Abstract

Abstract

The recent earthquakes that occurred in January and May 2020 in Puerto Rico have revealed the vulnerability of industrial buildings that use prestressed concrete double-T beams, due to poor connections and insufficient support lengths between the double-T beams and the supporting beams that are prefabricated. These beams sometimes are supported by concrete brackets representing an additional risk. In the supports, displacements have been observed in the joints causing diagonal cracks and angle separation related to the horizontal transfer between the joists and supporting beams. In these supports there is a lack of capacity due to shear and poor ductility due to the connection made with metal plates embedded in the web of the joists and angles located along the edge of the prefabricated beams.

Abstract

This paper discusses the use of composite materials in the design process of a horizontal bracing to column connection of an offshore semi-submersible platform to support two wind turbines. The geometry of the connection was optimized to improve the performance and reliability of the connection, columns and bracing tubes. These offshore foundations usually deal with massive structural tubes, and they are used to fit a huge amount of stiffeners. This paper will show how using some horizontal stiffeners combined with their intersection with horizontal bracings tubes, can improve drastically the behavior of the connection. A comparison between conventional materials (steel) and advanced materials (E-glass fibres and epoxy matrix) was performed and it was demonstrated how the use of composite materials makes necessary to modify the connection geometry and configuration to obtain an equivalent performance. This is due to the very different stiffness behavior shown by composites and steel. Therefore, the design of an offshore connection must be approached differently according to the used material. The composite laminate layout design process was also made. The material was evaluated using a Bureau Veritas normative note specifically applicable to composite ship hulls, but adapted to the needs of the materials used in this design, in terms of raw material requirements. The design process of a laminate panel of the connection is shown using the above mentioned standard. All data and results shown here were harvested within the scope of the European research project Fibregy (EU Horizon 2020, Ref. 952966).