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2016

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Articles 1111 - 1140 of 2181

Full-Text Articles in Civil and Environmental Engineering

Ndm-505: Development Of The Asce/Sei Standard For The Estimation Of Tornado Wind Speeds, J. Arn Womble, James G. Ladue, Marc L. Levitan, Tanya Brown-Giammanco, Bill Coulbourne, Franklin T. Lombardo, Gregory A. Kopp Jun 2016

Ndm-505: Development Of The Asce/Sei Standard For The Estimation Of Tornado Wind Speeds, J. Arn Womble, James G. Ladue, Marc L. Levitan, Tanya Brown-Giammanco, Bill Coulbourne, Franklin T. Lombardo, Gregory A. Kopp

Canadian Society for Civil Engineering

Development of the new ASCE/SEI consensus standard for wind speed estimation in tornadoes began in 2014 and is currently underway. The intent of the new standard is to standardize the methods used to estimate the wind speeds in tornadoes including improvements and expansions for the damaged-based Enhanced Fujita Scale (EF Scale), with potential to extend the scope of the standard to include other windstorms. The standard will include sections on the EF Scale, radar measurements, tree fall pattern analysis, data archives, forensic engineering analysis, in-situ measurements (anemometry), and remote-sensing applications. Users of the standard will include wind, structural and forensic …

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Ndm-506: Current Methods And Future Advances For Rapid, Remote-Sensing-Based Wind Damage Assessment, J. Arn Womble, Richard L. Wood, Ronald T. Eguchi, Shubharoop Ghosh, Mohammad Ebrahim Mohammadi Jun 2016

Ndm-506: Current Methods And Future Advances For Rapid, Remote-Sensing-Based Wind Damage Assessment, J. Arn Womble, Richard L. Wood, Ronald T. Eguchi, Shubharoop Ghosh, Mohammad Ebrahim Mohammadi

Canadian Society for Civil Engineering

Remote-sensing information provides an effective basis for the rapid assessment of wind damage. The development of remote-sensing based assessments has received notable attention over the past decade, although automated algorithms have not yet achieved the speed, objectivity, and reliability desired for practical implementation in time-critical damage assessments. The current standard practice for making swift, objective, and widespread assessments of wind damage currently consists of rapid visual interpretation of first-available imagery. Techniques for rapidly accomplishing widespread damage assessments by visual inspection have been implemented in recent major tornado outbreaks in Birmingham-Tuscaloosa, Alabama and Joplin, Missouri (2011). Quickly emerging technologies, such as …

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Ndm-510: Analysis Of Spatially-Varying Wind Characteristics For Distributed Systems, Thomas G. Mara Jun 2016

Ndm-510: Analysis Of Spatially-Varying Wind Characteristics For Distributed Systems, Thomas G. Mara

Canadian Society for Civil Engineering

Design wind speeds for various return periods are provided in most national design codes throughout the world (e.g., NBCC 2010, ASCE 7-10). The design wind speeds are often based on an extreme value analysis of historical data obtained from a number of meteorological stations distributed over the region of interest. However, only the extreme wind speed magnitude is typically available to the designer, which does not provide information on the directional characteristics or underlying probability distribution of the wind. These parameters of the local wind characteristics may be useful for designers of directionally-sensitive structures or for higher-order reliability-based design. This …

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Ndm-509: Full-Scale Test Methods For Multi-Layer Cladding Systems: Wind Tunnel Vs. Multi-Chamber Airbox, Connell S. Miller, Gregory A. Kopp Jun 2016

Ndm-509: Full-Scale Test Methods For Multi-Layer Cladding Systems: Wind Tunnel Vs. Multi-Chamber Airbox, Connell S. Miller, Gregory A. Kopp

Canadian Society for Civil Engineering

Wind loads on multi-layer wall systems are complicated because the loads on each particular layer are poorly understood and difficult to quantify. This is because of pressure equalization, which is the mechanism whereby the pressures on the external building surface are transmitted through the air-permeable outer layer to interior layers. Recent testing at IBHS in a full-scale wind tunnel has shown that the extent of pressure equalization is more limited than is assumed in the test standard, ASTM D3679-13. Multi-chamber pressure testing performed by the authors at the Insurance Research Lab for Better Homes was able to capture these features …

