Seismic Resistant Properties of Lightweight Aggregate Concrete

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1

The International Conference of Composites on Construction (CCC 2003)



Seismic Resistant Properties of

Lightweight Aggregate Concrete


Chung
-
H
o

Huang, and H
o
w
-
Ji

Ch
e
n
*

Department of Civil Engineering

National Chung
-
Hsing University

Taichung
,

Taiwan, R.O.C
.



ABSTRACT

Lightweight aggregate concrete posses
ses

lower unit weight and
better

damping
characteristic

than normal weight concrete. U
sing
it as a building material

can enhance the
seismic resistance of structures
. Th
is

research
investigates
the seismic
resistan
t properties
of
lightweight aggregate concrete
and
compare
s

with
those of
normal weight

concrete
.

T
he
test result
s

of
lightweight aggregate concrete and normal weight

concrete

show that
the unit weight of reinforced lightweight concrete is 20%
app
roximately
lower than that of
reinforced normal weight concrete at same strength level.
For low

strength

concrete

near 20
MPa
, l
ightweight aggregate concrete
appears

larger

damping ratio
.

T
h
e

stiffness
of
lightweight aggregate concrete i
s
similar to
that o
f
normal weight

concrete
.

As the concrete

strength
is
higher

near 40 MPa
,

lightweight aggregate concrete has similar
damping ratio

to
normal weight

concrete

but
the

stiffness is lower. Moreover,
the
natural
frequency and

damping ratio of reinforced concret
e beam
are

low
er than

those of plain concrete beam

because of the
r
einforc
ing
bars
effect.


Keywords

lightweight aggregate concrete

stiffness

natural
frequency

damping ratio


*correspondent

How
-
Ji Chen

Associate Professor of Department of Civil Engineering, National Chung
-
Hsing University

NO.
250, Kuo
-
Kwang Road, Taichung 40227, Taiwan

Tel: 886
-
4
-
2285
9390

Fax: 886
-
4
-
2285
5610

E
-
mail:
hjchen
@
mail.ce
.nchu.edu.tw


2

I
ntroduction

The seismic force is a response of inertia of ground acceleration.
I
n general,
the
magnitude

of
internal force of member due to
seismic
force is

related

to

the
seismic resistance properties
of structure
such as
the
mass, stiffness,
nature

frequency and damping ratio.
[1
-
3]

For the seismic force design, to know the
seismic resistance properties of structure building is very important.

U
sing
of lightweight aggregate concrete

(LWAC)

in building structure has
many advantages
,

e
specially reduc
ing

the mass of structure and possesses better
damping
characteristics.
[
4
-
6
]

the

light
weight

building structure
has

smaller
seismic force
when
subjected to

earthquake.
F
or the seismic resistance of
concrete per unit weight, lightweight aggregate
concrete
is better than normal
weight
concrete (
NWC).
T
his research investigates the seismic resistant
properties of lightweight aggregate concrete such as unit weigh
t of concrete,
stiffness, nature frequency and damping ratio.
T
he results are compared with
those of normal weight concrete.


Experimental

program

A

total of 32 flexural
reinforced

LWAC

beams as well as
NWC

beams were
made.
I
n the meantime, 18 non
-
reinforc
ed concrete beams were also made.
T
he
size of all specimens was 150 mm
×
200mm
×
1500mm. The test items
include
d
both damping and frequency tests.

B
esides, the reinforced concrete beams were
also tested for stiffness.
T
he summary of the specimen
quantity

are s
how
n

in
Table
1
.

M
aterials

T
he mixture proportions for
LWAC

and
NWC

are
shown

in Tables
2

and
3
.

3

Type

1
Portland cement was used with natural sand having a fineness modulus
of
2.67
. The coarse lightweight aggregate used was expanded
clay

with
maximum size
of
12.5

mm.
The aggregate
properties are

given in Table
4
.

