Study On Mechanical Behavior Of Cluster Shear Studs On Prefabricated Bridge

The design concept of bridges is becoming more and more lightweight,assembled and green and environmentally friendly,and precast concrete bridge decks are widely used in steelhybrid composite system bridges.However,the shear nail arrangement using prefabricated composite beam can only adopt the cluster type,and its force performance is different from the traditional cast-in-situ bridge deck uniform arrangement,and the calculation formula of the shear nail shear bearing capacity in the current specification is determined according to the single nail launch test,and there is no clear provision for the shear nail cluster arrangement.Therefore,it is necessary to study the mechanical properties of cluster nail connectors.The main study contents and findings are as follows:1.Abaqus software was used to establish the finite element model.The tangential behavior of the shear nail and the concrete contact surface and the steel beam and concrete contact surface adopts the contact interface algorithm of penalty function method.The normal behavior of shear nails and concrete contact surfaces,steel beams and concrete contact surfaces,adopts hard contact.The calculation results of the model are compared with the experimental results to verify the correctness and reliability of the simulation method.2.The tensile and compressive damage of the uniform shear nail model and the cluster shear nail model were compared and analyzed,and the analysis results showed that the concrete damage of the composite beam with the cluster arrangement of the shear nails was more serious than that of the uniform arrangement.The cracking load of concrete slabs in the composite beam arranged in the cluster arrangement is slightly lower than that in the uniform arrangement.3.Under the limit state,the maximum slip of the steel hybrid surface occurs at the end of the beam when the uniform shear nail is arranged,and the maximum slip occurs in the middle position of the span when the bundled shear nail is arranged.The slip value of the composite beam in the uniform arrangement of shear nails is slightly larger than that of the bundle arrangement.For bundled arrangement composite beams,the larger the bundle,the smaller the slip value.4.The parameter analysis of the factors affecting the force performance of the shear nail shows that the ultimate bearing capacity of the composite beam is greatly affected by the diameter of the shear nail,and the force of the shear nail in the beam tends to be more and more uneven with the increase of the diameter of the shear nail.When the length of the shear nail is long,the force of each shear nail in the beam is more uniform.The bearing capacity of the structure can be increased by increasing the number of shear nail rows,and the change of the number of shear nails has a great influence on the bearing capacity of the composite beam.The degree of shear connection has a great influence on the bearing capacity of the composite beam,and the bearing capacity increases with the increase of the degree of shear connection.5.According to the parameter analysis results and the comparison of formulas,a recommended formula suitable for calculating the shear bearing capacity of cluster shear nails is proposed,and the average value of the ratio of the calculated value of the formula to the test value is 0.92,and it is believed that the recommended formula can better calculate the shear bearing capacity of the cluster shear nail of the prefabricated bridge deck.6.The Dr.Bridge software was used to calculate the shear force of the joint surface of the Zhongbazhou River Bridge,and the shear bearing capacity of the shear nails was calculated using the suggested formula and the normative formula,and the shear resistance of each longitudinal and beam shear nail connection in the single-span downward bearing basket arch composite bridge was verified.The results show that the shear bearing capacity of each shear connection of Zhongba Zhou River Bridge meets the design requirements.The bearing capacity of the joint surface of the composite beam calculated according to the standard formula and the bearing capacity calculated by the formula proposed in this paper are greater than the shear force borne by the joint surface,and the calculation value of the standard formula is much greater than the shear value of the bearing,which is more conservative.