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Ndm-511: Pressure Fluctuations On The Roofs Of Low-Rise Buildings In Turbulent Boundary Layers, Abul Fahad Akon, Gregory A. Kopp Jun 2016

Ndm-511: Pressure Fluctuations On The Roofs Of Low-Rise Buildings In Turbulent Boundary Layers, Abul Fahad Akon, Gregory A. Kopp

Canadian Society for Civil Engineering

Buildings are often exposed to the highly turbulent atmospheric boundary layer flows near the earth’s surface. Roofs of low-rise buildings in particular are vulnerable to the resulting aerodynamic loads, especially during the extreme wind storms. For flat-roofed, low-rise buildings with relatively large plan dimensions, the approach flow separates at the leading edge of the roof and then reattaches creating a separation bubble. This separation bubble is a turbulent recirculating flow region that is responsible for causing large-magnitude uplift on the roof surface. Such large, uplifting forces can cause damage to the roofs and roof-mounted structures. There are a limited number …

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Ndm-514: Large Eddy Simulation Of Wind Induced Loads On A Low Rise Building With Complex Roof Geometry, Bodhisatta Hajra, Girma T. Bitsuamlak, Haitham Aboshosha, Ahmed Elshaer Jun 2016

Ndm-514: Large Eddy Simulation Of Wind Induced Loads On A Low Rise Building With Complex Roof Geometry, Bodhisatta Hajra, Girma T. Bitsuamlak, Haitham Aboshosha, Ahmed Elshaer

Canadian Society for Civil Engineering

Wind induced damage on low-rise buildings with complex roof geometry is common in coastal areas of USA, such as Florida and Louisiana. Available design codes provide information about the design of regular roof geometries (e.g. hip/gable roofs), but refer to wind tunnel modelling for complex roof geometries. Due to time and financial constraints physical modelling may not always be possible to carry out. Computational modelling through Large Eddy Simulation (LES) has been used successfully for several wind engineering applications. This paper presents comparisons between LES and previously obtained wind tunnel data of mean and peak pressure coefficients on a low …

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Ndm-515: An Original Model Of Infrastructure System Resilience, Jingjing Kong, Slobodan P. Simonovic Jun 2016

Ndm-515: An Original Model Of Infrastructure System Resilience, Jingjing Kong, Slobodan P. Simonovic

Canadian Society for Civil Engineering

Infrastructure systems of transportation, water supply, telecommunications, power supply, etc. are not isolated but highly interconnected and mutually coupled. Infrastructure interdependences can increase system vulnerability and produce cascading failures at the regional or national scales. Taking the advantage of network theory structure analysis, this paper models street, water supply network, power grid and information infrastructure as network layers that are integrated into a multilayer network. The infrastructure interdependences are detailed using five basic dependence patterns of network fundamental elements. Definitions of dynamic cascading failures and recovery mechanisms of infrastructure systems are also established. The main focus of the paper is …

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Ndm-516: Tsunami Vulnerability Assessment Of Canadian West Coast Communities Based On Evacuation Capability, Isabelle M. Cheff, Ioan Nistor, Dan Palermo Jun 2016

Ndm-516: Tsunami Vulnerability Assessment Of Canadian West Coast Communities Based On Evacuation Capability, Isabelle M. Cheff, Ioan Nistor, Dan Palermo

Canadian Society for Civil Engineering

The Canadian Pacific coast is located in a highly seismic region with active convergent plates with the potential to generate large tsunamis. The tsunami vulnerability of communities in British Columbia is assessed using geographical information system (GIS) model for potential run up heights between 3-25 m and the difference between the necessary pedestrian time to safety and the tsunami arrival time, defined as the available time (AT). Using these metrics, 8 communities were identified to be highly vulnerable to tsunami due to run ups of 25 m: Ucluelet, Gordon River 2 IRI, Tofino, Esowista 3 IRI, Hesquiat 1 IRI, Hope …