Two sizes of t
he longitudinal reinforcement
were

used in this investigation

(no.4
and no.6 deformed steel bars
)
. The stirrups used were
no.6 deformed steel

bars of Grade 40.
The
different

yield

str
ength in tension
was

283 MPa and
4
45

MPa

for the longitudinal reinforcement
s

and
281

MPa for the stirrup
reinforcement.


C
asting and curing

T
he concrete was place
d

in two layers in the beam and was appropriately
vibrated.
B
esides, six 100

mm*200

mm cylindr
ical specimens were also cast.
Immediately

after casting, all specimens covered with polyethylene sheets to
avoid escape of moisture.

Twenty
-
Four

hours after casting
,

t
he beams and
cylindrical

specimens were stripped and moved to
curing
room with 100% RH
,
23


for 28 days curing.


S
pecimen details and testing

T
he beams were
divided

into
two

groups

(
reinforced beam and
plain

concrete beam without reinforcement).
The

specimen details are
shown

in
Figure 1.
The

tested variables
included

concrete type, concrete
strength, space
of web reinforcement, amount of tensile reinforcement.
T
he summary of the
specimen
quantity

are show
n

in Table
1
.

T
he test method of compressive strength and modulus of elasticity of
concrete is in accordance with ASTM C469.
Reinforced conc
rete beam

was


4

loaded with a

central point load in the stif
f
ness

test. A
t each end of a reinforced
beam, a hinge was
used to

allow the flexure beam to rotate freely. A linear
voltage differential transducer (LVDT) was used to
measure
the vertical
deflection

at mid
-
span

section
.
T
he span was 142 mm
in length
. Details of the
test setup
are shown

in Figure 2.
The total load on the test

facility was increased
linearly

with a loading speed of 200 N/sec.

When

t
he total

load
reach
ed 8000 N,

stop test and
release

lo
ad.
T
he outputs from the load cell and LVDT were
continuously recorded by use of a computer and a 7V14M data acquisition
system.

I
n the frequency and damping tests, the bounded condition of the specimens
was
similar

to the stiff test.
T
he specimens were su
pport by two hinges, as
shown in Figure 3.

A
n
accelerometer

was fixed to the central point of the span
for measure the

variation

of
acceleration
. Using a hammer
beat

the
specimen;

let
it

induce a slight free vibration.
T
he frequency and damping of the
spec
imens

were
acquire
d by the
analysis

of

the

decay
ed
acceleration
.
T
he
analytic

method

was
in accordance with

the theory of structur
al

dynamic
.


Results

and Discussions

The

results of the basic properties tests on reinforced concrete beams are
summarized in
Table
4
. Table
5

summarizes frequency and damping of all
beams.

The mechanical

properties

of
concrete

As shown in Table
4
, the concrete
compressive

strength of LWAC was
varied between 27.4 MPa and 43.5 MPa, and varied between 23.1 MPa and 43.7
MPa for NWC.

Although

the
actual

compressive strength is not

complete


5

correspond with

design strength (20 MPa level and 40 MPa level), the
compressive strength of LWAC is
close to

NWC both at 20 MPa level and 40
MPa level.
I
t can
accept

that LWAC and NWC have s
imilar

compressive
strength and can
proceed

to compare other
characteristic
s under the same
strength level.

The

modulus of elasticity of LWAC is increasing with increase the concrete
compressive strength.
Moreover, a
t

the

same concrete strength level, t
he

modulus

of elasticity of LWAC is
smaller than NWC.

T
he results of unit weight of
reinforced

beam are
also

given in Table
4
.
The

unit weight of
reinforced

LWAC beam was

varied between 1800 kg/m
3

and
2000

kg/m
3
, and was about 20% lower than that of
reinforced

NWC b
eam.

T
he
stiffness

of reinforce
d

beam

This test measured the
stiffness

of t
he
simple

beams
;

the beams

were loaded
with a

central point load.

The

central point load

does not
exceed the

proportional limit. The stiffness (K) was defined as the
slope

of the
lo
ad
-
deflection
curve

(P
-
Δ

curve
)
, K=P/
Δ
.

T
he
results of the stiffness are
summarize
d in Table
4
. A
nalys
e
s

of the test
data

can
obtain

many
varied

graph,
as shown in Figures 4~6.

