This paper was originally published in Japanese in The Building Letter, Nov., 2004, The Building Center of Japan. English version was prepared by T. Sugano, one of the authors, May 2005.

Structural Design Method of Buildings for Tsunami Resistance (Proposed) Tsuneo Okada *1 Tadashi Sugano *2 Tadashi Ishikawa *3 Takero Ohgi *3 Shigemitsu Takai *3 Chisako Hamabe *3 Though there are indications of tsunami wave force for use in the design of embankments and other revetments, not much research has been conducted regarding the impact on structures of the inland incursion of tsunamis. It is thought based on past experience that reinforced concrete buildings would probably be safe, though quantitative assessments have not been implemented. The study was carried out on literature survey of previous studies on tsunami wave pressure and forces. The outline of structural design for Tsunami refuge buildings is proposed. When calculating wave pressure and force, they are determined as a function of maximum inundation depth based on an equation2) for the wave pressure of tsunamis that flow over perpendicular revetments without soliton break up and cause inland inundation. Since the tests were conducted under conditions of flat land with no obstacles subsequent to revetment overflow, the assessed values of wave pressure and force may be somewhat large. In addition, since much remains unknown about the effects on wave force when breaking window glass, etc., on pressure-exposed surfaces of structures, we decided to use wave pressure and force with sound pressure-exposed surfaces for our assessments to be on the safe side. Unconfirmed elements will have to wait for research to be conducted later.

A structural design method of buildings for tsunami resistance (proposed) Index

4.5. Equation for buoyancy Section 5. Combining loads Section 6. Design of pressure-exposed surfaces 6.1. Design of pressure-resistant members 6.2. Design of non-pressure-resistant members Section 7. Structural framework design Section 8. Examination of overturning and sliding8.1. Examination of overturning 8.2. Examination of sliding <Appendix> <References>

Section 1. Scope of application 1.1. Confirmation of application 1.2. Application to new construction 1.3. Application to existing structures Section 2. Terminology Section 3. Structural design Section 4 Equations for tsunami load 4.1. Equation for tsunami wave pressure 4.2. Equation for tsunami wave force 4.3. Reduction of horizontal load 4.4. Direction of horizontal load

*1 The Building Center of Japan Building Technology Research Institute President *2 The Building Center of Japan Building Technology Research Institute Senior Technical Adviser *3 The Building Center of Japan Building Technology Research Institute Senior Researcher

Section 1. Scope of application 1.1. Confirmation of application This design method applies to the structural design of buildings for tsunami resistance. When applying the method, the tsunami design inundation depth is appropriately set based on numerical simulations and past experience. 1.2. Application to new construction When applying this design method to new construction, items that are not defined in this design method are to comply with the Building Standards Law or based on the standards and guidelines of architectural institutions and organizations. 1.3. Application to existing structures Application to existing structures is acceptable as long as earthquake-proof safety is confirmed through Seismic Evaluation Standard for Existing Buildings or the structure is in compliance with the current Building Standards Law. Items that are not defined in this design method are to be based on the standards and guidelines of architectural institutions and organizations. <Comments> The Central Disaster Prevention Council, chaired by the Prime Minister with a membership consisting of the entire Cabinet including ministers in charge of disaster prevention, the heads of designated public institutions and persons of experience or academic standing, is to “promptly secure refuge facilities through the utilization of solidly-constructed buildings, etc.,” as provided for in the Framework for Tokai Earthquake Measures, and “promote the utilization, of so-called tsunami refuge buildings using the mid- to high-level stories of solidly-constructed high-rise buildings for refuge purposes,” as provided for in the Framework for Tonankai and Nankai Earthquake Measures. This design method treats tsunami load quantitatively and provides procedures for the structural design of buildings for tsunami resistance in order to enable the utilization of the tsunami refuge buildings. Equations for assessing tsunami load are usually considered to be a function of inundation depth. Inundation depth is known beforehand by numerical simulations, etc. Numerical simulations are explained in detail in the Tsunami and Tidal Wave Hazard Map Manual 1) edited by the Cabinet Office and others. The structural design flow indicated in Fig. 1-1 is assumed with this design method. In the case of new construction, a structural design is implemented in compliance with the Building Standards Law, which is then followed by the calculation of load and the design of pressure-exposed surfaces and the structural framework. In the case of application to existing structures, this design method is applicable to buildings with earthquake-proof safety that has been confirmed through Seismic Evaluation Standard for Existing Buildings or buildings that are in compliance with the current Building Standards Law in order to verify earthquake-proof safety for the earthquakes that occur prior to tsunamis. Though concrete buildings are suitable as tsunami refuge buildings taking into account the size of the load and the weight of the building, this design method does not necessarily place limits on the type of structure. The ultimate strength of the members and other items not specifically defined in this design method are to comply with the standards, guidelines, etc., of architectural institutions and organizations.

