Wind-resilient Civil Structures: What Can We Learn from Natureow in biomimetics between \Nature"...

$: Wind-resilient Civil Structures: What Can We Learn from Natureow in biomimetics between \Nature" (primarily biol-ogy) and \Technology" to solve human challenges. The ow of information$
Draft

Wind-resilient Civil Structures: What Can We Learn from Nature

Journal: Botany

Manuscript ID cjb-2019-0034.R2

Manuscript Type: Article

Date Submitted by the Author: 10-Aug-2019

Complete List of Authors: Zhang, Wei; Cleveland State University, Mechanical Engineering DepartmentGruber, Petra; University of Akron, Biomimicry Research and Innovation Center

Keyword: Bio-inspiration, Wind hazard mitigation, Plants as role models, Biomimetics, Civil structures

Is the invited manuscript for consideration in a Special

Issue? :Plant Biomechanics

https://mc06.manuscriptcentral.com/botany-pubs

Botany

Draft

Botany manuscript No.(will be inserted by the editor)

Wind-resilient Civil Structures: What Can We Learnfrom Nature

Wei Zhang · Petra Gruber

August 19, 2019

Wei ZhangMechanical Engineering Department, Cleveland State University, Cleveland, OH 44115E-mail: [email protected]

Petra GruberBiomimicry Research and Innovation Center, University of Akron, Akron, OH, 44325E-mail: [email protected]

Page 1 of 29


Botany

Draft

2 Wei Zhang, Petra Gruber

Abstract Due to changing weather patterns, catastrophic natural disastersare expected to happen more frequently and cause dramatic life and economiclosses worldwide. The United States experienced a historically high recordof weather disasters in 2017, with the economic losses exceeding 300 billiondollars. A major contributor to economic loss and threat to public safety isdamage, destruction, and failure of civil structures in the strong-wind dom-inated disasters. There is a pressing need for reconstruction and redesign ofcritical civil structures to better cope with high winds to mitigate the loss oflives and properties. The paper takes a biomimetic perspective to link problemareas with potential solutions for future bio-inspired technology development,by identifying the most vulnerable aspects of civil structures in strong windson one side, and wind-resilient examples of biological systems on the other side.Of particular interest are plants that thrive in high winds, as they have likelyadapted to manage the harsh environment under pressure of natural selection.Specific biological examples include the Saguaro cactus, reed grass, and theshape reconfiguration of leaves. A review of problem areas, abstracted prin-ciples, and exemplary biological role models shall inform and guide towardsnew designs of wind-resilient civil structures.

Keywords Bio-inspiration · Biomimetics · Civil structures · Plants as rolemodels · Wind hazard mitigation

Page 2 of 29


Botany

Draft

Wind-resilient Civil Structures: What Can We Learn from Nature 3

1 Introduction

Approximately 45 billion, 27 billion, and 24 billion USD are lost every yearin the United States, China, and Japan, respectively, due to natural hazardsaccording to the Centre for Research on the Epidemiology of Disasters. Thesenatural disasters include drought, flooding, hurricanes or tropical cyclones,severe storms, wildfire, winter storms, etc. Outrageous economic and life losseshave been accumulated year by year. It is estimated that 70 – 80% of economiclosses by natural hazard is caused by strong wind hazards and related waterhazards (Tamura and Cao, 2010; Kareem and Wu, 2012; Tamura et al., 2017).Almost 80% of insured losses have been caused by windstorms alone, and morethan 90% have been caused by wind and water hazards. Unfortunately, it isanticipated that the likelihood of these extreme wind events is continuing torise in the evolving climate conditions (Dinan, 2017).

Figure 1 demonstrates the billion-dollar disaster events from 1980 to 2018of the United States in terms of weather and climate disasters. The economiclosses are dominated by extreme-wind caused damage, including tropical hur-ricane and tornado losses. Hurricanes have resulted in the most damage of$850.5 billion and the highest average event cost of $22.4 billion per event,based on the report of National Oceanic and Atmospheric AdministrationNational Climatic Data Center (2018). For example, a series of tropical hur-ricanes, Harvey, Irma, and Maria caused widespread death and destructionto Texas, Florida and Puerto Rico and the U.S. Virgin Islands in 2017. As aresult, the year of 2017 reaches the cumulative damage exceeding $300 billion,the most expensive year in terms of weather and climate disasters.

Fig. 1 Cost of the United States billion-dollar disaster events during 1980 – 2018 (source:National Oceanic and Atmospheric Administration or NOAA.)

One of the major contributors to the striking economic loss and a se-vere threat to public safety is damage, destruction and failure of human-madestructure – critical civil infrastructures – in the strong-wind dominated disas-ters (Fig. 2). What engineering innovations could save lives, which otherwisemay be lost in the future hurricanes and tornadoes? How can we strategicallydesign and build civil structures that can withstand the extreme strong hur-ricane winds as forceful as Irma/Harvey and as the tornadoes leveling citieslike Joplin, Missouri? There is a pressing need to rethink and design new andretrofitting of existing civil structures that can endure high winds and miti-gate life and economic losses in the long term. To address the demand requiresnot only to re-assess the current building codes and standards, understandwind conditions with the evolving climate, but to advance new concepts andtechnologies to renew and re-design even the most common civil structures ofwind-resilient features.

Page 3 of 29


Botany

Draft


Fig. 2 Cylindrical structures are subjected to significant wind effects and may encounterfailure in extreme-wind events. (a) and (b) Collapsed power-line posts (Hurricane Irma2017); (c) Collapsed traffic sign;(d) Damaged coastal foundations (Hurricane Katrina 2005).

Biomimetics is an emerging field to systematically transfer informationfrom biology to technological applications. Defined as an innovation methodol-ogy, the process of biomimetics involves basic research, abstraction of workingprinciples, and translation of principles into an application field, as illustratedin Fig. 3. Biomimetics typically extracts knowledge about functions, mecha-nism or concepts in biology, that are then applied to an identified problemdomain by designers or interpreted by engineers. Biomimetics is a powerfultool to establish a generic frame of reference and methodology for creatingvalid analogies between application fields and biological role models (?) andhas great potential to solve a wide range of human challenges (Gebeshuberet al., 2009; Zari, 2010). Biomimicry is used in the context of this work as asynonym, but different from biomimetics and bio-inspired designs, its method-ology also integrates tools to achieve a sustainable design outcome. For exam-ple, bio-inspired engineering designs such as the kingfisher-beak nose of theShinkansen bullet train in Japan and the whale-tubercle-blades of wind tur-bines demonstrate high-performance technical solutions, while simultaneouslyproviding environmental, social and economic benefits and resilience (Fishet al., 2008; Fish, 2009; Fish et al., 2011; Choi et al., 2012). In the case ofwind resilience of the built environment, the underlying assumption is thatimproving wind resilience of civil structures, and thus longevity, also enhancesthe sustainability of the built environment, but no further research was carriedout about this aspect.

