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					COMPUTATIONAL MECHANICS
WCCM VI in conjunction with APCOM’04, Sept. 5-10, 2004, Beijing, China
 2004 Tsinghua University Press & Springer-Verlag




Theoretical and Experimental Analysis of Brick Chimneys,
Tokoname, Japan
T. Aoki 1*, D. Sabia2
1
  Graduate School of Design and Architecture, Nagoya City University, kitachikusa 2-1-10, Chikusa-ku,
  464-0083 Nagoya, Japan
2
  Department of Structural and Geotechnical Engineering, Politecnico di Torino, Corso Duca degli
  Abruzzi 24, 10129 Turin, Italy
e-mail: aoki@sda.nagoya-cu.ac.jp, donato.sabia@polito.it

Abstract For the purpose of obtaining the data concerning static and dynamic structural properties of
brick chimneys in Tokoname, a series of material test, dynamic test and static collapse test of the existing
two brick chimneys are carried out. From the material tests, Young’s modulus and compressive strength of
the brick used for these chimneys are estimated 3200MPa and 7.5MPa, respectively. The results of static
collapse test of the existing two brick chimneys are discussed here comparing with the results obtained by
FEA (Finite Element analysis). From the results of dynamic tests, the fundamental frequencies of Howa
and Iwata brick chimneys are estimated to be about 2.79 Hz and 2.93 Hz, respectively. Their natural modes
and damping factors are identified by ARMAV (Auto Regressive Moving Average) model. On the basis of
the static and dynamic experimental tests, numerical model has been prepared. According to the elastic
transient dynamic analysis, these brick chimneys seem to be vulnerable to earthquakes with 0.24 to 0.30 g.
Key words: brick chimney, dynamic test, static collapse test, ARMAV, Identification

INTRODUCTION
Tokoname City, Aichi Prefecture, is located in the center of the west coast of the Chita Peninsula, facing
Ise Bay to the west and hilly terrain extends to the east. Tokoname has long been noted for its production
of ceramic ware, and its history dates back to nearly 1,000 years ago. Along with Seto, Shigaraki, Echizen,
Tanba, and Bizen, Tokoname is included in the Rokkoyo (the nation’s six oldest ceramic producing
districts). And Tokoname is said to be the oldest and largest kiln site of them all. Even today, Ceramics is
one of the major industries in Tokoname where the tradition and the culture of Tokoname ware are still
alive. On the offshore waters of Tokoname City, the construction of the Central Japan International
Airport is now underway aiming to begin its operation in 2005 [1].
Pottery has been a drastically growing industry since the Meiji period as ceramic pipes started to be used as
a piping material for drainage. In these days, industrial materials or products for business use such as
sanitary wares and ceramic tiles are eagerly produced. “Tokoname ware” has a wide range of products
from tea-things, flower vases, bonsai pots, and ceramic ornaments to a new series of products such as
“handmade tableware” which meets the demands of the present age while preserving the tradition [1].
Until the first half of the Showa period, there were over 300 chimneys in Tokoname. Some of them were
destroyed by typhoon and/or earthquake. Unfortunately, according to the vulnerability for typhoon and/or
earthquake, chimneys which were not used were pulled down, or they were made half height, and now, the
number of chimneys is decreasing to 119 (Figure 1).
According to the results of an investigation on a history of earthquakes, it is the interval of about 100 to
150 years in the Tokai - Nankai area until now, and there is rising concern that earthquake of magnitude 8
class will occur in the first half of this century. The purpose of this paper is to obtain the data concerning
static and dynamic structural properties of brick chimneys in Tokoname to preserve them.
CHIMNEYS IN TOKONAME
According to an investigation of chimneys conducted by T. Kakita in August 1995, there were 152
chimneys including 55 perfect brick ones. Unfortunately, the number of Chimneys is decreasing to 119
including 45 perfect brick ones in January 2003 [2, 3]. Howa and Iwata brick chimneys were destroyed
due to construction of the access road to the Central Japan International Airport in January 2003 (Figures 2
and 3). But fortunately the chance of investigation relating to these two brick chimneys was obtained.
The profile of Howa and Iwata brick chimneys are listed in Table 1. Figure 4 shows the proportion of the
existing chimneys in Tokoname. As shown in Figure 4, the proportion of these two brick chimneys is
standard one in Tokoname.
As for Howa brick chimney, four iron angles of 75mm x 75mm x 6mm at corners are fastened by 12 series
of iron ties of φ 16mm. On the other hand, four iron angles of 40mm x 40mm x 3mm at corners are fastened
by 6 series of iron ties of φ 9mm in Iwata brick chimney. Electromagnetic Radar is applied in order to
estimate the thickness of chimneys. The thickness of Howa brick chimney is changed four times from the
top to the bottom, that is, 0.21m, 0.315m, 0.42m, and 0.53m. On the other hand, the thickness of Iwata
brick chimney is changed 0.11m at the top and 0.21m at the bottom (Figure 3).




