Seismic Response Characterisics Of Concrete Cable-stayed Bridges Considering The Pounding Effects

For the concrete cable-stayed bridge crossing active fault(CSBCAF), it dues to the ground motion and fault dislocation relative anisotropy of pounding effects,which will increases the risk significantly. For the significantly increased of vertical and horizontal displacement in the strong earthquake, the probability of the CSBCAF and the adjacent bridge abutments will inevitably. At present, scholars from domestic and foreign have carried out lots of research for medium-small span bridges of pounding effects, but the CSBCAF does have less research results and documentation for reference of project examples. The main reason for this situation is that the amount of long span bridge existing highway network in is still limited, and the number of CSBCAF is only a small part. On the other hand is that in most exsisting cable-stayed bridge have been made in recent years, the risk of pounding effects caused by the earthquake is not paid moreand more attention. However, it is inevitable that the cable-stayed bridge will build in the high intensity seismic zone. To meet the need of seismic safety performance,scholars should increase the study on the objective.Therefore,by taking the CSBCAF as the research objects,with how to analy the relationship between the frequency of collision effects as the starting point,and deep analysis on the ground motion, collision effect analysis model and structural crash damage grade evaluation of CSBCAF. The main work of the the owner side in the paper:(1) Mechanism about pounding effects of CSBCAF are given from the macroscopic angle, and referred to relative spatial collision between body position and form of the collision energy conversion process as the standard collision, the collision accident is classified. Ground motion characteristics of CSBCAF are studied, and also analyzed the mechanism of this type bridges. Taking a CSBCAF as an example, the difference of ground motion characteristics between adjacent bridge collision effects is studied. The results indicate that feature difference of dynamic response has the higher reaction than the same structures of collision system, and the medium-small span bridges has more sensitivity of feature difference of dynamic response than cable-stayed bridge.(2)A method is proposed of estimation practical frequency formulas for vertical vibration of floating system cable-stayed bridge. The method is based on the energy conservation law, and the frequency formula of the CSBCAF is obtained by analyzing, calculating and adjusting the time variables including auxiliary pier, the main tower and cables, etc. Compared this formula to estimate the corresponding finite element model, and the results show that the re of the requirement on errora is satisfied, and it has better applicability. The error may be due to the stiffness of the cable support tower. The method laid a foundation for the analysis of dynamic characteristic feature difference of dynamic response.(3)Calculation model of collision effect for CSBCAF under the earthquake. Pier rigidity and constraints is introduced into the modle, which is based on freedom vibration theory. The stress distribution law of different body collision is obtained by method of non-linear dynamic time-history analysis. The law of collision effect in colliding contact element stiffness, terrain conditions and the initial gap for CSBCAF is studied, and influence of the above factors on the seismic response between cable-stayed bridge and small span bridge is obtained.(4)Method of damage grade evaluation for CSBCAF is studied.Inflence law of collision damage for time-dependent effect of concret and vibration to the the CSBCAF. Based on the results of two studies, A method is proposed on the basis of pre-established only consider the effect of cross-fault collision damage concrete cable-stayed bridge rating system. On this basis, attenuation coefficient of stiffenese is evaluated as index,and combined with the maintainability as the damage level, lastly,method of damage grade evaluation for CSBCAF is proposed. Influence of different ground motion on Park damage indices distribution of pylon in longitudinal direction PGA level and frequency components of collision damage influence law is studied.(5)Countermeasures for CSBCAF of pounding effects is analysised, article’s response to CSBCAF for three damping rubber bearings, bearing shear key, stiffness and displacement restrictor is studied. It proposes two kind of new measures for vibration reduction.In this paper, the research results have a important significance to know deeply the theoretical and practical in cross-fault collision effect, and promote the development of seismic consider collisions for CSBCAF. The achivements may play a reference role in promoting the development of the countermeasures for CSBCAF of pounding effects.