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Cost vs. safety: A novel design for tornado proof homes
HBRC Journal (2015) xxx, xxx–xxx
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Cost vs. safety: A novel design for tornado proof homes Komali Kantamaneni *, Ibrahim Alrashed, Micheal Phillips Faculty of Applied Design and Engineering, School of Built and Natural Environment, University of Wales Trinity Saint David, Swansea SA1 6ED, United Kingdom Received 25 September 2014; revised 7 April 2015; accepted 24 May 2015
KEYWORDS Novel design – 3D CAD model; Tornado proof home; Missile steel and shield technology; Safety; Construction costs
Abstract Tornadoes are dangerous and destructive weather phenomena. The strongest category of tornadoes on the enhanced Fujita and TORRO scales is responsible for 75% of property destruction and deaths across the globe. These issues highlight the need for new design practices aimed at producing tornado proof homes in particular 3D CAD models in tornado prone zones at current climatic scenarios. Previous studies were entirely based on traditional slants and failed to offer a reliable tornado proof home, other than small rooms and trailers, while, none of the literature concentrated on multiple factors (cost, safety and high-wind proof). Therefore, a knowledge gap exists. In order to address the current research gap, this study attempts to develop an innovative 3D CAD model for tornado resistant homes by incorporating 2 PA (Two Path Analysis). Consequently, this study provides a new design using a 3D-CAD model for a tornado resistant home as in Path One and cost and safety scenarios in Path Two. However, this new design utilizes missile steel and shield technology. Preliminary results showed that, while this new design is safer and more technically sophisticated, it involves an increase of 25–30% in construction costs. However, this increased expense is low in comparison with rebuilding costs. ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Housing and Building National Research Center. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
* Corresponding author. Tel.: +44 (0) 1792481106. E-mail address: [email protected] (K. Kantamaneni). Peer review under responsibility of Housing and Building National Research Center.
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Tornadoes cause moderate to serious infrastructure damage and fatalities. Specifically, recurrent strikes of tornadoes are high in the U.S.A. (75%) followed by Canada (5%) and Bangladesh (3%) (Fig. 1) [1–7]. On average, >1200 tornadoes occur annually at various locations in the U.S.A., and recent statistical data revealed that from 742 tornado incidents in 2013, there were 54 fatalities with damage costs of $3.6 billion [8]. While, Structural damage costs at global and regional scales are >$8 billion and >$1.5 billion respectively, which comprises 60% of annual insurance loss [9].
http://dx.doi.org/10.1016/j.hbrcj.2015.05.004 1687-4048 ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Housing and Building National Research Center. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Please cite this article in press as: K. Kantamaneni et al., Cost vs. safety: A novel design for tornado proof homes, HBRC Journal (2015), http://dx.doi.org/10.1016/ j.hbrcj.2015.05.004
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Fig. 1
Global incidences of tornadoes [12].
According to Brooks et al. [10], since the 16th century there have been more than 20,000 deaths in 3600 tornado strikes. Many tornadoes have relatively low wind speeds (<180 km/h) and are between 40 and 100 m in diameter, potentially traveling many miles before dissipating. Some extremely violent tornadoes can reach speeds of >450 km/h, and can expand to >3 km in radius while traveling approximately 100 km [10,11]. Damage caused by tornadoes raises concerns regarding design methods and practices used for the construction of residential homes. However, the building of tornado resistant homes and the development of construction materials with steel components that are utilized to design residential structures against high winds are somewhat new. Consequently, this research paper will identify the importance of tornado proof homes, as well as financial consequences of loss. From a consideration of safety issues and utilizing a novel Three-Dimensional Computer Aided Design (3D CAD) model, a design for tornado proof houses will be developed. Subsequently, the novel designs will be analyzed and evaluated against construction cost and safety scenarios by incorporating 2PA – 2 Path Analysis methodology.
Background There has been a considerable amount of research on the designs and practices of tornado resistant homes, but this research is fairly limited. Martin [13] designed tornado escape capsules (Figs. 2 and 3) for the house trailer, which comprises a strongly constructed escape capsule with a lockable entrance. Silen [14] designed a model for a tornado protection building (Fig. 4), which has top and sidewalls. This is resistant to tornado windforces because, the metal sheet covering is reinforced by upright and straight beams bonded together in a structural framework. Both are feasible from a safety perspective but not from a cost viewpoint. Gopu and Levitan [9] proposed a low-cost lightwood frame construction for tornado resistant homes, while Green [15] suggested a portable pre-fabricated tornado shelter for use in tornado prone zones. Furthermore, Weber [16], Marroquin [17], Reed [18], Hillje [19] and Zubieta [20] suggested novel designs for tornado proof building/shelters. More recently, Zhou et al. [21] proposed a tornado safety room. While all models as mentioned above had diverse success rates from both cost and safety perspectives, it highlights that current design practices are not adequate to sufficiently resist tornado wind forces (400 mph). Consequently, this study focused on
Please cite this article in press as: K. Kantamaneni et al., Cost vs. safety: A novel design for tornado proof homes, HBRC Journal (2015), http://dx.doi.org/10.1016/ j.hbrcj.2015.05.004
Design for tornado proof homes
Figs. 2–4
3
(2 and 3) Tornado escape capsule [13]. (4) Tornado protection building [14].
construction designs for tornado resistant homes capable of resisting 400 mph winds using missile shield and steel technology. The designs utilized a new 3D-CAD model and considered cost and safety consequences.
Table 1 Wind measurement on Enhanced Fujita (EF) TORRO (T) scale [25].
