November 22, 2010 13:5 WSPC/S1793-4311/238-JET
00086
Journal of Earthquake and Tsunami, Vol. 4, No. 4 (2010) 269–284 c World Scientific Publishing Company DOI: 10.1142/S1793431110000868
STRUCTURAL DESIGN GUIDELINE FOR TSUNAMI EVACUATION SHELTER
A. PIMANMAS∗ , P. JOYKLAD∗,‡ and P. WARNITCHAI† ∗School of Civil Engineering and Technology Sirindhorn International Institute of Technology Thammasat University Pathumthani 12121, Thailand †School
of Engineering and Technology Asian Institute of Technology P.P. Box 4 Klong Luang Pathumthani 12120, Thailand ‡amorn@siit.tu.ac.th Accepted 7 June 2010
The tsunami that hit the Andaman beach of Thailand on 26 December 2004 demonstrated the need for safe evacuation shelter for the public. However, there exists no guideline for designing such a shelter. In response to this need, the Department of Public Works and Town & Country Planning (DPT) funded a project to develop the guidelines for designing tsunami shelters. The results of the project have been published as a design manual for tsunami resistant shelter. In this paper, the design approaches for such tsunami shelters are described. The shelters are classified into two categories: (1) shelter in the area where large debris is unlikely and (2) shelter in the area where large debris is likely. In the former case, a static load of a certain magnitude representing small-tomedium debris is assumed to act at random points on the structure at the inundation depth. In the latter case, the work-energy principle is adopted to balance kinetic energy of large moving mass with the work done through energy-absorbing devices installed around the perimeter of the lower floors of the building. In both cases, the structure consists of a main inner structure and an outer protection structure. The function of the main structure is to provide usable spaces for evacuees, whereas the outer protection structure protects the inner structure from debris impact. The main structure is designed to be either elastic or with a low acceptable damage level. The structural framing of the main and the protection structures can be concrete or steel structures that are capable of resisting lateral forces. The major difference between the two types of building lie in the way the outer structure is connected to the inner one. In the first category, the connector is rigid so that both the inner and outer structures resist the load together. In the second category, energy-absorbing connectors are used to absorb the impact energy. The structure must, therefore, be analyzed using a nonlinear static approach. The design guidelines for both building types are described conceptually in this paper. Keywords: Evacuation; shelter; tsunami.
Notation F = Impact force applied at the flow level (kN) h = Tsunami flow depth (m) 269
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
270
00086
A. Pimanmas, P. Joyklad & P. Warnitchai
W = Weight of debris (kN) g = Gravitational constant (9.81 m/sec2 ) t = The impact duration (sec) v = The velocity of the impact body (m/sec2 ) 1. Introduction On the 26 December 2004, South East Asian countries were hit by a tsunami caused by a 9.3 Richter earthquake o Sumatra in Indonesia. In Thailand, the tsunami killed over 5000 people and more than 2800 are still missing. As per Fig. 1, the tsunami also destroyed houses, oďŹƒces, shops, hospitals, schools, roads, and other infrastructures. The tsunami has prompted several investigations and studies worldwide, which are aimed at understanding the causes and mechanisms of tsunami and provide appropriate actions for preparation, mitigation, and prevention of the next tsunami [Meguro and Takashima, 2005; Trisler et al., 2005; Hettiarachchi and Samarawickrama, 2006]. Some of these studies include, but are not limited to tsunami early warning systems, land arrangement in shore regions, sea wall construction, as well as tsunami resistant shelter. The construction of a safe shelter to withstand tsunamis will contribute tremendously towards reducing the loss of lives. In the past, the structural design of shelter for tsunami has drawn little interest from the engineering community because tsunami is a very rare event. Considerable
Fig. 1.
Collapse of buildings in tsunami.
