Simulated tropical cyclonic winds for low cycle fatigue loading of steel roofing

David J. Henderson,John D. Ginger,Murray J. Morrison,Gregory A. Kopp 한국풍공학회 2009 Wind and Structures, An International Journal (WAS Vol.12 No.4

Low rise building roofs can be subjected to large fluctuating pressures during a tropical cyclone resulting in fatigue failure of cladding. Following the damage to housing in Tropical Cyclone Tracy in Darwin, Australia, the Darwin Area Building Manual (DABM) cyclic loading test criteria, that loaded the cladding for 10000 cycles oscillating from zero to a permissible stress design pressure, and the Experimental Building Station TR440 test of 10200 load cycles which increased in steps to the permissible stress design pressure, were developed for assessing building elements susceptible to low cycle fatigue failure. Recently the ‘Low-High-Low’ (L-H-L) cyclic test for metal roofing was introduced into the Building Code of Australia (2007). Following advances in wind tunnel data acquisition and fullscale wind loading simulators, this paper presents a comparison of wind-induced cladding damage, from a “design” cyclone proposed by Jancauskas, et al. (1994), with current test criteria developed by Mahendran (1995). Wind tunnel data were used to generate the external and net pressure time histories on the roof of a low-rise building during the passage of the “design” cyclone. The peak pressures generated at the windward roof corner for a tributary area representative of a cladding fastener are underestimated by the Australian/New Zealand Wind Actions Standard. The “design” cyclone, with increasing and decreasing wind speeds combined with changes in wind direction, generated increasing then decreasing pressures in a manner similar to that specified in the L-H-L test. However, the L-H-L test underestimated the magnitude and number of large load cycles, but overestimated the number of cycles in the mid ranges. Cladding elements subjected to the L-H-L test showed greater fatigue damage than when experiencing a five hour “design” cyclone containing higher peak pressures. It is evident that the increased fatigue damage was due to the L-H-L test having a large number of load cycles cycling from zero load (R=0) in contrast to that produced during the cyclone.

Campaign 9 of the<i>K2</i>Mission: Observational Parameters, Scientific Drivers, and Community Involvement for a Simultaneous Space- and Ground-based Microlensing Survey

Henderson, Calen B.,Poleski, Radosław,Penny, Matthew,Street, Rachel A.,Bennett, David P.,Hogg, David W.,Gaudi, B. Scott,Zhu, W.,Barclay, T.,Barentsen, G.,Howell, S. B.,Mullally, F.,Udalski, A.,Szyma&# Astronomical Society of the Pacific 2016 Publications of the Astronomical Society of the Pa Vol.128 No.970

<P>K2's Campaign 9 (K2C9) will conduct a similar to 3.7 deg(2) survey toward the Galactic bulge from 2016 April 22 through July 2 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax pi(E) for greater than or similar to 170 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this article we provide an overview of the K2C9 space-and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST.</P>

Simulated tropical cyclonic winds for low cycle fatigue loading of steel roofing

Henderson, David J.,Ginger, John D.,Morrison, Murray J.,Kopp, Gregory A. Techno-Press 2009 Wind and Structures, An International Journal (WAS Vol.12 No.4

Low rise building roofs can be subjected to large fluctuating pressures during a tropical cyclone resulting in fatigue failure of cladding. Following the damage to housing in Tropical Cyclone Tracy in Darwin, Australia, the Darwin Area Building Manual (DABM) cyclic loading test criteria, that loaded the cladding for 10000 cycles oscillating from zero to a permissible stress design pressure, and the Experimental Building Station TR440 test of 10200 load cycles which increased in steps to the permissible stress design pressure, were developed for assessing building elements susceptible to low cycle fatigue failure. Recently the 'Low-High-Low' (L-H-L) cyclic test for metal roofing was introduced into the Building Code of Australia (2007). Following advances in wind tunnel data acquisition and full-scale wind loading simulators, this paper presents a comparison of wind-induced cladding damage, from a "design" cyclone proposed by Jancauskas, et al. (1994), with current test criteria developed by Mahendran (1995). Wind tunnel data were used to generate the external and net pressure time histories on the roof of a low-rise building during the passage of the "design" cyclone. The peak pressures generated at the windward roof corner for a tributary area representative of a cladding fastener are underestimated by the Australian/New Zealand Wind Actions Standard. The "design" cyclone, with increasing and decreasing wind speeds combined with changes in wind direction, generated increasing then decreasing pressures in a manner similar to that specified in the L-H-L test. However, the L-H-L test underestimated the magnitude and number of large load cycles, but overestimated the number of cycles in the mid ranges. Cladding elements subjected to the L-H-L test showed greater fatigue damage than when experiencing a five hour "design" cyclone containing higher peak pressures. It is evident that the increased fatigue damage was due to the L-H-L test having a large number of load cycles cycling from zero load (R=0) in contrast to that produced during the cyclone.

