J-Stage (Journal of JSCE in Engish)
J-Stage (Journal of JSCE (E2 Division) in Japanese)
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Kyuichi MARUYAMA, Akira HOSODA, Yasushi TANAKA, Kenji KOSA, Tarou ARIKAWA, Norimi MIZUTANI
Vol. 5, No. 1, pp. 157-169, Journal of JSCE (in English)
Abstract:
This paper deals with how tsunami force acted on bridge girders when the
Great East Japan Earthquake broke out on March 11, 2011. First of all,
almost all data of bridge girders in the inundation area were collected.
Satellite images in internet websites were introduced to make a quick
survey on how many bridges were in the inundation area and how many of
them were damaged. Detailed data on the bridges, such as dimensions and
types, were obtained from authorities that have maintained those
bridges. For damage analysis of bridge girders, Prof. Kosa's method was
introduced to see whether bridges were washed away or not by tsunami.
Motion pictures of the tsunami taken by residents when it happened were
examined to evaluate the velocity and height of the tsunami. In order to
examine how bridge girders were washed away, an experimental
investigation was conducted using a big water channel. Hydrodynamic
analysis was conducted to evaluate the test results. In addition, a new
numerical simulation technique was developed to follow the movement of a
bridge girder during the tsunami.
Yukitomo TSUBOKAWA, Naoya KAWAMURA, Junichi MIZUKAMI, Ryota MAEKAWA
Vol. 5, No. 1, pp. 58-67, Journal of JSCE (in English)
Abstract:
The 2011 Tohoku Region Pacific Coast Earthquake struck off Tohoku and
Kanto regions of Japan on 11 March 2011. We conducted investigations of
structural and surface damage to pavement in the runway, taxiway and
apron at Sendai Airport for the purpose of re-opening the airport for
commercial flights. Many cracks were confirmed in the asphalt pavement
in the runway and taxiway. However, it was clarified that these cracks
except the one in the taxiway were not fatal structural damage that
would hinder the provisional use of the airport. Large settlement was
confirmed in a part of the asphalt pavement in the taxiway and concrete
pavement in the apron due to liquefaction. It was confirmed that these
settlement areas needed to be reconstructed for the re-opening of the
airport. Furthermore, the effect of the void underneath the cement
concrete slab on FWD deflection was clarified.
Yasushi TANAKA, Tetsuya ISHIDA, Ichiro IWAKI, Kazunori SATO
Vol. 5, No. 1, pp. 68-77, Journal of JSCE (in English)
Abstract:
“Reconstruction Roads” are the highways constructed to accelerate recovery from the Great East Japan earthquake that occurred in 2011. The total distance of Reconstruction Roads is approximately 360 km, which includes more than 250 bridges. Because Reconstruction Roads are located in a cold zone, durability against frost attack is necessary for their concrete structures. In addition to freezing and thawing effects, bridges also suffer from alkali silica reaction (ASR) and chloride attack from the use of deicing salt.
During the construction of a reinforced concrete (RC) slab of the “Mukai
sada-nai Bridge,” we designed the concrete and reinforcing materials to
be durable. A multiple defense strategy is a key phrase in our durability
design. To prevent possible deterioration, at least two countermeasures
were applied. The use of fly ash is a core countermeasure because it is
effective against both ASR and chloride attack. Air content was designed
at 6% to achieve antifrost performance. An expansive agent was also used
to reduce the risk of shrinkage cracks. Epoxy-coated reinforcing bars were
used to resist corrosion. An RC slab was carefully constructed at the Mukai
sada-nai Bridge. Wet curing continued for three months to obtain a pozzolanic
reaction. The quality of the hardened concrete was checked by element tests
and nondestructive tests. Additional costs to enhance durability were acceptable
with regard to risk control. Success at the Mukai sada-nai Bridge was followed
by the construction of other durable RC bridge decks on Reconstruction
Roads.
Abstract:
A damage identification method for inner cracks of RC bridge deck was investigated.
A local resonance of RC deck was excited by forced vibration test using
a portable shaker, and local resonance frequencies could be measured. As
the experimental results of the RC deck specimens, the local resonance
frequencies were significantly decreased on the area including an inner
void. Moreover, the damage estimating equation was proposed based on the
linearity relation between the local resonance frequency and the void length.
