Performance of FRP-concrete bridges under blast loading

Catastrophic failure from intentional terrorist attacks on surface transportation infrastructure could he detrimental to the society. In order to minimize the vulnerabilities and to ensure a safe transportation system, the issue of security for transportation structures, primarily bridges, which are subjected to man-made hazards is investigated in this study. A procedure for identifying and prioritizing "critical bridges" using a screening and prioritization processes is established. For each of the "critical" bridges, a systematic risk-based assessment approach is proposed that takes into account the combination of threat occurrence likelihood, its consequences, and the socioeconomic importance of the bridge. A series of effective security countermeasures are compiled in the four categories of deterrence, detection, defense and mitigation to help reduce the vulnerability of critical bridges. The concepts of simplified equivalent I-shape cross section and virtual materials are proposed for integration into a nonlinear finite element model, which helps assess the performance of reinforced concrete structures with and without composite retrofit or hardening measures under blast loading. A series of parametric studies are conducted for single column and two-column pier frame systems as well as for an entire bridge. The parameters considered include column height, column type, concrete strength, longitudinal steel reinforcement ratio, thickness, fiber angle and tensile strength of the fiber reinforced polymer (FRP) tube, shape of the cross section, damping ratio and different bomb sizes. The study shows the benefits of hardening with composites against blast loading. The effect of steel reinforcement on blast resistance of the structure is more significant than the effect of concrete compressive strength. Moreover, multiple blasts do not necessarily lead to a more severe destruction than a single detonation at a strategically vulnerable location on the bridges.

Coral Gables Virtual History

Florida International University has partnered with the City of Coral Gables to create a geospatially-enabled Virtual Historic City. With this tool, users may navigate to any point in the city at a selected time period (e.g. the Biltmore Hotel from the 1920s to 1940s) and experience the city as it was, through a wide variety of cultural artifacts and textual materials. A virtual walking tour of Coral Gables was also created, which includes an audio narration and 3D simulations providing the façades of historic buildings and landscape. Students, educators, historians, public policy administrators, architects, sociologists, environmental analysts, urban planners, and the general public can explore over 8,000 historical documents, photographs, oral histories, and maps that have been spatially registered to their relevant locations and time.