| With the development of society,the improvement of economic level and the enhancement of comprehensive national strength,more and more attention has been paid to the exploitation of marine resources in China and the construction of a series of large offshore projects such as sea-crossing bridge is in the ascendant.It takes several years or even ten years to build a sea-crossing bridge and a great deal of manpower and material resources are needed throughout the process.If the seismic safety of sea-crossing bridge is not guaranteed,it is likely to suffer irreparable and heavy losses when sea-crossing bridge encounters an earthquake.The extensive application of seismic isolation design in sea-crossing bridge has solved this problem and greatly improved the seismic safety of sea-crossing bridge.High damping rubber bearing has vertical bearing capacity,restoring force and damping used for absorbing energy and has the advantage of environmental protection,so it is favored by the designers of sea-crossing bridge.However,the high damping rubber bearings installed on sea-crossing bridge have been subjected to marine corrosion,atmospheric oxidation,solar ultraviolet radiation and other external factors.Due to weather factors such as overcast and sunny conditions,the lower bearings will be subjected to the alternate cycle of marine corrosion and atmospheric oxidation(Seawater Wet-dry cycles).At present,most of the researches on the durability of high damping rubber bearings focus on the durability of high damping rubber bearings used in inland environment,such as aging and fatigue.There are few reports on the durability of high damping rubber bearings used in marine environment.As one of the core components of sea-crossing isolated bridges,high-damping rubber bearing plays an important role in ensuring the seismic safety of bridge,so the importance of its durability is self-evident.Therefore,this paper systematically studies the durability of high damping rubber bearings used in marine environment according to the actual situation of the coastal areas of China.The main research work and results are as follows:1.Referring to the relevant studies on the performance deterioration of concrete under seawater wet-dry cycles,combined with the working environment of high damping rubber bearing on sea-crossing bridge and the actual climatic conditions of coastal cities in China,and according to the deterioration mechanism of high damping rubber materials,a reasonable laboratory test scheme of artificial accelerated seawater wet-dry-cycle test was established based on the Arrhenius formula and high damping rubber bearings and high damping rubber materials are designed and manufactured.2.Seawater wet-dry-cycle accelerated test has been carried out on the high damping rubber bearings.These bearings are regularly sampled and tested for mechanical properties including compression properties,shear properties,dependency of shear properties,ultimate shear properties and tensile properties.By comparing and analyzing the experimental results,the time-varying laws of mechanical properties of high-damping rubber bearings under seawater wet-dry cycles are obtained and a series of formulas are fitted to describe these laws to provide some reference for practical engineering.3.Seawater wet-dry-cycle accelerated test equivalent to the high damping rubber bearings has been carried out on the high damping rubber materials.These materials are regularly sampled and tested for mechanical properties including hardness,stress at a given elongation,tensile strength and elongation at break.By comparing and analyzing the experimental results,the time-varying laws of mechanical properties of high-damping rubber materials under seawater wet-dry cycles are obtained and a series of formulas are fitted to describe these laws to provide some reference for practical engineering.4.Performance deterioration of high damping rubber bearing under seawater wet-dry cycles has been discussed further.The Mooney-Rivlin model is chosen to describe the hyperelastic behavior of high damping rubber materials and the constitutive constants are obtained by the results of mechanical tests of rubber materials.The finite element analysis of high damping rubber bearings is carried out on ABAQUS and the results of finite element analysis are compared with the results of mechanical test of bearings. |
