Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression
Reactive powder concrete (RPC) with compressive strength higher than 170 MPa was prepared by using ordinary Portland cement, silica fume, ground granulated blast-furnace slag or fly ash. RPC shows high strength, constant Poisson’s ratio, high compressive peak strain but post-peak brittle failure. Ba...
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
2017
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| Цитувати: | Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression / S.H. Liu, L.H. Li, L. Wang // Проблемы прочности. — 2017. — № 1. — С. 149-155. — Бібліогр.: 11 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860093125717917696 |
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| author | Liu, S.H. Li, L.H. Wang, L. |
| author_facet | Liu, S.H. Li, L.H. Wang, L. |
| citation_txt | Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression / S.H. Liu, L.H. Li, L. Wang // Проблемы прочности. — 2017. — № 1. — С. 149-155. — Бібліогр.: 11 назв. — англ. |
| collection | DSpace DC |
| container_title | Проблемы прочности |
| description | Reactive powder concrete (RPC) with compressive strength higher than 170 MPa was prepared by using ordinary Portland cement, silica fume, ground granulated blast-furnace slag or fly ash. RPC shows high strength, constant Poisson’s ratio, high compressive peak strain but post-peak brittle failure. Based on the RPC mechanical behavior study, investigation of the interaction between steel tubes and core RPC was performed, in view of its effect on the bearing capacity and deformability of RPC filled steel tubular (RPCFT) stub columns subjected to axial loading. RPCFT stub columns have very high ductility and alleviate the RPC disadvantage of brittle failure. However, the confinement effect of steel tubes on RPC is lower than that of normal strength concrete and thus, it can be neglected during the design process for convenience and safety.
|
| first_indexed | 2025-12-07T17:24:18Z |
| format | Article |
| fulltext |
UDC 539.4
Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial
Compression
S. H . L iu ,abc1 L . H . L i,b an d L . W a n g c
a State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University,
Wuhan, China
b School of Civil Engineering and Architecture, Hubei University of Technology, Wuhan, China
c Nanchang Key Laboratory of Material and Structure Detection, Jiangxi University of Technology,
Nanchang, China
1 shliu@whu.edu.cn
Reactive powder concrete (RPC) with compressive strength higher than 170 MPa was prepared by
using ordinary Portland cement, silica fume, ground granulated blast-furnace slag or fly ash. RPC
shows high strength, constant Poisson’s ratio, high compressive peak strain but post-peak brittle
failure. Based on the RPC mechanical behavior study, investigation o f the interaction between steel
tubes and core RPC was performed, in view o f its effect on the bearing capacity and deformability o f
RPC filled steel tubular (RPCFT) stub columns subjected to axial loading. RPCFT stub columns have
very high ductility and alleviate the RPC disadvantage o f brittle failure. However, the confinement
effect o f steel tubes on RPC is lower than that o f normal strength concrete and thus, it can be
neglected during the design process fo r convenience and safety.
K eyw ords: com posite column, steel tubular, bearing capacity, load-strain behavior.
In tro d u c tio n . Reactive pow der concrete (RPC) is a new type ultrahigh perform ance
concrete (UHPC) w ith a high com pressive strength over 200 M Pa or m ore [1]. The use of
RPC in construction can significantly increase the bearing capacity o f structures and reduce
elem ent section sizes as well as structure deadweights. RPC becom es a highly dense
cem ent-based com posite w ith excellent strength and durability due to the elim ination o f
aggregates larger than 1 mm. RPC is applicable in long-span structures, high-rise buildings,
structural repair, and unique elements for m ilitary purposes [2-4]. W hile RPC is a brittle
m aterial and post-peak brittle failure often occurs w hen it is subject to high com pression
level w hich w ill lim it its application. A dding steel fibers can im prove the tensile ductility o f
RPC, but as indicated in this paper, steel fiber is not able to enhance the com pressive
ductility o f RPC. Furtherm ore, the liquidity o f fresh concrete is sharply reduced w hen the
volum etric ratio o f steel fiber exceeds 2%.
Reinforced concrete colum n is a com m on com pressive element. However, reinforced
h igh strength concrete (HSC) colum ns have a fatal shortcom ing that the cover layers often
burst too early and cause prem ature bucking o f reinforced bars even at the loads m uch
low er than the HSC com pressive strength [5, 6].