Figure 4 shows the unit weight of reinforced LWAC beam is lower than
reinforced NWC beam as concrete s
trength at 20 MPa level, but the stiffness of
reinforced LWAC beam is
similar

to reinforced NWC beam and the test values
are between 18000k
N
/m and 27000k
N
/m. As the concrete strength
attain
s

to

40MPa
level, for reinforced NWC beams, as unit weight increase
s, are
effective

in improving stiffness of simple beams.
F
or reinforced LWAC beams, are
ineffective

in improve stiffness by increasing unit weight.

From the Figure 5 it can be seen that the stiffness of reinforced LWAC beam

6

is
similar

to reinforced NWC bea
m under the same lower concrete strength (20
MPa level). As the concrete strength is higher (at 40 MPa), the stiffness of
reinforced NWC beam is 20% higher than that of reinforced LWAC beam. From
the two
regression
lines
(
in
F
ig
.

5
)

it can be found that th
e slope of NWC
beam
stiffness

is
steep
er than that of LWAC beam.
It means that t
he stiffness of
reinforced NWC beam

increases effectively with increasing the concrete
strength. However,
it is

ineffective

for reinforced LWAC beam.

The
elastic

formula

of sim
ple beam
defection
is
given

follows:
48EI
PL
3




From the
formula
it can be known that the stiffness (K=P/
Δ
) is function of
the material
propert
y (modulus of elasticity E), span of beam (L) and
cross
-
section

(the beam

s moment of inertia I). W
hen the simple beams have the
same
cross
-
section

and
equal

span,

t
he

stiffness of simple beam will
mainly

relate to modulus of
elasticity
. Using different materials

in reinforced beams
will
change

their stiffness; such as using lightweight aggregate concre
te and
normal weight concrete
because

their
modul
i

of elasticity are

different.

Table
4

shows modulus of
elasticity of
LWAC is 16300 MPa and 21400
MPa for NWC when the concrete strength at 20 MPa. As the concrete strength
attain
s

to

40MPa
level,
modulus of

elasticity of

LWAC is 19800 MPa and 25500
MPa for NWC. The
relationship

between the stiffness of reinforced beam and
modulus of elasticity of

pure concrete beam is shown in Figure 6.
T
he stiffness
of reinforced NWC beam

increases effectively with increasi
ng the
modulus of
elasticity of

concrete.
T
he stiffness of reinforced LWAC beam does not have the
same
behavior
.
A
s the concrete strength is lower (at 20MPa level), the ratio of
the

modulus of elasticity of

LWAC to
that

of NWC is 1.32, it is higher than th
e
ratio of the stiffness of reinforced LWAC beam to the stiffness of reinforced

7

NWC beam (which is about 0.97).

A
s the concrete strength at 40 MPa level, the
ratio of the
modulus of elasticity
(about 1.29) is similar to the ratio of the
stiffness (about 1.
19).

T
herefore
,
i
nfer
the ratio of the stiffness

from the
ratio of
the
modulus of elasticity
is
suitable
at high
strength
concrete, but it may be fail
at low
strength
concrete.


T
he
frequency and damping ratio of beams

T
he
frequency and damping ratio
are t
he basic material property

in seismic
assistance analysis
.
A
n
accelerometer

was used to measure
the

variation of
acceleration

to
investigate

t
he
frequency and damping ratio

of the free vibrated
beams. Every
specimen

tested ten times on
the
frequency
test
a
nd damping ratio
test respectively.

The

experimental results are
shown

in Table
5
.

T
he
analysis

of frequency

At low

strength
concrete level (20 MPa level), the
average

frequency

of
LWAC and NWC beam without reinforcement are 831 rad/sec and 821 rad/sec
tha
t

were obtained from
average

of ten tests of two specimens. As the concrete
strength is higher, the
average

frequency

of LWAC beam is 925 rad/sec and 967
rad/sec for NWC beam.

T
he results mean that increasing the concrete
strength

increases the
frequency

o
f concrete beam.