■ New building

NG

NO① Numerical simulation and past experience.

■ The check of application

Start

Available information of designinundation depth

s

③

⑥ Desisurface. Detc.

⑤ Es

④ Des

YES

Structural Design

gn of pressure-exposed esign of structural frame

t

NO

S

■ Existing buildings

timation of tsunami load

ign based on the Building Standard Law

⑤ Estimation of tsunami load

⑥ Design of pressure-exposedsurface. Design of structural frameetc.

NG

OK

t

stre

ngth

en

② Conformity to present Building Standard Law or conformity to the Seismic Evaluation Standard for Existing Buildings

NG

judgmen

New buildings

E

YE

OK

t

nd

Fig. 1-1 Structural design flow

judgmen

judgmen

OK

Section 2. Terminology The terminology used in this design method are defined as indicated below.

Design inundation depth : Design-use tsunami depth conjectured on the site. Depth of flood not run up height (m) Tsunami load : Tsunami-induced pressure and force that acts on buildings. This is a general term for

tsunami wave pressure, force and buoyancy. Tsunami wave pressure : Tsunami-induced pressure in the horizontal direction that acts on pressure-exposed

surfaces of buildings (kN/m2) Tsunami wave force : Tsunami-induced force in the horizontal direction that acts on buildings (kN) Buoyancy : Tsunami-induced force in the vertical upward direction that acts on buildings (kN) Pressure-exposed surface : Surface that is directly exposed to tsunami pressure Pressure-resistance member : Member that is directly exposed to and designed to withstand tsunami pressure

Non-pressure-resistant member:Member that is directly exposed to and yields to breakage by tsunami pressure, including glass windows, window frames, light-weight partitions, etc.

Structural framework : Frame that conveys the force received by pressure-exposed surfaces to the structure overall and the foundation

<Comments> The terms given in this section are a compilation of terms used in the following description of the design method that are not in general use or that need to be explicitly defined. Inundation depth is conjectured based on the results of numerical simulations, etc., and is the design inundation depth used in design. There are cases when hazard maps are produced that predict inundation depth based on the result of numerical simulations and it may be possible to obtain them on websites depending on the local government. If a hazard map indicating estimated inundation depths such as that shown in Fig. 2-1 is used, it is possible to set the design inundation depth by multiplying the inundation depth by the margin of safety ratio taking the importance, etc., of the buildings into account. The equation for the calculation of tsunami load in this design method is proposed based on tests of tsunami flowing over perpendicular revetments2), the configuration of which is illustrated in Fig. 2-2. In the tests, the building is positioned at a distance from the perpendicular revetment that is 2.5 – 20 times greater than the wave height. There are no obstacles in front of the building and it is exposed directly to the impact of the tsunami. The inundation depth is greatest at the leading edge of the inland incursion of the tsunami. The inundation depths indicated on the hazard map are the maximum estimated values. The inundation depths indicated in the tests, which serve as the basis for the load equations used in the design method, are not necessarily the same as the inundation depths shown on the hazard map; however, they are treated as equal for the purposes of the design method. Little research has been conducted regarding the quantitative assessment of the load exerted by inland incursions of tsunamis on buildings and a clearly defined correlation of design inundation depth with hazard maps or other easily obtainable resources remains an issue requiring further research in the future. Pressure-exposed surface and structural framework are defined and pressure-resistant member and non-pressure-resistant member in the pressure-exposed surface are defined as well in the design method. The relationship between the pressure-exposed surface and structural framework is indicated in Fig. 2-3. Since the load differs depending on the inundation depth or direction, even if it is the same member, a member can become either a pressure-resistant or non-pressure-resistant member.