The ductility o f RPC can be increased greatly w hen it is confined by a steel tube. The
first application o f RPC, the Sherbrooke pedestrian bridge took this structural form ation
[7]. However, although concrete filled steel tubular (CFT) colum n has been studied
thoroughly, research regarding ultrahigh strength concrete filled steel tubular columns
[8-11] is insufficient and far from immature.
During the past decades, steel tube-HSC com bined colum ns have been successfully
applied to m any high-rise buildings. Though the RPC used in this study is a HSC w ithout
coarse aggregates, the conclusion derived by this study can be extended to the HSC w ith
coarse aggregates as all types o f HSC share some com m on properties irrespective o f coarse
aggregates. However, lacking related design standards is a problem at present. M ost current
© S. H. LIU, L. H. LI, L. WANG, 2017
ISSN 0556-I7IX. Проблемы прочности, 2017, N2 1 149
mailto:shliu@whu.edu.cn
S. H. Liu, L. H. Li, and L. Wang
standards m ainly deal w ith concrete for the critical stress values below 60 MPa. To the best
o f the authors’ knowledge, some organizations, such as A ssociation Francaise de Genie
Civil (AFGC), Japan Society o f Civil Engineers (JSCE) and The International Federation
for Structural Concrete (FIB) are now com piling HSC and UHPC related technical
standards. The aim o f this study is to offer a sim ple yet reliable engineering form ula for
reference before these standards are available.
1. E xperim en ta l. Raw m aterials used for RPC preparation are as follows: P. O. 42.5
ordinary portland cement, silica fume (SF), ground granulated blast-furnace slag (GS), fly
ash (FA), polycarboxylate superplasticizer (40% solid content), tidy river sand (S) w ith
particle diam eters ranging from 0.2 to 0.4 mm, and m icro steel fiber (F) w ith a diam eter o f
0.2 m m and length o f 13 mm. Six types o f RPC (C 1-C 6) were prepared. The mix
proportions used are shown in Table 1.
T a b l e 1
RPC Mix Proportions (kg/m3) and Compressive Strength (MPa)
Code C SF GS FA W S F f prism fcub
C1 745 132 219 0 175 1096 0 116 126
C2 745 132 219 0 175 1096 37 118 134
C3 884 221 0 0 155 1105 0 137 163
C4 884 221 0 0 155 1105 150 145 178
C5 737 184 0 184 155 1105 75 144 170
C6 553 184 0 368 155 1105 150 147 172
The RPC m ixture w as prepared using a counterflow pan m ixer and w as cast into
molds. A fter dem oulding, they w ere cured at 90°C in steam for three days. A fter heating
treatm ent, the strength did not increase significantly anymore. Therefore, the strength was
m easured and regarded as the long-term strength (Table 1). M echanical properties o f RPC,
such as com pressive strength, 4-point bending strength param eters and Poisson’s ratio are
determ ined by the standard testing methods.
Steel tubes used in this study are seamless tubes w ith m oderate to thick wall
thickness. The preparation and curing o f RPCFT specim ens were sim ilar to the m ethods o f
RPC specimens. Loading setup o f RPCFT specim ens is also illustrated in Fig. 1. Loading
was controlled by displacem ent at the speed o f 10 ,«£/s till the axial deform ation rate o f the
colum ns reached about 5%. Two displacem ent transducers w ith a 120 m m gauge length
w ere used to record the axial com pressive strain.
N
. I .
| Test machine
Displacement
transducer
Concrete
| Test machine |
I
N
Fig. 1. Typical loading mode.
150 ISSN 0556-171X. npo6neMbi npouHocmu, 2017, № 1
Study on Behavior o f RPC Filled Steel Tubular Stub Columns
2. R esu lts an d D iscussion.
2.1. M echan ica l Properties. It is easily derived from Figs. 2 and 3 that steel fibers can
im prove bending ductility o f RPC significantly. The specim en containing 0.5% volume
fraction o f steel fibers showed a fragile fracture in testing. In contrast, the curve
corresponding to the specim en containing 2% steel fibers shows a long and m ild post-peak
descending phase. However, steel fibers play a lim ited role in im proving the ductility when
RPC are subjected to compression. W hen com pressive deform ation passed its peak value
corresponding to the peak stress, the loading-deform ation curves o f all specim ens exhibited
a drop follow ed by final fracture o f the specimens. U nlike norm al strength concrete (NSC),
no relatively com plete post-peak descending period can be captured for RPC, even at very
low loading speeds. So it is not available to utilize steel fibers to increase ductility for
com pressive m em bers o f RPC.
