Sandstorms are a common natural phenomenon that has the potential to cause severe disruptions to civil infrastructure. However, the effect of sandstorms on transmission tower structures has not received much attention. This paper proposes the simulation of the wind-sand loads for the analysis of transmission tower structures under sandstorm excitation by superposing the wind loads and sand particle loads. The wind load is generated based on Kaimal fluctuating wind power spectrum and the harmonic superposition method, and the sand load is constructed based on the law of conservation of momentum and sandstorm classification. A transmission tower was modeled and simulated in SAP2000 to explore the dynamic response of the tower towards wind-sand loads. A comparison of wind-induced and wind-sand-induced responses shows that the structural dynamic responses of transmission towers due to the wind-sand effect are pronounced. Particularly, the maximum longitudinal displacements and axial forces increased greatly. The results showed that the sandstorm loads for transmission towers cannot be neglected, and more attention should be paid to the structural design of transmission towers to resist such loads.

Steel catenary risers (SCR) have been widely used in the offshore oil industry. This paper proposes using a novel vibration control device, i.e., the pounding tuned mass damper (PTMD), to mitigate the flow-induced vibration of an SCR. The numerical model of the SCR and the PTMD has been established in ANSYS. The soil-pipe interaction is simulated by nonlinear springs based on p-y curves. A single degree of freedom structure is utilized to verify the PTMD model established in ANSYS using APDL. Afterwards, numerical studies are carried out to validate the vibration control performance of the proposed PTMD and to investigate the influence of mass ratio and the location of the PTMD. The numerical results imply that the PTMD is very effective in reducing the displacement of the SCR under different oceanic conditions. The vibration control effectiveness will increase with the increase in mass ratio. The maximum vibration reduction is achieved when the PTMD is located at the place where the largest amount of motion takes place.