Fig. 3 Schematics of information flow in biomimetics between “Nature” (primarily biol-ogy) and “Technology” to solve human challenges. The flow of information is bi-directional,through abstraction processes of working principles and concepts. “Biomimetics” refers toderiving new technical solutions from biological inspiration, and “Reverse Biomimetics” in-dicates the innovation process leading to novel research findings in biology (Speck and Speck,2008). In the current study, knowledge about wind-resilient examples and models from biol-ogy, specifically plants, shall inform innovation for vulnerable aspects of civil structures inhigh winds.

Biomimetics has been increasingly practiced in the context of architec-ture and construction, design and the arts in the last decade, and a biologicalparadigm seems to underlie current trends in novel designs (Gruber, 2010).Many examples for biomimetic applications are found at the scale of materialsand surfaces, such as the self-cleaning or easy-to-clean coatings for buildingmaterials. Structures and constructions informed from biology, mainly fromplant structures, are explored in prototypical experimental buildings such asthe experimental pavilions generated by the Institute for Computational De-sign (ICD) and Institute of Building Structures and Structural Design at the

Page 4 of 29


Botany

Draft


University of Stuttgart in Germany (Knippers et al., 2016). Products are beingdeveloped and integrated into architectural buildings such as the flectofin, anovel facade-shading system inspired by the opening mechanism of the flowerof the Bird-of-Paradise (Strelitzia reginae) (Knippers et al., 2016). “Livingarchitecture” and the “living building” strive for the integration of signs oflife into the design of buildings and environment, and have become visionaryconcepts for the extended search of new approaches to architectural design(Gruber, 2010; Beesley, 2019). Sensing and reactivity for example started tobe integrated in buildings with emerging computer systems, and in the mean-time have become a common capacity of buildings. Currently, many researchgroups focus specifically on growth of material structures and agency (Imhofet al., 2015; Gruber and Rupp, 2018). The realm of plants is exceptionally at-tractive and inspirational for architecture and civil structures, as plants sharecertain common aspects with buildings (Gruber, 2009; Speck et al., 2018). Sim-ilar to buildings, plants are exposed to their environment, usually without theoption of behavioral response to changing adverse conditions. The inability forlocomotion requires that plants have to cope with environmental influences onsite, so they have to withstand temperature and humidity changes, and copewith mechanical loading such as strong winds. We are particularly interestedin plants that thrive in high winds, as they have likely adapted to manage theharsh environment under the pressure of natural selection instead of escap-ing from it. Specific examples of plants of wind resilience include the Saguarocacti at Arizona desert, reed grass, and plants’ leaves that will be discussed inSection 3.

Methodologies and tools in biomimetics have been developed to facilitatethe knowledge transfer between biology and technology (Fayemi et al., 2017).Emerging translation tools and databases allow for open access analogy findingbut contain mainly published biomimetic examples. The German Engineer’sAssociation’s (VDI) Standard Beismann et al. (2012), the ISO standard onBiomimetics International Organization for Standardization (2015) and pub-lications of the Center for Biologically Inspired Design (CBID) at the Geor-gia Tech Institute provide guidelines for biomimetic and bio-inspired designprocesses (Goel et al., 2009). In this work we consider both, “top-down andbottom-up biomimetic approaches” or “problem-based and solution-based ap-proaches for bio-inspired design”. The starting point for the investigation inthis paper is a human challenge with a broad problem area that can be decom-posed into sets of vulnerability aspects. To establish new biomimetic conceptsfor wind-resilient solutions in civil and wind engineering, first new connectionsbetween specific fields of functional interests and the biology realm have to befound. The present paper identifies vulnerable aspects of the built environmentin high winds on the one hand, and demonstrates available mechanisms andconcepts for wind-resilience in biology on the other hand, for linking problemareas with potential biomimetic solutions.

Page 5 of 29


Botany

Draft


2 Damages of Civil Structures in High Winds

2.1 Wind Characteristics of Wind Storms

Civil structures are located within the 10-15% lowest portion of the atmo-spheric boundary layer (ABL) and under the effects of wind – one of the mostchallenging flows in fluid dynamics studies. The difficulty to accurately modeland predict ABL wind lies in the wide range of spatial and temporal turbulentscales that need to be resolved simultaneously, and complex characteristics ofthe underlying earth surface or terrains (Stull, 1988; Kaimal and Finnigan,1994). The turbulent boundary-layer wind and the associated momentum, en-ergy and scalar transport between the atmosphere and the earth surface havebeen extensively studied owing to its significance in a broad range of scienceand engineering fields. It has been well-established that the logarithmic profilesor power-law profiles can represent the turbulent boundary-layer wind in thesurface layer over a fairly large and homogeneous surface. However, the accu-rate description of wind over complex terrains, such as patches of non-uniformroughness and temperature, surface covered by individual or groups of plants,topography, suburban and urban areas, remains to be an active research topicin fluid dynamics, atmospheric science, civil and wind engineering. Full-scalefield observatory, numerical modeling, and laboratory tests complement eachother to continue enhancing our understanding and capability to predict theABL wind (Fernando et al., 2015).

The wind characteristics in extreme wind events, such as hurricanes, torna-does, and downbursts, are distinctly different from that of the ABL winds, asshown in Figs. 4 and 5 (Zhang and Sarkar, 2012; Rotunno, 2013; Hangan et al.,2017). An established measure of wind storm strength combines the sustainedwind speed and the damage indicator via post-disaster survey – Saffir-Simpsonscale for hurricanes and Enhanced Fujita scale for tornadoes. Tropical hurri-canes and tornadoes share features of high wind intensity, unsteadiness andstrong dependence on space and time. While the highest recorded wind speedin a tornado at Bridge Creek Oklahoma 1999 reaches 135 m/s (or 302 mph)based on the World Meteorological Organization’s world record of wind gust,the majority of extreme winds fall in the subsonic range, measured by theMach Number Ma (ratio of the air speed to that of the speed of sound in theair) less than 0.3. At the civil structure level, hurricane wind is assumed to fol-low the typical logarithmic profile in the hurricane boundary layer (Worsnopet al., 2017). However, when considering a tornado’s effects on a civil structureelement or a residential and commercial building, rich and complex dynamicaspects of tornado flows, including a high suction (low pressure) near the centerof the tornado (Hann et al., 2008; Karstens et al., 2010), single-cell, double-cellor multiple vortices as illustrated in Fig. 5 (Zhang and Sarkar, 2012; Rotunno,2013; Davies-Jones, 2015), intensified near-surface wind (Lewellen et al., 2000;Zhang and Sarkar, 2008) and ground roughness (Razavi et al., 2018), must betaken into account.

