Abstract

Connector is widely used in Very Large Floating Structures (VLFS) which have large dimensions to connect a number of modules. Articulated connector is a common kind of connector which releases rotation freedom so that loads can be reduced but the load evaluation is more complicated. It is important to evaluate load characteristics of articulated connector of large floating structure when it is designed; model experiment is a conventional and effective approach to evaluate loads of articulated connector. This paper firstly designs an experimental methodology to measure the loads of a specially-made articulated connector of multi-body. The articulated connector is of hinged connection between two bodies while a number of strain gages are arranged on the connector to measure strain deformation in three orientations. A calibration test is carried out to analyze the relationship of strain signal and connector loads before wave experiment. Then the load experiment of connector load of VLFS model is carried out in a wave tank; a number of wave cases are determined and performed. Further; a plenty of experimental strain data are obtained and transformed into load data of connector. Frequency-domain load Response Amplitude Operaters (RAOs) and time-domain load histories are both analyzed. The experimental method and conclusion presented in this paper has important reference for load evaluation of articulated connector of VLFS.

Introduction

Because the scale of the super large floating structure is larger than that of the general ship; if it is designed as a continuous structure like a ship; the bending moment and shear force acting on the structure will be very huge under the excitation loads of ocean wind; wave and current. According to the existing human engineering technology; it is impossible to manufacture the structure which can meet the strength requirements under this limit load. And large floating structures have different uses; so it is impossible to build them as a whole. Riggs and Ertekin (1999) proposed that modular construction scheme is needed from the point of view of easy maintenance and use. The existing large-scale floating structure are divided into several modules; and the modules are connected by special connecting devices. After the completion of the construction on land; each single module will be spliced at sea. Since the concept of large floating body was put forward in the 1990s; scholars from all over the world have never stopped studying the load and response of connectors of large floating structures. It was noted (Spry; 1999; Zueck; 2000; Palo; 2001) that there are three methods to investigate the connector load: analytical method; numerical method and experimental method at present. The results of the dynamic response test of the connector in the test tank are more accurate; and there are many successful examples in the field of marine engineering.

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