       Fig. 1 Landscape of Tokoname City (offered by K. Sughie)                            (a) Howa        (b) Iwata
                                                                                            Fig. 2 Brick Chimneys

                                                                            3.0

                                                                            2.5
                                                         Bottom width [m]




                                                                            2.0

                                                                            1.5

                                                                            1.0
                                                                                                     ● Brick
                                                                                                     □ Clay pipe
                                                                            0.5                      × Steel pipe
                                                                                                     ○ Partial collapse
                                                                            0.0
                                                                                  10
                                                                                  0   5  15     20    25
          (a) Howa              (b) Iwata                                       Height [m]
              Fig. 3 Plan and Section                          Fig. 4 Proportion of Chimneys in Tokoname

                         Table 1. Profile of Howa and Iwata Brick Chimneys (m)
                    Height    Bottom width      Top width                    Bottom thickness   Top thickness
          Howa       15.0         1.96            1.06                            0.53              0.21
          Iwata       8.2         1.16            0.68                            0.21              0.11
MATERIAL TESTS
In order to estimate Young’s modulus and compressive strength of the brick used for these brick chimneys,
core sampling tests are carried out. The diameter and height of the brick specimens are about 33mm and
50mm, respectively. From the material tests, Young’s modulus and compressive strength of the brick are
estimated 3200 MPa and 7.5 MPa, respectively [2, 3]. The specific gravity of the brick is determined about
16.5 kN/m3.

STATIC COLLAPSE TEST
For the purpose of obtaining the data concerning static structural properties of brick chimneys in
Tokoname to preserve them, pull down test of Howa and Iwata brick chimneys are carried out (Figures 5
and 6).
Upper part of the brick chimneys, wire rope was set and it was pulled by a derrick car until their collapse.
During the static collapse test, horizontal load and deformation at the top of the brick chimneys are
measured by means of load cell and laser range finder, respectively.
Ultimate horizontal load of Howa and Iwata brick chimneys are 32.15 kN (horizontal component is 29.13
kN) and 4.40 kN (horizontal component is 4.25 kN), respectively. Collapse mode is different among Howa
and Iwata brick chimneys. In case of Howa brick chimney, collapse occurs at the middle height of the
chimney, that is 8m height from ground level which is shown in Figure 5. On the other hand, as shown in
Figure 6, collapse of Iwata brick chimney occurs at the base of the chimney.




           (a) Crack at the middle height                               (b) Collapse
                           Fig. 5 Static Collapse Test of Howa Brick Chimney




               (a) Crack at the base                                    (b) Collapse
                          Fig. 6 Static Collapse Test of Iwata Brick Chimney
Figure 7 shows relationship between height of           15
Howa brick chimney and bending moment and its
admissible based on static equilibrium. From this       12                          Admissible
Figure, it is to note that collapse of Howa brick                                   Static