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
00086
Structural Design Guideline for Tsunami Evacuation Shelter
271
efforts have been directed towards the design of shelter structures for extreme wind and flood [FEMA361, 2000; FEMA55, 2000; Yazdani et al., 2005; Mohammadi and Heydari, 2008; Coulbourne et al., 2002]. Since the destructive 2004 tsunami, the design and construction of tsunami shelter has gained substantial attention especially in countries located close to the sea [Tang et al., 2008; Bird and DomineyHowes, 2006]. However, research results on designing tsunami-resisting structure have been so far very limited [Okada et al., 2006; Yeh et al., 2005]. As mentioned above, a tsunami is a rare event with very low probability of occurrence. Moreover, tsunami loading can be so large that it is uneconomical and impractical to design all structures to withstand tsunami. Consequently, a possible solution may be to provide the evacuation shelter in the location where evacuees can access within the limited time given by the tsunami warning system. The shelter must have sufficient strength to resist tsunami force of the maximum possible magnitude. The design of vertical evacuation shelter has to take into account several factors such as geographical condition of area, tsunami evacuation route, population density, community settlement format, and maximum run-up height recorded in the past tsunami events. Based on a survey along the coastline of Thailand [Pimanmas and Joyklad, 2007], the authors have roughly divided coastal communities into three categories, namely (1) tourism community, (2) local densely populated community, and (3) individual resort community. The settlement pattern has an impact on deciding whether to construct a new evacuation shelter or to retrofit an existing structure for tsunami resistance. If the target area has strong existing structures, it may be possible to retrofit the structures to function as tsunami shelter. However, in the lightly populated areas where there is no strong building, such as an individual resort area, the construction of a simple raised platform as temporary shelter may be considered (Fig. 2). In the area of dense population where there is no existing strong building, a new tsunami evacuation shelter building should be constructed.
Fig. 2.
Temporary raised platform structures.
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
272
00086
A. Pimanmas, P. Joyklad & P. Warnitchai
Fig. 3.
Fishing boat blown inland by tsunami wave at Naam kem village, Pang-Nga, Thailand.
As observed by the authors [Pimanmas and Joyklad, 2007], the collapse of many buildings was caused by the impact from debris such as logs, cars, ruins, and even large fishing boats, as per Fig. 3. Hence, the design of tsunami shelter must consider the debris impact force as well as wave pressure. This paper describes the guidelines for structural design of tsunami shelter with particular attention to debris impact force. 2. Design Criteria for Evacuation Shelter The general guidelines for a tsunami shelter are categorized into two broad areas; functional aspects and structural aspects. These are discussed below. 2.1. Functional aspects As per Fig. 4, the shelter should be located on the evacuation route in the tsunami hazard area where evacuees can reach the building within a reasonable time given by the tsunami warning system. The size of the building (floor area and number of storeys) may be estimated from the size of community and the required minimum area per evacuee. For instance, the FEMA55 [2000] requires a minimum area of 2 m2 per evacuee. Taking into account economic factors, the building should be designed to serve the purpose of the community in normal situations without tsunami. The access way to building should be free of any obstructions. The access ways between floors inside the buildings should consist of gentle ramps. Stairs with steep steps should be avoided to prevent stumbling of people ingressing into the building. Access ramps with a minimum width of 2 m are recommended to cater for the elderly, crippled, and children who can only move slowly. 2.2. Building configuration and structural form As per Fig. 5, irregular building shapes may induce undesirable forces, such as torsion in structural elements. Hence, the building configuration should be as simple
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
00086
Structural Design Guideline for Tsunami Evacuation Shelter
Fig. 4.
273
Evacuation route displayed on a tsunami hazard map.
Fig. 5.
Building configuration.
as possible. A rectangular layout is generally preferred over L-shape or irregular shape. The lower floors of the building should be free of obstructions to allow free flow of water. If walls or partitions are constructed, they should be breakable walls that are just strong enough to withstand wind pressure or other normal environmental loads outside the building. In the event of a tsunami, these walls should break readily to allow water to flow through. This provision is recommended to ensure that high water pressure will not build up on walls that will finally be transmitted to structural elements. Figure 6 compares the performance of structures with breakable and strong walls during a tsunami. As can be seen, when the wall
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
274
00086
A. Pimanmas, P. Joyklad & P. Warnitchai
Fig. 6.