EF/T scale rating
Gust (mph) speed – 3 sec
Anatomy of tornado winds
Distinctive damage
EF0 (T0&T1) EF1 (T2&T3)
65–85 86–110
EF2 (T4& T5)
111–135
EF3 (T6&T7) EF4 (T8&T9)
136–165 166–200
EF5 (T10&T11)
Over 200
EF6 (T12 or Open Ended)
300 to 400 mph (Under Consideration of NOAA)
Light damage Moderate damage Significant damage Severe damage Devastating damage Incredible damage Inconvenience damage
Measurement of tornado wind speed in severe weather conditions is a challenging task because of their occurrences at remote locations and short-lived nature. However, most of the tornadoes were not recorded by meteorological station networks across the globe due to the lack of sophisticated radar system such as Doppler on Wheels (DOW) [22]. Nonetheless, the damage of tornado strikes mainly depends on gust speed. This force destroys the construction and properties within seconds. Meanwhile, violent tornadoes are usually long-lived and cause severe destruction to structures (residential and commercial) and infrastructure [23,24]. Estimation of wind speed will usually acquired from post-tornado strikes. Nevertheless, wind intensity has often been categorized either using the Enhanced Fujita scale –EF (modified from E scale to EF scale in 2007) [25] or using the T-scale (TORRO Scale –Europe only) [26] or using both classifications (Table 1). However, they were initially devised as wind speed scales, but in practice, they are established and applied as explanatory scales that differentiate several levels (EF0-EF5) of destruction to structures (Figs. 5 and 6). Furthermore, highest wind speed in tornado history is 318 mph, which was recorded on 3rd May 1999 at Oklahoma [27], and more recently, above 200 mph winds recorded at the same state in 2013 [28]. Tornado losses (insurances) in the USA Based on insurances data for tornado damage in USA for the period of 1949–2006 explored that, more than 790 strong tornadoes caused >$6 trillion losses [32]. Nevertheless, in 2011
EF/T scale
thunderstorms and tornadoes together triggered the $29 billion property damage [33]. Chronological statistics revealed that, 2013 and 2011 stand out as the most destructive years of the past 63 years period and deliver an indication that extreme damage levels have the possibility to upsurge and should social change lead to growing exposure of fortune and property. Catastrophic tornado strikes and losses are very common in Oklahoma, Texas and Kansas. Missile steel and shield technology1 The maraging steel was developed in 1959 and then induced a great attention, particularly in the aerospace, nuclear and 1
Authors contacted steel companies and missile construction engineers for the possibility of transforming maraging steel into proposed models and designs.
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Fig. 5
F0 to F5 tornadoes’ damage [29,30].
Methodology There are no rigorous and precise methodologies (collective method) for designing and estimating the tornado proof homes within technical, fiscal and safety perspectives, while, most of the academic literature constructed on technical drawings [16,47,17–19,48,20,21]. Accordingly, a coherent and concise framework has been developed to design and assess tornado resistant homes and its costs by incorporating missile shield technology through – 2 Path Analysis (Fig. 11). This new methodology was constructed in two important paths: Fig. 6 F5 and EF5 tornados in the USA for the period of 1990–2013 [31].
military world because of its enormous mechanical properties. Maraging steel made up of high-nickel, extra-low-carbon, iron-base alloys held an inordinate promise of offering an amazing combination of structural strength and fracture robustness, while, these steels have high mechanical strength (1700–4000 MPa) and toughness, which means they can resist high winds and temperatures [34,35]. However, 0.0130 MPa are capable enough to resist the >400 mph winds [50,51,34]. Currently, some missiles are manufacturing alloys of one or two metals and composite materials [36–40]. Moreover, missile shield technology is a distinctive technology used in the formation of the body of the missile (Fig. 7). The steel is modified into a curved, arched, or sheet-like structure, based on the required properties and role of the missile; the steel is heated and then appropriately modified. Once formulated, it is then used to make the missile’s outer casing [41–43]. This technology offers good results and high success rates and consequently, missile steel has been used for the construction of tornado proof homes. While, many modern houses are also constructed of steel and often have innovative designs (Figs. 8 and 9), TATA Steel that is one of the world’s top 10 steel manufacturers offers many diverse steel structures and roofs (Fig. 10).
Path One (P1): The practical applicability of providing new 3D-CAD designs for tornado-proof homes; Path Two (P2): An initial estimate of construction costs and safety issues. Consequently, this methodology utilizes 17th version of Archi-CAD software to design an innovative tornado resistant home and subsequently assesses construction costs and safety issues based on collected data. Structural analysis of 3D-CAD design This newly designed house consists of four vital structures (Fig. 12a and b) as follows: 1. A vertical reinforced concrete pillar is located in the middle of the house. It penetrates through the roof and extends 25% higher than roof height. 2. Secondly, a maraging steel sheet, is folded and located inside the pillar. 3. Thirdly, an electric engine which is fixed inside the bottom of the pillar is used for propelling the steel sheet prior to a tornado strike. 4. Fourthly, a tornado alarm is fixed to the pillar and located outside the roof.
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Design for tornado proof homes
Figs. 7–10 [44–46].
5
(7) Missile body. (8) Steel home. (9) Inside the steel home. (10) TATA steel roof design for homes and commercial buildings
Moreover, there is another special structure in this model that is an iron frame base, which stabilizes the maraging steel roof during a tornado strike.
Results and discussion
Evaluation of construction costs and safety scenarios
Confronts in designing tornado proof homes
The second phase of the methodology evaluates the cost of the missile steel roof. It also assesses how safe and technically feasible this model is compared with other designs.
Path One (P1)
The design of the various components, materials and connections in a missile steel and shield construction to resist the anticipated level of wind loads is feasible. However, there are
Data Tornado data were obtained from National Atmospheric Administration (NOAA), Storm Prediction Center (SPC) and TORRO databases. Besides, recent information regarding tornado proof homes and economic costs was obtained from the academic literature (Journals, Books, Conference papers), while, data relating to maraging steel and its costs were obtained from metal and steel companies as well as NASA website. In addition, global housing and construction statistics were obtained from legitimate construction databases across the world, such as U.S. Census Bureau, Office for National Statistics (ONS)-UK, and National Buildings Construction Corporation (NBCC)-India. Subsequently, these data were analyzed for factual results.
Fig. 11
Methodology – 2 Path Analysis.
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Fig. 12
3D CAD model – straight elevation of tornado proof home. (b) Cross section with missile steel and shield technology.
Fig. 15
Fig. 13
Plan of tornado resistant home.
Fig. 16 Fig. 14
Plan view of tornado resistant home.
Normal view of home, showing steel pillar.