map of the inundation depth prediction

inundation depth prediction 0～1m 1～2m 2～3m

Fig. 2-1 Example of a tsunami inundation prediction map (hazard map)

Perpendrevetme

iInundation depthfor design

building

Fig. 2-2 C

・Seismwall

・*Waseismwallparti

・*Wi

・ Walls other than seismic-resistant walls (including partitions)

・Windows, etc.

PresNon-pressure-resistant member

Pressure-expossurface

* Items not broken by tsuna

designed not to break due to ts Fig. 2-3 Relationship be

Tsunam

icular nt

onfiguration of the tsunami of the load equation

*Columns

ic-resistant s lls other thanic-resistant

s(including tions) ndows, etc.

・Columns ・Girders ・Seismic-resistant walls ・Footing beams

sure-resistant member

ed Structural framework

mi load andunami load

tween the pressure-exposed surface and structural framework

Section 3. Structural design In the structural design of buildings to withstand tsunami load, the positioning of pressure-resistant and non-pressure-resistant members is clearly differentiated. <Comments> Tsunami load increases as the design inundation depth increases and pressure-exposed surfaces area increase. In addition, the load may also be greater than wind load or seismic load depending on the design inundation depth. Pressure-resistant walls bear an in-plane force when an earthquake occurs but also bear a out of plane force when a tsunami occurs. In the structural design of buildings to withstand tsunami load, pressure-resistant and non-pressure-resistant members must be clearly differentiated according to the load direction. The tsunami load generated throughout the entire structural framework of the building may be reduced depending on the placement of pressure-resistant members. For example, the building with piloti is one in which tsunami load is reduced, though earthquake-resistant performance is generally not favorable. It is necessary to design tsunami refuge buildings with design method taking both earthquake-resistant and tsunami-resistant design into account.

Other pressure-resistant members

Pressure-resistant members subjectto load in the direction of directtsunami advance

Non-pressure-resistant members

Portion surrounded by pressure-resistant members

x y

Direction of tsunami advance

Fig. 3-1 Example of differentiation of pressure-resistant and non-pressure-resistant members

Section 4. Equations for tsunami load 4.1. Equation for tsunami wave pressure Tsunami wave pressure in the direction of tsunami advance for structural design use is calculated by the following equation. qx = pg(3h − z)… (4.1.) Where, qx is the tsunami wave pressure in the direction of advance for structural design use (kN/m2) p is mass per unit volume of water (t/m3) g is gravitational acceleration (m/s2) h is design inundation depth (m) z is the height of the relevant portion from ground level (0 ≦z ≦3h) (m)

Fig. 4-1 Tsunami wave pressure based on equation 4.1. 4.2. Equation for tsunami wave force Tsunami force in the direction of advance for structural design use is assumed to be generated simultaneously with tsunami wave pressure in equation 4.1 and is calculated by the following equation.

Qx = pgB 3h − z( )z1

z2∫ dz

=12

pgB 6hz2 − z22( ){ − 6hz1 − z1

2( )

… (4.2.)

Where, Qx is tsunami wave force in direction of advance for structural design (kN) B is width of part of interest (m) z1 is the minimum height of pressure-exposed surfaces (0 ≦z1 ≦z2) (m) z2 is the maximum height of pressure-exposed surfaces (z1 ≦z2 ≦3h) (m)

Fig. 4-2 Tsunami wave force bas

Qx

z 1

z

x

z 2

design inundation depth

g

3h

qx

z

x

z

design inundation depth

building

h

3h

3ρgh

3ρgh

h

ed on equation 4

buildin

.2.