Page 6 of 29


Botany

Draft


Fig. 4 Hurricane Michael 2018 making landfall in the Florida Panhandle, one of the mostintense hurricanes on record (source: CIRA/RAMMB).

Fig. 5 Single-celled vortex in (a) and multiple vortices in (b) of near-ground tornadoessimulated at the Iowa State University Tornado simulator, after Zhang et al. (2012).

2.2 Wind Effects on a Cylindrical-shaped Structure

Cylindrical structures or cylindrical-shaped bluff bodies are commonly usedas basic civil structures, e.g., high-rise buildings, towers, offshore piles, coastalfoundations, chimney, and power line posts and cables, etc. They can be in-stalled either as an isolated element or in a group configuration. In extremewinds, cylindrical structures’ potential failure leads to catastrophic conse-quences. For example, the collapse of numerous power line posts and damageof cables in Hurricanes Harvey and Irma (Category 4 and 5) caused months ofpower outages, widespread service disruptions and delayed response to emer-gencies (Fig. 2 (c)-(d)). Building wind-resilient cylindrical structures, is pivotalto mitigate life and economic losses in extreme wind events.

The cylindrical shape, a seemingly simple geometry, generates remarkablycomplicated flow field and surface pressure (thus forces) under wind effects.Wind-induced loading upon a cylindrical element is sensitive to the specificgeometry (diameter, aspect ratio, variation along the axis) and surface rough-ness structure, along with the range of wind speed (i.e., the Reynolds numberRe) and the incident wind direction (Simui and Miyata, 2006; Demartino andRicciardelli, 2017). As wind passes by, a cylindrical element is subjected to thedrag force along the wind direction and the lateral (side) force in across-winddirection. The drag force is measured by the drag coefficient Cd, the ratio ofthe drag force to that of the dynamic pressure.

Variation of the drag coefficient as a function of the Reynolds number hasbeen long established for a standard circular-cross-sectional cylinder in a uni-form inflow (Zdravkovich, 1997; Pritchard and Mitchell, 2015). For a wide Renumber range, the vortex shedding generated by a cylinder creates a periodicforce normal to the wind direction. The cylinder also responds to this vor-tex shedding by oscillating at a frequency and amplitude (i.e., vortex-inducedvibration, VIV), leading to potential destruction. The non-dimensional pa-rameter Strouhal number St is used to characterize the VIV behavior. Suchforces can also generate moments with respect to the anchoring point, whichis critical to measure the intent to bend and even topple over.

To reduce the wind loading on a cylindrical structure under normal operat-ing and intermediate stress conditions, various passive and active flow controlstrategies have been developed to redece the drag and/or manage the VIV.Such strategies include adding O-rings and helicoidal wires and supplement-ing external momentum to the boundary-layer flow (Lim and Lee, 2004; Linet al., 2016; Morrison et al., 2016; Kim and Yoon, 2017), to alter the boundary-layer behavior and wake dynamics. Bio-inspired flow control strategies have

Page 7 of 29


Botany

Draft


emerged to be one of the new tools to address this issue (Guttag and Reis, 2017;Rinehart et al., 2017). For instance, the morphable cylinder inspired by theSaguaro cacti will be discussed in Section 3.1. A comprehensive review of theaerodynamics of a cylindrical shape with varieties of modifications is providedby Demartino and Ricciardelli (2017). However, it is unclear whether suchflow control strategies are valid to reduce wind-induced effects under extremewind events (of high Reynolds number and high turbulence), as the interactionbetween a structure and the wind is highly sensitive to the specific range ofwind speed, directions, and spacial and temporal scale of turbulence. As a re-sult, the fundamental understanding of aerodynamics of a modified cylindricalbluff body after applying flow controls in turbulent high winds encountered inwindstorms, is still lacking (Demartino and Ricciardelli, 2017).

2.3 Wind Effects on Low-rise Buildings

Non-engineered low-rise buildings, including residential, institutional, and com-mercial structures, represent the largest class of civil structures in the U.S. thatare among the most vulnerable under high winds. The minimal design windloads are standardized by the American Society of Civil Engineers (ASCE) pro-visions (Simui and Miyata, 2006). However, wind pressures on low-rise build-ings from the ASCE provisions have significant errors, for instance, higher than50% in the peak suction pressure, which may lead to vulnerable design whenexposed to wind storms (Kopp et al., 2008). Post-disaster assessments by U.S.Department of Homeland Security, Federal Emergency Management Agencyor FEMA indicate that the vulnerable aspects of buildings and structures areprimarily roof systems (roof cover, roof structure, roof deck), openings (win-dows and doors) and debris caused missile impacts on wall structure (Tokgozand Gheorghe, 2013). Damage is usually initiated in critical roof regions as-sociated with flow separation and conical vortices along the roof edges, andthen trigger a cascading failure of roof coverings, which may lead to collapseof the entire building owing to the lack of integrity of components.

Conical vortices occur as the wind approaches in a rang of oblique angleswhile flow separates as wind encounters sharp edges or eaves of a low-rise build-ing (Mooneghi and Kargarmoakhar, 2016). The highly transient, unsteady flowremains to be a challenge in experimental and numerical studies that aim toquantify the flow field and associated pressure distribution. Multiple factorsplay important and coupled roles, including the incoming wind characteristics(affected by upwind land cover and surrounding environment) and geometricdetails of roof corners and edge. To reduce high roof suction and the upliftforce, various aerodynamic mitigation devices have been tested (Kopp et al.,2005; Blessing et al., 2009; Suaris and Irwin, 2010). The existing architecturalfeature, such as the parapets and eaves, are modified to alter the flow pat-tern and pressure distribution. For example, Surry and Lin (1995) reportedthat porous parapets at the building edge effectively reduce roof suctions.The wind-tunnel studies on a low-rise gable-roof building by Suaris and Irwin

Page 8 of 29


Botany

Draft


(2010) found that perforated parapets at the roof corners and the ridge re-sulted in about 60% reduction in the peak pressure coefficients. Experimentalstudies on effects of various geometries of parapets and roof edges were alsoconducted by Kopp et al. (2005) and Blessing et al. (2009). On the other hand,dynamic mitigation devices have been researched. Chowdhury et al. (2019) ap-plied a system of lightweight small helicoidal wind turbines to the roof edge toreduce the roof suction and meanwhile generate electricity by converting thewind kinetic energy, which is promising for realization of wind-resilient andsustainable buildings. Other mitigation strategies include changing the roofslope, avoiding roof overhangs and reinforcing roof accessories and details. Itis noted that most of studies considered only an isolated low-rise building;however, with a cluster of surrounded buildings, the roof suction is substan-tially reduced (Solari, 2017). This has important implications for cost-effectivedesign. In addition, caution should be exercised if mitigation devices are to beattached to the roof edge. If the devices themselves cannot withstand strongwind and fall off, they may cause further damage as wind-born debris impact-ing on downwind structures.