3D-CAD model with steel cover with bottom frame.
some realistic confronts to developing these building models to be tornado resistant. In a tornado strike, the constructions are wedged by powerful winds (250 m/h); therefore, protecting the home from these winds without casualties is a huge challenge. If resistance home to wind impact has to be attained, subsequently the construction cost would rise substantially – in surplus of 25–30%, so raising the question regarding the cost of this extra investment. However, the current model is not an
exemption for those extra costs, but could be accepted by homeowners due to its special characteristics. Description of new invention Analysis of the deadliest and costliest tornadoes across the globe showed current strategies needed to be significantly improved by developing innovative tornado-proof homes. They are needed to protect people and property from severe tornadoes and accordingly, the proposed model would meet
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Design for tornado proof homes
Fig. 17
7
House designs across the world (Asia, Europe, US and Canada) with different square foot (SF).
such objectives. Previous models failed to offer a reliable tornado proof home, other than small rooms and trailers. However, this innovative approach addresses all previous design disadvantages. Structural (technical) portrayals All figures (Figs. 13–16) showing the new design for the tornado resistant home were developed with 3D-CAD and Archi-CAD software. Mechanism As tornado alarms give (Fig. 12a) a warning approximately thirteen minutes before tornado strikes, there is time for the maraging steel sheet to be propelled to the top of the pillar by an electric engine fixed at the base. Subsequently, it opens like an umbrella, which covers the house on three sides, leaving one side open for access (Figs. 14 and 15), and its direction will depend on the country concerned. Strong winds generally approach from three directions with weak winds from the fourth and therefore, the new design covers three sides only. After the tornado event, the steel cover folds automatically, and the electric engine will then return close into the reinforced concrete pillar and the top. Electric engine (Fig. 12b) is a small and powerful device, and it is capable enough to impel any size of maraging steel sheet during tornado strike. Due to its super design, it is also very apt to pull back the maraging steel cover as in the form of folded manner after tornado event. Path Two (P2) Costs ($) The newly proposed tornado resistant house will cost more than previous models because of the use of maraging steel.
Table 2
Tornado proof home – components and costs ($).
Components
Costs ($) – based on location and size
Maraging steel Concrete reinforced pillar Engine Tornado alarm Iron frame Labor costs
$15,000–$55,000 $1800–$10,000 $1000–$5000 $100–$300 $2000–$8,000 $ 200–$2000
Total costs
$20,100–$80,300
Note: These are the extra costs for tornado proof homes along with normal construction costs.
Based on various maraging steel company data and quoted prices, costs are between $4000 and $10,000 per ton. The process of transformation from crude maraging steel to the highest quality steel roof is a complicated and costly process. However, it depends on various factors such as the area of the house, its location (e.g. Asia, America and Europe) (Fig. 17) and construction costs. Homes in many countries, e.g. US, Canada, UK, Bangladesh and India (Applicable to individual houses, bungalows and single story commercial buildings and not applicable to Chain houses, Flats, multistory commercial buildings and hurts) have a floor area of between 600 and 3000 SF, and accordingly construction costs for these houses range between $90,000 and $300,000, while, the proposed tornado resistant home incurs 25–30% higher construction costs (along with normal construction costs) (Table 2), with maraging steel being the most significant component. However, in the long-term it is suggested that these increased costs would be returned as it will save on rebuilding costs and importantly reduce the loss of life.
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Fig. 18
Illustration of probable tornado wind and windborne debris damage to residential properties [49].
Table 3 Comparison of structural safety of the proposed design and existing models. Existing models
Protection
1. Tornado escape capsules
Did not offer the protection for whole home Not resistant to >400 mph winds
2. Low-cost light-wood frame construction model
3. Portable pre-fabricated tornado shelter 4. Underground structure
Fig. 19
3D-CAD model house during tornado strike.
Failed to offer protection for whole home Did not offer the protection for whole homes that are constructed on the land
Newly proposed design
Newly proposed design protects the whole building through its specially designed unique mechanism and components (margining steel) from air pressure and flying debris caused by tornado-force winds (>400 mph)
Maraging Steel comprises high strength and can withstand in >400 mph wind environment
Note: Explanation and reference of existing models are provided in the Background Section.
Safety As previously explained, from a safety perspective this proposed design is significantly safer than other models because of the maraging steel. Maraging steel has higher tensile strength, resistance and durability. Its use enables the building to withstand very severe atmospheric conditions and it will be capable of resisting unexpected changes in wind speed (>400 mph) and temperature, even under extreme circumstances. Material properties have made maraging steel a vital component of many missiles in use today, and based on this rationale, research has demonstrated its potential to produce a safe and resilient house. Novel 3D CAD model: feasibility and rationalization Four types of innovative structures and construction materials are introduced in the newly proposed 3D-CAD model, while, this model is significantly better model than existed models, based on flowing claims.
Claim 1 Maraging steel envelope offers an ultimate protection from >400 winds as well as heavy flying objects (Figs. 18 and 19) for the whole home which were not provided by existing models (Table 3) due it its unique design and materials. Claim 2 Maraging steel envelope also protects the human life from severe winds and flying objects, which also did not provide by previous designs, while there is no need to move to tornado shelters. Claim 3 This model saves the repeated re-construction costs.
