Reliability- and Mechanics-based Evaluation of Concrete Building Infrastructure

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Initiatives to improve the environmental sustainability of infrastructure must include more accurate assessment and rehabilitation of existing structures because they contain tremendous quantities of embodied energy that should not be wasted through demolition. Moreover, the 2012 collapse of the Algoma Mall in Elliot Lake and the subsequent Professional Engineers Ontario publication of structural condition assessment guidelines in 2016 emphasizes the critical importance of improved assessment measures to Canadian society. This need has independently been recognized by the American Concrete Institute, which formed Technical Committee 562 “Evaluation, Repair and Rehabilitation of Concrete Buildings” in 2006 to develop a new code for existing concrete structures, first published in 2013.******Meanwhile, the continuous drive to higher strength concrete and steel materials has made structures more susceptible to serviceability problems. Recent initiatives have markedly improved the accuracy of instantaneous deflections of concrete structures, but means to predict accurately the time-dependent deflections due to concrete shrinkage and creep remain elusive.******The long-term goal of the proposed research program, spawned by the Applicant's previous research and industrial experience, is to enhance practices for assessing, rehabilitating and managing existing infrastructure and for assessing the serviceability of concrete structures. These are necessary for engineers to make rational design, maintenance, repair and replacement decisions that will ensure Canada's infrastructure is managed safely, sustainably and economically.******The short-term objectives of the proposed research program are therefore to develop a new generation of reliability- and mechanics-based procedures for the rational safety assessment of existing concrete building infrastructure, to support current concrete standards, and to develop improved criteria for predicting the time-dependent deflection of concrete structures subjected to sustained loads. Six short-term objectives involving 5 USRA, 8 MESc, and 1 PhD students are envisaged: (1) benchmark safety levels implicit in current assessment practices; (2) develop consequence-based target reliability levels and associated assessment criteria; (3) assess the impact of reduced design life on specified transient loadings; (4) account for the uncertainty of proof-load test results in the quantification of the reliability of an existing structure; (5) quantify how loadings applied when newly placed concrete is less than a week old impact time-dependent deflections; and, (6) derive distinct factors for predicting the time-dependent deflections due to concrete shrinkage and creep.******The proposed research will provide the next generation of tools for assessing the safety and serviceability of concrete building infrastructure.**