                                                                 Height [m]
chimney occurs at the middle height of the chimney,       9
that is 8m height from ground level. From static
equilibrium, tensile strength of the brick chimney is     6
estimated to be 0.37 MPa.
As shown in Figures 10 and 11, analytical model is
                                                          3
composed of 9-node isoparametric Heterosis shell
elements which is consists of eight layers. The FEM
(Finite Element Method) based on isoparametric
                                                          0
                                                            0     10    20    30    40     50    60
degenerated shell elements is adopted for the                      Bending moment [kN m]
numerical analysis [4, 5]. The selective integration
rule is adopted for numerical integration. Total Fig. 7 Relationship between Height and Bending
number of nodes and elements are 1476 and 320,               Moment (Howa Brick Chimney)
respectively.
The yielding surface, given by Equation (1), for the FEM analysis is drown in Figure 8. The yielding
condition of bi-axial compressive masonry is expressed on the basis of the Duruker-Prager yielding
condition. The yielding function depends the mean normal stress I1 and the second stress invariant J2 as
follows,

f ( I 1 , J 2 ) = [β (3J 2 ) + αI 1 ]
                                    1/ 2
                                           =σ                                                                  (1)

where α=0.355 σ and β=1.355 are adopted based on the experimental data by Kupfer et al. [6, 7].
The masonry is assumed to yield in compression when the equivalent stress σ reaches to 30% of uni-axial
compressive strength, and the flow rule proposed by Prandtl-Reuss is applied to the masonry in the plastic
phase. The hardening rule of masonry is assumed based on the equivalent uni-axial stress-strain relation
defined by the conventional Madrid parabola.
Figure 9 shows the stress-strain relationship of concrete characterizing the element. The crush of masonry
is judged by equivalent strain. The function is defined by replacing the stress components of the yield
function with the strain components. The masonry is assumed to crush when the equivalent strain ε
reaches the ultimate strain ε u , and the analysis is performed under a condition that the stiffness after this
strain is to be zero (Figure 9(a)).




                                                             (a)                                (b)
Fig. 8 Yielding Condition for                   Fig. 9 Stress-strain Relationship for Concrete Constitutive Model
Concrete Constitutive Model

The crack of masonry is assumed to occur when the tensile principal stress exceeds the tensile ultimate
strength shown in Figure 9(b). Cracks are assumed to form in planes perpendicular to the direction of
maximum principal tensile stress which reaches the specified tensile strength. The cracked masonry is
anisotropic and smeared crack model is adopted. After cracking, for the sake of the expediency to achieve
numerical efficiency, a small amount of tension stiffening is assumed in uni-axial stress-strain
relationships represented as follows,

σ i = α ⋅ f t ' ⋅ (1 − ε i / ε m ),             εt ≤ εi ≤ εm   (i = 1,2)                                                            (2)

σt’ is reduced in the region of tension-compression as follows.

σ t ' = f t ' 1 + σ 2 / f c'(            )                                                                                          (3)

where σt’ denotes the cracking stress. σ2 and ft’ is the compressive stress perpendicular to the tensile
stress and the uni-axial tensile strength, respectively.
Structural characteristics of the brick chimneys are considered through material and geometrical
non-linear analyses. Material constants used in the analysis are Young’s modulus E = 3200 MPa,
Poisson’s ratio ν = 0.15, weight per unit volume γ = 16.5 kN/m3, ultimate tensile strength ft’ = 0.37 MPa
derived by static collapse test, ultimate compressive strength fc’ = 7.5 MPa, ultimate compressive strain εc
= 0.003, tension stiffening parameter εm = 0.002 and α = 0.5 (Figure 9).