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Design for tornado proof homes Claim 4 The mechanism (described in section 3) used in this design to propel Maraging steel from the base, is completely innovative, fiscally effective and simple process. Based on aforementioned issues, this research is concluding that, this model is more reliable, practicable, relatively safer and cost-effective than previous designs though it has high construction costs. (High construction costs are comparatively lower than repeated re-building costs). Conclusion This work described a novel 3D-CAD model incorporating missile steel and shield technology for tornado proof homes. It identified safety aspects for the construction and used Archi-3D-CAD software in the development of drawings. The newly designed model shows substantial advantages over most of the conventional resistant home designs or safe rooms via a vulnerability research study. Consequently, in this new design, a reinforced concrete pillar is located in the middle of the home, which extends a further 25% of its length above the roof. This supports a tornado alarm, while a maraging steel sheet folded within the pillar. Based on current advanced warnings of tornadoes, generally thirteen minutes before a tornado strike, alarms are sounded, and the steel sheet is released from the pillar, protecting three sides of the structure, while allowing access and egress. Following the event, the maraging steel sheet is returned into the pillar, and the top closed. The newly designed model shows substantial advantages over most of the conventional resistant home designs or safe rooms via a vulnerability research study. Therefore, this new 3D-CAD model provides a safer and more responsive construction than previous models. However, while tornado proof buildings/homes with missile shield technology are feasible construction costs are 25–30% higher than for standard construction. Therefore, a house can become a home for many years to come, even when in the midst of tornadoes. Conflict of interest The authors declare that they have no conflict of interest. Acknowledgments This study is supported by 111 Project ‘‘Hazard and Risk Science Base at Beijing Normal University’’ under Grant B08008, Ministry of Education and State Administration of Foreign Experts Affairs, People’s Republic of China. Authors are also immensely grateful to two anonymous reviewers for their useful comments that are helped to improve the quality of the manuscript. References [1] R. Peterson. Tornadoes of the former Soviet Union, in: Preprints, 20th Conf. on Severe Local Storms, Orlando, FL, Amer. Meteor. Soc, vol. 138141, 2000. [2] D. McCarthy, J. Schaefer. Tornado trends over the past thirty years, in: Preprints, 14th Conf. Applied Meteorology, Seattle, WA, Amer. Meteor. Soc, vol. 3, 2004.
9 [3] S.M. Verbout, H.E. Brooks, L.M. Leslie, D.M. Schultz, Evolution of the US tornado database: 1954–2003, Weather Forecast. 21 (2006) 86–93. [4] M. Clark, The’Super Tuesday’Tornado Outbreak of 5–6 February 2008 over the Southern US, Int. J. Meteor. 33 (2008) 127. [5] S.J. Hall, Editor’s report: storm chasing holiday 10–30th may 2011 (Part 1) the Joplin Tornado, Missouri 22 may 2011: a report from a storm Chaser’s perspective, Int. J. Meteoord. 36 (2011) 161. [6] S. Banik, H. Hong, G.A. Kopp, Assessment of the wind hazard due to tornado outbreaks in southern Ontario, J. Wind. Eng. Ind. Aerod. 107 (2012) 28–35. [7] NOAA. Monthly and Annual U.S. Tornado Summaries, 2014. (accessed 06.08.14) [8] NOAA. Tornadoes – Annual, 2013. [accessed 10.05.14]. [9] V. Gopu, M. Levitan, Best design practices for wood frame construction in tornado prone areas, World 15 (2012) 19. [10] H. Brooks, C.A. Doswell, Some aspects of the international climatology of tornadoes by damage classification, Atmos. Res. 56 (2001) 191–201. [11] T.P. Grazulis, J.T. Schaefer, R.F. Abbey. Advances in tornado climatology, hazards, and risk assessment since tornado symposium II, The tornado: Its structure, dynamics, prediction, and hazards, 1993, pp. 409–426. [12] C. Dolce, Tornado Strikes in the World, 2014. www. weather.com/news-tornado-around the world (accessed 02.06.14). [13] F.A. Martin. Tornado escape capsule for trailer homes. Google Patents, 1999. [14] A. Silen. Tornado protection building. Google Patents, 1978. [15] T.H. Green, Prefabricated portable tornado shelter, Google Patents, 2000. [16] R.C. Weber, Underground structure for residential and business use, Google Patents, 1982. [17] C. Marroquin. Tornado resistant house. Google Patents, 2008. [18] R.S. Reed. Tornado resistant dome house. Google Patents, 2010. [19] J. Hillje, Tornado storm shelter, Google Patents, 2012. [20] S.D. Zubieta, Hurricane and tornado resistant structure, Google Patents, 2013. [21] H. Zhou, K. Dhiradhamvit, T.L. Attard, Tornado-borne debris impact performance of an innovative storm safe room system protected by a carbon fiber reinforced hybrid polymeric-matrix composite, Eng. Struct. 59 (2014) 308–319. [22] J. Wurman, P. Robinson, C. Alexander, Y. Richardson, Lowlevel winds in tornadoes and potential catastrophic tornado impacts in urban areas, Bull. Am. Meteor. Soc. 88 (2007) 31–46. [23] J.H. Golden, J.T. Snow, Mitigation against extreme windstorms, Rev. Geophys. 29 (1991) 477–504. [24] J. Wurman, D. Dowell, Y. Richardson, P. Markowski, E. Rasmussen, D. Burgess, L. Wicker, H.B. Bluestein, The second verification of the origins of rotation in tornadoes experiment: VORTEX2, Bull. Am. Meteor. Soc. 93 (2012) 1147–1170. [25] C.A. Doswell, H.E. Brooks, N. Dotzek, On the implementation of the enhanced Fujita scale in the USA, Atmos. Res. 93 (2009) 554–563. [26] G. Meaden, Tornadoes in Britain: their intensities and distribution in space and time, J. Meteor. 1 (1976) 242–251. [27] D.W. Burgess, M.A. Magsig, J. Wurman, D.C. Dowell, Y. Richardson, Radar observations of the 3 May 1999 Oklahoma City tornado, Weather Forecast. 17 (2002) 456–471. [28] National Weather Service – Weather Forecast Office. Event Summary – May 19–20, 2013 Tornado Events, 2014. (accessed 23.06.14).