3 Wind-resilient Role Models in Nature

As described in Section 1 Introduction, the methodology of biomimetics andbio-inspired design proposes problem-based and solution-based approaches,depending on the starting point of the investigation being either a technicalquestion or an interesting biological observation (Goel et al., 2009). How-ever, this distinction is not always applicable. In the case of wind resilienceof civil structures, the problem area is large, and multiple vulnerable aspectsare identified. The traits of wind adaptation in biology deliver solution spacesthat might not be directly applicable to a specific technical problem. There-fore, in Table 1, an analogy matrix was intended to provide an overview thatallows for information flow in both directions. To take a distinct biomimeticapproach for wind hazard mitigation, role models in the column of “Aspectsof resilience” can be further explored, along with the references in Table 1.Researchers and engineers can also adapt their own biomimetic methodologiesto contribute to the climatic adaptation of civil structures.

Table 1 Analogy table to identify vulnerable aspects of the built environment in high

winds, and connect to mechanisms and strategies for wind-resilience in biology, specifically

in plants, to link problem areas with potential biological solutions via working principles.

Table 1 lists aspects of vulnerability in the built environment (left col-umn), working principles (middle) and aspects of resilience in biological struc-tures (right column). Aspects of vulnerability are primarily sorted accordingto scale, starting with group effects in settlements or civil structures, to indi-vidual buildings, building elements, material and surface, and generic aspects.The biological phenomena mentioned in the table are not fully described in

Page 9 of 29


Botany

Draft


this paper. Some of the biological examples are specific, and are backed up bybasic research (Saguaro cactus, reed grass, and plant leaves, etc.). However,some of them are generic (e.g., streamlined organism shape), so that manyexamples could serve as role models for a solution-based approach. Other se-lection criteria for the role model search would be applied in a future study tocreate a more specific link, such as enclosed volume, surrounding media, scaleand flow characteristics. The framework also includes abstract principles thatlink technology and biology, which can serve as guidelines for future designproposals.

3.1 Saguaro Cacti

Large desert succulents, such as the Saguaro cactus, Camegiea gigantea (Cac-taceae), experience high wind conditions in their natural habitat (Fig. 6). Theyare native to the Sonoran Desert in Arizona, the Mexican State of Sonora, andthe Whipple Mountains and Imperial County areas of California. Saguaros canbe seen as large cylindrical structures of a complex surface geometry featuredby longitudinal cavities (or ribs) and spines as well as a hemispherical free end.The primary trunks of adult saguaros can reach 8 m to over 15 m high anddiameters of 0.3 m to over 0.8 m (Benson, 1981; Hodge, 2000). On average,ten to 30 V-shaped longitudinal cavities span the length of the trunk. Theratio of cavity depth to the diameter of the cylinder is 0.07 ± 0.0015 (Gellerand Nobel, 1984; Talley and Mungal, 2002).

Saguaro cacti are exposed to winds as they are the prominent, long-lived,tall plants at the desert habitat. High winds accompanying heavy thunder-storms during July and August sometimes reach peak gusts of about 100miles per hour in local areas. The maximum differential velocity of Sonoranmicroburst during summer 2008 has a peak frequency of 20 to 25 m/s with themedian differential velocity of 24 m/s (Willngham et al., 1998). Nevertheless,one of the most dramatic weather events resulted in widespread mortality inAugust 1982, when strong winds higher than > 27.8 m/s toppled 140 Saguarowithin a 15-ha area (Pierson and Turner, 1998).

At the high wind conditions in their natural habitat and when in danger ofbeing uprooted by wind forces, Saguaro of the diameters of 0.5 m experiencewind at the Reynolds number at the order of magnitude of 106. Despite theirshallow root systems, the majority of Saguaro cactus can withstand high windswithout being toppled over. Given that the shape and surface details of anobject substantially affects the surrounding airflow, natural selection by windover Saguaro cacti’s life span (on average between 125 and 175 years) may favorthe particular morphology (Talley and Mungal, 2002; Liu et al., 2011). Groovesin the cacti’s surface have been believed to contribute to their resilience inwind, by adding structural support and reducing aerodynamic loads.

The Saguaro cacti have inspired studies on aerodynamics, with the primaryfocus on modified wake structure and drag reduction along-wind (Talley andMungal, 2002; Liu et al., 2011). In the context of cylindrical-shaped tall build-

Page 10 of 29


Botany

Draft


Fig. 6 Saguaro cacti in the natural environment. To cope with high winds potentially fromall directions, their shape is largely an axisymmetric cylindrical bluff body. (source: FlickRPaul Frankenstein CC2.0).

ing, cross-wind behavior of the building is closely related to human comfort.Letchford et al. (2016) tested a cactus-like cylinder with 24 circumferentialgrooves at Re of (1–2) × 104 to examine its efficacy for reducing motion of tallbuildings. The wind-tunnel results indicated that drag and along-wind momentof the cactus-shaped was about 20% lower than that of the baseline smoothcylinder. Similar results were found for along-wind fluctuating responses beinglower for the cactus-like shape. However, not much difference was noticed inthe crosswind fluctuating forces and moments between a standard and cactus-shaped cylinder. This study suggests that it may not be effective to minimizestructure deflection in the cross-wind direction from VIV.

The shapes of Cacti do vary somewhat as their water content changes orwith changes in age and climate conditions, but they do not have the abilityfor fast alterations in response to wind. Nevertheless, an engineered systemcan go beyond the limits to create a versatile mechanism to better adapt towind effects. A recent study by Guttag and Reis (2017) examined aerodynam-ics of morphable grooved cylinders – a grooved cylinder of a pneumatically-controlled cavity ratio. The morphable cylinders drag was consistently lowerthan fixed samples at Re up to 106.

While research work by Letchford et al. (2016) suggested minor effects onthe side-force and moments by the cacti-shaped model, it remains to deter-mine if Saguaro have mechanisms to suppress vortex shedding coming intoresonance with the natural bending frequencies or not at the relevant windspeeds. Therefore, the behavior of a Saguaro cactus in high wind conditionsduring July and August needs to be observed in the natural habitat to answerthis question. If such data are taken, one can also examine how structuraldeformation and motion of a Saguaro in the wind would affect wind-inducedforces. It is also beneficial to employ an alive Saguaro cactus in a controlledwind-tunnel experiment, to gain insights of the real physical characteristics ofSaguaro’s effects on flow behavior and their response in the high winds.

3.2 Reed Grass

To survive strong winds, some terrestrial plants have evolved a particular struc-ture that allows for flexibility, damping, and reconfiguration. The mechanicalcharacteristics relate to the fibre structure of plants in general and adaptationprocesses during growth, and affect different hierarchical scales of design. Themorphology and orientation of the fibres has been investigated and understoodfrom a biomechanics perspective. For example, bending of reed grass in thewind direction (Fig. 7) and streamlining of side branches leads to a reducedforce on the whole plant. Oscillating motions of flexible stems were associated

Page 11 of 29


Botany

Draft


with the aerodynamic response of such vegetation structures (Alben et al.,2002; Gosselin et al., 2010).