      (a) Deformation         (b) Crack pattern                              (a) Deformation          (b) Crack pattern
    Fig. 10 Result of FEA of Howa Brick Chimney                            Fig. 11 Result of FEA of Iwata Brick Chimney

                           35                                                                     5
                           30       Ultimate experimental load                                        Ultimate experimental load
    Horizontal Load [kN]




                                                                           Horizontal Load [kN]




                                                                                                  4
                           25
                           20                                                                     3

                           15                                                                     2
                           10
                                                    FEA                                           1                  FEA
                           5                        Experimental                                                     Experimental
                           0                                                     0
                                0   10      20     30   40    50    60             0 10 20 30 40 50 60 70 80
                                         Displacement [mm]                                 Displacement [mm]
                                             (a) Howa                                          (b) Iwata
                                              Fig. 12 Relationship between Horizontal Load and Displacement
Figure 10 shows deformation and crack pattern of Howa brick chimney. From FEA (Finite Element
Analysis) result, as shown in Figure 10(b), collapse occurs at the middle height of the chimney. This
collapse mechanism corresponds well to that of experimental result (Figure 5 (b)). On the other hand,
deformation and crack pattern of Iwata brick chimney are shown in Figure 11. Collapse occurs at the base
of the chimney which corresponds well to that of experimental result (Figure 6 (b)).
Figure 12 shows relationship between horizontal load and displacement of Howa and Iwata brick
chimneys obtained by FEA comparing with those of experimental results. From these Figures, ultimate
horizontal loads obtained by FEA correspond well to their ultimate experimental horizontal ones.

MICROTREMOR MEASUREMENT                                                0.05
For the purpose of obtaining the data concerning                                 N-S
dynamic structural properties of Howa brick           0.04                       E-W
chimney, as a first phase of dynamic test,                                       Vertical




                                                        [cm/sec sec]
microtremor by ambient vibrations are measured at     0.03
the top. Smoothed spectra by Parzen’s spectral
window of 0.5 Hz are given in Figure 13. In Figure    0.02
13, bold solid line, bold dotted line and fine soli d
line show the spectra of north-south, east-west and   0.01
vertical directions, respectively. According to the
observation of microtremor measurement, the           0.00
fundamental frequencies of Howa brick chimney are          0  5        10       15        20
estimated to be 2.95 Hz and 2.67 Hz in north-south                    [Hz]
and east-west directions, respectively. There is
difference between two directions due to the Fig. 13 Spectra observed in Microtremors (Howa)
window in north side (Figure 3).

ACCELERATION MEASUREMENT
In the second phase of dynamic test, as for both Howa and Iwata brick chimneys, acceleration of 6 points
is contemporaneously measured in north-south or east-west direction. One sensor is placed at the base of
the chimney and another one is placed at the top. Other sensors are placed as equally spaced. Excitation is
ground motion due to derrick car.

DYNAMIC IDENTIFICATION
The experimental dynamic parameters such as fundamental frequencies, modal shapes and damping
factors are identified by analysis of the accelerations time-history by means of ARMAV (Auto Regressive
Moving Average) techniques.

THE ARMAV TECHNIQUE
An ARMAV model [8, 9, 10] can be expressed in the state space according to the following expression (u
and x are the input and output):

{x [n]} = [a ]{x [n − 1]} + [b]{u [n]}                                                                 (4)

In these parametric models the system output x [n] is supposed to be caused by a white noise input u [n]
and the algorithm estimates the parameters’ values that minimize the residual variance. The parameter
estimation algorithm works as follows: a first ARV model, whose structure is
         p
x [n] = ∑ A[k ]x [n − k ] + u [n]
          ˆ                 ˆ                                                                          (5)
        k =1
is fitted to the data. Using the estimated autoregressive parameters A[k ] , the residual vector u [n] is
                                                                     ˆ                           ˆ
computed and used as input for the ARMAV model:
                             p                                q
x [n] = ∑ A[k ]x [n − k ] + u [n] + ∑ B[k ]u [n − k ]
          ˆ                 ˆ         ˆ ˆ                                                                                                        (6)
                            k =1                          k =1


An iterative procedure can then be started, to alternately refine the estimated parameters A[k ] , B[k ] and
                                                                                           ˆ       ˆ
the residual u [n] to minimize the residual variance. The procedure ends when the difference between the
             ˆ

parameters A[k ] and B[k ] , estimated in two consecutive iterations, is smaller than a desired value.
           ˆ         ˆ


RESULTS OF DYNAMIC IDENTIFICATION
In Figure 14, the frequency distributions of Howa and Iwata brick chimneys identified by the ARMAV
model are depicted in east-west and north-south directions, considering the complete time record.
Fundamental frequencies and damping factor identified by the ARMAV model are listed in Table 2.
Figure 15 shows natural mode shape both two orthogonal directions identified by the ARMAV model. As
for the mode shape, especially first mode shape, there is difference between Howa and Iwata brick
chimneys due to boundary condition. The foundation of Howa brick chimney is made in reinforced
concrete, and on the other hand, that of Itawa brick chimney is made in sand.

