Shaking Table Test Of Irregular Bridge And Study On Impact Response Spectrum

The curved bridge is widely used in highway interchange and bridge appro-ach road across ocean. There is various bend torsion coupling response under earth-quake because of the irregular plane and elevation for the curved bridge.Actual earthquakes is complex movement of multi-support and multi-dimensional,due to the wave-passage, the local site-response effects and incoherence,seismic excitation ofeach point of support for large span curved bridge is different. The seismic actionis more complicated when considering the irregularity of curved bridge. Consid-ering only single-support or one-dimension seismic action can not meet the dema-nd of earthquake resistant, then multi-dimensional and multi-support seismic acti- on should be considered.Earthquake damage shows that the earthquake caused by collision between the girder effect significantly is one of the important factors that cause bridge disaster.Combined with the seismic damage investigation and scientific experiments,establish mechanical model and analysis method with correct and reasonable, to study the dynamic response and failure mode of curved bridge under multi-support and multi-dimensional seismic action, and study the collision effect and damage mechanism is important topic in bridge seismic resis- tance. In view of the above problems, details of this paper are summarized as follows.1、Two scale 1/20 two-span reinforced concrete C-shaped and S-shaped curved bridge are designed and made,then the shaking test under the single direction and multi-support seismic action is studied used by extendable connection.The failure pattern and seismic response characteristics of the two curved bridge is analyzed,the purpose is to guide the two types of curved bridge seismic design.2、A scale 1/20 model of typical Y-shaped and irregular box girder curved bridge with reinforced concrete is produced and studied under multi-dimensional shaking table test. Dynamic response and the difference of straight beam and the curved beam under the under multi- dimensional seismic action is studied,the response of beam and pier,the collision effect between the branch of bridge are analyzed and discussed.3、The pounding contact element is used to simulate the pounding force between the girderes,and dynamic equation of multiple degree of freedom is derived. The precise integration method is used into solving motion equation of structure impact. The results by the precise integration method is verified using numerical example,the precise integration method for structural analysis of the collision is high accuracy,stability and reliability,the efficiency and accuracy is significantly raised.4、The theory of simplification is given by the girders and substructure on both sides of the bridge expansion joints. The typical system of two single degree freedom simplified by the adjacent beams is taken, four groups of collision structure geometric similarity ratio ignored is designed,then shaking table test is carried out. Influence factors and influence degree of structure pounding force is discussed.5、Based on the shaking table test of pounding, contact elements such as the linear elastic, viscoelastic and nonlinear elastic, as well as nonlinear elastic-damping are adopted in numercal anslysis, parameters of contact elements are determined according to the structure impact force. Characteristics and applicability of four kinds of contact elements is analyzed based on result of numerical simulation. The stiffness of contact elements are discussed combined with the existing impact test and theoretical study.6、The structural impact force response spectrum is proposed, the impact force response spectrum is taken using parameters of pounding test and the precise integration method, parameters of stiffness, recovery coefficient,gap, damping ratio and mass is discussed.7、The strategy of parallel computing for Numerical calculation is proposed,multiple parallel computing tasks are created by programming,making the most of the performance of Multi-CPU computer. Computational efficiency of impact spectrum is improved effectively.8、The structural acceleration response spectrum and dynamic coefficient spectrum is proposed. Comparison of acceleration response spectrum between pounding and without pounding is taken,parameters of damping ratio and gap for pounding is discussed. To inquire into amplification of the average response for ground motion input with pounding,dynamic coefficient spectrum is taken byⅠsite,Ⅱsite and Ⅲ site. Impact parameters of damping ratio and gap for pounding is discussed under different sites.9、The analytical model of Y shaped curve bridge is established,then the study under multi-dimensional excitation is taken. Study on influence of displacement, acceleration, impact force and internal force under multi-dimensional excitation is analyzed,and the impact mechanism and the law of dynamic response of Y shaped curve bridge under strong shock is discussed.