Breakable and strong walls.
is breakable, the damage to structure is minimal. On the other hand, in the case of a strong wall, structural elements were severely damaged as they are subjected to loadings transferred from the walls. There are a number of structural systems that are suitable for evacuation shelter, such as the moment-resisting frame, the shear wall–frame system, and the braced frame. A structural reinforced concrete wall can add significant lateral strength and rigidity to the building. The connection between members should be rigid and continuous to provide structural redundancy. Precast systems may be used but careful design of connections is required. Cast in-place reinforced concrete slab is preferred over prefabricated slab due to its inherent monolithic nature that constrains the floor to behave as a rigid diaphragm transferring lateral forces to all lateral force resisting elements. As per Fig. 7, unless properly connected with beams, precast planks should be avoided because uplift pressure can dislodge them. The foundation of shelter building should be supported on piles that are capable of resisting lateral loads. The design of pile foundation should consider the additional free length of pile created due to soil scouring below the base of footing. As per Fig. 8, soil scouring is an associated hazard to structures during a tsunami event. The use of spread footing requires attention to be paid to scouring beneath
Fig. 7.
Uplifting of Pre-cast Concrete Slabs.
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
00086
Structural Design Guideline for Tsunami Evacuation Shelter
Fig. 8.
275
Scouring of foundation by tsunami run up (Sri-lanka Tsunami).
the footing that may cause instability of foundation. Tie beams should be provided to connect footings together to increase structural integrity. 3. Conceptual Structural Design of Tsunami Shelter Previous research on tsunami effects on structure and field investigation by the authors indicated that the main forces that govern the design of tsunami resistant building were the wave forces (including hydrodynamic pressure and breaking wave force) and loads from floating debris. The possibility of large debris such as fishing boats, yatches, and warships may be high in some areas. For example, at Naamkem fisherman village in Pang Nga, Thailand, large fishing boats with the gross weight of approximately 800 kN were displaced several kilometers inland by the 2004 tsunami, (Fig. 3). The boats destroyed houses and buildings. On the other hand, in a tourism area such as Pa-tong beach, Phuket, huge debris is unlikely to be encountered but small-to-medium-sized debris such as logs, cars, and ruins are common. Since the nature and severity of debris impact vary from area to area, it is recommended that site-specific study be conducted to examine the likelihood of large debris in terms of size and frequency of occurrence. In this paper, the design method against debris impact is described. The conceptual design concept is differentiated into two categories, namely shelter design for large debris impact and design for small-to-medium-sized debris impact. In both cases, the structural configuration is fundamentally similar, that is, it consists of an inner and an outer structure (Fig. 9). The inner structure provides shelter for the evacuees while the outer structure provides protection for the inner one. Basically, the inner structure is identical in both the cases. But the major difference is the outer structure and the connection between them, which depends on the size of debris. The outer structure is needed only in the lower levels of buildings because its main purpose is to protect the inner structure from debris impact. Thus, its height is determined by the inundation depth. In principle, damages or even collapses are
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
276
00086
A. Pimanmas, P. Joyklad & P. Warnitchai
Interior frame
Rigid connectors
Fig. 9.
Perimeter beam (Exterior frame)
Energy-absorbing connectors
Schematic structural system for resisting tsunami.
permitted in outer protection structure, but damage to the main inner structure should be none or kept at acceptable level. In no case is the inner structure allowed to collapse. The structural form of the inner structure can be of any type that can resist lateral forces. Cast in-place reinforced concrete moment resisting frame is a possible candidate. Shear wall may be added if the building requires high lateral strength and/or stiffness in high run-up area. Protection structure can be constructed from steel or concrete. The column shape for both inner and outer structures should be circular to reduce drag force caused by hydrodynamic pressure [FEMA55, 2000]. Connection between the inner and outer structures is provided along the perimeter beams at each floor level of the structure. As mentioned earlier, the type of connection between inner and outer structures depends on the debris size. In the area with small-to-medium-sized debris, rigid connection via conventional steel or reinforced concrete beams and rigid floor diaphragm is normally sufficient. When there is a possibility of large debris impact, the connection should be able to absorb kinetic energy of moving debris. Energy-absorbing devices should be considered whenever it is impractical to resist the force through conventional rigid connection. In the event of large debris impact, rigid connection will impart large forces to the inner structure, causing structural elements to either yield or damage to absorb the kinetic energy. Alternatively, if the inner structure is designed to remain undamaged or elastic, the size of the structural elements may need to be excessively large to be able to resist the debris load. Consequently, it is considered impractical to use rigid connection to resist large debris impact. Energy-absorbing devices are preferred because they allow energy absorption through large deformation. Nowadays, there are plenty of commercial devices that absorb great energy without high reactions, such as marine fenders made from synthetic rubber, as shown
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
00086
Structural Design Guideline for Tsunami Evacuation Shelter
Fig. 10.