Fig. 2 Fig. 3
Fig. 2. Four-point bending curves of RPC specimens.
Fig. 3. Stress-strain curves for RPCs under axial compression.
P o isson’s ratio o f RPC keeps constant (about 0.2) till com pressive failure occurs
(Fig. 4). Growth o f P oisson’s ratio is caused by the propagation o f m icrocracks, w hich are
m ainly distributed in the interfacial transition zone (ITZ), a w eak link that dominates
strengths o f concretes [4, 5]. Low constant Poisson’s ratio o f RPC m eans that the ITZ is
elim inated and, thus, the strength and ductility are improved.
Relative strain
Fig. 4. Poisson’s ratio vs. relative compressive strain of RPC.
The Young m odulus o f RPC m easured in this study is 44 GPa. W ith higher strength
but relatively lower Young modulus, RPC has m uch greater deformability than conventional
concrete. The peak strain o f RPC is 3000-3700 pe, w hich exceeds the yield strain o f a
com m on steel. Steel tube enters plastic stage w hen its com pressive strain exceeds 1500 pe.
ISSN 0556-171X. Проблемы прочности, 2017, M 1 151
S. H. Liu, L. H. Li, and L. Wang
It can be derived from a sim ple computation: w hen the longitudinal strain o f an RPCFT
colum n reaches 3000 p,£ (approxim ately the peak strain o f RPC), the lateral strain o f the
steel tube is about 1200 p,£, yet the lateral strain o f RPC is only about 600 p,£. In another
word, the steel tube enters plastic status too early and before the peak strain o f RPC is
reached, the incongruity in lateral deform ation has cum ulated to a significant extent.
As a conclusion, because properties o f RPC are dram atically different from that of
NSC, behavior o f RPCFT columns differs from the norm al CFT columns. The difference is
reflected in two aspects: the load-stra in curve shape and the calculation o f bearing capacity.
The following two sections focus in these two aspects separately.
2.2. L o a d -S tra in B ehavior o f R P C F T S tu b C olum ns under U niaxial Compression.
The typical load-stra in curve o f a RPCFT stub colum n (with or w ithout steel fibers) under
axial com pression (Fig. 5) can be subdivided into the following four phases:
2000
O1500
2
« 1000o
500
0
0 0.5 1.0 1.5 2.0
A x ia l s t r a in (% )
Fig. 5. A typical load-strain curve of fibered RPC filled steel tubular stub columns under axial
compression.
(1) L inear Elastic Phase (OA): A t this phase, both the steel tube and the core RPC
correspond to the elastic stage, where the steel tube and core RPC operate independently.
(2) Elastic-Plastic Phase (AB): A t this phase, the steel tube enters a plastic stage, the
longitudinal rigidity o f steel declines, leading to the reduction o f the rigidity o f the column.
M eanwhile, Poisson’s ratio o f the steel tube increase quickly. However, core RPC is still at
the elastic stage and its Poisson’s ratio keeps constant because the critical deform ability o f
RPC is greater than that o f steel. As the lateral deform ation o f the steel tube is m ore than
that o f RPC, the steel tube and the core RPC still w ork independently, w hich is different
from an N SC filled steel tubular column. W hen the load increases to point B, the ultimate
bearing capacities o f both core RPC and the RPCFT stub colum n are achieved.
(3) D escending Phase (BC): W hen the ultim ate load level is reached, the load ing-
deform ation curve descends rapidly. The failure m ode o f the core RPC casted in steel tubes
is shear failure. To test this, w hen a specim en passed the point B and the load is stopped
im m ediately and extracted the PRC core (Fig. 6) via plasm a cutting. There was a shear
crack throughout the core, separating it into two wedges that can slip along the interface. I f
the loading continued, the two wedges w ould squeeze the tube wall and cause the
confinem ent force from the tube wall, w hich tends to arrest the slip.
(4) Platform phase (CD): A t this phase, the load-strain curve is horizontal. The
confinem ent force from the tube w all is high enough to stabilize the slip. RPCFT stub
columns exhibit excellent ductility. A n RPCFT stub colum n still possesses relatively large
bearing strength even w hen the longitudinal com pression strain is up to 5%.
