Civil and Environmental Engineering Commons^™

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), …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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, …

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 …

Ndm-552: Combined Probabilities Of Peak Wind And Snow Load Events, Jill V. Bond, Albert J. Brooks, Scott L. Gamble, Jan C. Dale

Canadian Society for Civil Engineering

The National Building Code of Canada 2010 (NBCC) defines several loading combination scenarios for use in structural design. Appropriate combination factors are provided based on the probability of failure due to the simultaneous occurrence of the specified loads. Load Combination Cases 3 and 4 of Table 4.1.3.2.A include the combination of wind and snow loads, which are transient in nature. The recommended combination factors are intended to provide a uniform degree of reliability for design. However, in reality, the probability of the simultaneous loading due to wind and snow depends on the local meteorological climate. This probability can be more …

Ndm-555: Experimental Investigations Of Large Scale Tld-Structure Interaction Via Real-Time Hybrid Simulation, Ali Ashasi-Sorkhabi, Oya Mercan

Canadian Society for Civil Engineering

In real-time hybrid simulation (RTHS), as a cost-effective experimental testing technique, computer simulations are coupled with physical testing. RTHS divides the test structure into analytical and experimental substructures, and synchronizes them as the equations of motion are being solved in real-time. When conducted properly, the load-rate dependent characteristics of the test structure could be accurately captured by the RTHS. This paper presents real-time hybrid simulation of a three story structure equipped with a large scale tuned liquid damper (TLD) using a recently developed computational/control platform at University of Toronto. TLDs are cost effective and low maintenance vibration absorbers that can …

Ndm-556: Wind Uplift Resistance Design Of A Green Roof, Mike Gibbons, Scott L. Gamble, J. Shayne Love

Canadian Society for Civil Engineering

Green roofs, also referred to as vegetated roofs, have increased in popularity in recent years in North America. Traditionally their use had been more prominent in European countries, such as Germany, however the North American design community have recently adopted them, thanks in part to programs such as LEED and the City of Toronto’s Green Roof Bylaw. Toronto’s Green Roof Bylaw mandates “green roofs on new commercial, institutional and residential development with a minimum Gross Floor Area of 2,000m2 as of January 31, 2010”. Also contained within the aforementioned Green Roof Bylaw is a requirement that the submitted green roof …

Ndm-557: Computational Modeling Of Hill Effects On Tornado Like Vortex, Zoheb Nasir, Girma T. Bitsuamlak

Canadian Society for Civil Engineering

Tornado is a complex flow structure, where high swirling flow closer to the ground converges to the center and then moves upward. As a result, it creates a high suction pressure at the ground near the center of the tornado. The main objective of this study is to analyse the impact over flow structure and ground pressure by implementing topographical changes. For the present study a one-celled tornado replicating a real EF-2 scale has been chosen. Previous study suggests that suction ground pressure is highest at the tornado core center, also it changes more sharply near the core center. As …

Ndm-558: Computational Modeling Of Tornadic Load On A Tall Building, Zoheb Nasir, Girma T. Bitsuamlak

Canadian Society for Civil Engineering

Numerical simulations are carried out to analyse the impact of tornadic load on a tall building. For the present study a one-celled tornado replicating a real EF-2 scale has adopted. A standard tall building based on the Commonwealth Advisory Aeronautical Research Council (CAARC) is used. For detail analysis, the tornado is placed in three different locations with respect to the center of the building. These locations are at the tornado center, at the core radii and outside core radii. As the building has rectangular cross section (plan wise), two different orientation of the building with respect to the center of …

Ndm-559: Experimental Investigation Of Two-Way Concrete Panels Exposed To Impact Load, Heba G. S. Bayoumy, Mohamed A. N. Abdel-Mooty, A. Samer Ezeldin

Canadian Society for Civil Engineering

Protecting existing and new structures from potential terrorist attacks and accidents is becoming an essential consideration in the design of most structures. Building façade is the first layer exposed to external loading, thus it acts as the first line of defence against external loads. Precast concrete panels are mostly used in external building's façade for modern construction, and therefore their resistance to other dynamic loads such as impact load needs further evaluation. This paper presents the results of an experimental research on two-way reinforced concrete panels as well as thin ferrocement concrete panels under impact loading. The impact test apparatus …