4.3. Reduction of horizontal load Tsunami horizontal load can be reduced depending on the conditions of obstacles in the area of inland incursion. 4.4. Direction of horizontal load It is conjectured that tsunami horizontal load is generated from all directions. However, that does not apply if it is possible to conjecture the direction of tsunami advance from the estimated distribution of inundation depth based in simulations, etc., or from the configuration of the coastline. Wave backwash is also taken into account depending on the actual conditions. 4.5. Equation for buoyancy Buoyancy generated by tsunamis is calculated by the following equation. Qz = pgV ….… (4.3) Where, Qz is buoyancy (kN) V is volume of the building inundated by a tsunami (m3) <Comments> Though tsunami wave force relating to seaport facilities is indicated in Port Facility Technological Standards and Commentary3), it generally does not indicate anything regarding the inland incursion of tsunamis. Tsunami Assessment Technology for Nuclear Power Plants4) introduces the results of existing research2), 5)-7) relating to the load of tsunami inland incursion, which can be summarized as indicated below.

(1) There are two types of assessment equations, one for assessing tsunami wave pressure and the other for assessing tsunami wave force.

(2) The equation for assessing tsunami pressure has been proposed as a linear function for inundation depths. (3) The equation for tsunami wave force has been proposed as an equation that includes drag force only or drag,

inertia, impact and hydraulic gradient force. (4) Drag force is derived as a function by multiplying flow velocity squared times inundation depth.

There is also a study8) that states that flow velocity is proportional to the square root of inundation depth and the following can be determined based on item (4) above.

(5) Drag force is a quadratic function of inundation depth. Based on the above, tsunami wave force can approximately be judged to be a quadratic function of inundation depth. With this design method, tsunami wave pressure is calculated according to equation 4.1. Tsunami wave force is calculated based on equation 4.2, integrated as the tsunami wave pressure of equation 4.1, generated simultaneously. Fig. 4-1 shows tsunami wave pressure based on equation 4.1 and Fig. 4-2 shows tsunami wave force based on equation 4.2.; however, since actual buildings have complex shapes, Fig. 4-3 shows a method taking tsunami wave load based on building shape into account reflecting tsunami wave pressure distribution. Equations 4.1 and 4.2 can also be thought to implicitly include the effects of normal hydrostatic pressure and flow velocity and the wave pressure distribution gradient is the same as when under normal hydrostatic pressure. Fig. 4-3(d) shows a case in which water depth h’ of pressure-exposed surfaces is less than design inundation depth h. Since the horizontal load of the tsunami is based on the design inundation depth, it may seem possible to determine if h were replaced by h’ in equations 4.1 and 4.2. However, there is a study8) indicating that the flow velocity referred to above is proportional to the square root of the inundation depth and h cannot simply be replaced by h’. In the design method, wave force in the case of (a) in which h’ = h and the case of (e) in which h’ = 0 is linearly interpolated and indicates wave pressure distribution as the same as that of equation 4.1 or when under normal hydrostatic pressure.

(a) When pressure-resistant members are all positioned from 0 to 3h in direction z

(b) When the building is 3h or lower

(c) When pressure-resistant membe

(e) When there are no pressure-

between 0 and h in di

3h

h

Design inundation depth

Building

z

x

Tsunami wave pressure distribution based on equation 4.1.

3ρgh

3h

h

Design inundation depth Building

z

x

3ρgh

Load of the lost portion is disregarded.

h’

3h

Design inundation depth

x

z

g

3(hh

’)1/2

Hfequation 4.2.

g

Tsunami wave pressure distribution based on equation 4.1.