Please cite this article in press as: K. Kantamaneni et al., Cost vs. safety: A novel design for tornado proof homes, HBRC Journal (2015), http://dx.doi.org/10.1016/ j.hbrcj.2015.05.004
10 [29] National Weather Service – Weather Forecast Office. Tornado Strength in Florida, 2009. (accessed 12.09.13). [30] FEMA. Damaged Property in Greensburg, Kansa, 2007. (accessed 20 August 2013). [31] SPC – Storm Prediction Center. F5 and EF5 Tornadoes in the US, 2014. (accessed 12.06.14). [32] S.A. Changnon, Tornado losses in the United States, Natural Hazards Review 10 (2009) 145–150. [33] K.M. Simmons, D. Sutter, R. Pielke, Normalized tornado damage in the United States: 1950–2011, Environ. Hazard. 12 (2013) 132–147. [34] A.M. Hall, C. Slunder, The metallurgy, behavior, and application of the 18-percent nickel maraging steels, DTIC Document (1968). [35] M. Ahmed, K. Hasnain, I. Nasim, H. Ayub, Magnetic properties of maraging steels in relation to nickel concentration, Metall. Mater. Trans. A 26 (1995) 1869–1876. [36] W.S. Chang, Impact of solid missiles on concrete barriers, J. Struct. Div. 107 (1981) 257–271. [37] D. Griffin, C.A. Field, Airborne missile launcher of modular construction, Google Patents, 1987. [38] A. Shakesheff, G. Purdue, Designing metal matrix composites to meet their target: particulate reinforced aluminium alloys for missile applications, Mater. Sci. Technol. 14 (1998) 851–856. [39] A.S. Smith, G.C. Hurst, J.L. Duerk, P.J. Diaz, MR of ballistic materials: imaging artifacts and potential hazards, Am. J. Neuroradiol. 12 (1991) 567–572. [40] P. Mangalgiri, Composite materials for aerospace applications, Bull. Mater. Sci. 22 (1999) 657–664. [41] J.A. Fant, B.E. Chitwood, M.S. Howeth, Composite structural beams and method, Google Patents, 1976.
K. Kantamaneni et al. [42] T.L. Attard, High strength and high elasticity composite materials and methods of reinforcing substrates with the same, Google Patents, 2011. [43] T.L. Attard, H. Zhou, Impact resistance of tornado shelters using a load bearing composite having a multi-phase hybrid polymeric interfacial cohesion mechanism, in: Proc ASCE Engineering Mechanics Institute Conf, Evaston, IL, 2013. [44] Roberts A. Cortese. How Products are Made, 2006. (accessed 15.04.13). [45] Jantzen Michael. Steel House: Modular, Prefab, Off-the-Grid Green Design, 2014. (accessed 25.04.14). [46] TATA Steel. Roofs, 2014. (accessed 12.03.14). [47] J.E. Minor, Windborne debris and the building envelope, J. Wind Eng. Ind. Aerod. 53 (1994) 207–227. [48] M. Grayson, W. Pang, S. Schiff, Three-dimensional probabilistic wind-borne debris trajectory model for building envelope impact risk assessment, J. Wind. Eng. Ind. Aerod. 102 (2012) 22–35. [49] Y. Tamura, Wind induced damage to buildings and disaster risk reduction, in: Proceedings of the APCWE-VII, Taipei, Taiwan, 2009. [50] A.C. Rodrigues, H.H. Bernardi, J. Otubo, Microstructural analysis of co-free maraging steel aged, J. Aerospace Technol. Man. 6 (2014) 389–394. [51] A.T. Ferris, Force instrumentation for cryogenic wind tunnels using one-piece strain-gage balances, National Aeronautics and Space Administration Report. 1980, p. 1.
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FULL LENGTH ARTICLE
Cost vs. safety: A novel design for tornado proof homes Komali Kantamaneni *, Ibrahim Alrashed, Micheal Phillips Faculty of Applied Design and Engineering, School of Built and Natural Environment, University of Wales Trinity Saint David, Swansea SA1 6ED, United Kingdom Received 25 September 2014; revised 7 April 2015; accepted 24 May 2015
KEYWORDS Novel design – 3D CAD model; Tornado proof home; Missile steel and shield technology; Safety; Construction costs
Abstract Tornadoes are dangerous and destructive weather phenomena. The strongest category of tornadoes on the enhanced Fujita and TORRO scales is responsible for 75% of property destruction and deaths across the globe. These issues highlight the need for new design practices aimed at producing tornado proof homes in particular 3D CAD models in tornado prone zones at current climatic scenarios. Previous studies were entirely based on traditional slants and failed to offer a reliable tornado proof home, other than small rooms and trailers, while, none of the literature concentrated on multiple factors (cost, safety and high-wind proof). Therefore, a knowledge gap exists. In order to address the current research gap, this study attempts to develop an innovative 3D CAD model for tornado resistant homes by incorporating 2 PA (Two Path Analysis). Consequently, this study provides a new design using a 3D-CAD model for a tornado resistant home as in Path One and cost and safety scenarios in Path Two. However, this new design utilizes missile steel and shield technology. Preliminary results showed that, while this new design is safer and more technically sophisticated, it involves an increase of 25–30% in construction costs. However, this increased expense is low in comparison with rebuilding costs. ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Housing and Building National Research Center. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
* Corresponding author. Tel.: +44 (0) 1792481106. E-mail address: [email protected] (K. Kantamaneni). Peer review under responsibility of Housing and Building National Research Center.
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Tornadoes cause moderate to serious infrastructure damage and fatalities. Specifically, recurrent strikes of tornadoes are high in the U.S.A. (75%) followed by Canada (5%) and Bangladesh (3%) (Fig. 1) [1–7]. On average, >1200 tornadoes occur annually at various locations in the U.S.A., and recent statistical data revealed that from 742 tornado incidents in 2013, there were 54 fatalities with damage costs of $3.6 billion [8]. While, Structural damage costs at global and regional scales are >$8 billion and >$1.5 billion respectively, which comprises 60% of annual insurance loss [9].
http://dx.doi.org/10.1016/j.hbrcj.2015.05.004 1687-4048 ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Housing and Building National Research Center. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Please cite this article in press as: K. Kantamaneni et al., Cost vs. safety: A novel design for tornado proof homes, HBRC Journal (2015), http://dx.doi.org/10.1016/ j.hbrcj.2015.05.004
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Fig. 1
Global incidences of tornadoes [12].
