Experiment Study On Hysteretic Performance Of SMA Support System And Analysis Of It’s Application In Offshore Platform

In recent years, shape memory alloy (referred to as SMA) has been applied broadly inmany fields. Two basic features of SMA are the shape memory effect andsuper-elasticity, among which super-elasticity is one of the most remarkable mechanicalproperties in civil engineering field. In this paper, SMA support and PFD-SMA supportsystem will be used in JZ20-2MUQ offshore platform structure, and analyze itsvibration control performance by the finite element software ANSYS and tests.The main research contents of this paper:(1) The tensile tests of SMA are conducted in different loading conditions, andgain the stress-strain curve at room temperature. according to the above curve, thispaper analyze the relationship of super-elastic characteristic parameters and loadingconditions, and contrast hysteretic energy-dissipating capacities of SMA wires, bars andplates. The results show that the influence on super-elastic properties of SMA bydifferent strain amplitude, cyclic numbers, and the pre-strain is significant, however theinfluence of loading frequency is very small; in practical applications, conductingcirculating training can be used to obtain stable hyper-elastic performance, and in orderto achieve better energy-dissipating effect, a certain pre-strain of SMA can be imposedbeforehand; change rule of hysteresis energy-dissipation of SMA wires, bars and platesis basic similar, but its specific consumption value and stress value decreasessuccessively, and its yield platform shortens. Reasonable SMA cross section shapeaccording to different requirements of energy consumption has to be selected inpractical application.(2) Firstly,conducting simulation analysis with SMA support, and compare theresults with SMA tensile test results,which show that the change rule of stress-straincurve gained by simulation analysis and test is similar. The results demonstrate thatSMA has good hysteresis dissipation characteristics and can be applied to structurevibration control; secondly the experiments on PFD-SMA system are conducted toanalyze the hysteretic performance of SMA supports and Pall-typed friction damper,and compare the hysteretic performance of SMA supports with different section areaand length. The conclusions are drawn that selecting appropriate length and high towidth ratio of section of SMA supports can achieve good hysteretic performance, andcan save materials also; influence on the hysteresis performance by sliding bolt’spreloaded force of the support system is significant. So choosing appropriate preloaded force is important in actual application.(3) This paper analyze the anti-seismic and ice force of jacket-typed offshoreplatform with SMA support and PFD-SMA support system through ANSYS program,and contrast its effect of vibration control with the original structure. According to theabove, analyze the vibration control effect of SMA support. The analyzed results showthat: support system fails to fully play its role because the stiffness of original structureis too great. So set vibration isolation layer in the original offshore platform structure toform isolation structure, which makes the deformation of vibration isolation layerincreasing, then SMA supports give full play to its ability, and energy dissipationcapacity is enhanced. The scheme can effectively control the displacement of jacket capand the acceleration of the deck because the stiffness of ocean platform structurereduces appropriately, which ensure stability of the platform and meet workers’ safetyand comfort. At the same time, vibration reduction effect of PFD-SMA support systemis more apparent relative to SMA support system,because Pall-typed friction damperconsumes a part of energy.