This study examined Hurricane Katrina damage in southeast Mississippi to identify stand and site characteristics that may contribute to wind-related damage. Aggregated forest plot-level biometrics were coupled with storm meteorology, topographical features, and soil attributes using GIS techniques to produce damage maps for specific tree species. Regression Tree Analysis was utilized to explore the relationship between damage type and distance variables (distance to coast/storm track). Results indicated that the total damage class had the greatest relationship with distance variables; individual damage classes (shear and blowdown) displayed a better relationship with stand-level variables (Quadratic Mean Diameter, Lorey’s Mean Height, Trees Per Hectare). Logistic regressions identified a negative relationship between damage and height variation, elevation, slope, and aspect and a positive relationship with TPH. For plots/stands nearest to the coast and storm track height variation, TPH, QMD, and LMH consistently predicted damage levels for most species examined.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Thesis (MscEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Low-rise buildings with crest fastenedmetal cladding are susceptible to failures in the vicinity of the fasteners during strongwind uplift conditions. These localised failures often lead to the progressive removal of cladding, which can cause disastrous building damage. In South Africa, the current metal cladding design approach is inadequate, since it solely relies upon manufacturer design specifications. These specifications are typically designated as broad design guidelines for the maximum allowable cladding support spacings which are independent from any specified design loads. This research focuses on the investigation of 0.50 mm ISQ550 IBR cladding systems to understand basic cladding behaviour during static wind uplift conditions and to quantify the uplift performance of IBR systems. The research investigation also included the improvement and performance evaluation of a full-scale cladding test method which applies an air-bag loading method to simulate static wind uplift conditions according to the revised SANS 10237:201X code of practice. This thesis may serve as a basis for further cladding research, and the development of suitable standardised metal cladding test methods in South Africa. Several experimental investigation methods and limited finite element analyses (FEA) were used to investigate IBR and the performance of the test methods. Tensile testing was used to determine the material properties of the cladding metal. The full-scale cladding assembly testing was used to investigate the behaviour of IBR and to evaluate the performance of the air-bag test rig. The localised behaviour of the cladding around the fasteners was also investigated with a small cladding subassembly test method. The FEA served as a supplementary investigation for IBR performance evaluation. The experimental investigation confirmed that the static wind uplift resistances of IBR systems are mainly governed by localised deformations of their fastened crests and fastener pull-through failures. The behaviour and performance of IBR systems are heavily dependent on the crest fastening arrangement. IBR systems with every crest fastening demonstrated a considerably higher wind uplift resistance than IBR systems with the standard alternate crest fastening arrangement. The measured fastener loads were independent from span length, whereas the overall uplift resistance of IBR reduced with increased span lengths. Load-span resistance data for 0.50 mm ISQ550 IBR was derived from testing to provide a rational framework for design. The FEA provided a reasonable simulation of IBR subjected to static wind uplift and confirmed the presence of high stress and strain concentrations around the fastener holes which cause fastener pull-through failures. Therefore, FEA can be used as an effective tool to investigate the behaviour of IBR. In conclusion, the