According to Brooks et al. [10], since the 16th century there have been more than 20,000 deaths in 3600 tornado strikes. Many tornadoes have relatively low wind speeds (<180 km/h) and are between 40 and 100 m in diameter, potentially traveling many miles before dissipating. Some extremely violent tornadoes can reach speeds of >450 km/h, and can expand to >3 km in radius while traveling approximately 100 km [10,11]. Damage caused by tornadoes raises concerns regarding design methods and practices used for the construction of residential homes. However, the building of tornado resistant homes and the development of construction materials with steel components that are utilized to design residential structures against high winds are somewhat new. Consequently, this research paper will identify the importance of tornado proof homes, as well as financial consequences of loss. From a consideration of safety issues and utilizing a novel Three-Dimensional Computer Aided Design (3D CAD) model, a design for tornado proof houses will be developed. Subsequently, the novel designs will be analyzed and evaluated against construction cost and safety scenarios by incorporating 2PA – 2 Path Analysis methodology.
Background There has been a considerable amount of research on the designs and practices of tornado resistant homes, but this research is fairly limited. Martin [13] designed tornado escape capsules (Figs. 2 and 3) for the house trailer, which comprises a strongly constructed escape capsule with a lockable entrance. Silen [14] designed a model for a tornado protection building (Fig. 4), which has top and sidewalls. This is resistant to tornado windforces because, the metal sheet covering is reinforced by upright and straight beams bonded together in a structural framework. Both are feasible from a safety perspective but not from a cost viewpoint. Gopu and Levitan [9] proposed a low-cost lightwood frame construction for tornado resistant homes, while Green [15] suggested a portable pre-fabricated tornado shelter for use in tornado prone zones. Furthermore, Weber [16], Marroquin [17], Reed [18], Hillje [19] and Zubieta [20] suggested novel designs for tornado proof building/shelters. More recently, Zhou et al. [21] proposed a tornado safety room. While all models as mentioned above had diverse success rates from both cost and safety perspectives, it highlights that current design practices are not adequate to sufficiently resist tornado wind forces (400 mph). Consequently, this study focused on
Please cite this article in press as: K. Kantamaneni et al., Cost vs. safety: A novel design for tornado proof homes, HBRC Journal (2015), http://dx.doi.org/10.1016/ j.hbrcj.2015.05.004
Design for tornado proof homes
Figs. 2–4
3
(2 and 3) Tornado escape capsule [13]. (4) Tornado protection building [14].
construction designs for tornado resistant homes capable of resisting 400 mph winds using missile shield and steel technology. The designs utilized a new 3D-CAD model and considered cost and safety consequences.
Table 1 Wind measurement on Enhanced Fujita (EF) TORRO (T) scale [25].
EF/T scale rating
Gust (mph) speed – 3 sec
Anatomy of tornado winds
Distinctive damage
EF0 (T0&T1) EF1 (T2&T3)
65–85 86–110
EF2 (T4& T5)
111–135
EF3 (T6&T7) EF4 (T8&T9)
136–165 166–200
EF5 (T10&T11)
Over 200
EF6 (T12 or Open Ended)
300 to 400 mph (Under Consideration of NOAA)
Light damage Moderate damage Significant damage Severe damage Devastating damage Incredible damage Inconvenience damage
Measurement of tornado wind speed in severe weather conditions is a challenging task because of their occurrences at remote locations and short-lived nature. However, most of the tornadoes were not recorded by meteorological station networks across the globe due to the lack of sophisticated radar system such as Doppler on Wheels (DOW) [22]. Nonetheless, the damage of tornado strikes mainly depends on gust speed. This force destroys the construction and properties within seconds. Meanwhile, violent tornadoes are usually long-lived and cause severe destruction to structures (residential and commercial) and infrastructure [23,24]. Estimation of wind speed will usually acquired from post-tornado strikes. Nevertheless, wind intensity has often been categorized either using the Enhanced Fujita scale –EF (modified from E scale to EF scale in 2007) [25] or using the T-scale (TORRO Scale –Europe only) [26] or using both classifications (Table 1). However, they were initially devised as wind speed scales, but in practice, they are established and applied as explanatory scales that differentiate several levels (EF0-EF5) of destruction to structures (Figs. 5 and 6). Furthermore, highest wind speed in tornado history is 318 mph, which was recorded on 3rd May 1999 at Oklahoma [27], and more recently, above 200 mph winds recorded at the same state in 2013 [28]. Tornado losses (insurances) in the USA Based on insurances data for tornado damage in USA for the period of 1949–2006 explored that, more than 790 strong tornadoes caused >$6 trillion losses [32]. Nevertheless, in 2011
EF/T scale
thunderstorms and tornadoes together triggered the $29 billion property damage [33]. Chronological statistics revealed that, 2013 and 2011 stand out as the most destructive years of the past 63 years period and deliver an indication that extreme damage levels have the possibility to upsurge and should social change lead to growing exposure of fortune and property. Catastrophic tornado strikes and losses are very common in Oklahoma, Texas and Kansas. Missile steel and shield technology1 The maraging steel was developed in 1959 and then induced a great attention, particularly in the aerospace, nuclear and 1
Authors contacted steel companies and missile construction engineers for the possibility of transforming maraging steel into proposed models and designs.
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Fig. 5
F0 to F5 tornadoes’ damage [29,30].
Methodology There are no rigorous and precise methodologies (collective method) for designing and estimating the tornado proof homes within technical, fiscal and safety perspectives, while, most of the academic literature constructed on technical drawings [16,47,17–19,48,20,21]. Accordingly, a coherent and concise framework has been developed to design and assess tornado resistant homes and its costs by incorporating missile shield technology through – 2 Path Analysis (Fig. 11). This new methodology was constructed in two important paths: Fig. 6 F5 and EF5 tornados in the USA for the period of 1990–2013 [31].
military world because of its enormous mechanical properties. Maraging steel made up of high-nickel, extra-low-carbon, iron-base alloys held an inordinate promise of offering an amazing combination of structural strength and fracture robustness, while, these steels have high mechanical strength (1700–4000 MPa) and toughness, which means they can resist high winds and temperatures [34,35]. However, 0.0130 MPa are capable enough to resist the >400 mph winds [50,51,34]. Currently, some missiles are manufacturing alloys of one or two metals and composite materials [36–40]. Moreover, missile shield technology is a distinctive technology used in the formation of the body of the missile (Fig. 7). The steel is modified into a curved, arched, or sheet-like structure, based on the required properties and role of the missile; the steel is heated and then appropriately modified. Once formulated, it is then used to make the missile’s outer casing [41–43]. This technology offers good results and high success rates and consequently, missile steel has been used for the construction of tornado proof homes. While, many modern houses are also constructed of steel and often have innovative designs (Figs. 8 and 9), TATA Steel that is one of the world’s top 10 steel manufacturers offers many diverse steel structures and roofs (Fig. 10).
