Seismic Performance And Stability Analysis Of Assembled Pier Of High Pier Long Span Continuous Rigid Frame Bridge

In recent years,the development of China’s bridge engineering is very rapid,the high pier large span continuous rigid bridge with a excellent spanning capacity to become a very competitive bridge type in mountainous areas.At the same time,the pier assembly construction method solves the problems of the overall cast-in-place pier construction such as large areas,long production cycles,and serious environmental pollution,and can effectively reduce costs.The bridge construction is still mainly based on the traditional cast-in-place construction,especially the research,and application of assembled piers for high pier large span continuous rigid bridges is less,and the seismic performance and stability performance are still in the exploration stage.This paper analyzes the mechanical characteristics,seismic performance,and stability of assembled piers of high pier continuous rigid frame bridges,the main research content and results include the following four aspects:(1)Analysis of existing assembled bridge pier theory and research to determine the research direction and analysis methods applicable to this paper.The simulation model was established based on the tests of integral cast-in-place piers and assembled piers,considering the selection of material units and the intrinsic structure model and analyzing the contact and boundary problems of the members,and the test model was constructed in equal proportion,and the simulation results were cross-referenced with the test results to verify the accuracy and applicability of the model simulation principles and techniques.the reliability of the modeling method.(2)Based on the actual engineering design and the model fitting concept,the model of the original bridge was constructed as a whole cast-in-place pier,and the assembled pier model applicable to the high pier continuous rigid bridge was designed,and the analysis of the static and seismic performance of the pier was carried out.Static tests were conducted to study the effect of design parameters on the hysteresis curve,residual displacement,and cumulative energy dissipation of the structure.The research shows that: in static performance,the assembled pier is affected by segmental joints,and the distribution of compressive stress damage and tensile stress damage is slightly different from that of the cast-in-place pier,but the overall static response is not much different;in seismic performance,the overall cast-in-place pier has better energy dissipation capacity and bearing capacity,and the assembled pier has smaller residual displacement and stronger self-resetting capability;in the analysis of the influence of design parameters,the main influence degree In the analysis of the influence of design parameters,the main influencing degree from largest to smallest is:prestressing tendon reinforcement rate,pier height and width ratio,constant load axial pressure ratio,and the number of pier sections.(3)The period and frequency of the high pier are calculated,and three seismic waves are selected with the characteristics of the actual project site,and the displacement time course of the top of the pier,acceleration time course of the top of the pier,the shear time course of the bottom of the pier and bending moment time course of the bottom of the pier are used as evaluation indexes.The results show that the ductility of assembled piers is better,and the large displacement of the structure appears later than that of cast-in-place piers,with strong recovery ability and smaller average displacement than the overall cast-in-place piers,which are only 48.3%,88.2% and 77.4% of the average displacement of cast-in-place piers respectively,with good self-resetting ability,but the integrity and stiffness are slightly inferior to that of cast-in-place piers.Under the effect of ground shaking,a small area of slip and tension will be generated at the joints between sections of assembled bridge piers,and the amount of slip and tension decreases with the increase of pier section height.(4)A bridge construction stage model was established to analyze the stability performance of assembled piers in the bare pier stage,maximum cantilever stage,and full bridge stage,summarize the performance change law,and verify the suitability of assembled piers for the full bridge from the aspect of stability.The results show that the self-weight has the greatest influence on the stability,and the minimum stability coefficients are 35.01,17.13,18.97 in each working condition in the three stages,the worst stability in the maximum cantilever stage,and the best stability in the bare pier stage.At the same time,it is proved that the assembled piers have good adaptability in the whole process of bridge construction and meet the stability requirements.