Fig. 7 Reed grass bending in wind (source: FlickR dr knox CC2.0).

Wind resilience of plants has been investigated for self-supporting treesand shrubs. Their mechanical design, brought about by ontogenetic variationsof different hierarchical stem levels, enables a so-called controlled flexibilitythat allows trees to reduce wind loads significantly by streamlining of the flex-ible crown region Speck and Burgert (2011). In addition to aerodynamic andstructural damping, energy dissipation in the hierarchically structured plantstems plays an important role in damping of dynamic wind loads in plants.The effects of incoming wind on the motion and damped oscillation of giantreeds were qualitatively analyzed (de Langre, 2008; Speck and Burgert, 2011;de Langre et al., 2012). The influence of tissue, cell, and cell wall structure ondamping behavior has been detailed for the culms of the giant reed (Arundodonax ). The hollow aerial culms of the giant reed are optimized towards highflexural stiffness by the morphology of the culm and the anatomy of the culmwall. Large differences in stiffness were detected between sclerenchymatousand parenchymatous tissues, with an indication to gradual changes withinthe tissues, mainly in cell parameters, but not in cellulose microfibril angles(Ruggeberg et al., 2010).

Reed grass is also a role model for the group effects, as it grows in densestands. Neighbouring plants shelter each other, and additional damping iscaused by friction between neighboring plants (Speck and Spatz, 2004). Im-pact resistance as another interesting property also relates to building mate-rials for wind resilience, as secondary damage by loose materials is a commonvulnerability of buildings. However, there is still a critical knowledge gap onthe effects of shape change patterns on dynamic behavior for flexible plants,especially for the case of a group of reed plants as the typical and represen-tative configuration, under strong wind condition. The research on reed grassand stems ties into different aspects of vulnerability in the built environment(Table 1), and can help to generate a variety of new concepts for the design ofbuildings, elements and materials with greater resilience. Speck et al. (2018)have also demonstrated the biomimetic transfer of those research findings toinnovative products, especially lightweight composite materials and gradedstructural designs (Speck et al., 2018).

3.3 Plant Leaves: Reconfiguration

The flow-induced reconfiguration of plant leaves is an example of flexible ad-justment to environmental forces to avoid or minimize damage. The effectwas described by Steven Vogel and others (Vogel, 2009; Gosselin et al., 2010).The evolution of leaves is adapted to mechanical aspects, but also to energy

Page 12 of 29


Botany

Draft


aspects in plants (Nicotra et al., 2011). The thermal management is anothermajor “design” factor. Thin sheets exposed to sun are prone to overheating,so leaf shape, and specifically the dissection characteristics are important. Theeffect of leaf shape on the function of evapotranspiration in particular has beenidentified as a promising source of bio-inspiration for thermal and architecturalapplications, to inform design of efficient evaporation-assisted heat exchang-ers and building envelopes (Gruber and Rupp, 2018). Empirical studies haveestablished basic relationships between leaf geometry, flexibility of materialand mechanical characteristics of petioles, and flow metrics. In strong winds,the flat leaves bent and finally form conical shape, yielding significant dragreduction and thus minimizing damage (Fig. 8). This curling to cones for dragminimization is an adaptation to strong wind situations, while the main func-tional adaptation of leaves is to ensure effective photosythesis.

Fig. 8 Leaves of deciduous trees change their configuration to reduce drag tested at windof 20 m/s. (a) Leaf of tulip poplar (Liriodendron tulipifera); (b) Cluster of white poplar(Populus alba); (c) Pinnate leaf of black locust (Robinia pseudoacacia); (d) Branch withleaves of American holly (Ilex opaca); (e) Leaves reconfiguration leads to significantly lowerdrag coefficient. From S. Vogel (2009).

Some plants with large leaves also take into account significant wind dam-age to leaves, which seems not to affect their main functionality. The largeleaves of the banana plant for example are often found torn along the mainfibre orientation so that the leaf surface ends up split into stripes of materialperpendicular to the strong middle axis (Fig. 9). Scientific investigation wascarried out for the role of the petioles, which allow for extensive and reversiblereconfiguration. Due to the flexible petioles, banana leaves shape change froman upright flat surface into a flag like streamlined shape in strong winds (En-nos et al., 2000). Reconfiguration and damage control are powerful strategiesto cope with strong wind loads to structures, and could help to conceptualizemore resilient building designs for areas prone to strong winds.

Fig. 9 Banana leaves torn in wind (left, source: P. Gruber (2019)) ; cross section of the flex-ible stalk (middle, P. Gruber (2009)); longitudinal section of the stalk showing the internalfibre arrangement of the extreme lightweight construction (right, P. Gruber (2009)).

4 Conclusions and Outlook

Wind-related hazards cause enormous life and economic losses that must beaddressed. Biomimetics has great potential to create viable solutions for thisgrand challenge. The analogy table is expected to connect the area of wind haz-ard with biological role models, and create a framework for further investiga-tion of mitigation strategies by identifying working principles and mechanisms

Page 13 of 29


Botany

Draft


in Nature. The examples from biology that are discussed in more details arerelated to multiple principles and problem areas of the built environment. Sofor future work, specific aspects and translation areas need to be focused. Someof the principles that are prominent in biology are not easily translatable tocivil structures and building construction. For those still interesting principles,more visionary concepts for structural design and building construction haveto be identified. Flexibility, for example, contradicts to fundamental character-istics of structures made for housing that provides a rigid and safe shelter forhuman habitation and activities. However, there are certainly parts of houseswhere rigidity is not an essential requirement. Roofs, for example, could haveflexible areas to adapt to wind effects. Roofs’ shape consistency is not necessar-ily a requirement. Shape adaptation or reconfiguration of overall systems andelements on different hierarchical levels, such as in trees, could deliver usefulconcepts for mitigating adverse wind effects on building elements. Integrateddesign of structure and function, is already being translated in several researchareas with parametric design and new computational fabrication technologies,such as fiber-based composite robotic production or 3D printing (Knipperset al., 2016). Not all principles identified in biology are applicable to the con-text of the built environment, but the analogy inspires new ideas and conceptsthat radically transforms the way we think of civil structures today.

Acknowledgements This research is partially supported by the the Faculty Startup Fundsfrom the Office of Research at the Cleveland State University (Zhang) and by the Universityof Akron faculty startup funding (Gruber).

References

Alben, S., Shelley, M., and Zhang, J. 2002. Drag reduction through self-similarbending of a flexible body. Nature, 420(6915):479–481.

Beesley, P. 2019. Living Architecture Systems Group, White Papers 2019.Riverside Architectural Press, Kitchener, Ontario.