Path One (P1): The practical applicability of providing new 3D-CAD designs for tornado-proof homes; Path Two (P2): An initial estimate of construction costs and safety issues. Consequently, this methodology utilizes 17th version of Archi-CAD software to design an innovative tornado resistant home and subsequently assesses construction costs and safety issues based on collected data. Structural analysis of 3D-CAD design This newly designed house consists of four vital structures (Fig. 12a and b) as follows: 1. A vertical reinforced concrete pillar is located in the middle of the house. It penetrates through the roof and extends 25% higher than roof height. 2. Secondly, a maraging steel sheet, is folded and located inside the pillar. 3. Thirdly, an electric engine which is fixed inside the bottom of the pillar is used for propelling the steel sheet prior to a tornado strike. 4. Fourthly, a tornado alarm is fixed to the pillar and located outside the roof.
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Design for tornado proof homes
Figs. 7–10 [44–46].
5
(7) Missile body. (8) Steel home. (9) Inside the steel home. (10) TATA steel roof design for homes and commercial buildings
Moreover, there is another special structure in this model that is an iron frame base, which stabilizes the maraging steel roof during a tornado strike.
Results and discussion
Evaluation of construction costs and safety scenarios
Confronts in designing tornado proof homes
The second phase of the methodology evaluates the cost of the missile steel roof. It also assesses how safe and technically feasible this model is compared with other designs.
Path One (P1)
The design of the various components, materials and connections in a missile steel and shield construction to resist the anticipated level of wind loads is feasible. However, there are
Data Tornado data were obtained from National Atmospheric Administration (NOAA), Storm Prediction Center (SPC) and TORRO databases. Besides, recent information regarding tornado proof homes and economic costs was obtained from the academic literature (Journals, Books, Conference papers), while, data relating to maraging steel and its costs were obtained from metal and steel companies as well as NASA website. In addition, global housing and construction statistics were obtained from legitimate construction databases across the world, such as U.S. Census Bureau, Office for National Statistics (ONS)-UK, and National Buildings Construction Corporation (NBCC)-India. Subsequently, these data were analyzed for factual results.
Fig. 11
Methodology – 2 Path Analysis.
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Fig. 12
3D CAD model – straight elevation of tornado proof home. (b) Cross section with missile steel and shield technology.
Fig. 15
Fig. 13
Plan of tornado resistant home.
Fig. 16 Fig. 14
Plan view of tornado resistant home.
Normal view of home, showing steel pillar.
3D-CAD model with steel cover with bottom frame.
some realistic confronts to developing these building models to be tornado resistant. In a tornado strike, the constructions are wedged by powerful winds (250 m/h); therefore, protecting the home from these winds without casualties is a huge challenge. If resistance home to wind impact has to be attained, subsequently the construction cost would rise substantially – in surplus of 25–30%, so raising the question regarding the cost of this extra investment. However, the current model is not an
exemption for those extra costs, but could be accepted by homeowners due to its special characteristics. Description of new invention Analysis of the deadliest and costliest tornadoes across the globe showed current strategies needed to be significantly improved by developing innovative tornado-proof homes. They are needed to protect people and property from severe tornadoes and accordingly, the proposed model would meet
Please cite this article in press as: K. Kantamaneni et al., Cost vs. safety: A novel design for tornado proof homes, HBRC Journal (2015), http://dx.doi.org/10.1016/ j.hbrcj.2015.05.004
Design for tornado proof homes
Fig. 17
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House designs across the world (Asia, Europe, US and Canada) with different square foot (SF).
such objectives. Previous models failed to offer a reliable tornado proof home, other than small rooms and trailers. However, this innovative approach addresses all previous design disadvantages. Structural (technical) portrayals All figures (Figs. 13–16) showing the new design for the tornado resistant home were developed with 3D-CAD and Archi-CAD software. Mechanism As tornado alarms give (Fig. 12a) a warning approximately thirteen minutes before tornado strikes, there is time for the maraging steel sheet to be propelled to the top of the pillar by an electric engine fixed at the base. Subsequently, it opens like an umbrella, which covers the house on three sides, leaving one side open for access (Figs. 14 and 15), and its direction will depend on the country concerned. Strong winds generally approach from three directions with weak winds from the fourth and therefore, the new design covers three sides only. After the tornado event, the steel cover folds automatically, and the electric engine will then return close into the reinforced concrete pillar and the top. Electric engine (Fig. 12b) is a small and powerful device, and it is capable enough to impel any size of maraging steel sheet during tornado strike. Due to its super design, it is also very apt to pull back the maraging steel cover as in the form of folded manner after tornado event. Path Two (P2) Costs ($) The newly proposed tornado resistant house will cost more than previous models because of the use of maraging steel.
Table 2
Tornado proof home – components and costs ($).
Components
Costs ($) – based on location and size
Maraging steel Concrete reinforced pillar Engine Tornado alarm Iron frame Labor costs
$15,000–$55,000 $1800–$10,000 $1000–$5000 $100–$300 $2000–$8,000 $ 200–$2000
Total costs
$20,100–$80,300
Note: These are the extra costs for tornado proof homes along with normal construction costs.
Based on various maraging steel company data and quoted prices, costs are between $4000 and $10,000 per ton. The process of transformation from crude maraging steel to the highest quality steel roof is a complicated and costly process. However, it depends on various factors such as the area of the house, its location (e.g. Asia, America and Europe) (Fig. 17) and construction costs. Homes in many countries, e.g. US, Canada, UK, Bangladesh and India (Applicable to individual houses, bungalows and single story commercial buildings and not applicable to Chain houses, Flats, multistory commercial buildings and hurts) have a floor area of between 600 and 3000 SF, and accordingly construction costs for these houses range between $90,000 and $300,000, while, the proposed tornado resistant home incurs 25–30% higher construction costs (along with normal construction costs) (Table 2), with maraging steel being the most significant component. However, in the long-term it is suggested that these increased costs would be returned as it will save on rebuilding costs and importantly reduce the loss of life.