                       18                                                                          20

                       16                                                                          18

                       14                                                                          16
                                                                                                   14
   Frequency Density




                                                                               Frequency Density




                       12
                                                                                                   12
                       10
                                                                                                   10
                        8
                                                                                                    8
                        6
                                                                                                    6
                        4                                                                           4
                        2                                                                           2
                        0                                                                           0
                         0             5      10        15        20   25                            0        5      10        15    20     25
                                             Frequency [Hz]                                                         Frequency [Hz]
                                   (a) East-west Direction (Howa)                                        (b) North-south Direction (Howa)

                       18                                                                          14

                       16
                                                                                                   12
                       14
                                                                                                   10
   Frequency Density




                                                                               Frequency Density




                       12

                       10                                                                           8

                        8                                                                           6
                        6
                                                                                                    4
                        4
                                                                                                    2
                        2

                        0                                                                           0
                         0             5      10        15        20   25                            0        5      10        15    20     25
                                             Frequency [Hz]                                                         Frequency [Hz]
                                   (c) East-west Direction (Iwata)                   (d) North-south Direction (Iwata)
                                             Fig. 14 Frequency Distribution identified by ARMAV Model
                             Table 2. Fundamental Frequencies and Damping Factors
                                                   Natural Frequency (Hz)        Damping factor (%)
                             Direction   Mode
                                                   ARMAV          FEA               ARMAV
                                           1st       3.0603      2.7572               7.953
                            North-Sout
                                           2nd       9.9725     11.1547               4.187
                                h
                                           3rd      22.3372     25.6448               5.372
                Howa
                                           1st       2.6918      2.6924               3.069
                             East-West     2nd       9.3494     10.9514               3.157
                                           3rd      22.7584     25.4511               4.613
                                           1st       2.9330      2.9547               4.739
                            North-Sout
                                           2nd      14.4932     15.5084               7.370
                                h
                                           3rd      21.8729     23.0881               3.882
                Iwata
                                           1st       2.9356      2.9547               6.984
                             East-West     2nd      13.7789     15.5084               6.750
                                           3rd      19.9204     23.0881               9.061

         1.0                                                       1.0
                N-S                  E-W                                 N-S               E-W
         0.8                                                       0.8

         0.6                                                       0.6
  Hi/H




                                                            Hi/H




         0.4                                                       0.4

         0.2                                                       0.2

         0.0                                                       0.0
                      1st          2nd           3rd                           1st       2nd          3rd
                            (a) Howa                                        (b) Iwata
                              Fig. 15 Natural Mode Shape identified by ARMAV Model




          1st                 2nd            3rd             4th             6th                      7th
                        Fig. 16 Natural Mode Shape determined by Eigenvalue Analysis (Howa)

The finite element model is composed of 20-node isoparametric solid elements (Figure 16). As for Howa
brick chimney, the boundary condition at the base of the chimney is assumed to be fixed and its rocking
behavior is not taken into account. On the other hand, as for the boundary condition at the base of Iwata
brick chimney, soil foundation is also taken into consideration. From the material tests, specific gravity
and Young’s modulus used in FEA are assumed to be 16.5 kN/m3 and 3200 MPa, respectively. Total
number of nodes and elements are 4416 and 360, respectively.
Natural mode shapes of Howa brick chimney determined by eigenvalue analysis are shown in Figure 16.
In FEA, torsional mode shape is appeared in fifth mode. Fundamental frequencies determined by FEA are
listed in Table 2 comparing with the results identified by ARMAV model.

