Sustained Loading Bond Response and Post-Sustained Loading Behaviour of NSM CFRP-Concrete Elements under Different Service Temperatures

Nowadays, one of the foremost procedures for strengthening concrete structures is the Near-Surface Mounted (NSM) technique. This paper presents an experimental study on the effect sustained loading and different service temperatures (steady and cyclic) have on NSM Carbon Fibre-Reinforced Polymer (CFRP)-concrete bonded joints and their post-sustained loading load-slip behaviour. Four experimental campaigns using eight NSM CFRP-concrete specimens were performed by employing two different service load levels (15% and 30% of the ultimate load) and combining two groove thicknesses (7.5 and 10 mm) and two bonded lengths (150 and 225 mm). Two steady state temperatures (20 and 40 °C) and two cyclic service temperatures (ranging between 20 and 40 °C) were programmed. The slip obtained was proportional to the sustained load level. Furthermore, higher slips were registered for specimens under higher mean temperatures in the cycle. After 1000 h of sustained load testing, the specimens were tested under monotonic loading until failure (post-sustained loading tests). In general, the ratio between the post-sustained loading ultimate load and the instantaneous ultimate load was close to the unity, although some differences were perceived in series S2 (steady 37.7 °C) with a mean increase of 6.3%, and series S3-B (cyclic temperature ranging between 24.6 and 39.2 °C) with a mean reduction of 9%.

Design of Large-Size Suction Embedded Plate Anchors for Permanent Mooring Systems in the Gulf of Mexico

Suction embedded plate anchors (SEPLAs) are an economic solution for the mooring system of a floating production platform and have been deployed both in the Gulf of Mexico (GoM) and around the globe with excellent field performance records. The design of SEPLAs has gradually matured over the past two decades for conventional SEPLAs, but debates continue both in the industry and academia, e.g., on the function of the flap and the required keying. These design aspects become more critical for permanent mooring systems in the GoM where the anchors have to resist large mooring tensions from hurricanes, and balancing safety and economy is a challenge. Thus, the objective of this paper is to present design considerations for large-size SEPLAs for permanent mooring systems in the GoM. The design considerations in this paper include the embedment loss, the functions of the flap and keying, cyclic loading, sustained loading, keying disturbance, and out-of-plane loading. Recommendations are provided to advance the design of large-size SEPLAs, and more specific guidance is offered relative to the ambiguous requirements currently in the industry guidelines.