The RC deck was removed from the highway road bridge, and the distributions
of local resonance frequencies were measured. It was indicated that the
local resonance frequencies were decreased on the areas including inner
cracks. Moreover, as the experimental results of field test on the highway
bridge, it was shown that the areas including inner cracks were fairly
identified based on the decrease of local resonance frequencies obtained
by the forced vibration test.
Abstract:
The authors have proposed a method of joining the rebars of RC wall structures
such as box culvert. It is effective for productive improvement of wall
member with mechanical splices at the same section regardless of the plastic
hinge zone. There are many reports where wall member’s deformation capacity
is raised by using mechanical splices at the same section. However, it’s
mechanism has not been completely explained yet. This report shows a buckling
resistance test for main bars using Japanese class “A” mechanical splice
in full scale sized wall specimen tested under cyclic seismic loading.
As a result, mechanical splices at the plastic hinge zone of wall members
effectively improved the buckling resistance of rebars, and the member’s
deformation capacity was superior than joint-less specimen.
Masafumi HIRATA, Yuji SHIRANE, Kousuke MINAMI, Nobuaki SASAKURA, Yoshimitsu NAKAJIMA
Vol. 73, No. 2, pp. 165-178, Journal of JSCE (Division E2) (in Japanese)
Abstract:
The compaction for fresh concrete is very important work to control the
quality of the RC structures. However, the judgments for compaction interval
and time are often left to workers in the construction site, and therefore
the compaction control is not performed enough. The main factor for this
problem is that the quantitative controlling method for compaction effect
by the internal vibrator is not yet established.
In this paper, the authors suggest an easy and real time controlling method
for compaction effect of the fresh concrete using the acceleration of the
internal vibrator. This method can estimate viscosity, compaction range,
compaction time for fresh concrete simultaneously with compaction work.
As a result of comparison between the estimation and experimental value,
the effectiveness of this method was confirmed.
Shinji URANO, Hiroshi NEMOTO, Yoshitomo YAMADA, Kohei SAKIHARA
Vol. 73, No. 2, pp. 179-190, Journal of JSCE (Division E2) (in Japanese)
Abstract:
In this paper, MPS method was applied to fluid analysis of fresh
concrete with vibration. MPS method is one of the particle method, and
it is suitable for the simulation of moving boundary or free surface
problems and large deformation problems. The constitutive equation of
fresh concrete is assumed as Bingham model. In order to set fluidity
change of fresh concrete based on the decrement of the acceleration, the
Bingham model is supposed to be the yield stress and the plastic
viscosity of fresh concrete that decreased most in the neighborhood of
the vibrator.
To evaluate verification of compactability of fresh concrete, numerical
analysis examples of compaction at the part of haunch section of wall were
performed. As a result, it was found that the MPS method was suitable for
the simulation of compaction of fresh concrete with vibration.
Yukio HIROI, Takashi YAMAMOTO, Yoshihiko TODA, Yusuke TAKAGI
Vol. 73, No. 2, pp. 191-206, Journal of JSCE (Division E2) (in Japanese)
Abstract:
Satoshi IWANO, Tadashi WATANABE, Shinya UCHIDAI
Vol. 73, No. 2, pp. 207-219, Journal of JSCE (Division E2) (in Japanese)
Abstract:
The purpose of this study is to establish a method to measure
fundamental frequency for the reinforced concrete of which thickness is
around 2.5 meters by the Impact Elastic Wave Method. It is considered
that earlier studies have not devised a practicable and reproducible
method. In this study, passage and arrival time of the multiply
reflected P-wave was validated by numerical analysis based on 2D elastic
body wave equation and then measuring method and analysis method were
proposed. In the result, the measuring method with multiple sensors on
the surface of the measured concrete was devised, then the devised
measuring method was tested on actual concretes of which thickness are
1.6 meters and around 2.5 meters. As a result, the fundamental frequency
of the reinforced concrete is objectively determined by the Fourier
Transform of the composed function from cross-correlation functions
between the input waveform and measured waveforms by each sensor. In
addition, the type of elastic waves is discriminated by measuring phase
difference between measured waveforms by each sensor.
