| As one of the main natural disasters,earthquakes caused a large number of casualties and property losses.China is an earthquake-prone country,lots number of beam bridges have been collapsed and destroyed in the 2008 Wenchuan earthquake and the subsequent Yushu earthquake.Therefore,the improvement of the seismic capacity of such bridges has attracted attention.Since the 1960 s,seismic isolation technology was introduced into structures and has become one of the most mature technical methods in the vibration control field.Its basic principle is to install seismic isolation devices between the upper and lower structures of the bridge to improve the seismic capacity of the bridge structure.Among these devices,the laminated steel plate rubber bearing,the lead rubber bearing and other bearings are widely used in some important projects due to their mature manufacturing technology and stable working properties.Considering cost control,due to the high cost and heavy weight of these bearings,it is possible to seek more economic seismic isolation devices.In this paper,a nylon fabric core reinforced rubber bearing is proposed and the mechanical properties of this bearing and the feasibility of its application is deeply studied.The main results of this thesis are as follows:1.The studies of fiber-reinforced rubber bearings at home and abroad were reviewed.Depending on the different external and geometric structures of the bearings,fiber-reinforced rubber bearings are divided into three types: unbonded bearings,bonded bearings,and other forms.The performance studies of various fiber-reinforced rubber bearings are introduced from three aspects: theory,experiments,and finite element analysis;and the engineering application of fiber-reinforced rubber bearings in structures has been further summarized.2.Fabric core conveyor belt rubber bearing(CBRB)with low cost and a simple manufacturing process has been proposed and four samples of such bearings have been produced,including four-layer,five-layer,five-layer with inner pattern and six-layer fabric core CBRBs.In this paper,the vertical compression test and compression shear tests are carried out on the four types of bearings.Results show that the vertical stiffness of the bearings is small,but the vertical damping ratio can reach 7%;the bearings work well within 100% horizontal shear strain,but the ultimate shear strain reached up to 200% for the bearing with obvious interlayer cracks,which means that the bonding quality between layers is the key influencing factor of the ultimate deformation.3.Based on fabric core conveyor belt rubber bearing,a new type of low-cost nylon fabric core reinforced rubber bearing is designed and manufactured.The reinforcement layer of the bearing is the nylon impregnated cloth used in the conveyor belt instead of the sandwich steel plate.The vertical compression test and compression shear test are carried out on the bearings.Results show that the vertical stiffness of the bearings is small,but the vertical damping ratio can reach 7%;the performance of the bearing is not significantly degraded when the shear strain is 300%,and the equivalent damping ratio of the bearing first decreases and then increases in the range of 9%-13% with the increase of shear strain.4.A numerical model of a continuous girder bridge was established using finite element software,and nylon fabric core reinforced rubber bearing was simulated through connecting element in the software.The feasibility of applying the bearings to small and medium-sized bridges under static and dynamic forces was studied.The results show that nylon fabric core reinforced rubber bearing work well under both loads,and can theoretically be applied to small and medium-span bridges. |
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