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Ndm-518: Effects Of Non-Traditional Isolator Placement For Seismic Retrofit, Adrian P. Crowder, Tracy C. Becker Jun 2016

Ndm-518: Effects Of Non-Traditional Isolator Placement For Seismic Retrofit, Adrian P. Crowder, Tracy C. Becker

Canadian Society for Civil Engineering

Seismic isolation delivers improved performance by means of a flexible layer at which lateral deformation is concentrated. However, for seismic retrofit applications base isolation systems can be of considerable expense, in significant part because of major alterations required at the base of the structure. The cost of introducing an additional diaphragm, constructing a seismic gap, and modifying the foundation causes the initial cost of isolation to be significantly higher than traditional non-isolation retrofit methods. To minimize initial costs, isolators may be placed directly at the top of the column level, without an additional diaphragm, instead of at the base of …

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Ndm-522: Decentralized Semi-Active Control For Multi-Performance-Based Design, Young-Jin Cha Jun 2016

Ndm-522: Decentralized Semi-Active Control For Multi-Performance-Based Design, Young-Jin Cha

Canadian Society for Civil Engineering

Traditional performance-based design (PBD) that has a single performance level has been widely researched by changing section sizes of structural members or material properties to resist single hazard levels. However, this approach has limitations in terms of achieving performance and alternative design options for the owner. To overcome these limitations of the traditional PBD method, a multi-performance-based control design (MPBCD) methodology is newly proposed. The MPBCD integrates a decentralized semi-active control algorithm with semi-active smart damping devices and an advanced multi-objective optimization method. The multi-objective optimization is used to achieve various sets of performance-based control designs. The control designs satisfy …

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Ndm-519: Wind Testing Of Span-Wire Traffic Signal Systems, Peter A. Irwin, Ioannis Zisis, Benito Berlanga, Bodhisatta Hajra, Arindam Chowdhury Jun 2016

Ndm-519: Wind Testing Of Span-Wire Traffic Signal Systems, Peter A. Irwin, Ioannis Zisis, Benito Berlanga, Bodhisatta Hajra, Arindam Chowdhury

Canadian Society for Civil Engineering

Traffic signals are a critical part of the transportation infrastructure and it is important that they be robust enough to resist extreme wind storms lasting several hours. Failure of the signal systems results in unsafe traffic conditions during and after a storm, and the time taken for repairs delays recovery. A significant fraction of existing signals use span-wire supporting systems. The wire spans can range from 15 m to 60 m, depending on the width of the highway intersection, and exhibit nonlinear characteristics. The typical signal system used in Florida consists of the signal units, a catenary wire, hangers, a …

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Ndm-523: Use Of An Unmanned Aerial Vehicle (Uav) To Assess Transportation Infrastructure, Immediately After A Catastrophic Storm Event, Laird D. Ferguson, Lindon Miller, Mike Wolfe, Jared Mcginn, Lloyd Waugh Jun 2016

Ndm-523: Use Of An Unmanned Aerial Vehicle (Uav) To Assess Transportation Infrastructure, Immediately After A Catastrophic Storm Event, Laird D. Ferguson, Lindon Miller, Mike Wolfe, Jared Mcginn, Lloyd Waugh

Canadian Society for Civil Engineering

From September 29 to October 1, 2015 over 200 mm of rain deluged parts of southern New Brunswick. The catastrophic rain event washed away bridge size culverts and conventional bridges, including the surrounding soil and asphaltic concrete pavement. Also erosion encroached on the driving lane of road and highway embankments at over 100 locations. Several homes and businesses were left stranded. A fast and efficient means was required to assess the impact on infrastructure after the storm. This paper presents the procedure and outcomes of using digital imagery captured with Unmanned Aerial Vehicles (UAVs) for post-disaster assessment. The use of …

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Ndm-524: Case Study To Assess The Sensitivity Of Prestressed Concrete Poles To Tornadoes, Ahmed M. Ibrahim, Ashraf A. El Damatty Jun 2016

Ndm-524: Case Study To Assess The Sensitivity Of Prestressed Concrete Poles To Tornadoes, Ahmed M. Ibrahim, Ashraf A. El Damatty