DYNAMIC CHARACTERISTICS OF BRICK CHIMNEYS
On the basis of the static and dynamic experimental tests, numerical model has been prepared. The
bending vibrational analytical model based on multi lumped mass model is adopted here for the elastic
transient dynamic analysis [11, 12]. The assumptions using our analysis are as follows;
1) the boundary condition at the base of Howa brick chimney is fixed. On the other hand, soil
    foundation of Iwata brick chimney is taken into consideration by modifying Young’s modulus of the
    first beam element,
2) the thickness of each block is constant,
3) Young’s modulus of the brick determined by material test is used here, and
4) damping factor is proportional to mass and 2 % is adopted.
The over 0.02 g accelerations observed in Tokoname City from 1997 are used as an input acceleration, that
is north-south and east-west directions of 980422 (April 22, 1998), 980821 (August 21, 1998), 991129
(November 29, 1999), 010411 (April 11, 2001), 010621 (June 21, 2001), 010927 (September 27, 2001),
030709 (July 9, 2003) and 040106 (January 6, 2004) [13]. The maximum acceleration of each earthquake
wave is normalized to be 0.1 g.
         1.0                                                    1.0

         0.8                                                    0.8

         0.6                                                    0.6
  Hi/H




                                                         Hi/H




                                         980422EW                                           980422EW
                                         990821EW                                           990821EW
                                         991129EW                                           991129EW
         0.4                             010411EW
                                                                0.4                         010411EW
                                         010621EW                                           010621EW
                                         010927EW                                           010927EW
         0.2                             030709EW               0.2                         030709EW
                                         040106EW                                           040106EW

         0.0                                                    0.0
            0.0     0.2    0.4    0.6    0.8     1.0               0.0    0.2   0.4   0.6    0.8       1.0
                          (a) Howa                                        (b) Iwata
                                Fig. 17 Maximum Shearing Coefficient Response
     1.0                                                    1.0

     0.8                                                    0.8

     0.6                                                    0.6
  Hi/H




                                                         Hi/H




     0.4                                                    0.4
                                         Howa                                                Howa
     0.2                                                    0.2
                                         Iwata                                               Iwata
     0.0                                                    0.0
               0 100 200 300 400 500 600 700 800                      0   5     10     15    20        25
                           [cm/sec2]                                             [cm/sec]
     Fig. 18 Maximum Acceleration Response                        Fig. 19 Maximum Velocity Response
     1.0                                                     1.0
                                                                                               Howa
     0.8                                                     0.8                               Iwata

     0.6                                                     0.6
  Hi/H




                                                          Hi/H
     0.4                                                     0.4

     0.2                                Howa                 0.2
                                        Iwata
     0.0                                                     0.0
        0.0     0.2    0.4 0.6    0.8   1.0                        0   1     2  3    4     5     6
                       [cm]                                                   [tonf]
     Fig. 20 Maximum Displacement Response                   Fig. 21 Maximum Shear Force Response

     1.0                                                     1.0
                                        Howa
     0.8                                                     0.8
                                        Iwata
     0.6                                                     0.6
  Hi/H




                                                          Hi/H


     0.4                                                     0.4
                                                                                              Howa
     0.2                                                     0.2
                                                                                              Iwata
     0.0                                                     0.0
        0.0   0.51.0 1.5 2.0 2.5 3.0                            0.0    0.2       0.4   0.6     0.8     1.0
                  [x103tonf cm]
   Fig. 22 Maximum Bending Moment Response                Fig. 23 Maximum Shear Coefficient Response

     1.0                                                     1.0

     0.8                                                     0.8

     0.6                                                     0.6
  Hi/H




                                                          Hi/H




     0.4                                                     0.4
                      Howa                                                   Howa
     0.2              Iwata                                  0.2             Iwata

     0.0                                                     0.0
        0.0     0.2    0.4     0.6     0.8      1.0             0.0    0.2       0.4   0.6     0.8     1.0

