Department of Civil Engineering
National Institute of Technology (KOSEN), Akashi CollegeStudies on maintenance of aged steel bridges
NameMIYOSHI Takao

StatusProfessor

E-mailmiyoshi@akashi.ac.jp

JSCE (Japan Society of Civil Engineers), JSSC (Japanese Society of Steel Construction),

Affiliations

JSME (The Japan Society of Mechanical Engineers)
aged steel, material properties, built-up member, small size suspension bridge, ultimate strength, finite element

Keywords

methodMaterial properties of aged steel and its investigation
Ultimate strength evaluation and repair method of built-up members with damage caused by corrosion

TechnicalSupport Skills

Ultimate strength evaluation of steel members with thinning and crack caused by corrosion
An effect of cable system deterioration on mechanical behavior of small size suspension bridge

Research Contents(1) Investigation on material properties of aged steel removed from actual bridge(2) A study on load carrying capacity of built-up column with vanished lacing bar(3) A study on load carrying capacity and deformation properties of small size suspension bridge with deteriorated cable system
Morimura bridge (before restoration)

Bridge axis direction
Y (V)
X (U)
(Lower chordside)
Z (W)Centroid Rigid bar(Node O0)Transverse dir. of bridge axis
U = V = W = θX = θZ = 0
U0
20th. L.B.

Node on channel
shaped steel

107
5 Rigid (gusset)
portion
E.T.P. portion

Lower chord：Channel – shaped steel(160 x 65 ) x 2 + Lacing bar
Stress-strain curve of channel –shaped steel flangeσ (N/mm2)

400300•
Flange-1
Flange-2
Flange-3
Y. S.
T. S.

200

100
01080

Chemical content
analysis of weband lacing bar

Content (x10-2) (%)

06020ε (%)

30(Upper chordside)100
Brittle fracture percentage (%)

500

8060

Transition curve

20

Equivalent stress N/mm20-60

Web
Lacing bar
R1 (Kim et al.)R2 (Kim et al.)
SM400A (Kim et al.)

-40
-20
0
Temperature T (℃)

2040[Ref.] Kim et al. : Mechanical Properties ofWelded Joints and Weldability of SteelUsed in Bridges for Long Term -Repair andReinforcement by Welding on -Existing
Old Steel Bridges (I)-, Steel Const. Eng.,
Vol.23, No.46, pp.19-25, 2005.

MnPSNiCrMoCuVB

Numerical investigation on the ultimate strength of built-up member withvanished lacing bars (L.B.)(Vanishment of fourth lacing bars does not give significant effect on theload carrying capacity.)
Cable tension
TensionPcm Ceq

Several material test results of removed member from Morimura bridge (completedin 1906)(Tensile strength of removed member is lower than its minimum proof value (400N/mm2). Percent brittle fracture of removed member shows 100% below -20
degrees Celsius. Carbon content of removed member is low compared to that ofcurrent steel. Contents of phosphorus and sulfur are high as well.)

Built-up column withVanished 4th. L.Bs.

No-damage

0Si

L.B. portion

2nd. L.B.
700
E.T.P. portion
795
Rigid (gusset) portion
PCompression (introduced as a compulsory displacement)

20

C

Elimination of L.B. caused bycorrosion in actual bridge

4730

O0Test40

1st. L.B.

V = W = θX == θZ = 0

Relationship between percent
brittle fracture and temperatureby Charpy impact test ofchannel – shaped steel web-804040

700

Main cable
Suspender rope

Main towerWind stay cable
Wind cable
Frame analysis model of small size suspension bridge(Finite displacement analysis will be conducted after calculation of theshape and prestress of cable system under dead load.)

Available Facilities and Equipment
Universal hydraulic testing machine (2000kN capacity)

General purpose finite element analysis program MSC Marc/Mentat

Personal computer （Dell Precision 3640）

Self-made non-linear finite element analysis program

Personal computer （Be-Clia）

Exterior digital caliper gauge (TECLOCK GMD-1J)

Fortran compiler (Intel)

Digital point micrometer (Niigata Seiki MCD232-25P)

General purpose pre and post processor GiD

Portable Data Logger (TML TDS-150)