Marine fenders.
(a) Tube and Mamdrel
(b) W-frame
(c) Folding tube
(d) Flattening tube
Fig. 11.
277
Metallic energy absorbing devices.
in Fig. 10. Other possible solutions include mechanical devices made of metal such as those illustrated in Fig. 11 [Kelly, 1978].
4. Design of Shelter Without Large Debris Impact In the area without large debris impact, the major design loads are wave pressure (hydrodynamic and breaking wave forces) as well as impact load from small to medium debris, such as logs, cars, or damaged members. Conventional structural form is deemed suďŹƒcient to withstand lateral forces, but the outer structure is still required to protect the inner structure. The connection between the inner and outer
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
278
00086
A. Pimanmas, P. Joyklad & P. Warnitchai Table 1.
Impact duration recommended by FEMA55. Duration (t) of impact (sec)
Type of construction materials Wood Steel Reinforced Concerte Masonry
Wall
Pile
0.7–1.1 NA 0.2–0.4 0.3–0.6
0.5–1.0 0.2–0.4 0.3–0.6 0.3–0.6
structures should be rigid in order that both structures resist the load together. The energy absorbing devices may not be necessary as long as the debris is not excessively large. To evaluate the force from debris impact, the following equation based on momentum conservation may be used: F =
Wv gt
(1)
FEMA55 [2000] recommends t-values as shown in Table 1. The velocity of impact body is assumed to be equal to the flow velocity given below: v = k gh (2) k is an empirical constant. FEMA55 [2000] recommends k = 2.0 as the upper bound for tsunami wave. Based on the study of tsunami flow velocity recorded in Thailand, the above value was found to be too high, thus k = 1.4 has been recommended in the “Standard for designing tsunami evacuation shelter and evaluating public buildings for tsunami resistance in moderate tsunami hazard area” [Department of Public Works and Town & Country Planning, 2008]. The k value may vary from area to area, thus it should be empirically determined from record data of past tsunami events or from numerical study. Unless reliable data is obtained, the above FEMA55 factor may be used as a conservative estimate. According to FEMA55 [2000], a design static force of 4.45 kN (1000 lb) is recommended for residential buildings. This force is too low and not adequate for shelter design. The actual impact force during a tsunami event is normally much larger. For example, assuming truck weight of 210 kN (normal Thai Truck) and inundation depth of 6 m, the impact force is calculated by Eq. (1) to be approximately 800 kN. Design procedure for buildings without large debris impact may follow the traditional structural design taking into account lateral static force of debris impact and wave pressure. The purpose of the outer structure is to protect the inner structure from being hit by debris. The principle is that the outer frame can be damaged or even collapsed, but the inner structure cannot. The rigid connection enables both frames to act together in resisting the load. To provide effective protection, columns of the outer structure should have large size and should be closely spaced. Reinforced concrete shear wall may be added to increase lateral resistance of the inner structure. For both inner and outer structures, pile foundations should be used to provide support for lateral forces.