The load-deform ation behavior presents some sim ilarities to the one noticed in
concrete cylinders confined by unbonded, non-resin im pregnated elastic fiber ropes
(vinylon or polypropylene) o f high tensile strain [6, 7]. There tem porary load drop was
observed and finally load regaining. Despite the fact that the study concerns plain concrete
152 ISSN 0556-171X. npodneuu nponnocmu, 2017, № 1
Study on Behavior o f RPC Filled Steel Tubular Stub Columns
Fig. 6. Compressive failure mode of RPC in steel tubes.
externally confined w ith fiber ropes, it m ay share some com m on characteristics o f the
behavior o f cracked RPC that interacts w ith an external steel jacket. A lso, this behavior is
characteristic for FRP-confined noncircular square colum ns, the tem porary load drop and
then load regaining has been observed in some cases.
2.3. E ng ineering F orm ula fo r C alculating the A x ia l B earing Capacity o f R P C F T
C olum ns . M ost formulas on the bearing capacity o f CFT columns from literature and
standards resem ble the following equation:
N c — fc A c + a fy A s , (1)
where N c is the bearing capacity, f c is uniaxial com pressive strength o f RPC, A c is the
cross section area o f RPC, f y is the tensile yield strength o f steel tube, A s is the cross
section area o f steel tube, and a is a factor not less than 1 to reflect the interactive extent,
and it m aybe 1.975 in European EC4 (1994), 1.7 in Chinese CECS 104:99 (1999), 1.27 in
Japanese A IJ (1997) and 1 in A m erican ACI (1999).
It is too early to draw any conclusions regarding w hich code is m ore accurate.
Because the partial factors, the m aterial testing m ethods, etc., vary in different countries,
and some o f the above codes take into account the long-term effects, such as concrete creep.
This study com pares the a values reflected in these codes, in order to check their
applicability to high-strength concrete. For long colum ns, the slenderness factor should be
introduced into the form ula for stub colum ns, however, this is beyond the scope o f this
paper.
The value o f a derived by the least m ean square regression o f the test data is 1.4. The
com parison o f the experim ental data obtained via Eq. (1) for different a values is depicted
in Fig. 7, w here points located above the diagonal line im ply that the respective calculation
results overestim ate the bearing capacity and vice versa. It is obvious that larger a (such as
in CECS and EC4) w ould lead to unsafe calculations.
The form ula N c — f cA c + f y A s , w hich is sim ilar to the ACI code, is tem porarily
adopted for calculation o f RPCFT colum ns, since it can guarantee their safe estimation. The
interaction between steel tubes and concrete degrades w ith the strength o f concrete.
ISSN 0556-171X. npodneMbi npouuocmu, 2017, № 1 153
S. H. Liu, L. H. Li, and L. Wang
Nf, kN
c
Fig. 7. Calculation results for different a values.
However, this disadvantage is trivial w ith respect to the fact that this type o f columns
enables the utilization o f RPC in com pression members.
C onclusions. RPCFT stub colum ns exhibit very high ductility and alleviate the RPC
disadvantage o f brittle failure. Steel tube confinem ent can improve the ductility o f RPC,
reducing the risk o f collapse o f structures resulted from fragile failure o f RPC under
high-stress conditions. Failure m ode o f RPCFT stub colum ns under axial com pression is o f
shear type.
The form ula N c = f cA c + f y A s is tem porarily adopted for calculation o f RPCFT
columns, since it can guarantee their safe estimation. The interaction betw een steel tubes
and concrete degrades w ith the strength o f concrete.
A cknow ledgm ents. This project is funded by the N ational N atural Science Foundation
o f China (51208391).
1. P. R ichard and M. Cheyrezy, “Com position o f reactive pow der concretes,” Cement
Concrete Res., 25, No. 7, 1501-1511 (1995).
2. V. H. Perry and D. Zakariasen, “Overview o f UHPC technology, materials, properties,
m arkets and m anufacturing,” in: Proc. o f the 3rd Int. Symp. on H igh Performance
Concrete/PCI N ational Bridge Conference (October 19-22, 2003, Orlando, FL), Paper
60 (2003).
154 ISSN 0756-171X. npo6n.eubi 2017, № 1
Study on Behavior o f RPC Filled Steel Tubular Stub Columns
3. M. Alkaysi, S. El-Tawil, Z. C. Liu, and W. Hansen, “Effects o f silica pow der and
cem ent type on durability o f ultra h igh perform ance concrete (UHPC),” Cement
Concrete Comp., No. 66, 47 -56 (2016).
