Study on the mechanical behavior of steel reinforced high strength concrete subjected to impact loading

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1 Inernaional Journal of e Pysical Sciences Vol. 6(3), pp , 4 July, 2 Available online a p:// DOI:.5897/IJPS.72 ISSN Academic Journals Full Leng Researc Paper Sudy on e mecanical beavior of seel reinforced ig sreng concree subeced o impac loading Guoping Jiang*, Si Huan, Cuie Jiao and Weiun Tao Earquake Engineering Researc Tes Cener of Guangzou Universiy, Guangzou 545, Cina. Acceped 26 May, 2 In is paper, e impac experimens of seel fiber reinforced concree wi same impac velociy and differen seel fiber conens are processed by one-sage lig gas gun. Troug e manganin gauges embedded in e arge, e volage-ime signals are recorded. Lagrangian meod is used o analyze e flow field, en e paricle velociy (u), specific energy, specific volume wi ime are obained. Moreover, i was observed from e measured pressure-ime curves a e decay facor is smaller in e seel reinforced ig sreng concree. Te dynamic response is analyzed. Key words: Concree, relaionsip, seel fiber. INTRODUCTION Ulra-ig performance cemeniious composie is a ype of building maerial wi very ig sreng and durabiliy. Wi ig sreng and duciliy, i is suiable for bridge decks, in sell srucures, nuclear power plans and defensive faciliies a may experience impac loads (Tang, 24; Jacques and Cee, 24; Bonneau e al., 996; Ricard and Ceyrezy, 995). Bu e iger e sreng of e concree, e iger e brile. So i necessary o add e seel fiber o e ig sreng o increase is mecanical propery. Also, o design and analyze ese srucures beer, i is imperaive o invesigae e mecanical caracerisics and consiuive model of seel fiber reinforced ig sreng concree. A grea number of ess ave been conduced o find e effec of srain rae on e dynamic sreng of concrees. A few meods, suc as direc impac es, spli Hopkinson pressure bar (SHPB) es, plae impac es and e lig gas gun es, are commonly used o deermine e dynamic maerial properies (Tang, 24; Jacques and Cee, 24; Bonneau e al., 996; Ricard and Ceyrezy, 995; Hao and Tarasov, 28). Te spli Hopkinson pressure bar (SHPB) is an effecive meod o obain e dynamic sress srain curves of maerials. *Corresponding auor. lp22999@26.com Tel: Te srain rae of concree in SHPB es is usually 2 /s and below. Using a long barrel, e srain rae of concree can reac 3 o 4 /s. I is commonly undersood a dynamic maerial properies are differen from e corresponding saic maerial properies. For example, e recen dynamic compressive ess of masonry maerial properies (clay brick and morar) indicaed a e maerial yield and ulimae sreng, yield and ulimae srain, elasic modulus and Poisson s raio all cange wi e srain rae (Hao and Tarasov, 28). I was found a e sreng of e morar and clay brick increase by wo o ree imes a srain rae of abou /s. Oer ess on concree maerials (Groe e al., 2) and rock maerial (Li e al., 24) also indicaed a similar increase of compressive sreng. Subsanially more significan increase in concree maerial ensile sreng was also observed by many researcers (Sculer e al., 26). Tis penomenon of maerial sreng increase a ig srain rae is ermed srain rae effec. Undersanding e srain rae effec is very imporan in assessing e srucural capaciy in resising impac and blas loads. THE EXPERIMENTS Maerials preparaion Te sreng grade of cemen is P II 52.5 according o e

