Hydroelastic responses of a Truss Pontoon Mobile Offshore Base – An experimental investigation

The present study focuses on the details of 1:150 scaled model tests conducted on a Semisubmersible type Very Large Floating Structures (VLFS), namely Truss Pontoon Mobile Offshore Base (TP-MOB) under regular waves. The laboratory tests were performed in a deep water wave basin at the Indian Institute of Technology Madras (IIT Madras). The model, governed by Froude and Cauchy scaling laws, was constructed of thermoplastic polyurethane (TPU) sheet with internal steel stiffener plates. The top deck was constructed using thicker TPU to bring in the elasticity effect. The responses of the model were measured for regular waves with different wave frequencies at a constant wave height of 0.04 m and various heading angles. Three different accelerometers recorded the responses at three different locations for different heading angles. From the recorded time series Response Amplitude Operators (RAOs) of vertical displacements, roll, and pitch are obtained. The characteristics frequency response curve obtained from the experiments are consistent with that reported in the literature by Suzuki et al. (1996). The results indicate the presence of resonant elastic modes in the wave excitation ranges. The uncertainty analysis carried out indicated that the uncertainty in the frequency responses is generally small for kd values greater than 0.2. •A novel-Truss Pontoon Mobile Offshore Base (TP-MOB) VLFS is investigated experimentally under regular wave conditions for different heading angles.•Details of the fabrication of the 1:150 scaled model are presented.•Responses of the model, namely vertical displacement besides roll and pitch motion are measured by sensors at three locations.•Response Amplitude Operators (RAOs) are obtained, and these plots show the characteristic diminishing peaks of the elastic body responses within the wave excitation range, unlike the case of a barge.•Results ascertained that the frequency response curve obtained is consistent with existing literature (Suzuki et al., 1996).