Canadian Society for Civil Engineering

Transmission line structures play a vital role in transmitting electricity from the source of production to the distribution system. The main components of a transmission line are the conductors, the insulator strings, the ground wires and the supporting towers. Among the different types of supporting towers, prestressed concrete transmission poles have the advantages of low installation and maintenance costs, appropriate delivery time, and corrosion resistivity. To the best of the authors’ knowledge, this paper represents the first investigation conducted to assess the response of cantilever prestressed concrete poles to tornadoes. The localized nature of the tornadoes and the extended length …

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Ndm-525: Effects Of Tornado Wind Speeds On Concrete Road Barriers, Aaron L. Jaffe, Eric R. Lalonde, Gregory A. Kopp Jun 2016

Ndm-525: Effects Of Tornado Wind Speeds On Concrete Road Barriers, Aaron L. Jaffe, Eric R. Lalonde, Gregory A. Kopp

Canadian Society for Civil Engineering

Wind speeds can be difficult to measure during tornadoes due to their destructive nature. They pose a significant threat to lives and infrastructure in many parts of Canada and the U.S. The Enhanced-Fujita scale focuses on estimating these wind speeds by observing damage to different types of buildings, but significantly less research has been performed on the damage of other structures. Learning more about the effects of high wind speeds on these structures will help improve the ease and accuracy of future tornado classification. A wind tunnel study was performed at the Boundary Layer Wind Tunnel Laboratory of Western University. …

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Ndm-526: Investigation Of Stable And Unstable Fiber-Reinforced Elastomeric Isolators, Niel C. Van Engelen, Michael J. Tait, Dimitrios Konstantinidis Jun 2016

Ndm-526: Investigation Of Stable And Unstable Fiber-Reinforced Elastomeric Isolators, Niel C. Van Engelen, Michael J. Tait, Dimitrios Konstantinidis

Canadian Society for Civil Engineering

Fiber-reinforced elastomeric isolators (FREIs) are a potentially low-cost alternative to conventional steel-reinforced elastomeric isolators. FREIs can exhibit a non-linear horizontal force-displacement relationship characterized by a softening and stiffening phase, similar to other adaptive isolation devices such as the triple friction pendulum. This non-linear relationship is a consequence of unique deformations that occur during horizontal displacement denoted as rollover, which causes softening, and full rollover, which causes stiffening. The magnitude of the softening due to rollover is primarily governed by the width-to-total height aspect ratio of the FREI. If the aspect ratio is low, below about 2.5, the isolator may be …

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Ndm-528: An Approach To Classification Of Natural Disasters By Severity, H. Jithamala Caldera, S. C. Wirasinghe, L. Zanzotto Jun 2016

Ndm-528: An Approach To Classification Of Natural Disasters By Severity, H. Jithamala Caldera, S. C. Wirasinghe, L. Zanzotto

Canadian Society for Civil Engineering

Existing scales for natural disasters describe severity in terms of intensity. Intensity scales are not highly correlated with impact factors such as fatalities, injuries, homelessness, affected population, and cost of damage. The descriptive words for disasters are also not sufficient to clearly comprehend the real magnitude of severity as there is no consistent method to distinguish one terminology from another. Further, data collection standards vary among countries and, therefore, comparisons across space and time are difficult to make. Several discrepancies between various sources of information complicate the interpretation of trends in disaster data. Furthermore, comparing different events and obtaining a …

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Ndm-529: Numerical Evaluation Of Wind Loads On A Tall Building Located In A City Centre, Ahmed Elshaer, Haitham Aboshosha, Girma T. Bitsuamlak, Ashraf A. El Damatty Jun 2016

Ndm-529: Numerical Evaluation Of Wind Loads On A Tall Building Located In A City Centre, Ahmed Elshaer, Haitham Aboshosha, Girma T. Bitsuamlak, Ashraf A. El Damatty