Ndm-561: Municipal Risk Assessment Tool (Mrat), Scott Praill

Canadian Society for Civil Engineering

MRAT is a made-in-Canada tool that overlays municipal data sets and insurance claims data onto an interactive map. The tool allows infrastructure managers to accurately identify areas with frequent insurance claims and easily identify where a more in-depth assessment should occur. The tool facilitates an understanding of risk factors to potentially impacted areas allowing owners to start to diagnose problems and generate solutions before flooding occurs. The process began with an original objective that would identify areas where there are an increased number of insurance claims. Early in its development, it became obvious that it could be a valuable tool …

Ndm-562: Behaviour Of Concrete Columns With Gfrp Circular And Rectilinear Confining Reinforcement, Zahra Kharal, Shamim A. Sheikh

Canadian Society for Civil Engineering

Glass Fibre-Reinforced Polymer (GFRP) bars are becoming a feasible alternative to steel bars to produce corrosion- free reinforced concrete structures. In an effort to assess the effectiveness GFRP spirals and GFRP rectilinear ties as internal reinforcement in columns, an extensive research program is underway at the University of Toronto. Fifteen 356 mm diameter full-scale circular columns and sixteen 305 mm x 305 mm cross-section square columns were constructed and tested under simulated earthquake loading. This extended abstract presents an example comparison of the experimental behaviour of circular and square concrete columns with internal reinforcement comprising of steel longitudinal bars and …

Ndm-563: The Vertical, Rotational And Lateral Response Of Unbonded Fiber Reinforced Elastomeric Isolators, Yasser M. Al-Anany, Michael J. Tait, Mark Torrie, Alexander N. Sciascetti

Canadian Society for Civil Engineering

Bridge structures often experience damage during an earthquake, which is one of the most devastating types of natural disasters. Base isolation can be employed to mitigate earthquake-induced damage. The main concept of base isolation is to reduce the seismic demand on the structure by shifting its fundamental time period away from the predominant periods associate with earthquakes. Base isolation involves placing horizontally flexible isolators between the bridge superstructure (i.e. deck/girder) and the substructure (i.e. pier/column). There are two main types of seismic isolators: (1) elastomeric, and (2) sliding. A fiber reinforced elastomeric isolator (FREI) is a particular type of reinforced …

Str-805: Experimental Evaluation Of The Robustness Of Wt Connections Under Quasi-Dynamic Load, Megan E. Hayes, Christopher H. Raebel, Christopher M. Foley

Canadian Society for Civil Engineering

Flexible (simple) shear connections commonly used in steel-framed buildings are very economical and are relatively easy to fabricate. These connections are used for shear resistance, but recent studies have shown that they are capable of sustaining an interaction of rotational and axial load demand necessary for steel-framed building structures to help resist collapse in the event of unanticipated damage scenarios.

The objective of this paper is to outline and discuss an experimental effort designed to evaluate the robustness of flexible WT connections. The experimental program included twelve full-scale tests of a system consisting of two wide flange beams connected to …

Str-806: Experimental Evaluation Of The Robustness Of Single Plate Shear Connections Under Quasi-Dynamic Load, Jacklyn E. Lesser, Christopher H. Raebel, Christopher M. Foley

Canadian Society for Civil Engineering

Flexible (simple) shear connections commonly used in steel-framed buildings are very economical and are relatively easy to fabricate. These connections are used for shear resistance, but recent studies have shown that they are capable of sustaining an interaction of rotational and axial load demand necessary for steel-framed building structures to help resist collapse in the event of unanticipated damage scenarios.