air-bag test method used in this research investigation provided an effective method for evaluating the uplift performance of crest fastened metal cladding. However, the air-bag load method is not capable of accurately simulating a true uniformly distributed uplift load. It is recommended that direct air pressure testing be adopted for any further research or commercial testing ofmetal cladding because direct air pressure testing is an effective and proven test method for accurate simulation of static and cyclic wind uplift conditions. / AFRIKAANSE OPSOMMING: Metaalbekleding met kruinvashegting op lae geboue is geneig om te faal by die vashegters tydens toestande van sterkwind-opheffing. As vashegters faal kan bekleding progressief verwyderwordomrampspoedige skade aan die gebou te veroorsaak. Die huidige ontwerpmetode vir metaalbekleding in Suid-Afrika is onvoldoende, aangesien dit slegs gegrond is op vervaardigers se ontwerpspesifikasies. Spesifikasies word gewoonlik verklaar as breë ontwerpriglyne vir die maksimum toelaatbare spasiërings van ondersteunings sonder enige oorwegings vir ontwerpbelastings. Hierdie navorsing fokus dus op 0.50mm ISQ550 IBR metaalbekleding omdie basiese gedrag van bekleding tydens wind-opheffing beter te verstaan en die ophefweerstand van IBR te kwantifiseer vir ontwerpdoeleindes. Verder ondersoek hierdie navorsing ook die verbetering en evaluasie van ’n volskaalse bekledingstoetsmetode wat statiese wind-opheffing naboots met verspreide lugsakbelasting volgens die hersiende SANS 10237:201X gebruikskode. Hierdie proefskrif kan dien as ’n grondslag vir verdere navorsing en die ontwikkeling van geskikte standaard-toetsmetodes vir metaalbekleding in Suid-Afrika. Verskeie eksperimentele toetsmetodes en beperkte eindige-element-analises (EEA) is gebruik om die gedrag van IBR en die toets-opstellings te ondersoek. Trektoetse is gebruik om die meganiese eienskappe van die bekledingsmetaal te bepaal. Volskaalse toets-opstellings is gebruik om die weerstand van IBR te ondersoek en die lugsaktoetsmetode te evalueer. Die gelokaliseerde gedrag van die bekleding rondom die vashegters was ook ondersoek met klein toets-opstellings. EEA het gedien as ’n aanvullende ondersoek om die gedrag van IBR te evalueer. Die eksperimentele ondersoek het bevestig dat die wind-ophefweerstande van IBR-stelsels hoofsaaklik bepaal word deur gelokaliseerde deformasies van die vasgehegde kruine en die vashegters se deurtrekweerstand. Die gedrag en weerstand van IBR-stelsels is ook grootliks afhanklik van die toegepaste vashegtingsmetode. IBR stelsels met vashegting deur elke kruin het ’n hoër ophefweerstand verskaf as IBR-stelsels met die standaard vashegtingsmetode deur elke tweede kruin. Die gemete vashegterbelastings was onafhanklik van die spanlengtes, terwyl die algehele ophefweerstand van IBR verminder het vir langer spanlengtes. Toetsdata is gebruik om ophefweerstande vir 0.50mm ISQ550 IBR oor verskeie spanlengtes af te lei sodat ’n rasionele raamwerk vir ontwerp bewerkstellig kan word. Die EEA het die gedrag van IBR tydens toestande van statiese wind-opheffing redelik goed nageboots en het ook die teenwoordigheid van hoë spannings- en vervormingskonsentrasies rondom die vashegtergate, wat vashegters laat deurtrek, bevestig. Daarom kan EEA as ’n effektiewe instrument gebruik word om die gedrag van IBR te ondersoek. Ten slotte word dit afgelei dat die lugsaktoetsmetode van hierdie navorsingsondersoek ’n effektiewe metode verskaf het vir die gedrag-evaluering van kruinvasgehegte bekleding tydens wind-opheffing. Die lugsaktoetsmetode kan egter nie ’n ware gelykverspreide ophefbelasting naboots nie. Daarom word dit voorgestel dat toetsmetodes wat direkte lugdruk aanwend gebruik moet word vir enige verdere navorsing of kommersiële toetse van metaalbekleding, aangesien dit ’n effektiewe en bevestigde toetsmetode is wat statiese en sikliese opheftoestande akkuraat kan naboots.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on August 9, 2009). Includes bibliographical references (p. 96-99).