Sustainable Forestry: The Imperative of Soil Mapping in Forest Resource Inventory, Modelling and Management in Scotland, UK

Andrew John Nolan,Bill Rayner,Andy Kennedy,Christine Brown,David Donnelly,John Bell,David Henderson,Willie Towers,Richard Hewison,David Riach 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

OPTIMAL SURVEY STRATEGIES AND PREDICTED PLANET YIELDS FOR THE KOREAN MICROLENSING TELESCOPE NETWORK

Henderson, Calen B.,Gaudi, B. Scott,Han, Cheongho,Skowron, Jan,Penny, Matthew T.,Nataf, David,Gould, Andrew P. IOP Publishing 2014 The Astrophysical journal Vol.794 No.1

<P>The Korean Microlensing Telescope Network (KMTNet) will consist of three 1.6 m telescopes each with a 4 deg(2) field of view (FoV) and will be dedicated to monitoring the Galactic Bulge to detect exoplanets via gravitational microlensing. KMTNet's combination of aperture size, FoV, cadence, and longitudinal coverage will provide a unique opportunity to probe exoplanet demographics in an unbiased way. Here we present simulations that optimize the observing strategy for and predict the planetary yields of KMTNet. We find preferences for four target fields located in the central Bulge and an exposure time of t(exp) = 120 s, leading to the detection of similar to 2200 microlensing events per year. We estimate the planet detection rates for planets with mass and separation across the ranges 0.1 <= M-p/M-circle plus <= 1000 and 0.4 <= a/AU <= 16, respectively. Normalizing these rates to the cool-planet mass function of Cassan et al., we predict KMTNet will be approximately uniformly sensitive to planets with mass 5 <= M-p/M-circle plus <= 1000 and will detect similar to 20 planets per year per dex in mass across that range. For lower-mass planets with mass 0.1 <= M-p/M-circle plus < 5, we predict KMTNet will detect similar to 10 planets per year. We also compute the yields KMTNet will obtain for free-floating planets (FFPs) and predict KMTNet will detect similar to 1 Earth-mass FFP per year, assuming an underlying population of one such planet per star in the Galaxy. Lastly, we investigate the dependence of these detection rates on the number of observatories, the photometric precision limit, and optimistic assumptions regarding seeing, throughput, and flux measurement uncertainties.</P>

Development and validation of a numerical model for steel roof cladding subject to static uplift loads

Amy C. Lovisa,Vincent Z. Wang,David J. Henderson,John D. Ginger 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.17 No.5

Thin, high-strength steel roof cladding is widely used in residential and industrial low-rise buildings and is susceptible to failure during severe wind storms such as cyclones. Current cladding design is heavily reliant on experimental testing for the determination of roof cladding performance. Further study is necessary to evolve current design standards, and numerical modelling of roof cladding can provide an efficient and cost effective means of studying the response of cladding in great detail. This paper details the development of a numerical model that can simulate the static response of corrugated roof cladding. Finite element analysis (FEA) was utilised to determine the response of corrugated cladding subject to a static wind pressure, which included the anisotropic material properties and strain-hardening characteristics of the thin steel roof cladding. The model was then validated by comparing the numerical data with corresponding experimental test results. Based on this comparison, the model was found to successfully predict the fastener reaction, deflection and the characteristics in deformed shape of the cladding. The validated numerical model was then used to predict the response of the cladding subject to a design cyclone pressure trace, excluding fatigue effects, to demonstrate the potential of the model to investigate more complicated loading circumstances.

Development and validation of a numerical model for steel roof cladding subject to static uplift loads

Lovisa, Amy C.,Wang, Vincent Z.,Henderson, David J.,Ginger, John D. Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.5

Thin, high-strength steel roof cladding is widely used in residential and industrial low-rise buildings and is susceptible to failure during severe wind storms such as cyclones. Current cladding design is heavily reliant on experimental testing for the determination of roof cladding performance. Further study is necessary to evolve current design standards, and numerical modelling of roof cladding can provide an efficient and cost effective means of studying the response of cladding in great detail. This paper details the development of a numerical model that can simulate the static response of corrugated roof cladding. Finite element analysis (FEA) was utilised to determine the response of corrugated cladding subject to a static wind pressure, which included the anisotropic material properties and strain-hardening characteristics of the thin steel roof cladding. The model was then validated by comparing the numerical data with corresponding experimental test results. Based on this comparison, the model was found to successfully predict the fastener reaction, deflection and the characteristics in deformed shape of the cladding. The validated numerical model was then used to predict the response of the cladding subject to a design cyclone pressure trace, excluding fatigue effects, to demonstrate the potential of the model to investigate more complicated loading circumstances.

Correlation of internal and external pressures and net pressure factors for cladding design

Geeth G. Bodhinayake,John D. Ginger,David J. Henderson 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.3

Net pressures on roofs and walls of buildings are dependent on the internal and external pressure fluctuations. The variation of internal and external pressures are influenced by the size and location of the openings. The correlation of external and internal pressure influences the net pressures acting on cladding on different parts of the roof and walls. The peak internal and peak external pressures do not occur simultaneously, therefore, a reduction can be applied to the peak internal and external pressures to obtain a peak net pressure for cladding design. A 1:200 scale wind tunnel model study was conducted to determine the correlations of external and internal pressures and effective reduction to net pressures (i.e., net pressure factors, ) for roof and wall cladding. The results show that external and internal pressures on the windward roof and wall edges are well correlated. The largest ̌, , highest correlation coefficient and the highest are obtained for different wind directions within 90o ≤ ≤ 135o, where the large openings are on the windward wall. The study also gives net pressure factors for areas on the roof and wall cladding for nominally sealed buildings and the buildings with a large windward wall opening. These factors indicate that a 5% to 10% reduction to the action combination factor, specified in AS/NZS 1170.2(2011) is possible for some critical design scenarios.