4. Y. Su, J. Li, C. Q. W u, et al., “Effects o f steel fibres on dynam ic strength o f U H PC,”
Constr. Build. M ater., 114, 708-718 (2016).
5. M. P. Collins, D. M itchell, and J. G. M acGregor, “Structural design considerations for
high strength concrete,” Concr. Int. Des. Constr., 15, 27 -34 (1993).
6. S. R. Razvi and M. Saatcioglu, “ Strength and deform ability o f confined high-
strength-concrete colum ns,” A C I Struct. J., 91, No. 6, 678-687 (1994).
7. P. Y. Blais and M. Couture, “Precast, prestressed pedestrian bridge - w orld ’s first
reactive pow der concrete structure,” P C I J., 44, No. 5, 60-71 (1999).
8. Z. Y. Lin, Research on B ehavior o f R P C F illed Circular Steel Stub A xia l Columns,
D issertation, Fu Zhou University, Fuzhou, China (2004).
9. X. C. Pu, H. J. Pu, and Y. W. W ang, “Preparation and study on kilom eter com pressed
m aterial,” Concrete, No. 3, 3 -9 (2003).
10. P. Y. Y an and J. W. Feng, “M echanical behavior o f UHPC and UH PC filled steel
tubular stub colum ns,” in: E. Fehling, M. Schmidt, and S. Sturwald (Eds.), Ultra High
P erform ance Concrete (UHPC), Proc. o f the 2nd Int. Symp. on U ltra H igh
Perform ance Concrete (M arch 5-7 , 2008, Kassel, Germany), K assel U niversity Press
GmbH, K assel (2008), pp. 355-362.
11. J. Zhang, E xperim ent Investigation on Behavior o f Reactive Pow der Concrete F illed
Steel Stub-C olum ns , D issertation, Fu Zhou University, Fuzhou, China (2003).
Received 30. 08. 2016
ISSN 0556-171X. npo6n.eMbi 2017, № 1 155
|
| id | nasplib_isofts_kiev_ua-123456789-173593 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0556-171X |
| language | English |
| last_indexed | 2025-12-07T17:24:18Z |
| publishDate | 2017 |
| publisher | Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| record_format | dspace |
| spelling | Liu, S.H. Li, L.H. Wang, L. 2020-12-12T14:45:45Z 2020-12-12T14:45:45Z 2017 Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression / S.H. Liu, L.H. Li, L. Wang // Проблемы прочности. — 2017. — № 1. — С. 149-155. — Бібліогр.: 11 назв. — англ. 0556-171X https://nasplib.isofts.kiev.ua/handle/123456789/173593 539.4 Reactive powder concrete (RPC) with compressive strength higher than 170 MPa was prepared by using ordinary Portland cement, silica fume, ground granulated blast-furnace slag or fly ash. RPC shows high strength, constant Poisson’s ratio, high compressive peak strain but post-peak brittle failure. Based on the RPC mechanical behavior study, investigation of the interaction between steel tubes and core RPC was performed, in view of its effect on the bearing capacity and deformability of RPC filled steel tubular (RPCFT) stub columns subjected to axial loading. RPCFT stub columns have very high ductility and alleviate the RPC disadvantage of brittle failure. However, the confinement effect of steel tubes on RPC is lower than that of normal strength concrete and thus, it can be neglected during the design process for convenience and safety. This project is funded by the National N atural Science Foundation of China (51208391). en Інститут проблем міцності ім. Г.С. Писаренко НАН України Проблемы прочности Научно-технический раздел Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression Исследование характеристик стальных трубчатых образцов, заполненных реакционно-порошковым бетоном, при испытании материала на осевое сжатие Article published earlier |
| spellingShingle | Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression Liu, S.H. Li, L.H. Wang, L. Научно-технический раздел |
| title | Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression |
| title_alt | Исследование характеристик стальных трубчатых образцов, заполненных реакционно-порошковым бетоном, при испытании материала на осевое сжатие |
| title_full | Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression |
| title_fullStr | Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression |
| title_full_unstemmed | Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression |
| title_short | Study on Behavior of RPC Filled Steel Tubular Stub Columns under Axial Compression |
| title_sort | study on behavior of rpc filled steel tubular stub columns under axial compression |
| topic | Научно-технический раздел |
| topic_facet | Научно-технический раздел |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/173593 |
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