The objective of this paper is to outline and discuss an experimental effort designed to evaluate the robustness of single plate shear connections under a quasi-dynamic loading scenario simulating the loss of a central column. The experimental program included eleven …

Str-807: Ansys Modeling Of Post-Tensioned Steel Beam-Column Connections Under Cyclic Loading, Saber Moradi, M. Shahria Alam

Canadian Society for Civil Engineering

Permanent deformations in a steel moment resisting frame can be eliminated by using post-tensioned (PT) elements. This paper presents the development of three-dimensional finite element models of PT steel beam-column connection subassemblies. Knowing that there is limited experimental data in the literature on PT steel connections with top-and-seat angles, reliable finite element models can be used to investigate the load carrying behaviour of PT steel connections as well as producing more data for these new connections. In this paper, finite element modelling, meshing, and analysis are performed in the commercial software, ANSYS. The analysis includes geometric and material nonlinearities, pre-loaded …

Str-808: Re-Testing Of A Fire-Damaged Bridge, Alexander M. C. Au

Canadian Society for Civil Engineering

A proof load test was performed on a fire-damaged bridge in October 2008 and its load capacity was confirmed. The bridge was then re-opened for full traffic shortly after the load test. It was further repaired in 2009 which included concrete patching and carbon fibre reinforced polymer (CFRP) warping of 6 girders in the main span. The bridge is located at one of the busiest highways of the country with many heavy trucks passing daily. Also, reinforced concrete could deteriorate much faster than usual after the fire accident. In 2014, the Bridge Office was requested to re-test the bridge in …

Str-810: A Formulated Approach To Cisc Shear Connection Resistance And Flexibility Design, Josiah J. Matthews, Kaveh Arjomandi

Canadian Society for Civil Engineering

The design of simple shear connections has been extensively studied by several researchers. The design requirements for ductility and strength of these connections have been established through both experimental and theoretical approaches. However, the current Canadian design guidelines such as the Handbook of Steel Construction published by the Canadian Institute of Steel Construction (CISC) do not provide a formulated approach for the design of shear connections. In addition, the CISC design approach is somewhat out dated when it comes to providing adequate rotational ductility. In this paper, a formulated approach for the design of bolted double angle shear connections considering …

Str-811: Examination Of Effective Length Factor For Rc Columns In Non-Sway Frames, S. Ali Mirza, Timo K. Tikka

Canadian Society for Civil Engineering

The Canadian Standards Association (CSA) Standard for Design of Concrete Structures (A23.3-04) permits the use of moment magnifier method for computing the design ultimate strength of slender reinforced concrete (RC) columns that are part of non-sway frames. This computed strength is influenced by the column effective length factor K, effective flexural stiffness EI, and equivalent uniform bending moment diagram factor Cm among others. Previous investigations by the authors examined the equations available in literature for computing EI and Cm factor. For this study, nearly 3000 simple non-sway reinforced concrete frames subjected to short-term loads were simulated and used to investigate …

Str-813: Fragility Of Low-Rise Controlled Rocking Steel Braced Frames With Different Base Rocking Joints, Taylor C. Steele, Lydell D. A. Wiebe

Canadian Society for Civil Engineering

Controlled rocking steel braced frames (CRSBFs) are resilient seismic force resisting systems that can self-centre the structure and prevent structural damage during design-level earthquakes. Energy dissipation may be provided to limit peak displacements, while post-tensioning provides self-centering after rocking. Previous studies have shown that designing energy dissipation and the post-tensioning components in CRSBFs using a response modification factor of R = 8 is sufficient to prevent collapse of structures during earthquakes higher than the design level. However, designers have unique control over the hysteretic behaviour of the system, even after the response modification factor is selected. Additionally, recent studies have …

Str-814: Lessons Learned From The Nairn Avenue Overpass Concrete Girder & Pier Repairs, David A. Neilson, Darren Burmey, Scott Loptson

Canadian Society for Civil Engineering

The Nairn Avenue Overpass is a 213 m long, 11-span, 4-lane + sidewalk precast prestressed concrete I-girder bridge over the CP Keewatin Subdivision line in Winnipeg, MB. The superstructure consists of three continuous segments with deck joints at piers #3 and #8. The structure was built in 1967, and underwent major strengthening and rehabilitation of the deck, girders, and bearings in 1985. Piers consist of a cast-in-place pier cap approximately 18 m long supported on two cast-in-place columns approximately 7 to 8 m tall supported on concrete pile caps over timber raft-pile foundations.

Leaking omega-style strip seal deck joints at …