z

x

3h

Design inundation depth

h

No load because the tsunami passes under the building

z

x

Design inundation depth

3h

* Excluding windows and other small openin

Fig. 4-3 Tsu

3ρg

h

rs shift in dir

resistant mem

rection z

h

gs

nami wav

Buildin

ection x (d) When pressure-resistant members are missing

between 0 and h in direction z

h

g

3ρg

h

Buildin

bers

e pressure distribution based on

building

3ρg

h

shape

Buildin

ypothesized distribution based on low velocity implicitly included in

3 ρg(hh’)1/2

In addition, since window openings and other small apertures are not thought to have any great effect on tsunami load, that is not indicated in the diagrams. It is possible to eliminate the load generated by openings in the design of pressure-exposed surfaces; however, since the building overall is subjected to load due to tsunami incursion through such openings, it is desirable in the design of the structural framework to take load into account with the idea that there are also members in the openings. The characteristics of (b) - (e) have not thus far been clarified and updates based on future research results are desirable including (a), which is the most basic. Equation 4.12) is proposed based on tests targeting structures with a distance from perpendicular revetments of 2.5 – 20 times the height of the wave. In addition, since there are no obstacles between the perpendicular revetments and the structures, the structures are directly exposed to the effects of tsunami wave pressure. There are also studies9),10) indicating that, once over the revetments, force is reduced by trees, structures, etc., and it is thought that flow velocity also decrease. In this design method, it is considered possible to reduce the load according to the state of obstacles in the area of inland incursion based on special surveys. Topography is especially complex in the vicinity of river estuaries, ports and harbors that tsunami load is conjectured to be generated from all directions. On flat topography, etc., however, it is thought to be possible to conjecture the direction of tsunami advance through the appropriate use of numerical simulation results, etc. However, since it is conceivable even in such case that the direction of tsunami advance may differ from the assumed direction based on the analysis assumptions of numerical simulations, distribution of structures in the surroundings and other factors, it would be preferable to assume that the load in the perpendicular direction will be half or more of the load in the direction of advance as indicated in Fig. 4-4.

qy >0.5qx … (4.4.)

Qy >0.5Qx … (4.4’)

Where, qy is tsunami wave pressure in the direction perpendicular to the direction of advance (kN/m2) Qy is tsunami wave force in the direction perpendicular to the direction of advance (kN) In addition, since there are reports that greater damage to residences, etc., is inflicted by wave backwash, it would be preferable to assume, unless a special study is conducted, that the load is the same as that in the direction of advance.

y

xbuilding

Perpendicular direction

more than 0.5qx、or more than 0.5Qx

Perpendicular direction

more than 0.5qx、or more than 0.5Qx

Wave backwash qx or Qx

Direction of advance qx or Qx

Fig. 4-4 Horizontal load direction

Section 5. Combining loads A combination of loads as indicated below is taken into account in the design of structures to withstand tsunami load. G + P + 0.35S + T (regions of heavy snowfall) G + P + T (regions other than regions of heavy snowfall) Where, G is force generated by dead load P is force generated by live load S is force generated by snow cover load T is force generated by tsunami load Unless a special study, etc., is conducted, regions of heavy snow are those regions designated by specified government agencies as provided for in Article 86, Paragraph 2 Proviso, Enforcement Regulations of the Building Standards Law. <Comments> A combination with dead load, etc., is taken into account in this design method, rather than a combination of tsunami load and seismic load. Section 6. Design of pressure-exposed surfaces 6.1. Design of pressure-resistant members Pressure-resistant members are to be less than ultimate strength and shall be able to effectively convey force in the structural framework. In addition, if required, water shutoff is also taken into account. 6.2. Design of non pressure-resistant members Non pressure-resistant members yield to breakage without any damage to the structural framework. In addition, consideration is also given to avoid impairment of the functions of the structure to withstand inundation.

… (5.1.)

<Comments> Tsunami load increases as design inundation depth increases. For example, if design inundation depth is 1m, based on equation 4.1, the maximum tsunami wave pressure is 29.4kN/m2, on the order of 10 times greater than wind pressure. It would be difficult in both technological and economical terms to design all pressure-exposed surfaces as pressure-resistant members. In addition, if pressure-exposed members are broken and the structure is inundated, problems would arise with its usage. Accordingly, in this design method, a clearly defined distinction is made between pressure-resistant and non-pressure-resistant members.

Section 7. Structural framework design It is confirmed by the following equation that the horizontal load carrying capacity of the structural framework is equal to or greater than the horizontal load of the tsunami in all directions at each story.

