Slip-Resistant Connections with Hot-Dip Galvanized Faying Surface Under Freeze-Thaw Cycles and/or Low Temperature

In some occasions, outdoor steel structures like wind towers, bridges, winter sports facilities, and so on are subjected to extreme environmental conditions with the presence of ice and/or with below-zero temperatures. Sometimes in these situations, surface protection of the steel structure is usually designed using hot-dip galvanizing to improve its durability. In these special circumstances, the structure's connections are also exposed to adverse climatic agents. International standards and codes such as Eurocode 3 or EN1090-2 do not provide indications for these cases. In this experimental research, 24 specimens of non-slip joints with hot-dip galvanized faying surfaces and HV M16 and M20 bolts have been studied. Twelve specimens were subjected to fourteen twelve-hour freeze-thaw cycles, with temperature oscillation and periodic immersion in water. Next, six of the connections were subjected to a slip test under monotonic load at a temperature of -20 ± 0.5 °C and the other six at room temperature. The results were compared with joints kept at room temperature and not subjected to freeze-thaw cycles for the same period of time. The main conclusion of this piece of research is that the short-term slip resistance behavior of joints with hot-dip galvanized surfaces is not reduced for the cases studied.