Seismic Performance Analysis And FRP Reinforcement Of Long-Span Stone Arch Bridge

Bridge engineering as a highway traffic lifeline engineering,in ensuring the normal operation of the highway transportation plays an important role in earthquake relief.Nowadays,long-span stone arch bridge is still widely used in highway traffic transportation system,and the study of seismic performance analysis and reinforcement measures of long span stone arch bridge is significant for ensuring its normal use function under earthquake action.Using the finite element analysis software ABAQUS,the finite element calculation model of a long-span stone arch bridge and the finite element calculation model of the long-span stone arch bridge reinforced by different fiber reinforced materials(FRP)were established respectively.The following researches were carried out on the long-span stone arch bridge:(1)Based on the damage mechanics theory,the damage variable was introduced,and the two-parameter Weibull distribution function was used to reflect the damage evolution law of stone masonry.The constitutive model parameters were determined according to the characteristic conditions of the whole process stress-strain curve of stone masonry and the experimental compressive strength,and the constitutive formula of stone masonry uniaxial compression was derived and established.The uniaxial compression constitutive curve of masonry is compared with the measured stress-strain curve of stone masonry.The results show that the constitutive curve is in good agreement with the test curve.The constitutive relation curve of stone masonry under uniaxial compression is compared with that of typical masonry.The results show that the constitutive relation curve is basically consistent with that of typical masonry.The uniaxial compression constitutive model of stone masonry is applied to the numerical simulation of stone arch bridge,and the results show that the constitutive model can be well applied to the numerical simulation of stone arch bridge,with high calculation accuracy.(2)The seismic response of a long-span stone arch bridge is analyzed by using dynamic time-history analysis method.The results show that the transverse peak displacement of the long-span stone arch bridge occurs at the L/4 span of the main arch circle,and the transverse peak displacement occurs at the top of the main arch circle.The transverse peak displacement is much larger than the transverse peak displacement,and the transverse stiffness of the structure is larger.Along the bridge direction is the weak direction of the structure;Under the action of earthquake,the stress of the upper structure of the main arch ring of the long-span stone arch bridge is less,and the stress of the main arch ring is more concentrated,among which the stress concentration phenomenon is more obvious at the arch foot of the main arch ring.(3)The influence of design parameters on seismic response of long-span stone arch bridge is studied.The results show that with the increase of masonry strength,the peak stress of key sections in main arch circle increases gradually,the peak displacement of main arch circle decreases continuously,and the sensitivity of key sections in main arch circle to stress concentration changes.The peak stress and peak displacement of each key section of the main arch ring of the catenary and parabolic structures are close,and the peak stress and peak displacement of the main arch ring of the parabolic structure are much larger than that of the catenary and parabolic structures.In order to avoid the phenomenon of stress concentration at the arch foot,the structure with the arch axis type of catenary or parabola should be selected.With the increase of sagittal span ratio,the vertical peak displacement of the arch decreases gradually,while the transverse peak displacement increases gradually,and the peak stress of the key section of the main arch circle decreases gradually.With the increase of sagittal span ratio,the stress distribution of the key section of the main arch circle tends to the mid-span section.The most reasonable range of sagittal span ratio of the long-span stone arch bridge is between 1/6 and 1/5.(4)The Pushover analysis method of capability spectrum analysis method and modal Pushover analysis method are studied in the seismic response analysis of long-span stone arch bridge.Combined with the calculation results of dynamic time history analysis method,the applicability and accuracy of the three analysis methods are compared and analyzed.The results show that the displacement calculation results of the multi-mode loading mode are close to those of the inverted triangle loading mode,and the fluctuation of the error results of the multi-mode loading mode is stable.The accuracy of the calculation results of the same lateral loading mode varies with different ground motion input.The range of resultant shear force of arch foot can be estimated by the calculation results of multi-mode and uniform loading mode.The results of performance point displacement and arch foot shear force obtained by modal Pushover analysis method(MPA)are closer to the results of dynamic time-history analysis method,and MPA analysis method can make a more accurate assessment of seismic response analysis of long-span stone arch Bridges.(5)The arch ring of the long-span stone arch bridge was strengthened by pasting FRP materials,and the seismic performance of the reinforced structure was analyzed.The effects of FRP materials,FRP width and FRP thickness on the seismic response of the long-span stone arch bridge were studied respectively.The research shows that the peak displacement and peak stress of the structure after reinforced by FRP materials are decreased significantly under the earthquake,and the structure is in a safe state.Under the same strengthening conditions,the reinforcement effect of GFRP materials is better than that of CFRP materials,and the width of FRP reinforcement has the greatest influence on the stress response of the structure after reinforced.When selecting GFRP to strengthen the large-span stone arch bridge,it is most reasonable to choose the width of 1200 mm.The thickness of FRP reinforcement has little influence on the displacement and stress response of the reinforced structure.The optimal reinforcement scheme of FRP should be GFRP material with thickness of 1mm and width of 1200 mm.