Volume 4, Number 5, February 2007

Seismic Safety Evaluation of Dams
Against Large Earthquake Motions in JapanOn March 30, 2005, the Ministry of Land Infrastructure and Transport (MLIT) submitted “Draft ofGuidelines for Seismic Safety Evaluation of Dams” (referred as “Guidelines”) to all Regional Bureaus andtheir related organizations. The draft Guidelines systematically describes methods for evaluating seismic
safety of dams subjected to large earthquakes. The Guidelines identify basic evaluation methods including
earthquake motions used for seismic evaluation and safety and earthquake response analysis.
The Guidelines are organized as four chapters as shown in Figure 1. The Guidelines require seismic
safety, setting of earthquake motions for seismic safety evaluation, and evaluation methods of seismic
safety of dam bodies and their appurtenant structures.
Chapter 1 Basic matters
1.1 Intent of the guidelines
1.2 Definitions of terms
1.3 Scope of application
1.4 Basics of seismic safety evaluation
1.5 Required seismic safety
1.6 Stored water levels to be considered in seismic safety evaluation
Chapter 2 Earthquake motions used for seismic safety evaluation
2.1 Selection of assumed earthquakes
2.2 Setting of level 2 earthquake motions used for seismic safety evaluation
Chapter 3 Evaluation of seismic safety of dam bodies
3.1 Policy for evaluation of seismic safety of dams
3.2 Seismic safety evaluation of concrete dams
3.3 Seismic safety evaluation of embankment dams
Chapter 4 Evaluation of seismic safety of appurtenant structures
4.1 Appurtenant structures to be subjected to seismic safety evaluation
4.2 Seismic safety evaluation of appurtenant structures
Figure 1. Organization of “Draft Guidelines”

Earthquake motions used for the evaluation are level 2 earthquake motions generated by large
earthquakes. When performing seismic safety evaluation of concrete gravity dams against large
earthquake motions the Guidelines account for the damage process due to tensile crack generated in a
dam body. In the case of seismic evaluation of rockfill dams, attention is given to earthquake-induced
sliding deformation.
The “Guidelines” will be modified in the future to address verification with respect to existing dams. The
Guidelines are considered to be “trial implementation” and studies will be performed toward formal
application.
Contact: Takashi Sasaki, Deputy Team Leader, Dam Structure Research Team, Hydraulic Engineering
Research Group, PWRI, sasaki@pwri.go.jp

Task Committee G: Transportation Systems
The Panel’s Task Committee G: Transportation Systems was formally established at the 13th Annual
Meeting of the UJNR Panel on Wind and Seismic Effects of UJNR, May 1981, Tsukuba, Japan. Surface
transportation systems play a vital part of commerce and interaction between people, safety, and mobility.
Among the surface transportation infrastructure, highway bridges are the most vulnerable to wind andearthquake hazards due to their open exposure to those natural hazard forces. The objectives of thisTask Committee (one of seven comprising the Panel) are to plan, promote, and foster research on thebehavior of highway bridges when subjected to wind and seismic forces and to disseminate research
results as technical bases for developing or revising specifications and guidelines. This work is performed
through conducting workshops, exchanging researchers, and performing cooperative research
programs.
The most visible activity of Task Committee G is the annual US-Japan Bridge Engineering Workshop(see photographs 1 and 2). This workshop provides the venue to exchange recent research results andtechnologies among the Federal Highway Administration/National Institute of Land Infrastructure andManagement/Public Works Research Institute (FHWA/NILIM/PWRI) researchers, government bridge
engineers, and related academic and industrial researchers/practitioners. The first workshop was held at
Tsukuba, Japan, in February 1984 and workshops have been held annually except 1986 alternating
between the US and Japan. The latest 22nd workshop was held in Seattle, WA, 2006, see
http://www.pwri.go.jp/eng/ujnr/newnl/enl_43.pdf. Approximately 800 technical papers were presented inprevious TC G workshops. The workshop papers after the 19th Workshop are available by visiting
http://www.pwri.go.jp/eng/ujnr/tc/g/tc_g.htm. Numerous researchers were exchanged between theFHWA, NILIM, PWRI and other research institutes.
This Task Committee has achieved many joint research projects, including:•
Coordinated experimental research study on the seismic performance of bridge pier andcolumns,•
Coordinated research study on aeroelastic, and aerodynamic response of cable-supported
bridges with emphasis on cable inspection, vibration and corrosion protection, and•
Coordinated research study on use and performance of structural materials including newmaterials.
Furthermore, this Task Committee performed jointed post-earthquake investigations of transportation
systems from the 1994 Northridge and the 1995 Hyogo-ken Nanbu (Kobe) Earthquakes. The Task
Committee has been incrementally planning its future through its annual workshops, joint research, guest
researcher exchanges, and its large number of publications.
Contact: Mr. Jiro Fukui, Structures Research Group, Public Works Research Institute (PWRI),
fukui@pwri.go.jp and Dr. Philip Yen, Federal Highway Administration, ' Wen-huei.Yen@fhwa.dot.gov.

Photo 1. Bridge Engineering Workshop(Saint Louis, 2002)

Photo 2. Study Tour (Kintaikyo Bridge, 2003)