Beismann, H., Bertling, J., Beyer, H.-G., Boblan, I., Erb, R., Fischer, M.,Herdy, M., Jordan, A., Kesel, A., Menzel, S., et al. 2012. Biomimeticsconception and strategy differences between bionic and conventional meth-ods/products.

Benson, L. 1981. The Cacti of Arizona. The University of Arizona Press.Blessing, C., Gan Chowdhury, A., Lin, J., and Huang, P. 2009. Full-scale

validation of vortex suppression techniques for mitigation of roof uplift.Engineering Structures, 31(12):2936–2946.

Choi, H., Park, H., Sagong, W., and Lee, S.-i. 2012. Biomimetic flow controlbased on morphological features of living creatures. Phys. Fluids, 24:121302.

Chowdhury, A. G., Moravej, M., Zisis, I., Irwin, P., Tremante, A., and Hajra,B. 2019. Mitigation of Aerodynamic Uplift Loads Using Roof IntegratedWind Turbine Systems. Frontiers in Built Environment, 5:1–9.

Page 14 of 29


Botany

Draft


Davies-Jones, R. 2015. A review of supercell and tornado dynamics. Atmo-spheric Research, 158-159:274–291.

de Langre, E. 2008. Effects of Wind on Plants. Annu. Rev. Fluid Mech.,40(1):141–168.

de Langre, E., Gutierrez, A., and Cosse, J. 2012. On the scaling of dragreduction by reconfiguration in plants. Comptes Rendus - Mecanique, 340(1-2):35–40.

Demartino, C. and Ricciardelli, F. 2017. Aerodynamics of nominally circularcylinders: A review of experimental results for Civil Engineering applica-tions. Engineering Structures, 137:76–114.

Dinan, T. 2017. Projected Increases in Hurricane Damage in the UnitedStates: The Role of Climate Change and Coastal Development. Ecol. Econ.,138:186–198.

Duryea, M. L., Kampf, E., and Littell, R. C. 2007. Hurricanes and the UrbanForest : I . Effects on Southeastern United States Coastal Plain Tree Species.33(March):83–97.

Ennos, A. R., Spatz, H., and Speck, T. 2000. The functional morphology ofthe petioles of the banana, Musa textilis. J. Exp. Bot., 51(353):2085–2093.

Fayemi, P. E., Wanieck, K., Zollfrank, C., Maranzana, N., and Aoussat, A.2017. Biomimetics: Process, tools and practice. Bioinspir. Biomim., 12(1).

Fernando, H. J. S., Pardyjak, E. R., Sabatino, S. D., and Chow, F. K. 2015.The materhorn unraveling the intricacies of mountain weather. Bull. Am.Meteorol. Soc., 96:1945–1967.

Fish, F. E. 2009. Biomimetics: determining engineering opportunities from na-ture. In Proceeding of SPIE volume 7401, Biomimetics and Bioinspiration,740109 (21 August 2009).

Fish, F. E., Howle, L. E., and Murray, M. M. 2008. Hydrodynamic flow controlin marine mammals. Integr. Comp. Biol., Pp. 1–13.

Fish, F. E., Weber, P. W., Murray, M. M., and Howle, L. E. 2011. The tuber-cles on humpback whales’ flippers: Application of bio-inspired technology.Integr. Comp. Biol., 51(1):203–213.

Gardiner, B., Berry, P., and Moulia, B. 2016. Review: Wind impacts on plantgrowth, mechanics and damage. Plant Sci., 245:94–118.

Gebeshuber, I. C., Gruber, P., and Drack, M. 2009. A gaze into the crystalball: Biomimetics in the year 2059. volume 223, Pp. 2899–2918.

Geller, G. and Nobel, P. 1984. Cactus ribs: influence on PAR interception andCO2 uptake. Photosynthetica, 18:482–494.

Goel, A. K., Vattam, S. S., and Helms, M. E. 2009. Biologically inspired design:Human reasoning using nature’s experiences. In Proceedings of the IJCAIWorkshop on Grand Challenges in Reasoning From Experience, Pasadena,California.

Gosselin, F., De Langre, E., and MacHado-Almeida, B. A. 2010. Drag reduc-tion of flexible plates by reconfiguration. J. Fluid Mech., 650:319–341.

Gruber, P. 2009. Biomimetics in architecture – inspiration from plants. InProceedings of the 6th Plant Biomechanics Conference, Cayenne, Pp. 412–419.

Page 15 of 29


Botany

Draft


Gruber, P. 2010. Biomimetics in Architecture: Architecture of Life and Build-ings. SpringerWienNewYork, Ambra Verlag, Germany.

Gruber, P. and Rupp, A. I. K. S. 2018. Investigation of leaf shape and edgedesign for faster evaporation in biomimetic heat dissipation systems. Pro-ceedings SPIE 10593, Bioinspiration, Biomimetics, and Bioreplication VIII,105930H (27 March 2018), P. 14.

Guttag, M. and Reis, P. M. 2017. Active aerodynamic drag reduction onmorphable cylinders. Phys. Rev. Fluids, 2(12):1–14.

Hangan, H., Refan, M., Jubayer, C., Romanic, D., Parvu, D., Lotufo, J., andCostache, A. 2017. Novel techniques in wind engineering. J. Wind. Eng.Ind. Aerod., 171:12–33.

Hann, F. L., Sarkar, P. P., and Gallus, W. A. 2008. Design, construction andperformance of a large tornado simulator for wind engineering applications.Engineering Structures, 30(4):1146–1159.

Hodge, C. 2000. All about Saguaros. Arizona Highways.Imhof, B., Gruber, P., and Birkhauser-AG 2015. Built to Grow: Blending

Architecture and Biology, Edition Angewandte. Birkhauser Verlag AG.International Organization for Standardization 2015. ISO 18458:2015

Biomimetics - Terminology, concepts and methodology. Pp. 1–6.Kaimal, J. C. and Finnigan, J. J. 1994. Atmospheric boundary layer flows:

their structure and measurements. Oxford University Press, New York.Kareem, A. and Wu, T. 2012. Wind induced effects on bluff bodies in turbulent

flows: nonstationary, non-Gaussian and nonlinear features. In Proceedingsof The Seventh International Colloquium on Bluff Body Aerodynamics andits Applications (BBAA7), Shanghai, China.

Karstens, C. D., Samaras, T. M., Lee, B. D., and Finley, C. A. 2010. Near-Ground Pressure and Wind Measurements in Tornadoes. Mon. WeatherRev., 138:2570–2588.

Kazemi, A., Van de Riet, K., and Curet, O. 2017. Hydrodynamics of mangrove-type root models: the effect of porosity, spacing ratio and flexibility. Bioin-spir. Biomim., 12(5):056003.