Canadian Society for Civil Engineering

Estimation of wind-induced loads and responses is an essential step in tall building design process. Wind load for super tall buildings is commonly evaluated using boundary layer wind tunnel (BLWT) tests. However, the recent development in computational power and techniques is encouraging designers to explore numerical wind load evaluations using a Computational Fluid Dynamics (CFD) approaches. CFD can provide a faster estimation for building loads and responses with lower cost and satisfactory accuracy for preliminary design stages. The current study investigates the accuracy of evaluating wind pressure and building responses of a typical tall building (CAARC building). Two configurations are …

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Ndm-530: Aerodynamic Optimization To Reduce Wind Loads On Tall Buildings, Ahmed Elshaer, Girma T. Bitsuamlak, Ashraf A. El Damatty Jun 2016

Ndm-530: Aerodynamic Optimization To Reduce Wind Loads On Tall Buildings, Ahmed Elshaer, Girma T. Bitsuamlak, Ashraf A. El Damatty

Canadian Society for Civil Engineering

Wind is one of the governing load cases for tall building design, which produces high level of straining actions, deflections and lateral and transverse vibrations. Keeping those vibrations within the comfort limits is becoming a key aspect in tall building design, especially for buildings with high aspect ratio. Improving the aerodynamic performance of the tall building by modifying its shape can lower building motions, which reduces the additional expenses for external damping systems and alleviate the high cost associated with lateral support systems. In the present study, an aerodynamic shape optimization procedure is developed by combining Computational Fluid Dynamics (CFD), …

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Ndm-531: Wind Tunnel Testing Of Residential Neighbourhood Model To Analyze Roof Failures In High Winds, Eric R. Lalonde, Gregory A. Kopp Jun 2016

Ndm-531: Wind Tunnel Testing Of Residential Neighbourhood Model To Analyze Roof Failures In High Winds, Eric R. Lalonde, Gregory A. Kopp

Canadian Society for Civil Engineering

The EF-Scale estimates tornado wind speeds by the damage left in their wake, including the damage done to residential houses. The scale was developed based on an expert elicitation process, and so empirical testing is useful in determining its accuracy. Wind tunnel testing is often used to test low-rise buildings but building code configurations tend to be single, isolated houses, even though residential houses are much more common in suburban environments with many neighbouring buildings. The objective of this testing was to assess the roof-failure wind speeds for residential buildings in typical neighbourhood patterns and compare them to rural residence …

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Ndm-534: Sensitivity Of Wind Induced Dynamic Response Of A Transmission Line To Variations In Wind Speed, Saif Haddadin, Haitham Aboshosha, Ayman M. El Ansary, Ashraf A. El Damatty Jun 2016

Ndm-534: Sensitivity Of Wind Induced Dynamic Response Of A Transmission Line To Variations In Wind Speed, Saif Haddadin, Haitham Aboshosha, Ayman M. El Ansary, Ashraf A. El Damatty

Canadian Society for Civil Engineering

This paper studies the dynamic behavior of a multi-span transmission line system under synoptic wind considering various speeds to determine the range of wind speeds in which the system experiences resonance. A finite element numerical model was developed for the purpose of this study. This model is employed to assess the dynamic behavior of a self-supported lattice tower line under various wind speeds. Dynamic Amplification Factor (DAF), defined as the ratio between the peak total response to the peak quasi-static response, is evaluated. It is found that conductors’ responses exhibit large DAF compared to the towers especially at low wind …

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Ndm-535: Structural Modelling And Verification Methods To Develop A Cable Roof Harness Retrofit System, Joshua D. Rosenkrantz, Adnan Enajar, Ryan Jacklin, Ashraf A. El Damatty Jun 2016

Ndm-535: Structural Modelling And Verification Methods To Develop A Cable Roof Harness Retrofit System, Joshua D. Rosenkrantz, Adnan Enajar, Ryan Jacklin, Ashraf A. El Damatty

Canadian Society for Civil Engineering

Load paths in light-frame wood structures have historically been nailed connections between the sheathing and rafters, and toenail connections between the rafters and stud walls. However, these connections have poor resistance to uplifting forces, as occurs in high wind speed events, causing sheathing or roof-to-wall-connection (RTWC) failures. The improvements made to building codes after Hurricane Andrew affected only new construction, and the economic losses caused by roof failures in homes built prior to 1993 from Hurricane Katrina pointed to a need to retrofit older structures. This paper will investigate the design, analysis, and testing of a temporary cable-netting roof harness …

