| Due to the aging of natural rubber bridge bearings,ozone corrosion and other durability problems,the service life of rubber bearings is short,and the replacement cost of bearings is expensive and traffic is interrupted.The metal rubber bearing is made of metal rubber material instead of natural rubber material.The test results show that the metal rubber bearings can meet the requirements of the mechanical properties of the bearings during normal use of the bridge,and have good durability,which has a good application prospect in small and medium-span highway bridges.Most of the research on metal-rubber bearings is experimental research,and the theoretical calculation of horizontal recovery force model,stiffness and initial stiffness after shear yield is required for seismic design,and the current research in this area is still blank.Based on the results of the compression shear test of metal-rubber bridge bearings,this paper conducts research on the horizontal resilience model of metal-rubber bridge bearings,reveals the calculation formula of the key parameters of the support resilience model,and provides a theoretical basis for the design of the supports and the seismic response analysis of the metalrubber beared bridges.The main research content,methods and research work of this paper are as follows:(1)Introduction to the size determination and compression shear test of metal rubber bridge bearing.Determine the metal rubber material model,wire diameter,spiral coil diameter and support size,and process and make metal rubber support.Introduce the main devices and instruments of the press shear test,and design and complete the press shear test of metal rubber support.(2)Formula for calculating stiffness after shear yield of metal-rubber bridge bearings.Based on the area of overlapping part after shear yield of support and Haringx theory,the formula for calculating stiffness after shear yield of support is derived theoretically.Combined with the results of compression shear test and compression test,the linear relationship between compression modulus and shear modulus is obtained,and the calculation formula of stiffness after yield derived from theory is practically simplified.(3)The formula for calculating the initial stiffness of the support shear is derived.Considering the initial force state of the support,the differential equation is established to derive the calculation formula of the initial stiffness of the support.Combined with the test results,the parameters of the formula derived from the theory are simplified,and the simplified calculated value is compared with the experimental value,and it is found that with the increase of compressive stress,the difference between the calculated value and the experimental value is decreasing,and the initial stiffness calculation formula has better accuracy.(4)Research on calculation method of support yield force.According to the yield displacement obtained by the experiment,the variation law of yield displacement under different compressive stresses is analyzed,the calculation method of yield shear strain is given,and the yield force is calculated by the initial stiffness and yield shear strain.(5)Study on hysteresis rule of metal-rubber bridge bearing recovery force model.The shear hysteresis law of metal-rubber bearings is simulated by the two-line model,and the hysteresis curve obtained according to the theoretical formula is in good agreement with the test hysteresis curve,and the two-line recovery force model can be used as the recovery force model of metal-rubber bearings for seismic response analysis. |
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