Tornadoes pose a significant danger to human life and structures. Research regarding the effects of tornado-induced loads on residential buildings is in incipient stages and there are no specialized construction standards in place to recommend criteria applicable to structures for withstanding tornadic winds. Three residential house models with different geometries were tested in the Wind-induced Damage Simulator (WDS) built at the University of Ottawa. The WDS is capable of simulating pressures induced by multidirectional and tornadic winds. The peak pressure coefficients were calculated on the walls and roofs of the houses and an analysis was performed on the effects of house model orientation, roof pitch angle, and exposure duration. The peak pressure coefficients were then compared to the NBCC 2015 code to clarify if there were any limitations of the current wind design criteria. It was found that the building orientation did not have a significant effect on pressure coefficient trends and magnitudes on the walls and roofs. For the low roof pitch angle models, it was noticed that the suction on the roof was much greater than the higher roof pitch angle models. An interesting observation was made that found that the leading edge of the walls in the direction of the clockwise tornadic flow were always under greater suction than the trailing edge, which causes a torsional effect on the entire model. When comparing the peak pressure coefficient values to the NBCC 2015 recommended values for the secondary cladding members, it was found that the CpCg stipulated in the code were similar to the experimental tornado Cp’s for the walls. However, the Cp’s on the roof were much greater in the experiments when compared to the NBCC 2015. The CpCg of Zones S and Zone R, which are the edges and central regions of the roof, greatly exceed the minimum values in the NBCC 2015. More experiments for residential house models of different geometries should be conducted in order to propose new tornado-induced pressure coefficients to be used in the design of the structure located in tornado-prone areas.Tornadoes pose a significant danger to human life and structures. Research regarding the effects of tornado-induced loads on residential buildings is in incipient stages and there are no specialized construction standards in place to recommend criteria applicable to structures for withstanding tornadic winds. Three residential house models with different geometries were tested in the Wind-induced Damage Simulator (WDS) built at the University of Ottawa. The WDS is capable of simulating pressures induced by multidirectional and tornadic winds. The peak pressure coefficients were calculated on the walls and roofs of the houses and an analysis was performed on the effects of house model orientation, roof pitch angle, and exposure duration. The peak pressure coefficients were then compared to the NBCC 2015 code to clarify if there were any limitations of the current wind design criteria. It was found that the building orientation did not have a significant effect on pressure coefficient trends and magnitudes on the walls and roofs. For the low roof pitch angle models, it was noticed that the suction on the roof was much greater than the higher roof pitch angle models. An interesting observation was made that found that the leading edge of the walls in the direction of the clockwise tornadic flow were always under greater suction than the trailing edge, which causes a torsional effect on the entire model. When comparing the peak pressure coefficient values to the NBCC 2015 recommended values for the secondary cladding members, it was found that the CpCg stipulated in the code were similar to the experimental tornado Cp’s for the walls. However, the Cp’s on the roof were much greater in the experiments when compared to the NBCC 2015. The CpCg of Zones S and Zone R, which are the edges and central regions of the roof, greatly exceed the minimum values in the NBCC 2015. More experiments for residential house models of different geometries should be conducted in order to propose new tornado-induced pressure coefficients to be used in the design of the structure located in tornado-prone areas.

Modern forestry research and management emphasize infusing management practices with an understanding of natural disturbance regimes -- often called ecological forestry. Forestry practices emulating aspects of natural disturbance regimes are considered an effective tool to balance silvicultural and ecological objectives. Size, shape, and spatial distribution of canopy gaps formed by Hurricane Michael were studied across multiple site factors in a longleaf pine (Pinus palustris Mill.) woodland in southwest Georgia. No significant differences were observed in gap size or shape among landscape factors, but spatial distribution of gaps differed among landscape factors. The results observed highlight the ecological importance of the event and provide some insight into interactions at the landscape level. The implementation of a large, rapid, single disturbance event as a model for ecological silviculture may be more practically applied than disturbances such as lightning or insects which occur over longer timeframes.

Starka vindar orsakar stora skador för det svenska skogsbruket och samhället. Därför är det viktigt att kunna hitta de bestånd som har hög sannolikhet att drabbas av dessa skador. För att lyckas med detta krävs ett enkelt verktyg där bestånden kan bedömas med denutrustning och den kunskap som finns ute på de svenska skogsgårdarna.Den här studien utvärderar och testar ett verktyg som är framtagen av Olofsson & Blennow (2005). Resultatet visar att verktyget fungerar och att det är användarvänligt. Av 90 undersökta bedömningarresulterade 23 % i hög sannolikhet för stormskador på den undersökta gården i norra Halland. Studien visar också på vikten av att använda aktuella data och arbeta med hög noggrannhet i framtagandet avbeståndsdata. De viktigaste parametrarna för att bedömasannolikheten var beståndskantshöjd och HD-kvot.

𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧) Tropical forests are the world’s most structurally complex ecosystems, providing key functions like biomass accumulation and harboring biodiversity. Yet climate-change poses a potential threat to the stability of these forests – tropical cyclones in the North Atlantic are projected to increase in intensity, leading to higher forest damage rates, potentially reducing their carbon sequestration and biodiversity potential. Hurricane Maria in 2017 was a possible portent of this dynamic, causing widespread devastation in Puerto Rico. How do forests resist such severe disturbances? Forests ecosystems contain ecological memory – physical and biological legacies from past natural disturbances like fires and windstorms – that can increase their resilience to future disturbances. In fire-prone forests, for example, prior exposure to non-severe fires has been shown to increase resistance to severe wildfires. Does the same mechanism apply in cyclone-prone tropical forests? In this dissertation, I examine how chronic exposure to non-hurricane winds impacts hurricane damage at the tree, stand, and landscape scales in Puerto Rico. Specifically, I ask – 1) Do chronic winds alter tree architecture to reduce their risk of stem-breaks? 2) Do chronic winds reduce forest stand structural complexity? 3) Do chronic winds and lower canopy structural complexity reduce individual tree and forest stand damage from Hurricane Maria? 𝐌𝐞𝐭𝐡𝐨𝐝𝐬) I used a novel combination of remote sensing, fieldwork, and high-resolution Light Detection and Ranging (LiDAR) data collected in 2016 to address the above questions. In Chapter 1, I connected sub-meter resolution GPS data and 30 years of forest inventory with 0.03m resolution airborne LiDAR data to evaluate chronic wind impacts on the tree architecture and wind-risk of 124 forest trees of four key species. In Chapter 2, I used machine learning, remote-sensing and LiDAR data to predict the chronic wind impacts on the canopy height and structural complexity of ~20,000 0.28 ha forested sites across climatic, forest age and topographic gradients. In Chapter 3, I used pre-storm size and damage assessment field data for ~7,000 trees of 160 species across 14, 0.25 ha sites spanning an 800 m elevation gradient, alongside a remote-sensing dataset of ~12,000 forests to evaluate multiscale drivers – including canopy structural complexity – of individual, stand and landscape level hurricane damage. 𝐑𝐞𝐬𝐮𝐥𝐭𝐬 𝐚𝐧𝐝 𝐜𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧𝐬) At the individual tree scale, I found that long-lived species grew ~3.5 m shorter and ~ 4 m2 smaller crowns on average due to chronic wind-exposure, substantially reducing their estimated wind-risk, whereas short-lived species did not respond architecturally to chronic winds. At the stand and landscape scales, I found that chronic winds reduced canopy height by 2.12 m on average, and that structural complexity decreased substantially with forest age. I found that stand-level hurricane damage was primarily a function of increased canopy structural complexity, which in turn decreased with elevation; and that individual tree damage increased with stem size and varied only slightly by species, with short-lived species much more susceptible to damage. My findings suggest that tropical forest resistance to increasingly severe hurricanes depends largely on the physical structure of their canopies, and only then on adapted species-level life-history traits. The physical structure of forest canopies, in turn, changes substantially with exposure to non-hurricane winds. In old-growth forests in Puerto Rico, there is therefore evidence that ecological memory driven by exposure to non-hurricane winds can protect forests from severe wind disturbances. However, younger, more structurally complex forests may be potentially increasingly more vulnerable in a changing climate.

This thesis presents the distribution of strong wind and wind pressure in the Greater Victoria area associated with winter mid-latitude cyclones based on climate data from the School-Based Weather Station Network during 6 selected days in the winters of 2006, 2007 and 2008. The objectives of this study are i) to test whether synoptic conditions favourable to severe mid-latitude cyclonic storms that are well described in the literature were associated with the selected storms, ii) to determine the time patterns of high wind speed and its direction and maximum gusts, iii) to test necessity of considering the spatial variation in air density and its controls in general assessments of the spatial variation in wind pressure and wind damage potential in the local area, iv) to identify potential areas susceptible to wind damage. Observations taken every second were from Davis Vantage Pro2 TM Plus weather stations located on the southern edge of school building roofs. Thirty-minute means and gust wind speeds were used. All six storms went north of Victoria. The synoptic conditions associated with the selected mid-latitude cyclones agreed with the ones described in literature. Strongest winds at most stations were generally from the southwest, and multiple wind speed peaks were found. The daily iii  maximum gust wind speeds were found before and/or after the highest mean wind speed peak. The spatial variation in air density and its controls were found to be negligible. Although there are a number of interacting causes of the distribution, strongest winds were at stations with smooth surrounding surfaces, close to the southern shoreline, on exposed slopes and/or near relief constrictions. The area with greatest wind speeds and damage potential was found from the east of downtown extending to Lansdowne Middle School. This study provides new knowledge of winds in the Greater Victoria area and contributes to people’s better response to wind storms, land use planning and forecasting severe windstorms. / Graduate / 0368 / mmatsuda@uvic.ca