Shinji UTSUNO, Toru YAMAJI, Kazuhide YONAMINE, Yoshikazu AKIRA, Hiroyuki
KOBAYASHI, Yoichi WATABE, Michio YOSHIDA, Yuichi MAEZONO, Yoshiyuki KAWASE,
Shigeru MATSUMOTO
Vol. 73, No. 2, pp. 220-238, Journal of JSCE (Division E2) (in Japanese)
Abstract:
In this paper, the cathodic protection characteristics in seabed soil
were investigated by monitoring the current density and the potential of
the steel pipe pile in seabed soil. (1) In the seabed soil, as the
depth from the seabed was deeper, the period until the potential of
steel reach the protective potential was longer. However, the effect was
fully obtained at the every depth of pile by the cathodic
protection.(2) Regarding a cathodic protection mechanism in the seabed
soil, the cathodic protection was considered to be achieved by
continuing the protective current, even if feeble. (3) The supply of
protective current was affected by the soil resistivity based on the
ground survey. In addition, we proposed a design method of cathodic
protection in consideration of the soil resistivity, based on the
potential and current density distribution analysis using the finite
element method.
Shinichi HATTORI, Toshiro KAMADA, Shinya UCHIDA, Hibiki ASAKURA, Koki TERASAWA
Vol. 73, No. 2, pp. 239-250, Journal of JSCE (Division E2) (in Japanese)
Abstract:
In evaluation of imperfectly grouted part of tendon ducts in PC members,
the influences given on vibration of sheath were investigated using a
mechanical and a magnetical input method. These methods control the
parameter of impact and generate elastic waves with high repeatability
and accuracy. For this purpose, the specimens having a number of holes
penetrating to the sheath were used, which enabled to observe the
vibration directly on the sheath. As a result, it was found that the
penetration and reflection properties of elastic wave at the sheath
changed due to the existence of void in the sheath. Next, by defining
“wave energy” of the detected signals at the grouted part and the
ungrouted part, the detection capability of ungrouted part was made
clear under the available placement of impact and detection. Thus, it
was found that the magnetical input method has the larger detection
capability of ungrouted part than the mechanical input method. By
considering application of these methods at the concrete structures in
use, a new inspection flowchart of evaluating ungrouted part was
proposed.
Hiroshi KAZAMA, Jun TOMIYAMA, Yuji SUNAKAWA, Masaya HIGA, Syunsuke OBATA
Vol. 73, No. 3, pp. 251-270, Journal of JSCE (Division E2) (in Japanese)
Abstract:
Recently, fly ash, which is a byproduct from burning pulverized coal in
coal-fired power plants, has been used to improve a durability of
concrete structures in Okinawa Prefecture. Especially, the
superstructure and substructure of Irabu bridge, which has been in
service since January 2015, was constructed by using fly ash concrete in
order to achieve the durable more than 100 years.
This paper showed
results of durability investigations on fly ash concrete (FAC) which a
part of fine aggregate was replaced by non-JIS fly ash exposed to the
coastline in northern Okinawa Main Island for about 11 years.
It was
found from the results that FAC reduces the chloride permeability of
concrete, natural current method and polarization resistance method can
diagnose the corrosion levels of reinforcing bar in FAC and normal
concrete (BC) specimens using the same criteria, and progress of
carbonation does not affect to corrosion of reinforcing bar in FAC and
BC specimens under a coastal area with high humidity.
Also, from
petrological diagnosis on a concrete core taken from BC specimen, it was
revealed that ASR is not the main cause of the cracks observed on the
surface of specimens.
Shintaro MIYAMOTO, Yoshifumi HOSOKAWA, Hiroshi MINAGAWA, Emi ISAKA, Jun YAMAGUCHI, Ryuichiroh KUGA, Makoto HISADA
Vol. 73, No. 3, pp. 271-290, Journal of JSCE (Division E2) (in Japanese)
Abstract:
The purpose of this study was to clarify the mechanism of transformation
of cement minerals and the property of ions diffusivity in hardened
cement paste on the basis of the results of the diffusion cell tests.
The aqueous solutions enclosed in the cells were sulfuric acid,
hydrochloric acid, sodium sulfate and sodium chloride. As a result, this
study provided an explanation about the mechanism of the dissolution of
portlandite and other cement minerals caused by pH decrease due to the
action of proton and the penetration of anions. Furthermore, based on
the explanation, this study considered the mechanism of the expansion
failure caused by ettringite formation in case that monocarboaluminate
is a main cement minerals in AFm phase. In addition, this study provided
the evidence that the effect of Co-existence of cations on the
diffusivity of anions should be taken in to account when considering the
expansion failure of hardened cement paste due to chloride ions
diffusivity and sulfate ion penetration.