T
he
main
reason

is
high
strength

concrete
possess more dense texture than

low strength concrete.

For the reinforced concrete beams, the
average

frequency

of reinforced
LWAC beam is 748 rad/sec that is higher than the
average

frequency

of
r
einforced NWC beams
(701

rad/sec)

at lower concrete strength level (20MPa).
As the concrete strength is higher, the
average

frequency

of reinforced LWAC
beam is 746 rad/sec and 723 rad/sec for reinforced NWC beam.

B
ased on the dynamic theory,

the
frequenc
y

(
ω
) is function of the mass (m)

8

and stiffness (K) of
member

(
m
K
ω

).
T
he frequency increases with increasing
the stiffness of structure or decreasing the mass of
member
.
A
s the concrete
strength is lower (at 20MPa level), the stiffness of
reinforced LWAC beam is
similar

to reinforced NWC beam, and the unit weight of LWAC beam is lower
than NWC beam.
Therefore
,
the
frequency

of reinforced LWAC beam is higher
than the
frequency

of reinforced NWC beam.

As the concrete strength
attain
s

to

40MPa

level,

the stiffness and unit weight of reinforced LWAC beam are both
lower than reinforced NWC beam. So, they have a similar frequency.

It can be seen that the
frequency

of reinforced concrete beam

seem to have

no relationship with

space of web reinforce
ment

and
amount of tensile
reinforcement
. However, the
frequency

of reinforced concrete beam is about
10%~25% lower than pure concrete beam
because

installed reinforcement.

T
he
analysis

of
damping ratio

A
s the concrete strength is lower (at 20MPa level), t
he damping ratio of
LWAC beams is 8.11% and 6.89% for NWC beams.

LWAC is better than NWC
in damping
characteristic
. As the concrete strength at

40MPa
level, LWAC
beams and NWC beams have damping ratios of 7.13% and 7.43% respectively.

For the reinforced c
oncrete beams, the damping ratio of reinforced LWAC
beams is varied between 2.52% and 4.22%.
A
s well as reinforced NWC beams,
is varied between 1.73% and 3.85%. At lower concrete strength level (20MPa)
reinforced LWAC beam is better than reinforced NWC bea
ms in damping ratio.
As the concrete strength
attain
s

to

40MPa
level,

they
posses

a similar
behavior
.

From Table 6 it can also be seen that the damping ratio of reinforced
concrete beam

seem to have

no relationship with

space of web reinforcement

and
reinf
orcement ratio
. However, the damping ratio of reinforced concrete

9

beam is lower than pure concrete beam
because

installed reinforcement.

Conclusions

Experimental results of

s
eismic
r
esistant
p
roperties of

l
ightweight
a
ggregate
c
oncret
e
are presented.

On th
e basis of results obtained in

this study the
following conclusions can be drawn.

1.

The stiffness of reinforced NWC beam increases with increasing concrete
strength and modulus of elasticity of concrete. For reinforced LWAC beam
is ineffective.
A
t lower conc
rete strength level (20MPa),

the stiffness of
reinforced LWAC beam is
close

to
that for
reinforced NWC beam.

As the
concrete strength
attain
s

to

40MPa
level,

the stiffness of reinforced NWC
beam is 20% higher than that of reinforced LWAC beam.

2.

For plain co
ncrete beams, increasing concrete strength increases the
frequency.

A
t lower concrete strength level (20MPa level),

the frequency of
LWAC beam is
near that for

NWC beam.

As the concrete strength
attain
s

to

40MPa
level,

the

frequency of LWAC beam is lower t
han that of NWC
beam.
Moreover
, at lower concrete strength level (20MPa level),

the
damping ratio of pure LWAC beam is better than
that for

NWC beam.

As
the concrete strength
attain
s

to

40MPa
level,

the damping ratio of LWAC
beam is
close

to
that for
NWC b
eam.

3.

For reinforced concrete beams, at lower concrete strength level (20MPa
level),

the frequency and damping ratio of reinforced LWAC beam are
higher than
those for
reinforced NWC beam.