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
00086
Structural Design Guideline for Tsunami Evacuation Shelter
279
5. Design of Shelter with Large Debris Impact The previous tsunami demonstrated that the wave could carry large fishing boats and even warships that demolished complete buildings. Field investigation by the authors [Pimanmas and Joyklad, 2007] found that the average gross weight of the fishing boats may be as high as 800 kN. Assuming the flow depth of 6 m high, √ the flow velocity is calculated by Eq. (2) to be v = 1.4 9.81 × 6 = 10.74 m/s, and with Eq. (1), the static force is calculated to be 3200 kN. If the recommendation of AASHTO [1991] is adopted, the static force can be as high as 12,000 kN. This is evidently a huge force, making it impractical to design structural members by conventional procedure. The alternative approach, based on the work and energy principle, is proposed. The key idea is to balance the kinetic energy of moving debris mass with the potential energy absorbed by connections between inner and outer structures. The kinetic energy (KE) of debris of mass m moving at the flow velocity v is given by 1 mv 2 (3) 2 The kinetic energy is dissipated or converted into potential energy by the connections, which can be expressed by the integral of force and deformation as W = f (x)dx (4) KE =
where f (x) is the reactive force and x is deformation. To maintain energy balance, KE must be equal to W (Fig. 12). The desirable characteristics of the energyabsorbing connector are ability to absorb large amount of energy and low reactive forces. The force-deformation response of the connector is shown as an example in Fig. 13. To obtain this desirable performance, the yield force should be low and deformation to failure should be high. Marine fenders made of synthetic rubber
Fig. 12.
Force-displacement and capacity curve.
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
280
00086
A. Pimanmas, P. Joyklad & P. Warnitchai
Fig. 13.
Force-deformation of dissipating device used in design example.
Shear walls
Interior column
18.00 m.
Perimeter beam Energy absorbing connectors
Exterior column 27.00 m. Fig. 14.
Structural plan for building resisting large debris impact.
are examples of such connectors. It should be noted that the main inner structure should possess suďŹƒcient lateral resistance to resist the reaction transferred from the connector without incurring damage to its structural elements. For this purpose, rigid structural walls may be added to enhance lateral strength and rigidity, as illustrated in Fig. 14. If the inner structure is weaker than the connectors, large inelastic deformation cannot be mobilized in the connectors. The inner structure itself would be loaded beyond its elastic range, causing undesirable damage or even failure to the main structure. To calculate the work done by the connectors, they should be modeled as nonlinear elements that link the perimeter beams between the outer and inner structures at oor levels. The force-deformation response of the nonlinear link can be obtained from manufacturer if a commercial connector such as rubber fender is used, otherwise it can be obtained from the laboratory test if a customized connector is used. The area under the capacity curve equals the elastic strain energy of the main structure and the energy absorbed by the connectors. The design of a shelter starts
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
00086
Structural Design Guideline for Tsunami Evacuation Shelter
281
with the calculation of kinetic energy (Eq. (3)) for a known debris mass (m) and flow velocity (v). The main inner structure should be designed to remain elastic under the reactions transmitted from connectors. The sum of energy absorption due to connectors plus elastic strain energy of the main structure should be at least equal to the kinetic energy. For this purpose, the nonlinear static push-over analysis is recommended to calculate the energy absorption. The area under the capacity curve represents the total stored energy (W ). The debris impact should be assumed to act at various positions of the building, which, in turn, gives rise to different work done W . The structure is safe if the minimum value of W is equal to or greater than the kinetic energy. It should be cautioned that the perimeter beam should be sufficiently rigid laterally in order to distribute the impact force to as many connectors as possible and thereby ensure that as many connectors as possible are absorbing the impact energy concurrently. If the perimeter beam is not rigid, only few connectors will be mobilized, and the work done will not be sufficient to dissipate all the kinetic energy. This may cause some structural elements of the inner structure to yield or deform inelastically to provide the balance of the remaining kinetic energy. As in the case of a shelter without large debris impact, the columns of the outer structure should be closely spaced to prevent small-to-medium-sized debris from passing through and hitting columns of the main inner structure. As mentioned earlier, the energy-absorbing connectors need to undergo large deformation to absorb the necessary energy without high reactive forces. This implies that the outer protective structure will have to displace over a large distance to accommodate the deformation of energy-absorbing devices. The foundation should be designed to allow such movement. Furthermore, the energy-absorbing connectors should only be mobilized when there is a large impact. They should not be mobilized under hydrodynamic action or impact force from smaller debris. Thus, the yield force of the connectors must be greater than the force caused by hydrodynamic pressure but lower than that due to large debris. 6. Design Example of Tsunami Shelter in Area with Large Debris Impact This section illustrates an example of a tsunami shelter that is designed to resist large debris impact. The shelter consists of the inner and outer protective structures. The inner structure is a typical cast-in-place reinforced concrete structure. The shelter is designed for 1000 evacuees, with an area of 2 m2 per person. The total number of storeys including roof floor is five. As Fig. 15 shows, the storey height is 4.5 m for the first storey, 4.0 m for the second storey, and 3.0 m for the other floors. The structure is designed for tsunami with the inundation depth of 6.0 m. The first and second storeys have no partition walls to allow water as well as small- and medium-sized debris to pass through. The walls of the other floors are constructed of conventional masonry. The main structure consists of 6×4 bays in plan, each bay
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
282
00086
A. Pimanmas, P. Joyklad & P. Warnitchai Shear walls
+ 14.5 m. + 11.5 m. + 8.5 m.
