Nonlinear Analysis And Research Of Seismic Response Of Long-Span Concrete Filled Steel Tubular Arch Bridges

In this thesis, the problems of nonlinear seismic response analysis of large span CFST arch bridge are researched, conside red respectively the interaction between soil, foundation and s tructure under the conditions of uniform and non-uniform seismi c excitation. In the past decades' years, long span CFST arch b ridges developed very fast all over our country including earth quake regions. With the span longer and longer, the problem of wind vibration and seismic of CFST arch bridge can' t be ignore d. Computer simulation analysis is mostly applied to seismic re sponse analysis of CFST arch bridge because the seismic experim ents are too costly. At present, literatures researched on allo ver aseismatic performance analysis of long span CFST arch brid ge are few and some of them have their limitations. For the str ongest earthquake in South-China was happened in Guangxi in the past recently years, this thesis research on the aseismatic per formance of two large span CFST arch bridges in Guangxi (Guilin Shijiadu Lijiang Bridge—176m half-through CFST arch bridge and Nanning Yonghe Bridge— 346m below-through CFST arch bridge). T he main contents are follow:1. Nonlinear computational model of CFST is studied. Elasti c-plastic constitutive matrixes of Ottosen Strenght Criterion i s established by elastic-plastic incremental theory; Computatio nal program of elastic-plastic increment constitutive relation based on Mises Yield Criterion and Ottesen Strenght Criterion i s programmed; The stiffness matrix, geometric stiffness matrix and large deformation geometric stiffness matrix of spatial bea m element are studied.2. Hysteretic performance of restoring force of CFST member is studied. With large finite element analysis software, specia 1 module of hysteretic restoring force analysis of CFST member is programmed by the further development language (UIDL) and in ternal control language (APDL) in ANSYS. Tri-axial stresses ind uced by the interaction between steel tubular and concrete is s tudied with new modeling method (simulating concrete by spatial solid element and steel tubular by shell element).3. The interaction models between soil, foundation and stru cture are studied. Three methods are introduced to build the in teraction models between soil, foundation and structure. They a re Finite Element Method, Substructures-Finite Element Method a nd Infinite Element-Finite Element Method. Spatial 8-node singl e-direction infinite element introduced to simulate semi-infinite domain of the soil that can be couple with spatial 8-node is oparametric element introduced to simulate the foundation. Then, computational program of spatial infinite format is programmed. With the general finite element software (ABAQUS), a new single -direction infinite element as user element is coupled with the corresponding element in ABAQUS, and the interaction model of i nfinite element-finite element is built.4. Time history analysis methods of seismic response of lon g span structures is studied. The widely used methods to solve dynamic equations are compared. Considering travel wave effect, spatial effect and partial coherent effect, the model of accele ration power spectral density of ground movement in seismic bas ed on random process is studied. The stationary duration Ts(s) and spectral factor S0(cm2/s3) corresponded with scale of seismi c magnitude and the distance of near or far seismic area and se ismic intensity and site classification in West-China are deduc ed. These factors provide scientific proof for the random proce ss model of ground motion in West-China. Stationary and non-sta tionary random process model and acceleration power spectral fu notion sxg (ω) under spatial and partial coherent effect are studied. Based on random vibration theory, acceleration power spect ral density model are established and the artificial earthquakewaves program is programmed, which could create artificial eart hquakc waves corresponded with site classification, seismic for tification intensity, traveling wave and partial coherence effe ct.5...