Development of Nonlinear Analysis Tools for Concrete Frame Buildings under Extreme Loads

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The need for nonlinear analysis methods for extreme loads has increased considerably in recent years. Heightened levels of terrorist threat, for example, have resulted in many government and commercial buildings being assessed and strengthened for possible bomb explosions and vehicle impacts. Frequent occurrences of destructive earthquakes and associated loss of life have required prompt assessment and reinforcement of many existing buildings worldwide for earthquake resilience. A number of analysis methods are available and commonly used in industry for extreme loads. These methods are based on overly simplified theories and neglect shear effects. This approach simplifies the modeling process and significantly reduces the analysis time required. Consequently, structural engineers with basic nonlinear analysis knowledge can use these methods. However, recent research studies have demonstrated that impact, blast and earthquake loads result in significant shear damage and the current methods used in industry tend to provide unreliable and inaccurate results. A number of advanced analysis tools, in the form of computer software, are available in the literature to consider shear effects. These tools, however, are overly complex and require expert knowledge on concrete and shear modeling. One reason for this is that they are general purpose tools for many materials (e.g., steel, wood, and concrete), loading conditions (e.g., static, dynamic, and thermal), and engineering disciplines (e.g., mechanical, geotechnical, and structural). This requires end users to make expert decisions and customize the tool for the structure being analyzed. Consequently, these tools are mostly suitable for academic researchers only. The long-term objective of my research is to develop comprehensive analysis methods by which the safety and performance of concrete structures can accurately be assessed under various loading conditions. My main goal is to provide structural engineers in industry with user-friendly nonlinear analysis software and documentation developed specifically for certain types of concrete structures. The anticipated outcome is to replace the overly simplified analysis methods currently used in industry and allow for more accurate, more economical, and safer design of concrete structures. As an important milestone, the objective of this research program is to develop an analysis method for impact, blast and earthquake loads and accurately consider shear effects with a simple modeling process suitable for use in industry. This will be achieved by developing a specialized method for only concrete frame buildings. The most suitable analysis options and parameters will be pre-implemented and end users will not need to make selections or inputs for them. Accurate shear and concrete modeling will be achieved by further developing an existing analysis procedure which was previously proven successful. More analytical and experimental work will be undertaken to advance our current knowledge and modeling capabilities for impact, blast and earthquake loads. The developed method will be implemented into a user-friendly computer tool to facilitate the transfer of the developed knowledge to industry and research communities. This tool and the related users’ manual will be made available over the internet for Canadian engineers and researchers, and it will be compatible with the latest computer systems. Concrete frame structures continue to be one of the most common building systems in Canada. The developed software will contribute to our capability to accurately analyze and assess the safety and performance of existing and new frame buildings to minimize the devastating effects of impact, blast, and earthquake loads.