Roof 4th Perimeter beam 3
rd
+ 6.0 m. + 4.5 m.
+ 0.0 m.
2nd
Exterior column
1st 27.00 m.
Fig. 15.
Elevation of building resisting large debris impact.
measuring 4.5 m × 4.5 m in both longitudinal and transverse directions. Shear walls are provided at the center and the corners of the inner structure to increase lateral strength and rigidity. The pile foundations are designed to support the columns and shear walls in the event of scouring. The outer protective structure is also a cast in-place reinforced concrete frame. It is connected to the inner structure by rubber fenders installed at the column positions along the perimeter beams of the first two storeys. The clear distance between the two structures is 2 m. The design loads included self-weight, superimposed dead load (floor finishing and partition walls), live load, buoyancy force, hydrodynamic pressure, wind load, and debris impact force. The minimum design live load was 5 kN/m2 for public building. Based on an inundation depth of 6 m, Eq. (2) with k = 1.4, the design tsunami flow velocity is 10.74 m/s. The hydrodynamic pressure is calculated according to FEMA55 [2000] and is distributed vertically along the height of columns of the first two stories. The wind pressure was calculated according to local design code. The structure was designed to resist the debris of 800 kN (80 tonnes), representing typical large fishing boats found in the area. Based on this debris mass and a flow velocity of 10.74 m/s, the kinetic energy that the structure must be able to absorb is 4600 kJ. The number of energy-absorbing connectors can be roughly estimated from the force-deformation characteristics of a rubber fender shown in Fig. 13. As shown, each fender can absorb about 497 kJ, thus, 10.5 fenders are required to absorb the total kinetic energy. The structural plan layout and elevation of the building is shown in Figs. 14 and 15, respectively. A total of 14 fenders (7 for each floor) is used in longitudinal direction, and 10 fenders (5 for each floor) in the transverse direction. After determining the number of energy-absorbing connectors, the whole structural model of the building is constructed with energy-absorbing connectors modeled as nonlinear spring elements. The nonlinear static pushover is conducted with several pushover locations on the structure. Figure 16 shows the pushover
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
00086
Structural Design Guideline for Tsunami Evacuation Shelter
283
Push1- E = 10,465 kJ
3.00E+07
Push2 - E =5,111 kJ Push3 - E =7,888 kJ 2.50E+07
Force (N)
2.00E+07
1.50E+07
1.00E+07
tran
sve
5.00E+06
l
ina
tud
rse longi
Push2
Push1
Push3
0.00E+00 0
0.1
0.2
0.3
0.4
0.5
0.6
Displacement (m)
Fig. 16.
Capacity curves under various load positions.
curves for these locations. The area under each curve represents the energy absorption for the corresponding pushover location. As shown in the figure, the minimum energy absorption is 5.1 × 103 kJ which is greater than the required energy 4.6 × 103 kJ, indicating that the energy-absorption capacity is greater than the energy demand. The inner structure is then designed using the above loads plus reactive forces transmitted from fenders. 7. Conclusions This paper presents the design concept for evacuation shelter in tsunami-prone area. Two different design approaches are proposed depending on the size of debris. Impact of small-to-medium-sized debris can be represented by an equivalent static load that acts at various positions on the building. For large debris, the design approach is to absorb the kinetic energy of moving debris by means of energyabsorbing devices. The basic structural form in both cases is the same; it consists of an inner structure for providing usable floor area and the outer structure for protecting the inner structure. For small-to-medium debris, the connection between the two structures is designed to be rigid so that the entire structure can resist the load together. For large debris, energy-absorbing connectors are recommended to dissipate the kinetic energy of the moving mass. A nonlinear pushover analysis should be performed to calculate the energy absorption capability of the structure. The nonlinear connectors should be modeled by nonlinear springs in the structural model.