Qui>Qi … (7.1)

Where, Qui is shear force carrying capacity of the i-story (kN) Qi is the shear force of the tsunami generated in the i-story (kN) <Comments> Shear force carrying capacity is based on the same approach as the shear force carrying capacity due to seismic load provided for in Article 82-4, Item 1, of the Building Standards Law. It is necessary to be aware of the following cautions, however, due to the differences between tsunami load and seismic load. (1) Tsunami wave load concentrates in pressure-exposed surfaces. (2) It is necessary to make a judgment regarding a rigid floor assumption if there are stairwells or other openings

near pressure-exposed surfaces, etc. Section 8. Examination of overturning and sliding 8.1. Examination of overturning It is confirmed that the structure does not overturn due to tsunami load. Buoyancy is taken into account in the examination of overturning. 8.2. Examination of sliding It is confirmed that the structure does not slide due to tsunami load. Buoyancy is taken into account in the examination of sliding. <Comments> Seismic load is ordinarily greater in the upper stories and tsunami load is greater in the lower stories. This means that, if the same shear force is generated in the building, the overturning moment due to the tsunami load becomes smaller than that of seismic load. In this design method, the overturning moment due to tsunami load is compared to the resistance moment of the structure in accordance with Building Foundation Structural Design Guidelines11). The examination is carried out taking buoyancy into account if necessary.

Mo<Mr ... (8.1.)

Where, M0 is overturning moment due to tsunami wave force (kNm) Mr is resistance moment of the structure (kNm)

Cases in which buildings themselves are moved are frequently observed in tsunami damage. An examination of sliding is required if there are no piles and Building Foundation Structural Design Guidelines11) are followed in this design method. The examination is carried out taking buoyancy into account if necessary. In addition, if there are piles and the piles and foundation are rigidly connected together, it is confirmed whether or not force is conveyed from the foundation to the piles for Qk below and that the stresses of the piles are less than ultimate strength.

Qk <µ(W − Qz ) … (8.2.)

Where, Qk is horizontal tsunami load generated in the foundation (kN) Qz is buoyancy (kN) µ is the friction coefficient of the reinforced concrete foundation and the ground W is the total weight of the building (kN) <Acknowledgement> In conducting this research, the Building Center of Japan (BCJ) surveyed the results of existing research, requested experts at the forefront of tsunami research to provide lectures and study sessions were held twice. The first time, Mr. Tetsuya Hiraishi of the Port and Airport Research Institute gave a lecture entitled Tsunami wave force acting on coastal structures. The second time, Prof. Fumihiko Imamura of the Disaster Control Research Center, Graduate School of Engineering, Tohoku University, gave a lecture on Tsunami occurrence and damage, Prof. Koji Fujima of the Department of Architectural Environment Engineering, School of Systems Engineering, National Defense Academy of Japan, on Tsunami wave action theory and numerical analysis, and Mr. Masashi Matsuyama of the Abiko Research Institute Department of Fluid Science of the Central Research Institute for Electric Power Industry on Tsunami wave force experiments. In addition, we also received valuable opinions from members of the Tsunami Damage Estimate and Alleviation Research Subcommittee (Japan Society of Civil Engineers) and reflected this advice in the present design method. We would like to take this opportunity to express our appreciation to all of them. <Appendix> A1. Literature survey of previous studies on tsunami wave pressures and forces.

Here in , previous experimental studies of wave pressures and forces on structures of the inland incursion of tsunami are reviewed. Tsunami Assessment Technology for Nuclear Power Plants Civil Engineering Institute of Japan(In Japanese), Feb.2002.introduces the results of existing research.

A1) Equation for tsunami wave pressure without soliton break up ( Asakura et.al. 20002))

The following Eq.(A-1) and (A-2) are proposed empirical formula based on tests of tsunami wave flowing over perpendicular revetments.

・・・・・・・（A-1） gzzpm ρη )3()( max −=

in case of hc /h＝0.73 : maximum tsunami wave pressure by Eq.(A-1)（0 ≦ z/ηmax ≦ 3） mp : height of the relevant portion from ground level. z : gravitational acceleration g : maximum inundation depth ηmax

: mass per unit volume of water ρ h : static water depth at revetment hc : height of revetment from static water level

A2) Equation for tsunami wave pressure with soliton break up ( Asakura et.al. 20002))

