Nonlinear Response Of Double-trough Aqueduct Structure Under Strong Earthquake And Seismic Reliability Analysis

As a common water conveyance structure,aqueduct is widely used in cross-regional water conveyance and diversion projects.Due to the engineering structure of top-heavy,it is easy to cause earthquake damage and even collapse damage,endangering the safety of people’s lives and property in the surrounding areas.Moreover,the nonlinear response of double-trough aqueduct structure under strong earthquakes is often extremely complex.In view of this,taking Shuangji River aqueduct project as an example,the nonlinear dynamic response analysis and overall seismic reliability of large reinforced concrete double-trough aqueduct are studied from two basic points of nonlinearity and randomness,which provides theoretical basis for performance-based seismic design of large double-trough aqueduct structure.The specific research contents are as follows :(1)In this paper,a nonlinear reinforced concrete material subroutine suitable for fiber beam element model is developed based on Fortran language program.The pseudo-static test of one-story-one-span frame structure and the numerical simulation of pier shaking table model test are carried out,and the numerical simulation results are in good agreement with the experimental results,which verifies the applicability and good convergence of the nonlinear reinforced concrete material subroutine developed in this paper to simulate the nonlinear response of the structure.(2)Combined with fiber beam element model and efficient numerical algorithm,the dynamic nonlinear response analysis model of large reinforced concrete double-trough aqueduct structure is established.With Shuang Ji river aqueduct project as an example,the different seismic input nonlinear dynamic time history response analysis,comparative analysis of the aqueduct structure seismic response of the linear elastic and non-linear model calendar calculation results,the aqueduct structure under the action of earthquake acceleration,velocity,displacement of the nonlinear response values were greater than linear elastic dynamic response values,internal force response value is less than the linear elastic response values;Based on the time history calculation results of displacement,acceleration,bending moment and shear force,the nonlinear response law of large aqueduct structure is analyzed.(3)From the perspective of energy absorption and dissipation,the overall collapse criterion of the aqueduct structure under earthquake is established.By compared the overall seismic response of the aqueduct structure and the material yield conditions of key parts,and comparing with the nonlinear dynamic analysis results of the aqueduct structure and the collapse judgment criterion based on the displacement angle limit of the pier top,the refined model of the aqueduct structure and the dynamic catastrophe analysis method are verified accuracy and feasibility.The results show that the aqueduct structure collapse judgment criterion based on effective energy can accurately determine whether the aqueduct structure collapses or not,and can accurately give the collapse critical time.It lays a foundation for the seismic reliability analysis of large-scale aqueduct structures.(4)The overall seismic reliability analysis method of the aqueduct structure under random earthquake action based on two levels is developed.Under the fortification standard of "small earthquake is not bad",the criterion of pier top displacement angle limit is introduced as the structural failure control index.The effective energy judgment criterion was introduced as the structural failure control index under the "inverted" fortification standard.Combined with the random ground motion model with physical mechanism and the probability density evolution method,the seismic reliability performance of the aqueduct structure under the action of random earthquakes was quantitatively analyzed.The results show that the coupling of randomness and nonlinearity will have a significant impact on the dynamic response of the aqueduct structure.The overall seismic reliability analysis method based on different levels of fortification levels can accurately solve and evaluate the overall seismic reliability of the aqueduct structure under different fortification levels.The results provide a new idea for the study of seismic reliability of aqueduct structures,which is of great significance to ensure the safety of the structure in service.