November 22, 2010 13:5 WSPC/S1793-4311/238-JET
284
00086
A. Pimanmas, P. Joyklad & P. Warnitchai
Acknowledgment The authors are very grateful to the Department of Public Works and Town & Country Planning (DPT) for providing the research fund to carry out this work.
References AASHTO [1991] American Association of State Highway and Transportation Officials, Guide Specification and Commentary for Vessel Collision Design of Highway Bridges, Washington, USA. Bird and Dominey-Howes. [2006] “Tsunami risk mitigation and the issue of public awareness,” Australian J. Emergency Management 21(4), 29–35. Coulbourne, W. L., Tezak, S. and Mcallister, T. P. [2002] “Design guidelines for community shelters for extreme wind events,” J. Architectural Eng. (ASCE) 8(2), 69–77. Department of Public Works and Town & Country Planning [2008] Standard for Designing Tsunami Evacuation Shelter and Evaluating Public Buildings for Tsunami Resistance in Moderate Tsunami Hazard Area, Military of Interior, Bangkok, Thailand (in Thai). FEMA361 [2000] Federal Emergency Management Agency, Design and Construction Guidance for Community Shelter, Washington, U.S.A. FEMA55 [2000] Federal Emergency Management Agency, Coastal Construction Manual, Washington, U.S.A. Hettiarachchi, S. and Samarawickrama, S. [2006] “The tsunami hazard in Sri Lanka strategic approach for the protection of lives, ecosystems and infrastructure,” Coastal Eng. J. 48(3), 279–294. Kelly, J. M. [1978] “The development of energy-absorbing devices for aseismic base isolation systems,” Report No. 78–01, University of California, Berkeley, California. Meguro, K. and Takashima, M. [2005] “Proposal of a sustainable tsunami disaster mitigation system for the Indian Ocean region,” in Report on the 2004 Sumatra Earthquake and Tsunami Disaster, K. Meguro (ed.), (International Center for Urban Safety Engineering Institute of Industrial Science, University of Tokyo, Japan), pp. 129–134. Mohammadi, J. and Heydari, A. Z. [2008] “Seismic and wind load consideration for temporary structures,” Practice Periodical on Structural Design and Construction (ASCE) 13(3), 128–134. Okada, T., Sugano, T., Ishikawa, T., Ohgi, T., Takai, S. and Hamabe, C. [2006] “Structural Design Method of Buildings for Tsunami Resistance,” Building Technology Research Institute, Building Center of Japan. Pimanmas, A. and Joyklad, P. [2007] “Measures for tsunami evacuation shelters in Phuket and Pang-Nga,” Proc. 12th National Convention on Civil Engineering (NCCE12), Pisanulok, Thailand, pp. 319–324. (In Thai). Tang, Z., Lindell, K. M., Prater, C. S. and Brody, S. D. [2008] “Measuring tsunami planning capacity on US Pacific coast,” Natural Hazards Rev. 9(2), 91–100. Trisler, C. J., Simmons, R. S., Yanagi, B. S., Crawford, G. L., Darienzo, M., Eisner, R. K., Petty, E. and Priest, G. R. [2005] “Planning for tsunami–resilient communities,” Natural Hazards 35, 121–139. Yazdani, N., Townsend, T. and Kilcolins, D. [2005] “Hurricane wind shelter retrofit room guidelines for existing houses,” Practice Periodical on Structural Design and Construction (ASCE) 10(4), 246–252. Yeh, H., Robertson, I. and Preuss, J. [2005] “Development of design guidelines for structures that serve as tsunami vertical evacuation sites,” Division of Geology and Earth Resources, Washington State Department of Natural Resources, U.S.A.