Entity

Time filter

Source Type

Morrison, United States

Guner S.,Morrison Hershfield Ltd | Vecchio F.J.,University of Toronto
Proceedings, Annual Conference - Canadian Society for Civil Engineering | Year: 2011

Due to elevated terror threats and the frequent occurrences of destructive earthquakes, nonlinear dynamic analysis methods have been increasingly used in recent years for the performance assessment, upgrading and design verification of frame structures. Currently available analytical procedures, however, are typically overly simplistic, reducing each structural component to a single-degree-of freedom system for the impact and blast analyses, and employing a lumped-plasticity approach for the seismic and progressive collapse analyses. Micro finite element methods, on the other hand, are typically overly complex and time consuming, thus having limited applicability to large frames found in practice. In both types of methods, modeling shear mechanisms remains a significant challenge, typically handled by neglecting shear effects altogether. A research initiative is undertaken to develop a nonlinear analysis procedure that accurately considers shear effects within a multi-degree-of-freedom distributed-plasticity formulation - but one that does not require extensive pre-selection of analysis options and input of hysteresis model parameters, and one that is suitable for large-scale applications. Applicable to reinforced concrete plane frames subjected to impact, blast and seismic loads, the procedure uses an explicit three-parameter time-step integration method and directly considers the effects of the loading rate on the material behaviours. Structural damping is intrinsically incorporated through the nonlinear concrete and reinforcement hysteresis models implemented. Significant second-order mechanisms, such as membrane action, concrete out-of-plane confinement effects, and reinforcement dowel action, are inherently accounted for. This paper provides an overview of the procedure developed and discusses its application to eleven previously tested specimens to examine its accuracy, reliability and practicality. Source


Guner S.,Morrison Hershfield Ltd | Vecchio F.J.,University of Toronto
ACI Structural Journal | Year: 2010

An analytical procedure was recently developed for the nonlinear analysis of reinforced concrete frame structures consisting of beams, columns, and shear walls under monotonic and pushover loading. The advantage of the procedure lies in its inherent and accurate consideration of shear effects and significant second-order mechanisms within a simple modeling process suitable for use in practice. Herein, the application of the procedure to 33 previously tested specimens, two-thirds of which were shear-critical, is presented to verify the algorithms developed. Important considerations in nonlinear modeling are also discussed to provide guidelines for general modeling applications. The procedure is found to simulate the experimental behaviors of the specimens examined with a high level of accuracy. Experimental strengths, stiffnesses, ductilities, and failure modes were all calculated accurately. Computed parameters such as crack widths, reinforcement strains, and member deformations were also represented successfully. The procedure exhibits excellent convergence and numerical stability, requiring little computational time. Copyright © 2010, American Concrete Institute. All rights reserved. Source


Deluce J.R.,Morrison Hershfield Ltd | Deluce J.R.,University of Toronto | Vecchio F.J.,University of Toronto
ACI Structural Journal | Year: 2013

Uniaxial tension tests were conducted on 12 plain reinforced concrete (RC) and 48 large-scale steel fiber-reinforced concrete (SFRC) specimens, each containing conventional longitudinal reinforcement, to study their cracking and tension-stiffening behavior. The test parameters included fiber volumetric content, fiber length and aspect ratio, conventional reinforcement ratio, and steel reinforcing bar diameter. "Dog-bone" tension tests and bending tests were also performed to quantify the tensile properties of the concrete. It was found that the cracking behavior of SFRC was significantly altered by the presence of conventional reinforcement. Crack spacings and crack widths were influenced by the reinforcement ratio and bar diameter of the conventional reinforcing bar, as well as by the volume fraction and aspect ratio of the steel fiber. Details and results of the experimental investigation are provided and discussed.Copyright © 2013, American Concrete Institute. All rights reserved. Source


Ebisa Fola M.,Morrison Hershfield Ltd | Rennie C.D.,University of Ottawa
Journal of Hydraulic Engineering | Year: 2010

Empirical downstream hydraulic geometry equations for consolidated clay-dominated cohesive bed (nonalluvial) natural streams are presented using data from six rivers in eastern Ontario, Canada and four rivers from other regions. The width exponent (0.57) was comparable to the exponents reported for previous studies; however, the depth exponent (0.52) was greater for clay-dominated cohesive bed than for typical alluvial gravel-bed and sand-bed rivers. The width to depth ratio of smaller channels (Qbf<20 m3/s) was greater for consolidated clay bed than for either sand-bed or gravel-bed channels. This study suggests that the concept of hydraulic geometry and bankfull (channel forming) discharge can be extended to nonalluvial consolidated clay-bed channels. © 2010 ASCE. Source


Teasdale-St-Hilaire A.,Morrison Hershfield Ltd
Thermal Performance of the Exterior Envelopes of Whole Buildings - 12th International Conference | Year: 2013

There is a growing awareness in the residential building industry about the significance of energy use in buildings and the desire to minimize energy consumption and costs. In the construction industry, the importance of building commissioning to verify the installation and performance of various building systems is rising. Post-occupancy evaluation (POE) of buildings goes beyond commissioning. POE is the systematic assessment of building performance during service and typically includes analysis of the users' perceptions. A literature survey revealed the lack of a comprehensive POE methodology for multi-unit residential buildings (MURBs) that addresses the major building systems, including the building envelope. To fill this gap, a POE framework has been developed for MURBs. As very limited information is available in the public domain on the performance of MURBs, the information obtained from POEs could be of use to identify avenues of improvements to the benefit of building owners and occupants and to develop benchmark data on performance indicators to support the development of building codes, regulations, and guidelines. Evaluating the performance of new, innovative building systems and practices applied to newly constructed or retrofitted MURBs can serve to show whether promised benefits are actually delivered. The POE protocol focuses on seven performance areas: energy efficiency, water use efficiency, indoor air quality, lighting and the visual environment, acoustics, thermal comfort, and building envelope performance. This paper presents the literature survey findings, the protocol's objectives, the qualitative and quantitative indicators used to gauge performance, and an overviewof the methodology's various tasks, with emphasis on the building envelope performance assessment, and its interaction with other systems. © 2013 ASHRAE. Source

Discover hidden collaborations