As the concrete strength
attain
s

to

40MPa
level,

the frequency and da
mping ratio of LWAC beam
are

close

to
those for
NWC beam.

4.

C
ompar
ing
the seismic resistance properties
between

LWAC and NWC
,


10

unit weight of lightweight aggregate concrete is about 20% lower than
that
for
NWC at the same concrete strength.
A
s the concrete
st
rength

is at
20MPa level, LWAC is similar to NWC in stiffness and possesses better
damping
characteristic
.
A
t higher concrete strength level (at 40MPa level),
LWAC is similar to NWC in damping
characteristic
, but LWAC is lower in
stiffness.


References

1.

Ber
tero, V. V., and Popov, E. P., "Seismic Behavior of Ductile Moment
-
Resisting
Reinforced Concrete Frames,"
Reinforced Concrete Structures in Seismic Zones
, SP
-
53,
American Concrete Institute, Detroit, PP. 247
-
291
(
1977
)
.

2.

Viwathanatepa, S., Popov, E. P., and

Bertero, V. V., "Seismic Behavior of R. C. Interior
Beam
-
Column Subassemblage," EERC Report No. UCB/EERC
-
79/14, Earthquake
Engineering Research Center, University of California, Berkeley

(
1979
)
.

3.

Forzani, B., Popov, E. P., and Bertero, V. V., "Hysteretic B
ehavior of Lightweight
Reinforced Concrete Beam
-
Column Subassemblages," EER Report No. UCB/EERC
79/01, Earthquake Engineering Research Center, University of California, Berkeley

(
1979
)
.

4.

V. V. Bertero, E. P. Popov and B. Forzani, "Seismic Behavior of Lightw
eight Concrete
Beam
-
Column Subassemblages,"
ACI Journal
, PP. 44
-
52

(
1980
)
.

5.

Sekhniakshivile, E. A., "
On the Effective Use of Light Concrete and Reinforced Concrete

11

in Construction in Seismic Regions
," Proceedings, Sixth World Conference on Earthquake
Engine
ering, V. 3, PP. 2034
-
2024
(New Delhi, Jan. 1977)
.

6.

Paramzim, A. M., and Gorovitz, I. G., "
Analysis of Light
-
weight Concrete Use in
Seismic
-
Resistant Multistory Buildings
," Proceedings, Sixth World Conference on
Earthquake Engineering, V. 3, PP. 2124
-
2125
(Ne
w Delhi, Jan. 1977)
.


12


Table 1
T
he summary of the specimen
quantity

LWAC beams

NWC beams

Beam

number

Design
strength

(MPa)

Tensile

steel

Stirrups

quantity

Beam

number

Design
strength

(MPa)

Tensile

steel

Stirrups

quantity

RLC20410

20

4
-
#4

#3@100mm

2

RC20410

20

4
-
#4

#3@100mm

2

RLC20610

4
-
#6

#3@100mm

2

RC20610

4
-
#6

#3@100mm

2

RLC20415

4
-
#4

#3@150mm

2

RC20415

4
-
#4

#3@150mm

2

RLC20615

4
-
#6

#3@150mm

2

RC20615

4
-
#6

#3@150mm

2

LC20

0

0

3

NC20

0

0

3

RLC40410

40

4
-
#4

#3@100mm

2

RC4
0410

40

4
-
#4

#3@100mm

2

RLC40610

4
-
#6

#3@100mm

2

RC40610

4
-
#6

#3@100mm

2

RLC40415

4
-
#4

#3@150mm

2

RC40415

4
-
#4

#3@150mm

2

RLC40
6
15

4
-
#4

#3@150mm

2

RC40
6
15

4
-
#4

#3@150mm

2

LC40

0

0

3

NC40

0

0

3






Table 2
Mixt proportions of lightweight aggr
egate concrete

Design
strength

(MPa)

Cement

Water

30min

Absorption
(%)

Sand

3/4"~1/2"

1/2"~3/8"

3/8"~#4

20

297

194

29

734

179

213

175

40

480

194

29

664

166

197

162




Table
3

Mixt proportions of normal weight concrete

Design
strength


(MPa)