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Fig. 18
Illustration of probable tornado wind and windborne debris damage to residential properties [49].
Table 3 Comparison of structural safety of the proposed design and existing models. Existing models
Protection
1. Tornado escape capsules
Did not offer the protection for whole home Not resistant to >400 mph winds
2. Low-cost light-wood frame construction model
3. Portable pre-fabricated tornado shelter 4. Underground structure
Fig. 19
3D-CAD model house during tornado strike.
Failed to offer protection for whole home Did not offer the protection for whole homes that are constructed on the land
Newly proposed design
Newly proposed design protects the whole building through its specially designed unique mechanism and components (margining steel) from air pressure and flying debris caused by tornado-force winds (>400 mph)
Maraging Steel comprises high strength and can withstand in >400 mph wind environment
Note: Explanation and reference of existing models are provided in the Background Section.
Safety As previously explained, from a safety perspective this proposed design is significantly safer than other models because of the maraging steel. Maraging steel has higher tensile strength, resistance and durability. Its use enables the building to withstand very severe atmospheric conditions and it will be capable of resisting unexpected changes in wind speed (>400 mph) and temperature, even under extreme circumstances. Material properties have made maraging steel a vital component of many missiles in use today, and based on this rationale, research has demonstrated its potential to produce a safe and resilient house. Novel 3D CAD model: feasibility and rationalization Four types of innovative structures and construction materials are introduced in the newly proposed 3D-CAD model, while, this model is significantly better model than existed models, based on flowing claims.
Claim 1 Maraging steel envelope offers an ultimate protection from >400 winds as well as heavy flying objects (Figs. 18 and 19) for the whole home which were not provided by existing models (Table 3) due it its unique design and materials. Claim 2 Maraging steel envelope also protects the human life from severe winds and flying objects, which also did not provide by previous designs, while there is no need to move to tornado shelters. Claim 3 This model saves the repeated re-construction costs.
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Design for tornado proof homes Claim 4 The mechanism (described in section 3) used in this design to propel Maraging steel from the base, is completely innovative, fiscally effective and simple process. Based on aforementioned issues, this research is concluding that, this model is more reliable, practicable, relatively safer and cost-effective than previous designs though it has high construction costs. (High construction costs are comparatively lower than repeated re-building costs). Conclusion This work described a novel 3D-CAD model incorporating missile steel and shield technology for tornado proof homes. It identified safety aspects for the construction and used Archi-3D-CAD software in the development of drawings. The newly designed model shows substantial advantages over most of the conventional resistant home designs or safe rooms via a vulnerability research study. Consequently, in this new design, a reinforced concrete pillar is located in the middle of the home, which extends a further 25% of its length above the roof. This supports a tornado alarm, while a maraging steel sheet folded within the pillar. Based on current advanced warnings of tornadoes, generally thirteen minutes before a tornado strike, alarms are sounded, and the steel sheet is released from the pillar, protecting three sides of the structure, while allowing access and egress. Following the event, the maraging steel sheet is returned into the pillar, and the top closed. The newly designed model shows substantial advantages over most of the conventional resistant home designs or safe rooms via a vulnerability research study. Therefore, this new 3D-CAD model provides a safer and more responsive construction than previous models. However, while tornado proof buildings/homes with missile shield technology are feasible construction costs are 25–30% higher than for standard construction. Therefore, a house can become a home for many years to come, even when in the midst of tornadoes. Conflict of interest The authors declare that they have no conflict of interest. Acknowledgments This study is supported by 111 Project ‘‘Hazard and Risk Science Base at Beijing Normal University’’ under Grant B08008, Ministry of Education and State Administration of Foreign Experts Affairs, People’s Republic of China. Authors are also immensely grateful to two anonymous reviewers for their useful comments that are helped to improve the quality of the manuscript. References [1] R. Peterson. Tornadoes of the former Soviet Union, in: Preprints, 20th Conf. on Severe Local Storms, Orlando, FL, Amer. Meteor. Soc, vol. 138141, 2000. [2] D. McCarthy, J. Schaefer. Tornado trends over the past thirty years, in: Preprints, 14th Conf. Applied Meteorology, Seattle, WA, Amer. Meteor. Soc, vol. 3, 2004.
9 [3] S.M. Verbout, H.E. Brooks, L.M. Leslie, D.M. Schultz, Evolution of the US tornado database: 1954–2003, Weather Forecast. 21 (2006) 86–93. [4] M. Clark, The’Super Tuesday’Tornado Outbreak of 5–6 February 2008 over the Southern US, Int. J. Meteor. 33 (2008) 127. [5] S.J. Hall, Editor’s report: storm chasing holiday 10–30th may 2011 (Part 1) the Joplin Tornado, Missouri 22 may 2011: a report from a storm Chaser’s perspective, Int. J. Meteoord. 36 (2011) 161. [6] S. Banik, H. Hong, G.A. Kopp, Assessment of the wind hazard due to tornado outbreaks in southern Ontario, J. Wind. Eng. Ind. Aerod. 107 (2012) 28–35. [7] NOAA. Monthly and Annual U.S. Tornado Summaries, 2014.
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10 [29] National Weather Service – Weather Forecast Office. Tornado Strength in Florida, 2009.
K. Kantamaneni et al. [42] T.L. Attard, High strength and high elasticity composite materials and methods of reinforcing substrates with the same, Google Patents, 2011. [43] T.L. Attard, H. Zhou, Impact resistance of tornado shelters using a load bearing composite having a multi-phase hybrid polymeric interfacial cohesion mechanism, in: Proc ASCE Engineering Mechanics Institute Conf, Evaston, IL, 2013. [44] Roberts A. Cortese. How Products are Made, 2006.
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