| With the increasing traffic demand of highway bridge,the existing highway bridge can not meet the demand of its capacity.Therefore,bridge width has become a high-quality method to solve heavy traffic,improve the common bearing capacity of Bridges,improve the transverse distribution of Bridges,and improve the traffic capacity of highway Bridges.In the traditional practical engineering of old bridge width,most of the beam body with the same section structure is used to widen and rebuild.However,there are few researches on the influence of different section structural forms of bridge and local damage of old bridge on transverse transmission.Therefore,it is of theoretical and practical significance to study the transverse distribution law of new and old Bridges and transverse transfer after damage.Based on the project of the 6th section of Lin-Jin Expressway from Lin’an to Jiande Section,Anren Interconnecting Shijia Reservoir split-width bridge and Hangxinjing Main line split-width bridge,this paper adopts two different sectional structure forms of bridge splitwidth,namely high T-beam and box beam,low T-beam and hollow plate,to carry out rigorous drawing design,scale test research and finite element analysis,and mainly carries out the following work contents and conclusions:(1)This paper effectively combines the research status and future development trend of the bridge width expansion at home and abroad,and introduces the calculation method of the influence of the transverse distribution coefficient of the bridge.In view of the few studies on the transverse distribution law,the paper introduces in detail the transverse distribution law of the old bridge widening and reconstruction with different section structure forms under the action of static load;(2)In order to investigate the deflection and bearing capacity of the new and old Bridges after bridge widening,based on the actual dimensions of Shijia Reservoir bridge of Anren Interworking and Hangxinjing Main line bridge of the sixth section of Linan-Jiande Section project of Linjin Expressway,1:3.In the design of the scale member,the load of the member in the elastic stage is determined by finite element simulation in advance.The static load test under various load conditions is carried out on the two groups of T-girder-box girder and Tgirder-hollow plate broadening members.Moreover,the model size,measuring point layout,test loading scheme and measuring content of the component and concrete pedestal are introduced in detail.(3)Describe and analyze the test process and results,and compare and analyze the index parameters such as reinforcement strain,concrete strain,deflection and transverse distribution coefficient of each test component under different working conditions.The test results show that under different working conditions,the transverse distribution coefficients of different section structures are basically the same along the span of the bridge,and the transverse distribution coefficients of the load at the span and the quarter span are basically the same.Compared with the single point loading condition and the symmetric loading condition,the distribution of the lateral distribution coefficient of the symmetric loading condition is more reasonable than that of the single point loading condition.No matter the load is loaded at any position of the section,the deformation of the mid-span section is the largest.By comparing the mid-load condition with the off-load condition,it is obvious that the deformation of each section is smaller than that of the corresponding section under the mid-load condition,indicating that the off-load condition is more conducive to the extension of the force and life of the bridge.Compared with the bridge width with the same section structure,the bridge width with different section structure(especially the box girder T beam width with similar bending stiffness)has a good transverse load transfer effect and can be applied in practical engineering.However,the transverse distribution coefficient of the hollow girder T beam width with large bending stiffness difference is poor according to the measured deflection,which is not conducive to the overall stress of the bridge.(4)The finite element software ABAQUS was used to establish and analyze the bridge model of the widened box girder and hollow slab in the elastic working stage.The plastic damage constitutive model of concrete was adopted,and based on a large number of model trials,the stiffness damage degree of the finite element model of the damaged section of the box girder was determined.The deflection,stress and strain of T-beam,box girder and hollow slab were investigated.There is a good agreement between the simulation results and the test results,which reflects the reliability of the finite element model simulation results and verifies the accuracy of the test.(5)This paper expounds the load transfer law of splitwidth with different section structure forms under static load conditions.After the overall structure calculation and parameter analysis,combined with numerical simulation,the influence law of load transfer on the splitwidth with different section structure forms under different working conditions is analyzed after the joint work of the new bridge and the old bridge.Based on the submodel method,a fine finite element model of the damaged position of the bridge was established.The test results were compared with the calculated results of the finite element model,and the finite element model was modified.The influence law of load transfer on the width of the bridge with different section structures before and after the damage was analyzed.(6)Through finite element simulation of bridge width with the same section structure and bridge width with different section structure,it is found that the transverse distribution of bridge width with the same section structure is more reasonable,the transverse distribution coefficient of box girder T beam section width is close to that of box girder-box girder section,and the transverse distribution coefficient of load of hollow plate T beam section width is quite different from that of hollow plate-hollow plate section width.It shows that the box-beam-tbeam with different section structure can be applied to the actual bridge width engineering,but whether the hollow slab T-beam can be applied to the actual bridge width engineering needs to be further studied.(7)Through the finite element simulation,the influence of the damage degree of local flexural stiffess of the mid-span section of the box girder on the transverse distribution coefficient of the bridge is studied.The results show that the transverse distribution coefficient of the box girder and T-beam section increases gradually with the increase of the loss degree of flexural stiffness.Moreover,the transverse distribution coefficient of the damaged box girder section is larger than that of the undamaged T beam section,indicating that the transverse distribution of load of the damaged box girder is offset to the damaged box girder section,which is easy to cause structural damage and thus lead to safety accidents.(8)Through the finite element simulation of the influence of the damage range on the transverse distribution coefficient,the results show that when the damage degree of the middle section of the box girder span is the same,the transverse distribution coefficient of the box girder and T-beam section gradually increases with the increase of the damage range of the middle section of the box girder span,and the transverse distribution coefficient of the middle section of the box girder span is the largest,indicating that the box girder section bears more internal forces with the increase of the damage range.The most unfavorable section is in the mid-span section of box girder,which is easy to cause structural damage and lead to safety accidents.(9)Through the finite element simulation of the influence of different damaged locations on the transverse distribution coefficient,the results show that when the damage degree and damage range of the middle section of the box girder span are the same,the transverse distribution coefficient of the bridge is the largest when the local damage occurs in the middle section of the box girder span,but no matter where the local damage location of the box girder section is,the influence on the transverse distribution coefficient of the T-beam is small.This indicates that the damage of the mid-span section of the box girder has the greatest influence on the transverse distribution of the bridge.It is necessary to strengthen the monitoring and reinforcement of the mid-span damaged position.(10)Taking the three,seven,nine and ten working conditions of member M1 elastic stage as examples,the eccentric pressure method,the articulated beam method and the rigid beam method are respectively used to calculate the transverse distribution coefficient and the measured data are compared and analyzed.The analysis shows that the average error is the minimum when using the rigid beam method.For the bridge width of 5m span box girder-T beam with different section structure,The rigid beam method is more reasonable when the joints are rigid-connected and the width-span ratio is less than 0.5. |
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