Cement

Water

Sand

Coarse
aggregate


20

280

197

781

1056

4
0

410

196

675

1056




Illustration of Symbol

For example RLC20410,
RLC
:
reinf
orced
lightweight aggregate

concrete

beam
.
20
:
d
esign strength
20MPa
.
4
: #4 longitudinal reinforcement

10: the space of
web reinforcement is 100mm



13



Table 4
T
he
basic properties

of the specimen
s

LWAC beams

NWC beams

Com.

strength

(MPa)

Elastic

modulus
E(MPa)

Beam

number

Unit
weight

(kg/m3)


S
tiffness

K (Ton/
m)

Com.

strength

(MPa)

Elastic

modulus
E(MPa)

Beam

number

Unit
weight

(kg/m3)


S
tiffness

K
(Ton/m)

27.4

163
00

RLC20410

17
90

190
0

23.1

214
00

RC20410

23
20

207
0

RLC20410

1
800

17
70

RC20410

23
10

189
0

RLC20610

194
0

27
70

RC20610

242
0

2470

RLC20610

1950

24
80

RC20610

2420

226
0

RLC20415

178
0

260
0

RC20415

2320

25
20

RLC20415

179
0

20
50

RC20415

23
30

19
20

RLC20615

19
10

271
0

RC20615

239
0

249
0

RLC20615

191
0

2260

RC20615

238
0

231
0

43.5

19800

RLC40410

19
10

230
0

43.7

255
00

RC40410

236
0

2
8
00

RLC40410

19
10

22
80

RC40410

238
0

258
0

RLC40610

20
20

253
0

RC40610

244
0

297
0

RLC40610

20
20

278
0

RC40610

24
50

28
80

RLC40415

18
50

222
0

RC40415

23
50

28
20

RLC40415

18
60

22
00

RC40415

2320

27
50

RLC40615

1990

24
30

RC40615

24
20

30
80

RLC40615

198
0

2
600

RC40615

24
20

321
0


14



Table 5
T
he
results

of the
f
requency and damping ratio

LWAC

NWC

fc'
(M
P
a)

Beam

number

Frequency
ω
(rad/sec)

Damping
ratio
ζ

(%)

fc'
(M
P
a)

Beam

number

Frequency
ω
(rad/sec)

Damping
ratio
ζ

(%)

27.4

LWAC20

865

(831)

7.59

(8.11)

23.1

NC20

781

(821)

6.84

(6.89)

797

8.61

861

7.00

830

8.12

796

6.82

RLC20410

712

(723)

4.02

(4.22)

RC20410

616

(619)

2.66

(2.57)

733

4.41

621

2.48

RLC20610

810

(816)

2.61

(3.36)

RC20610

727

(729)

2.56

(2.75)

821

4.11

731

2.93

RLC20415

710

(737)

2.85

(3.09)

RC20415

707

(709)

1.63

(1.73)

764

3.32

710

1.83

RLC20615

703

(718)

3.88

(3.28)

RC20615

768

(749)

2.60

(2.54)

732

2.67

730

2.48

43.5

LWAC40

983

(925)

6.46

(7.13)

43.7

NC40

954

(967)

7.76

(7.43)

891

7.23

980

7.77

901

7.71

966

6.77

RLC40410

753

(728)

2.70

(2.60)

RC40
410

769

(745)

2.38

(2.42)

702

2.50

721

2.45

RLC40610

783

(760)

2.63

(2.52)

RC40610

706

(712)

2.30

(2.55)

737

2.40

718

2.79

RLC40415

727

(742)

2.70

(2.70)

RC40415

744

(727)

3.90

(3.85)

757

2.69

710

3.79

RLC40615

755

(756)

3.69

(4.17)

RC40615

720

(708)

2.30

(2.48)

