Study On The Dynamic Model Test Of Structure Of Large Scale Ship Lift Tower

The vertical gear-rack typed ship-lift has widely applied in large water conservancy and hydropower projects in China, in view of its fast speed of passing dam and its safe and reliable operation. Because of its complex structure and lack of foundation of seismic research, the research on seismic theory and technique for vertical gear-rack typed ship-lift is urgently needed.The Research on key scientific problems and techniques is carried on, which includes dynamic characteristics, dynamic response, the anti-collapse performance and overturing stability under rare earthquake, with close combination of most large-scale gear-rack typed ship-lift of Xiang Jiaba with defense intensity of8degree. The comprehensive means of calculating analysis, dynamic failure test based on large-scale shake table, elasto-plastic static and dynamic analysis are used for seismic research.(1) Focus on the advantage and disadvantage of gravity distortion and strain distortion similarity laws, the right dynamic similaity law is put forward by shake table test and theoritical analysis which is more suitable for large-scale ship lift tower structure with the characteristic of "tower with thin wall, strong column and weak beam", it is preferable to apply gravity distortion law in design of the model of reinforced concrete ship lift, because the test results of tower structure emphasis on safety and that of cross beams are more reasonable, based on forecast performances of prototyped structure according to gravity distortion model, gravity distortion law is applied to1/25scaled shake table test of ship lift.(2) The1/25scaled shake table model of XIANGJIABA ship lift, including towers, ship chamber model and balance chain systems is tested, considering the test scheme of reducing coupling force by setting damper to the longitudinal guiding beam which locates between the ship chamber and the tower. Test results show that:the stiffness of top cross beams are so weaker that the beams would easily crack under ground motions; the prototyped structure can satisfy the Three-Level performance objectivity of undamaged under minor earthquake, repairable under moderate earthquake and non-collapsed under major earthquake; at design seismic level, the installment of damper has effect to reduce the coupling forces of longitudinal guiding beam, the maximum longitudinal coupling forces can reduce about15%～22%.(3) Elasto-plastic static and dynamic analysis method are used to study the weak parts and possible failure modes of the ship lift tower, the comparison of test and analysis results shows the failure laws are equal between shake table test and elasto-plastic analysis. The analysis results further indicate that the structure are reasonable designed to have better seismic performances with multiple seismic fortification lines against exceeding design earthquake.(4) Based on MATLAB7.0platform, the numerical program of solving rocking equations of rigid bodies are compiled, after verifying its reliablity, the overturing stability of ship lift tower are analyzed. Results show that the charateristic of earthquake waves, aspect ratio and size of structures have effect on overturning stabilities. The tensile stress concentration zones of tower bottom of ship lift should be paid more attention so as to prevent bottom disengagement resulting rocking instability.(5) Aiming at scaled ground motion in shake table test with charaterisics of pulse which can not consider the cumulative effect of earthquake duration, and it is unsafe to forecast seismic performance of prototyped structure by using test results, the idea on the development of model materials and dynamic model design considering cumulative effect of earthquake duration is proposed, and preliminary attempts has carried on.