The Seismic Response Analysis On Long-span And Cable-stayed Steel-truss-girders Bridge Based On The Nonlinear Behaviors

For buildings on the ground, earthquake is an occasional, sudden and huge destructive load. As an life-and-death engineering of transport system, bridge often suffers from earthquakes, and sometimes the damage even brings immeasurable loss. Therefore, the aseismatic design of bridges has become an crucial job for each bridge engineer.With advances in technology, more and more new materials and new structural forms appear in the design and construction of bridges. Meanwhile, the span and function of bridges also shows a boosting and breaking trend. In recent years, some long-span and cable-stayed steel-truss bridges have been built in china. This type of bridge combinates cable-stayed system and steel-truss system in structure, contains concrete, carbon steel and high-strength steel wire in material, and satisfies the dual needs of highway and railway transport in function, which proposes a number of new issues in the aseismatic study of long-span and cable-stayed bridges. At the background of some long-span and cable-stayed steel-truss bridge in china, this paper performs nonlinear aseismatic analysis for this bridge, considering the spatial effect, the traveling wave effect and non-uniform excitation effect of earthquake and also the nonlinear factors of the bridge. The main contents include the following aspects:(1) Composes a systematic study and elaboration of the bridge aseismatic theories, aseismatic design methods and the nonlinear behaviors of the bridge structure.(2) Provides a detailed analysis and simulation for the spatial model of the bridge, in order to reflect the structural characteristics accurately. On this basis, analyzes the dynamic characteristics of the bridge.(3) Studies the earthquake input, which is an important factor on the nonlinear time-history analysis of the bridge. Then, states the reasonable method of choosing earthquake waves and the method of entering earthquake waves, combing the spatial effect, the traveling wave effect and non-uniform excitation effect of earthquake.(4) Combining the structural type and source of non-linearity, performs nonlinear dynamic time-history analysis for the bridge. On this basis, analyzes the seismic responses of cable-stayed system and steel-truss system regarding their respective non-linearity, and studies the liable failure parts and possible failure modes of the two systems under strong earthquakes.At the basis of finite element dynamic analysis, some serious problems about aseismatic analysis on this type of bridge are summarized:The accuracy and reasonableness of the simulation of this type of bridge is important to the analytic analysis, as some connections of this type of bridge are quite intricate; The spatial effect, traveling wave effect and non-uniform excitation effect of earthquake should be considered when analyzes the seismic behavior of this type of bridge; Analysis on the nonlinear source of cable-stayed system and steel-truss system is necessary, and the results should be considered in the time history analysis; It is necessary to study the weak and vulnerable parts when do aseismatic analysis of this type of bridge.