Kim, H. J. and Yoon, H. S. 2017. Effect of the orientation of the harborseal vibrissa based biomimetic cylinder on hydrodynamic forces and vortexinduced frequency. AIP Advances, 7:105015.

Knippers, J., Nickel, K. G., and Speck, T. 2016. Biomimetic Research for Ar-chitecture and Building Construction, volume 8. Springer, Cham, Switzer-land.

Kopp, G. A., Mans, C., and Surry, D. 2005. Wind effects of parapets on lowbuildings : Part 4 . Mitigation of corner loads with alternative geometries.J. Wind. Eng. Ind. Aerod., 93:873–888.

Kopp, G. A., OH, J., and Inculet, D. 2008. Wind-Induced Internal Pressuresin Houses. J. Struct. Eng., 134:1129.

Letchford, C. W., Lander, D. C., Case, P., Dyson, A., and Amitay, M. 2016.Bio-mimicry inspired tall buildings: The response of cactus-like buildingsto wind action at Reynolds Number of 104. J. Wind. Eng. Ind. Aerod.,150:22–30.

Page 16 of 29


Botany

Draft


Lewellen, D., Lewellen, W., and Xia, J. 2000. The Influence of a Local SwirlRatio on Tornado Intensification near the Surface. J. Atmosp. Sci., 57:527–544.

Lim, H. C. and Lee, S. J. 2004. Flow control of a circular cylinder with O-rings.Fluid Dyn. Res., 35:107–122.

Lin, Y. F., Bai, H. L., Alam, M. M., Zhang, W. G., and Lam, K. 2016. Effectsof large spanwise wavelength on the wake of a sinusoidal wavy cylinder. J.Fluid Struct., 61:392–409.

Liu, Z., Shi, L. L., and Yu, J. 2011. TR-PIV measurement of the wake behinda grooved cylinder at low Reynolds number. J. Fluid Struct., 27(3):394–407.

Mooneghi, M. and Kargarmoakhar, R. 2016. Aerodynamic mitigation andshape optimization of buildings: Review. J. Build. Eng., 6:225–235.

Morrison, H. E., Brede, M., Dehnhardt, G., and Leder, A. 2016. Simulatingthe flow and trail following capabilities of harbour seal vibrissae with theLattice Boltzmann Method. J. Comput. Sci., 17:394–402.

National Oceanic and Atmospheric Administration National Climatic DataCenter 2018. Billion-Dollar Weather and Climate Disasters: Overview.Available from http://https://www.ncdc.noaa.gov/billions/ [accessed 03April 2019].

Nicotra, A. B., Leigh, A., Boyce, C. K., Jones, C. S., Niklas, K. J., Royer,D. L., and Tsukaya, H. 2011. The evolution and functional significance ofleaf shape in the angiosperms. Funct. Plant Biol., 38(Gates 1980):535–552.

Pierson, E. A. and Turner, R. M. 1998. An 85-year study of saguaro (carnegieagigantea) demography. Ecology, 79(8):2676–2693.

Pritchard, P. J. and Mitchell, J. W. 2015. Introduction to Fluid Mechanics.John Wiley & Sons, Inc.

Razavi, A., Zhang, W., and Sarkar, P. P. 2018. Effects of ground roughness onnear-surface flow field of a tornado- like vortex. Exp. Fluids, 59(11):1–16.

Rinehart, A., Shyam, V., and Zhang, W. 2017. Characterization of sealwhisker morphology: Implications for whisker-inspired flow control appli-cations. Bioinspir. Biomim., 12(6).

Rotunno, R. 2013. The Fluid Dynamics of Tornadoes. Annu. Rev. Fluid Mech.,45:59–84.

Ruggeberg, M., Burgert, I., and Speck, T. 2010. Structural and mechanical de-sign of tissue interfaces in the giant reed Arundo donax. J. R. Soc. Interface,7(September 2009):499–506.

Schulgasser, K. and Witztum, A. 1997. On the Strength of Herbaceous Vas-cular Plant Stems. Ann. Bot., 80(1):35–44.

Simui, E. and Miyata, T. 2006. Design of Buildings for Wind: A Guide forASCE 7-10 Standard Users and Designers of Special Structures. John Wiley& Sons, Inc.

Solari, G. 2017. Wind loading of structures: Framework, phenomena, toolsand codification. Structures, 12:265–285.

Speck, O. and Spatz, H. C. 2004. Damped oscillations of the giant reed Arundodonax (Poaceae). Am. J. Bot., 91(6):789–796.

Page 17 of 29


Botany

Draft


Speck, T., Bold, G., Masselter, T., Poppinga, S., Schmier, S., Thielen, M.,and Speck, O. 2018. Biomechanics and Functional Morphology of PlantsInspiration for Biomimetic Materials and Structures. in Geitmann, A., Gril,J. (eds) Plant Biomechanics. Springer, Cham.

Speck, T. and Burgert, I. 2011. Plant Stems: Functional Design and Mechanics.Annu. Rev. Mater. Res., 41(1):169–193.

Speck, T. and Speck, O. 2008. Process sequences in biomimetic research. WITTrans. Ecol. Environ., 114:3–11.

Stull, R. B. 1988. An Introduction to Boundary Layer Meteorology. Springer,Dordrecht.

Suaris, W. and Irwin, P. 2010. Effect of roof-edge parapets on mitigatingextreme roof suctions. J. Wind. Eng. Ind. Aerod., 98:483–491.

Talley, S. and Mungal, G. 2002. Flow around cactus-shaped cylinders, Centerfor Turbulence Research. Annual Research Briefs. Pp. 363–376.

Tamura, Y. and Cao, S. 2010. Climate Change and Disaster Risk Reduction.In Proceedings of the 2010 APEC-WW and IG-WRDRR Joint WorkshopWind-related Disaster Risk Reduction (WRDRR) Activities in Asia-PacificRegion and Cooperative Actions, Incheon, Korea.

Tamura, Y., Nishijima, K., Matsui, M., Phuc, P. V., and Kopp, G. A. 2017.From Load Estimation to Performance Estimation From Model-Scale Testto Full-Scale Test : With Special Interest in Asian Region. Frontiers in BuiltEnvironment, 3(February):1–12.

Tokgoz, B. E. and Gheorghe, A. V. 2013. Resilience quantification and its ap-plication to a residential building subject to hurricane winds. InternationalJournal of Disaster Risk Science, 4(3):105–114.

Vogel, S. 2009. Leaves in the lowest and highest winds: temperature, force andshape. New Phytol., 183(1):13–26.

Willngham, K., Thompson, E. J., Howard, K., and Dempsey, C. 1998. Char-acteristics of sonoran desert microbursts. Ecology, 79(8):2676–2693.

Worsnop, R. P., Lundquist, J. K., Bryan, G. H., Damiani, R., and Musial, W.2017. Gusts and shear within hurricane eyewalls can exceed offshore windturbine design standards. Geophys. Res. Lett., 44:6413–6420.