・・・・・・・（A-2） gzzzpm ρηη )3,44.5max()( maxmax −−=in case of hc /h＝0.73

pm : maximum tsunami wave pressure by Eq.(A-2)（0 ≦ z/ηmax ≦ 3） z ,g ,ηmax ,ρ ,h ,hc are indicated in Eq.(A-1)

3ηm

ax

3ρgηmax

Building

wave pressure

ηm

axim

um in

unda

tion

dept

h m

ax

2.4ρgηmax 3ρgηmax

3ηm

ax

2.2η

max

0.8η

max

Building

wave pressure

Fig.1 Tsunami wave pressure based on Eq.A-1 Fig.2 Tsunami wave pressure based on Eq.A-2 A3) Equation for tsunami wave pressure without soliton break up ( Ikeno et.al. 20015)) ・・・・・・・（A-3） p αρ32 −= ( ) gzaz Hm 2.)(

pm : maximum tsunami wave pressure by Eq.(A-3)（0≦z/aH≦3:above the surface of the static water） z : height above the ground aH : tsunami wave amplitude

a : impact coefficient ( = 1.36) ρ,g are indicated in Eq.(A-1)

A4) Equation for tsunami wave forces ( Ohmori et.al. 20006)) The time history analysis is performed for the experimental data from which Eq.(A-1) and (A-2). were

derived. In the analysis, tsunamic force is assumed to be composed of drag, inertia, impulse, and hydraulic gradient forces.

・・・・・・・（A-4） ηρηρ uCBuF +=1 dBu ηηρηθρ ++ )(1BLuC MDH &2 dx

gBLuCS2 drag force inertia force impulse force hydraulic gradient force

in case of hc /h＝0.73

FH : tsunami force by Eq.(A-4) B : width of structure L : length of structure CD : drag coefficient ( = 2.05) CM : mass coefficient ( = 2.19) Cθ : impact coefficient ( = 3.6tanθ) θ : angle of wave

u u． : acceleration of tsunami wave in the direction of advance

: velocity of tsunami wave in the direction of advance

η : inundation depth g,ρ ,h ,hc are indicated in Eq.(A-1)

A5) Equation for tsunami force to house (Iizuka and Matsutomi 20007)) This studies were perfomed in order to make the relationship between drag forces and damage degrees of

houses. Drag forces are evaluated based on damages of houses due to recent earthquakes occurred in Japan. ・・・・・・・（A-5） BF 1 ρ= hfDHD huC 2

2 FHD : Horizontal force by Eq.(A-5) CD : drag coefficient ( = 1.1～2.0)

u : velocity in inland hf : inundation depth in front of the house <References> (Not translated) 1) 財団法人 沿岸開発技術研究センター：津波・高潮ハザードマップマニュアル：2004 年 4 月

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波力に関する実験的研究：海岸工学論文集 第 47 巻(2000) pp.911-915

3) 社団法人 日本港湾協会：港湾の施設の技術上の基準・同解説： 1999 年 4 月

4) 社団法人 土木学会 原子力土木委員会 津波評価部会：原子力発電所の津波評価技術： 2002 年 2 月

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海岸工学論文集 第 48 巻(2001) pp.846-850

6) 大森政則、藤井直樹、京谷修、高尾誠、金戸俊道、池谷毅：直立護岸を越流した津波の水位・流速お

よび波力の数値計算：海岸工学論文集 第 47 巻(2000) pp.376-380

7) 飯塚秀則、松冨英夫：津波氾濫流の被害想定：海岸工学論文集 第 47 巻(2000) pp.381-385

8) 松冨英夫、飯塚秀則：津波の陸上流速とその簡易推定法：海岸工学論文集 第 45 巻(1998) pp.361-365

9) 平石哲也、竹村慎治、長瀬恭一：南太平洋地域における植林による津波対策法の適用性：海岸工学論

文集 第 48 巻(2001) pp.1411-1415

10) 原田賢治、今村文彦：人工植生モデルの抵抗による津波減衰効果に関する研究：土木学会東北支部技

術研究発表会（平成 13 年度）pp.208-209

11) 社団法人 日本建築学会：建築基礎構造設計指針： 2001 年 10 月工学図書株式会社： 2001 年版 建築

物の構造関係技術基準解説書： 2001 年 3 月