756

4.64

696

2.66










15











Figure 1. Specimen details
















Figure 2 Testing setup for stiff test









Figure
3

Testing setup for the test of frequency and damping ratio


0.2m
0.15m
0.13m
0.08m
4-#4
#3
0.2m
0.15m
0.13m
0.08m
4-#6
#3
MTS
Load
Load cell
Support
LVDT
0.71m
0.71m
Specimen
Accelerometer
0.71m
0.71m
Specimen

16










Figure 4
U
nit weight of reinforced concrete effects on the stiffness
(K)













Figure 5
C
ompressive concrete strength effects on the stiffness (K)














Figure 6
M
odulus of elasticity effects on the stiffness (K)

20
25
30
35
40
45
f
'
c

(
M
P
a
)
16000
18000
20000
22000
24000
26000
28000
30000
32000
34000
K

(
k
n
/
m
)
RLC(20MPa)
RLC(40MPa)
RC(20MPa)
RC(40MPa)
The growing line of K value of RLC
The growing line of K value of RC
16000
18000
20000
22000
24000
26000
E

(
M
P
a
)
16000
18000
20000
22000
24000
26000
28000
30000
32000
34000
K

(
k
n
/
m
)
RLC(20MPa)
RLC(40MPa)
RC(20MPa)
RC(40MPa)
The growing line of the stiffness of RLC
The growing line of the stiffness of RC
1600
1800
2000
2200
2400
2600
T
h
e

u
n
i
t

w
e
i
g
h
t

o
f

r
e
i
n
f
o
r
c
e
d

c
o
n
c
r
e
t
e

(
k
g
/
m
3
)
16000
18000
20000
22000
24000
26000
28000
30000
32000
34000
K

(
k
n
/
m
)
(
b
)

f
'
c
=
4
0

M
P
a

L
e
v
e
l
RLC (40MPa)
RC (40MPa)
1600
1800
2000
2200
2400
2600
T
h
e

u
n
i
t

w
e
i
g
h
t

o
f

r
e
i
n
f
o
r
c
e
d

c
o
n
c
r
e
t
e

(
k
g
/
m
3
)
16000
18000
20000
22000
24000
26000
28000
30000
32000
34000
K

(
k
n
/
m
)
(
a
)

f
'
c

=

2
0

M
P
a

L
e
v
e
l
RLC (20MPa)
RC (20MPa)

17
























Design
strength

(MPa)

Cement

Water

30min

Absorption
(%)

Sand

3/4"~1/2"

1/2"~3/8"

3/8"~#4

20

297

194

29

734

179

213

175

40

480

194

29

664

166

197

162







LWAC beams

NWC beams

Beam

number

Design
strength

(MPa)

Tensile

steel

Stirrups

quantity

Beam

number

Design
strength

(MPa)

Tensile

steel

Stirrups

quantity

RLC20410

4
-
#4

#3@100mm

2

RC20410

4
-
#4

#3@100mm

2

RLC20610

4
-
#6

#3@100mm

2

RC20610

4
-
#6

#3@100mm

2

RLC20415

4
-
#4

#3@150mm

2

RC20415

4
-
#4

#3@150mm

2

RLC20615

4
-
#6

#3@150mm

2

RC20615

4
-
#6

#3@150mm

2

LC20

20

0

0

3

NC20

20

0

0

3

RLC40410

4
-
#4

#3@100mm

2

RC40410

4
-
#4

#3@100mm

2

RLC40610

4
-
#6

#3@100mm

2

RC40610

4
-
#6

#3
@100mm

2

RLC40415

4
-
#4

#3@150mm

2

RC40415

4
-
#4

#3@150mm

2

RLC40
6
15

4
-
#4

#3@150mm

2

RC40
6
15

4
-
#4

#3@150mm

2

LC40

40

0

0

3

NC40

40

0

0

3


Design
strength

(MPa)

Ceme
nt

Water

30min

Absorption
(%)

Sand

3/4"~1/2"

1/2"~3/8"

3/8"~#4

20

297

194

29

734

179

213

175

40

480

194

29

664

166

197

162


Design
strength

(MPa)

Cement

Water

Sand

Coarse
aggregate


20

280

197

781

1056

4
0

410

196

675

1056