Stochastic Response Anslysis On Composite Truss Bridge Made Up Of Sections And Concrete Slab Due To Earthquake Excitation

Steel truss structure is a common bridge structure.It is widely used in highway bridges and railway bridges due to its many advantages such as light weight,material saving,simple and quick construction.However,it also has certain shortcomings.For example,ordinary steel truss bridges mostly use steel plates as bridge decks.Although the steel plates are light in weight,they are relatively easy to fatigue and damage.This problem has always been difficult to overcome;some trusses of truss bridges It is made of reinforced concrete.Due to the poor tensile strength of concrete,the ability of the bridge is limited.The steel-concrete slab truss structure is a new type of long-span structure.The steel truss is subjected to tensile stress,and the concrete bridge deck is subjected to compressive stress.The two materials each exert their own advantages and cooperate perfectly.This cooperation has improved the shortcomings of the traditional truss structure,that is,it can be applied to the construction of long-span highways and railway bridges,and can also be reasonably applied to the construction of bridges shared by roads and railways.At present,the research on this type of structural bridge is still focused on the analysis of the construction technology and the stress of the joints.The research on seismic performance is far from sufficient.Therefore,this paper uses the finite element analysis software Ansys to analyze the seismic dynamics of long-span steel-concrete slab truss bridges.The main research contents are as follows:1.Briefly introduces the development history of steel bridges,summarizes the development status and prospects of steel-concrete slab composite truss bridges,and expounds the research progress of random theory on the seismic direction of bridges.2.The theory of random vibration analysis is introduced.Based on the random vibration theory,the mathematical calculation form and seismic response dynamics equation of the structure under random earthquake are deduced in detail.According to its development history,the existing seismic power spectrum model is introduced in detail.The advantages and disadvantages of these models are reviewed,and the calculation formulas of spatial effects of ground motion are given.Several commonly used coherent effect models are introduced.3.The basic dynamic characteristics of long-span steel-concrete slab combined truss bridges are studied.By simplifying the steel-concrete slab truss structure,the finite element calculation model of the bridge is created in ANSYS,and the relevant calculation parameters of the model are set reasonably according to the actual situation.Modal analysis of the steel-concrete composite truss structure.Obtain the first 100-order natural vibration frequency and vibration mode and list the first 6 stages for corresponding analysis.4.The random seismic response analysis of steel-concrete slab composite truss bridge is carried out.The random vibration theory is used to randomly respond to the earthquake analysis under the uniform excitation of the structure,and further verified by time history analysis.The spatial effect model and related parameters are reasonably selected,and the random seismic response analysis of the steel-concrete slab combined truss bridge under the spatial characteristics of ground motion is carried out.Firstly,the coherence effect,traveling wave effect and local field effect are studied separately.Then the three kinds of spatial effects are combined to comprehensively analyze the influence of ground motion spatial characteristics on the random seismic response of steel-concrete slab combined truss bridge.The results under the incentive were compared and analyzed.