2 3 In. J. Pys. Sci Figure. Scemaic diagram of e experimen. () Proecile assembly, (2) lig camber, (3) flyer, (4) arge, (5) base board, (6) managanin gauges, (7) recycle bin, (8) specimen. relevan Cina sandard. Te maximum paricle size of naural sand is 2.5 mm wi a fineness modulus of 2.6. Te equivalen diameer, leng and ensile sreng of e seel fiber are.2 mm, 3 mm and 8 MPa respecively. Te mix proporion is adoped C by e Cina sandard.te volumeric seel fiber concenraion and 5% are used wic called CV and CV 5,Te saic sreng of wic are 58.3 and 64.6 MPa respecively. Specimens ave a diameer of 92 mm and a leng of 8 mm. Tere are four specimens assembled. Te flyer as e same diameer and mm leng. Considering conac, is leng is raer small and i due o e dynamic loading condiions. Te analysis of e es is based on e assumpion of no laeral effec, erefore long specimens compared wi e diameer mus be avoided. A second poin afer sriking, a sress wave propagaes in e flyer and e specimens. Wen i arrives a e ead face of e flyer, a sparsiy reflecion sress wave is produced. To avoid e reflecion wave from cacing up wi e specimens, e leng of flyer mus be long compared wi e diameer. Te design of e experimens Te one-sage lig gas gun as been one of e main experimenal seups for esing concree and reinforced concree specimens. Te experimens are carried ou in e Earquake Researc Cener laboraory of Guangzou Universiy in Cina. Te diameer and leng of e gun is mm and 3 m, respecively. Te range of impac velociies is from 2 o 8 m/s e error of wic is less an 5% and e level of impac is less an -3 rad. Te responses of srain raes range from 3 o 4 /s. Te one-sage lig gas gun apparaus is sown in Figure. Upon impac, e flyer is placed on e proecile assembly. Te ig pressure gases are suddenly released o propel e proecile assembly o move along e gun camber. Wen e proecile assembly wi a ig velociy collides wi arge, ig pressure pulses are produced. Tese volage-ime signals will be recorded by e ree H gauges (Figure 2). Te deails of e H gauges (5 Ω) are described in Cai e al. (2) and Ma e al. (26). Te signals can be obained by e oscilloscopes and can be canged o e pressure by using e following formula: R σ = (.3252 ±.69) + ( ±.464)( ) R R σ = (.4 ±.55) + (5.469 ±.2773)( ) R ( Gpa) (.5Gpa) Were σ is e pressure, R is e cange of e resisance, R is e iniial resisance. From e formula e pressure-ime curves are obained (Figures 3 and 4). LAGRANGIAN METHOD Te record of -D Lagrangian meod is used o calculae e flow field disribued in e esed maerials. Te experimenal emporal curves are used o calculae ()

3 Jiang e al. 3 Figure 2. H ype gauges..6 8m m 6m m Time (µs) Figure 3. Te CV sress-srain curves experimened m m 6 m m Time (µs) Figure 4. Te CV5 sress-srain curves experimened.

4 32 In. J. Pys. Sci. e value-ime relaions of paricle velociy, relaive specific volume and inernal energy per uni volume on every Lagrangian posiion. Te relaionsip of experimen, academic model and e numerical simulaion is esablised by e Lagrangian meod. Conservaion equaions in one-dimension are as follows (Cosovos and Pavlović, 27): 2 p u u = ν ( ) d (2) u v v = ( ) τ d u e e = v p( ) τ d ρ Were is e densiy, u u is paricle velociy, is paricle velociy of sock fron, v is relaively specific v volume, is relaively specific volume of sock fron, E E is inernal energy per uni volume, is inernal energy per uni volume of sock fron, and, 2 is sar ime and end ime, respecively. is Lagrangian posiion. Te pa lines and paricle lines are adoped o preven e useful informaion los in inegral along e isocrones lines. Te analogical poins (Huan e al., 989) (e caracerisic poins on e waves suc as e end poin of elasic wave, e peak poin of plasic wave ec.) in e pressure-ime curves are conneced o esablis e pa lines. Te paricle lines are e curves of e parameers varied wi e ime recorded by e Lagrangian gauges. Te inegral along isocrone lines can be canged along e pa lines and paricle lines: (3) (4) Te paricle velociy, relaive specific volume and inernal energy per uni isories are all obained from Equaions 7, 8 and 9 wi e inegral along e pa lines and paricle lines of pressure isories and relaively radial displacemen isories. Te inegral along isocrone lines canged along e pa lines and paricle lines wi no oer suppose by e Equaions 5 and 6. Te error is mainly from e experimen and e curves fiing. Te leas square curves fiing meod is adoped wi e B-spline funcion as es funcion o preven e error diffusing o e wole flow field. Te deails of e error analysis of 2-D Lagrangain meod were described in Huan e al. (989), Huan e al. (99) and Zou and Hao (28a,b). Seel reinforced effec Te problem in dynamic maerial esing is e laeral inerial confinemen. Some researcers argued a e increase in maerial sreng observed during dynamic es is caused, a leas parially, by inerial confinemen (Zou and Hao, 28a, b; Tang e al., 992). In is researc, from Figure 5 e sress peak value- Lagrangain posiion curves (Figure 6) is obained. I can be observed a a e firs Lagrangain posiion e pressure beween e wo ype concree are nearly e same. Bu e seel reinforced ig sreng concree weakens more slowly an e ig sreng concree. Te seel reinforced e mecanical beavior of e ig sreng concree. Te mecanism of reinforced effec can be resolved from Figure 7(a). Seel girds are perpendicular o loading direcion and increase e inensiy of e concree, so e load-carrying capaciies of seel reinforced ig sreng increase oo. Conclusions p d p p d ( ) = ( ) ( ) ( ) d d u d u u d ( ) = ( ) ( ) ( ) d d So, e Equaions 2, 3, 4 can be wrien as follows: u = u ρ 2 p [( ) p ( ) ( ) ] d (5) (6) (7) Te sock properies of C concree is invesigaed by gas gun planar impac ecnique. Te manganin pressure gauge is used o measure e pressure-ime curves of e samples. Te pysical quaniies are all obained by e Lagrange meod. Te seel reinforced effec as been analyzed. Moreover, i is observed from e measured pressure-ime curves a e rae-sensiiviy of dynamic response for C concree is no negligible, sowing marked sress relaxaion and dissipaion. v = v + 2 u [( ) u ( ) ( ) ] d 2 v E = E P ( )( ) d (9) (8) ACKNOWLEDGMENTS Te auors graefully acknowledge e financial suppor from Naional Naural Science Foundaion of Cina (Proec and 57822).

