Anti-seismic Analysis And Isolation Study Of Quayside Container Crane

Frequent earthquake disasters have brought a great loss of life and property to people,and also increased the urgency of seismic analysis and research. Large quayside bridgehandling machines, located in modern harbor or dock where earthquakes are frequent, arethe main equipments used for handling containers or other heavy cargos. They are not onlythe basis of promoting the rapid development of harbor trade, but also the importantpassage of providing the emergency rescuing supplies during the natural disasters. Atpresent, numerous investigations on the modeling and dynamic seismic analysis of largeengineering structures have been carried out. However, all these studies only have focusedon the high buildings, gravity dams and highway bridges, and did not consider thedynamic behaviors of large handling machines.In this paper, a quayside container crane is first selected as an analysis object. Then,the seismic behaviors of the crane under different working conditions and seismic loadsare investigated through numerical simulation and a series of shaking table tests. Thedetailed research and main conclusions in this dissertation are summarized as follows:(1) By use of the static analysis, response spectrum analysis and time-history analysis,the seismic responses of the crane structure under different working conditions andseismic loads are studied. The results show that the crane itself has relatively highearthquake resistance and overall stability, and can ensure the structural safety under theearthquake loads with moderate seismic fortification.(2) According to the relevant theory of structure reliability, the reliability analysismodel of the crane structure is developed. The failure probability p_f and reliability index βat different dangerous sections of the crane are calculated through using the limited statemethod. The results demonstrate that the pfat dangerous sections are all relatively small,and all the β are more than zero. Owing to the influence of load partial coefficient, thereliability index β obtained from limited state method is smaller than that obtained fromallowable stress method. (3) The dynamic characteristics and seismic responses of the crane with and withoutisolation system are researched through numerical simulations. The comparison resultsshow that significant reduction in the seismic response amplitude can be seen for thestructure with the isolation system. In addition, the reliability analysis model of the cranewith the isolation system is also established and the corresponding anti-seismic reliabilityanalysis is carried out still using the limited state method. The results show that when theisolation system is used, the reliabilities at different locations are all improved.(4) A finite element model of1:50scale model is developed based on the dynamicsimilitude law. Through comparing with the calculation results of the prototype structure,it can be found that the dynamic characteristics and seismic behaviors of the prototype arewell represented by the1:50scale model with small errors.(5) Experimental model of1:50scale model of the crane and the correspondinganti-seismic isolator are made. Then using these two models, a hammering modal test anda series of shaking table tests are performed to obtain the dynamic performances andseismic responses of the crane structure with and without isolation system. The test resultsshow that this experimental model can accurately predict the dynamic performances andseismic behaviors of the actual structure. Under the earthquake action (peak groundacceleration of the seismic loads is0.1g), the structure remains the elastic stage. When theanti-seismic isolator is used, the bending strain and acceleration responses at differentnodes are significantly reduced. It means that the design of this isolator is accurate.(6) Elastic-plastic seismic performances of the crane structure under7degree rareearthquake and8degree rare earthquake are carried out by considering plastic deformationof material. The calculation results demonstrate that the whole model is still in the elasticstage after the action of7degree rare earthquake. However, the bottom carts of partialworking conditions have appeared the derailment phenomenon. After8degree rareearthquake, partial components and sections of the model has entered the plastic stage.Meanwhile, both landside and waterside bottom carts lift off the wheels.