    Fig. 24 Distribution Of Shear Force(Qi/QB)          Fig. 25 Distribution Of Bending Moment(Mi/MB)

Figure 17 (a) and (b) shows the maximum shearing coefficient response of Howa and Iwata brick
chimneys. There is a little different in the response between the upper part (1/3 height from the top) and the
lower part of the chimneys. Figures 20 to 25 show the maximum acceleration response, the maximum
velocity response, the maximum displacement response, the maximum shearing force response, the
maximum bending moment response, and the maximum shearing coefficient response concerning Howa
and Iwata brick chimneys as the average of 16 earthquake waves. From Figure 23, the base shearing
coefficient is determined to be 0.15.
The distribution of the shearing force and the bending moment are shown in Figures 24 and 25. As for the
distribution of the bending moment, there is a little difference between those two brick chimneys.
As the brick chimneys are statically determinate structures, we can safely assume that the collapse of them
is caused by the tensile failure of the mortar between the bricks. When the tensile stress of each section of
the brick chimneys reaches the tensile strength, σt = 0.37 MPa derived by static collapse test is assumed
here, we defined the brick chimneys as collapse. We call the maximum acceleration of the input wave “the
collapse minimum acceleration α” when the brick chimneys are collapsed. From the maximum bending
moment response under the condition that the maximum acceleration is 0.1 g, α is determined by Equation
(7).
             N      1
α = (σ t +     )Z                                                                                          (7)
             A M (0.1) × 10
where α is the collapse minimum acceleration g, M(0.1) is the maximum bending moment response under
the condition that the maximum acceleration of the input wave is 0.1 g, σt is the tensile strength, N is the
axial force (kN), A is the cross section (mm2), and Z is the section modulus (mm3).
According to the elastic transient dynamic analysis in Figure 25 and Equation (7), those structures seem to
be vulnerable to earthquakes with 0.157 and 0.123 g and the collapse occurs at the middle height of the
brick chimneys. When material non-linearity is taken into consideration, the collapse minimum
acceleration will be grater than those obtained here. If the multiple factor is assumed to be 1.5, the collapse
minimum acceleration seems to be 0.236 and 0.184 g. When using the damping factor identified by
ARMAV model, the collapse minimum acceleration seems to be 0.300 and 0.238 g.

CONCLUDING REMARKS
The following concluding remarks were obtained:
1) From the material tests, Young’s modulus and compressive strength of the brick used for these
   chimneys are estimated 3200MPa and 7.5MPa, respectively.
2) The results of static collapse test of the existing two brick chimneys are discussed here comparing with
   the results obtained by FEA. Ultimate horizontal loads obtained by FEA correspond well to their
   ultimate experimental horizontal ones.
3) From the results of dynamic tests, the fundamental frequencies of Howa and Iwata brick chimneys are
   estimated to be about 2.79 Hz and 2.93 Hz, respectively. Their natural modes and damping factors are
   identified by ARMAV model.
4) According to the elastic transient dynamic analysis, these brick chimneys seem to be vulnerable to
   earthquakes with 0.24 to 0.30 g.
How to strengthening and preserving those brick chimneys is remaining problem.

Acknowledgements The authors wish to appreciate the cooperation of Mr. Tomizou Kakita of
Ex-director of INAX Kiln Plaza and Museum, Mr. Keizo Umehara of Tokoname City, and Mrs. Keiko
Sugie of the representive of Tokoname hometown circle “Tsuchinoko”. Also, to KiK-net of National
Research Institute for Earth Science and Disaster Prevention for earthquake waves. The financial supports
were offered by Grants-in-Aid for Scientific Research (Kakenhi), The Hibi Research Grant, Tokai
Academic Encouragement Grant and The Grant-in-Aid for Research in Nagoya City University.

REFERENCES
[1] Citation from http://www.city.tokoname.aichi.jp/html/intro_e/top.html
[2] T. Aoki, Study on preservation and use of historical masonry structures, Report of The Hibi Science
    Foundation, 5, (2003), 83-133, (in Japanese).
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