5 Jiang e al. 33 CV.6 CV Srain Figure 5. Te sress -srain curves a differen posiion..6 5% Figure 6. Te sress peak value-posiion curves. Sress (mm)

6 34 In. J. Pys. Sci. a In eria fo rces Figure 7. (a) Laeral inerial confinemen under uniaxial compression; (b) under uniaxial ension. REFERENCES Bonneau O, Poulin C, Duga J (996). Reacive powder concree: from eory o pracice,concre. In., 8 (4): Cai JC, Yu B, Zou M, MQ (2). Fracal caracerizaion of sponaneous co-curren imbibiion in porous media. Energy Fuels, 24(3): Cosovos DM, Pavlović MN (27). Numerical invesigaion of concree subeced o ig raes of uniaxial ensile loading. In. J. Impac Eng., Available online: doi:.6/.iimpeng.3.6. Groe DL, Park SW, Zou M (2). Dynamic beaviour of concree a ig srain raes and pressure: I. experimenal caracerizaion, In. J. Impac Eng., 25: Hao H, Tarasov B (28). Experimenal sudy of dynamic maerial properies of clay brick and morar a differen srain raes, Aus. J. Sruc. Eng., 8(2): Huan S (988). Sock iniiaion and wo-dimenional Seady-sae deonaion in eerogeneous explosives. PD, Sae Key Laboraory of Explosion Science and Tecnology, Beiing Insiue Tecnology Beiing. Huan S, Ding J (99). A wo-dimensional Lagrangian ecnique for flow field measuremen under ig dynamic pressure. Aca Mecanica Sinaica, 6: b Huan Si, Ding J (989). A wo-dimensional Lagrangian ecnique for sock iniiaion diagnosis. Nin Symposium (Inernaional) on Deonaion, Augus 28 Sepember, Porland, Oregon. OCNR 329-7, p Jacques R, Cee L (24). Firs recommendaion for ulra-igperformance concree and example of applicaion, in: M. Scmid, E. Feling, C. Geisenansluke (Eds.), UlraHig Performance Concree, Kassel Uni. Press, Kassel, pp Li HB, Zao J, Li JR, Liu YQ, Zou QC (24). Experimenal sudies on e sreng of differen rock ypes under dynamic compression, In. J. Rock Mec. Mining Sci., p.-6. Ma GW, Dong A, Li J (26). Modeling srain rae effec for eerogeneous brile maerials. s Inernaional Conference on Analysis and Design of Srucures agains Explosive and Impac Loads, Sep, Tianin, Cina. Transacion of Tianin Uni., 2(Suppl.), pp Ricard P, Ceyrezy M (995). Composiion of reacive powder concree, Cem. Concre. Res., 25 (7): 5 5. Sculer H, Mayrofer C, Toma K (26). Spall experimens for e measuremen of e ensile sreng and fracure energy of concree a ig srain raes, In. J. Impac Eng., 32: Tang MC (24). Hig performance concree pas, presen and fuure, in: M. Scmid, E. Feling, Geisenansluke C (Eds.),Ulra Hig Performance Concree, Kassel Uni. Press, Kassel, pp Tang T, Malvern LE, Jenkins DA (992). Rae effecs in uni-axial dynamic compression of concree. ASCE J. Eng. Mec., 8():8-24. Zou XQ, Hao H (28a). Modelling of Compressive Beaviour of Concree-like Maerial a Hig Srain Rae, In. J. Solids Sruc., 45(7): Zou XQ, Hao H (28b). Mesoscale modeling of concree ensile failure mecanism a ig srain rae, In. J. Compu. Sruc., 86(2):