Zari, M. P. 2010. Biomimetic design for climate change adaptation and miti-gation. Architectural Science Review, 53(2):172–183.

Zdravkovich, M. 1997. Flow Around Circular Cylinders Vol. 1.: Fundamentals.Oxford University Press, New York.

Zhang, W. and Sarkar, P. P. 2008. Effects of Ground Roughness on Tornado-like Vortex using PIV. In Proceedings of the American Association of WindEngineering workshop, Vail, Colorado, Pp. 1–7.

Zhang, W. and Sarkar, P. P. 2012. Near-ground tornado-like vortex structureresolved by particle image velocimetry (PIV). Exp. Fluids, 52:479–493.

Page 18 of 29


Botany

Draft


5 Captions

Fig. 1 Cost of the United States billion-dollar disaster events during 1980 –2018 (source: National Oceanic and Atmospheric Administration or NOAA.)Fig. 2 Cylindrical structures are subjected to significant wind effects and mayencounter failure in extreme-wind events. (a) and (b) Collapsed power-lineposts (Hurricane Irma 2017); (c) Collapsed traffic sign; (d) Damaged coastalfoundations (Hurricane Katrina 2005).Fig. 3 Schematics of information flow in biomimetics between “Nature” (pri-marily biology) and “Technology” to solve human challenges. The flow of in-formation is bi-directional, through abstraction processes of working principlesand concepts. “Biomimetics” refers to deriving new technical solutions frombiological inspiration, and “Reverse Biomimetics” indicates the innovation pro-cess leading to novel research findings in biology (Speck and Speck, 2008). Inthe current study, knowledge about wind-resilient examples and models frombiology, specifically plants, shall inform innovation for vulnerable aspects ofcivil structures in high winds.Fig. 4 Hurricane Michael 2018 making landfall in the Florida Panhandle, oneof the most intense hurricanes on record (source: CIRA/RAMMB).Fig. 5 Single-celled vortex in (a) and multiple vortices in (b) of near-groundtornadoes simulated at the Iowa State University Tornado simulator, afterZhang et al. (2012).Fig. 6 Saguaro cacti in the natural environment. To cope with high winds po-tentially from all directions, their shape is largely an axisymmetric cylindricalbluff body. (source: FlickR Paul Frankenstein CC2.0).Fig. 7 Reed grass bending in wind (source: FlickR dr knox CC2.0).Fig. 8 Leaves of deciduous trees change their configuration to reduce dragtested at wind of 20 m/s. (a) Leaf of tulip poplar (Liriodendron tulipifera);(b) Cluster of white poplar (Populus alba); (c) Pinnate leaf of black locust(Robinia pseudoacacia); (d) Branch with leaves of American holly (Ilex opaca);(e) Leaves reconfiguration leads to significantly lower drag coefficient. From S.Vogel (2009).Fig. 9 Banana leaves torn in wind (left, source: P. Gruber (2019)) ; crosssection of the flexible stalk (middle, P. Gruber (2009)); longitudinal sectionof the stalk showing the internal fibre arrangement of the extreme lightweightconstruction (right, P. Gruber (2009)).

Page 19 of 29


Botany

Draft


Table 1 Analogy table to identify vulnerable aspects of the built environment in highwinds, and connect to mechanisms and strategies for wind-resilience in biology, specificallyin plants, to link problem areas with potential biological solutions via working principles.

Aspects of vulnerability Working principles Aspects of resiliencein the built environment in biological systems

Groups Increase of wind speed Co-creation of patterns Collective shape adaptationby certain settlement pattern by single elements (Canopies, de Langre (2008),

reed, Speck and Spatz (2004))

Individuals Unfavourable building shape Shape adaptation and Streamlined organism shape andcan increase wind speed and forces reconfiguration to wind guidance reconfiguration of shape

(Trees, Gardiner et al. (2016))

Cylindrical-shaped Surface morphology to alter Longitudinal cavities (ribs)structure/bluff bodies boundary-layer flow and wake (Saguaro cactus, Liu et al. (2011),(towers, posts) Talley and Mungal (2002))

Elements Foundations Spread anchoring in the soil Strong and large root systemsBuildings toppling over (Mangrove roots, Kazemi et al. (2017))

Large planes Shape adaptation and Curved shapes, no largeexposed to wind (facades, roof) reconfiguration to reduce planes exposed to wind

frontal areas (Trees, Gardiner et al. (2016))

Openings Hide or close openings None or protected openings(windows and doors) temporarily (Stomata, de Langre (2008))

Extruding elements Avoid extruding elements No large-scale extrusions(awnings, eaves)

Construction details Integrated structural design Integrity and coherence ofConnections primarily designed biological structuresto withstand gravity (Plant stems, Schulgasser and Witztum (1997)

Edges Avoid long, straight edges No long edge lines, flexibleroof ridge and eaves or adapted edge design design to minimize forces

to minimize forces (Trees, Gardiner et al. (2016))

Loose parts Good connection of No additive connections,create secondary damage all elements less loose elementsto surrounding areas (Trees, Gardiner et al. (2016))

Materials and Layers Good connection of layers No layers, integrated systemsSurfaces especially at the edges (Fibre based structures, plant

tissues Speck et al. (2018)

Generic aspects Damage control Plan for controlled failure Damage does not lead tocomplete failure or death,sometimes no loss of functionality(Defoliation, Duryea et al. (2007))

Rigidity Flexibility and reconfiguration Flexibility and shape change(Plant leaves, Vogel (2009)

Vibration Damping by material or structure Hierarchical or fractal shapeespecially at natural frequency organization leads to damping(fluttering, structural failure) effects (Reed, Speck and Spatz (2004))

Page 20 of 29


Botany

Draft

Figure 1

90x55mm (300 x 300 DPI)

Page 21 of 29


Botany

Draft

Figure 2

113x64mm (300 x 300 DPI)

Page 22 of 29


Botany

Draft

Figure 3

87x50mm (300 x 300 DPI)

Page 23 of 29


Botany

Draft

Figure 4

162x91mm (300 x 300 DPI)

Page 24 of 29


Botany

Draft

Figure 5

393x175mm (300 x 300 DPI)

Page 25 of 29


Botany

Draft

Figure 6

338x217mm (300 x 300 DPI)

Page 26 of 29


Botany

Draft

Figure 7

84x56mm (300 x 300 DPI)

Page 27 of 29


Botany

Draft

Figure 8

120x43mm (300 x 300 DPI)

Page 28 of 29


Botany

Draft

Figure 9

158x40mm (300 x 300 DPI)

Page 29 of 29


Botany

Wind-resilient Civil Structures: What Can We Learn from Natureow in biomimetics between \Nature"...

Documents

Transcript of Wind-resilient Civil Structures: What Can We Learn from Natureow in biomimetics between \Nature"...