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Ndm-536: Effect Of Wind Speed And Terrain Exposure On The Wind Pressures For Elevated Steel Conical Tanks, Ahmed Musa, Haitham Aboshosha, Ashraf A. El Damatty Jun 2016

Ndm-536: Effect Of Wind Speed And Terrain Exposure On The Wind Pressures For Elevated Steel Conical Tanks, Ahmed Musa, Haitham Aboshosha, Ashraf A. El Damatty

Canadian Society for Civil Engineering

Steel liquid storage tanks in the form of truncated cones are commonly used as containment vessels for water supply or storing chemicals. A number of failures have been recorded in the past few decades for steel liquid tanks and silos under wind loading. A steel conical tank vessel will have a relatively small thickness making it susceptible to buckling under wind loads especially when they are not fully-filled. In this study, a wind tunnel pressure test is performed on an elevated conical tank in order to estimate the external wind pressures when immersed into a boundary layer. The tested tank …

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Ndm-538: Wind Tunnel Testing Of A Multiple Span Aeroelastic Transmission Line Subjected To Downburst Win, Amal Elawady, Haitham Aboshosha, Ashraf A. El Damatty, Girma T. Bitsuamlak Jun 2016

Ndm-538: Wind Tunnel Testing Of A Multiple Span Aeroelastic Transmission Line Subjected To Downburst Win, Amal Elawady, Haitham Aboshosha, Ashraf A. El Damatty, Girma T. Bitsuamlak

Canadian Society for Civil Engineering

A 1:50 scale aeroelastic wind tunnel test for a multi-span transmission line system is conducted at the WindEEE dome under downburst wind. WindEEE is a novel three-dimensional wind testing facility capable of simulating downbursts and tornadoes. This test simulates a transmission line consisting of v-shaped guyed towers holding three conductor bundles. Details about the model design, the wind field and the test setup are provided. A downburst loading case that is critical for the line design and causes unbalanced tension load on the conductors is investigated in the current study. Resulting line responses obtained from the test are compared with …

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Ndm-539: Iron Ore Mine Waste Floodwater Extent Mapping Utilizing Remote Sensing Derived Indices, A. M. Elshorbagy, Ahmed Shaker Jun 2016

Ndm-539: Iron Ore Mine Waste Floodwater Extent Mapping Utilizing Remote Sensing Derived Indices, A. M. Elshorbagy, Ahmed Shaker

Canadian Society for Civil Engineering

The collapse of two iron ore mine dams in south-eastern Brazil on 5 November 2015 is one of the recent environmental disasters. The clean-up and environment recovery would take several years and cost billions of dollars. Mapping the extent of the affected areas and monitoring the water quality deterioration is a challenge. In this study the new optical satellite SENTINEL 2 imagery along LANDSAT 8 were utilized to test the applicability of the Land Surface Water Index (LSWI) and Modified Normalized Difference Water Index (MNDWI) in the mapping process. The systematic coverage of the study area from the aforementioned satellites …

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Ndm-540: The Use Of Remote Sensing Technique To Assess Flood Hazard In City Of Jeddah, Saudi Arabia, Kamil Faisal, Ahmed Shaker Jun 2016

Ndm-540: The Use Of Remote Sensing Technique To Assess Flood Hazard In City Of Jeddah, Saudi Arabia, Kamil Faisal, Ahmed Shaker

Canadian Society for Civil Engineering

The City of Jeddah became lately one of the typical regions that affected by natural hazard. Previous flood that occurred in 2009 was one the most tragic natural disaster in the history of Saudi Arabia, which caused death for more than one hundred people. On 17th of November 2015, Jeddah turned into a disaster zone again due to heavy rainfall and the lack of drainage system. The objectives of the study are (1) To illustrate the hazard areas in the City of Jeddah that need an urgent drainage system; and (2) To evaluate the threats that the City of Jeddah …

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Ndm-541: The Heat Loads Of A Tuned Mass Damper, J. Shayne Love, Trevor C. Haskett Jun 2016

