Test And Simulation Research On Force Performance Of Fabricated Bridge Expansion Device Under Vehicle Loading

As an important part of the highway bridge structure,the expansion device has the functions of transmitting vehicle loading,adjusting the deformation of the bridge deck,and ensuring smooth traffic,However,the anchorage area of the bridge expansion device is prone to fatigue damage.Compared with the traditional expansion device,the fabricated bridge expansion device designed with steel box-concrete combination structure has the advantages of fast installation and easy replacement.It has important engineering practice significance.According to the stress characteristics,structural characteristics and construction technology of the fabricated bridge expansion device,the layout plan of the measuring points on the expansion device during the field test was formulated;based on the investigation of the road bridge vehicle loading in China,the vehicle quality of the test vehicle was determined to be overload proportion;heavy trucks with different axle loadings are used for field test,and the actual strain of the expansion device under static loading and dynamic loading is collected.In addition,a finite element mechanical analysis model of the expansion device was established to perform mechanical simulation analysis of the fabricated expansion device.The strain values of the fabricated bridge expansion device under the action of 8 different static axial loadings are analyzed,and it is concluded that the device’s strain response has local characteristics,and the maximum strain appears at the cross section where the centerline of the wheel trajectory contacts the box,The strain value increases obviously with the increase of axle loading.Under the action of the largest vehicle static axle loading,the maximum normal stress of the box bottom plate,the maximum shear stress of the side plate and the main stress are used to check the strength of the device box,and the conclusion of the strength check of the box bottom plate and the side plate is obtained.According to the test data of the fabricated bridge expansion device under the dynamic loading of 16 different vehicles,the stress time history curves of three dangerous parts are drawn.According to the selected S-N curve,the device is subjected to fatigue check calculation and the fatigue damage is calculated.The analysis shows that: the side panel of the box body of the expansion device does not cause fatigue damage;the bottom panel does not cause fatigue damage under the action of a standard truck;the fatigue damage of the bottom panel and internal concrete is related to the vehicle overload rate and the driving speed,and the vehicle overload rate affects the device the fatigue damage effect is significant,and the increase of the driving speed increases the fatigue damage of the bottom plate of the box to a certain extent,but it has little effect on the fatigue damage of the internal concrete.Based on the change law of the finite element mechanical simulation data of the fabricated expansion devices with different box thicknesses under the standard static axial loading,combined with the strength verification conclusion and fatigue analysis conclusion of the box body,the thickness design of the upper plate and the bottom plate of the box body is proposed.The recommended value is 10 ～ 12 mm,and the recommended thickness design for the side and rear plates is 4mm.