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New designs of precast bridge parapets made with fibre reinforced concretes (FRC) were developed using nonlinear finite element calculations. A monolithic FRC parapet and a hybrid FRC parapet were designed. The latter parapet consisted of a shell of ultra-high performance FRC paired with a normal strength concrete core. Furthermore, two new anchorage systems were optimized for parapet installation on a new deck or for parapet replacement on an existing structure. Quasi-static tests showed that the load-carry capacity of the parapet designs exceed the PL-2 or TL-4 parapet specifications of CSA and AASHTO. The finite elements model developed in the project has satisfactorily reproduced the stiffness, ultimate strength, and failure mode of parapets. Additional numerical analyses were conducted for the hybrid parapet to provide design recommendations related to construction aspects and further optimizations. [ABSTRACT FROM AUTHOR]

This paper describes a functional tool for engineers to make rational design decisions by balancing cost and safety. Focus is on seismic design, in which nonlinear structural response must be considered. For this purpose, we implement and apply a state-of-the-art algorithm for reliability-based design optimization. The work extends the OpenSees software, which is rapidly gaining users in the earthquake engineering community. Consequently, design optimization with sophisticated nonlinear finite element models of real structures is possible. An object-oriented software architecture is employed that focuses on maintainability and extensibility of the software. This approach also offers flexibility in the choice of optimization and reliability methods for each specific problem, supported by the decoupled nature of the optimization algorithm. Our work utilizes and extends the existing tools for structural reliability analysis in OpenSees. In particular, we employ response sensitivities that are computed within the finite element code by direct differentiation. The implementation is tested through case studies with nonlinear structural response. Discontinuous response gradients are overcome by use of fibre cross sections and smoothed material models. The numerical examples include the seismic design optimization of a six-storey, three-bay, reinforced concrete building. [ABSTRACT FROM AUTHOR]