Ndm-541: The Heat Loads Of A Tuned Mass Damper, J. Shayne Love, Trevor C. Haskett

Canadian Society for Civil Engineering

Modern tall buildings are often susceptible to excessive wind-induced motions. Tuned mass dampers (TMDs) are used to improve occupant comfort by reducing structural accelerations during common winds, and also to reduce building drift during stronger winds. A TMD is an auxiliary mass that is connected near the top of the structure through elements that produce restoring and damping forces. If the TMD is designed to have the appropriate natural frequency and damping ratio, vibrational energy from the structure is transferred to the TMD where it is dissipated through the TMD damping. This additional source of energy dissipation increases the effective …

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Ndm-546: Case Studies On The Impact Of Surrounding Buildings On Wind-Induced Response, John Kilpatrick Jun 2016

Ndm-546: Case Studies On The Impact Of Surrounding Buildings On Wind-Induced Response, John Kilpatrick

Canadian Society for Civil Engineering

In multi-tower and/or multi-phase developments, the impact of prominent nearby surroundings can play a large role in the aerodynamic conditions of proposed developments. This paper focuses on two case studies: i) two 160 m tall residential towers atop a prominent transportation terminal and ii) a tall (220 m) residential tower in complex terrain with significant future development. Comparisons will be made of the structural wind loads on the towers under various sheltering conditions. Both cases quantifies the amplification of wind loads due to vortex shedding off an existing upwind building 4 to 6 building widths upstream, as well as the …

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Ndm-547: Risk Analysis Of Wind Loading Including Future Changes In Surrounding Buildings, Peter A. Irwin, Jeff Stanton Jun 2016

Ndm-547: Risk Analysis Of Wind Loading Including Future Changes In Surrounding Buildings, Peter A. Irwin, Jeff Stanton

Canadian Society for Civil Engineering

Wind tunnel tests of tall buildings are capable of accurately determining the wind loads on a building in its current surroundings, since the surroundings are included in the wind tunnel modelling. The tests may also include some future developments if they are known to be imminent. However, the question of the effects of possible longer term changes in surroundings needs to be considered. In some cases the development of the city may be mature resulting in little likelihood of future changes, but in rapidly developing cities the possible changes may be significant. It is known that buildings very close to …

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Ndm-550: Comprehensive Study Of Wind-Induced Torsional Loads On Low- And Medium-Rise Buildings, Mohamed Elsharawy, Ted Stathopoulos, Khaled Galal Jun 2016

Ndm-550: Comprehensive Study Of Wind-Induced Torsional Loads On Low- And Medium-Rise Buildings, Mohamed Elsharawy, Ted Stathopoulos, Khaled Galal

Canadian Society for Civil Engineering

This paper summarizes the findings of extensive wind tunnel parametric investigations on wind-induced torsion acting on rectangular flat- and gable-roofed buildings. Experiments collected data for different configurations in terms of terrain exposure, wind direction and building height. In addition, wind load combinations (i.e. shear forces and torsion) in transverse and longitudinal building directions were examined. Comparisons with the results obtained from provisions specified in current design standards and codes of practice were also carried out. Three building models (scaled at 1:400) have the same horizontal dimensions (length = 61 m, width = 39 m) but with different gabled-roof angles (0o, …

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Ndm-551: Towards A Robust Wind Tunnel Based Evaluation Of Extreme Wind Loads, Haitham Aboshosha Jun 2016

Ndm-551: Towards A Robust Wind Tunnel Based Evaluation Of Extreme Wind Loads, Haitham Aboshosha

Canadian Society for Civil Engineering

Proper modeling of the boundary layer flow is essential for wind load evaluation under extreme events such as hurricanes. This layer is formed due to the interaction of wind with natural or man-made obstacles over the surface of the earth. Such interactions generate drag forces proportional to the roughness of the ground which shape the characteristics of the boundary layer, including mean velocity and turbulence intensity profiles, as well as the spectral contents and correlations. In the current study, a robust technique for evaluating extreme wind loads using wind tunnels is proposed and validated. The technique is based on automatic …

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