structure Temerture [ o C]

28 Therml conductivit Steel Therml conductivit [W/m K] Constnt ter 800 C Temerture [ o C]

29 CONCRT

30 3.3 Therml roerties o concrete Therml elongtion o concrete It is ssumed tht siliceous concrete exnds more t elevted temertures thn clcreous concrete. Therml strin [x10-3 ] Siliceous ggregte 6 Clcreous ggregte No urther therml exnsion Temerture [ o C]

31 3.3. Seciic het o concrete The moisture content is modelled b the ek vlues situted between 100 C nd 115 C. 3.3 Therml roerties o concrete Seciic het [kj/kg K].5 (Moisture content u 3%) For both siliceous nd clcreous ggregtes 1.5 (u 1.5%) (u 0%) Temerture [ o C]

32 3.3 Therml roerties o concrete 3.3. Densit o concrete Percentge reduction o densitr Densit reduces due 0.8 to wter loss Temerture [ o C]

33 3.3.3 Therml conductivit o concrete 3.3 Therml roerties o concrete Determined between the lower nd uer limit vlues: Therml conductivit [W/m K] Set b NA Lower limit Uer limit For both siliceous nd clcreous ggregtes Temerture [ o C]

34 3.4 Therml elongtion o reinorcing nd restressing steel Therml elongtion Δl /l [x10-3 ] Prestressing steel 14 1 Reinorcing steel Phse chnge in crstl structure Temerture [ o C]