Study On The Elastic-plastic Dynamic Response Of30m Arch Truss With Different Rise-span Ratio Under Earthquake Effect

The large-span steel spatial arch truss, as a kind of large spatial structures, is widely designed for the main stress system of large-scale public buildings. Earthquake is one of the disasters that harass human being all long. The main approach to alleviate the losing of life and belonging is anti-seismic engineering. The great-span arch truss construction in all previous earthquake often become the asylum of disaster victims, its security under earthquake and the massive lives and the vast fortune of building are closely linked. Over80%of the big and medium cities in China are in the earthquake zones, therefore, dynamic elasto-plastic analysis of steel-pipe arch truss under earthquake effect is of great practical significance.Taking30m span steel arch truss for research object, the main works are as follows:1、The design of the steel-pipe arch truss model with seven different rise-span ratio were completed according to the current national relevant code.2、The elasto-plastic dynamic response under earthquake action for30m span fall triangle section arch trusses have been studied by using the SAP2000 program, in the coupe of analysis, non-linear analysis of material and geometry and the effect of gravity and dampwer included. The accomplishment of the dynamic elastic-plastic time history analysis of the model is by choosing three kinds of seismic wave and adopting the plastic hinge theory. The dynamic response was studied according to the characteristic targets-acceleration curves by increasing the seismic acceleration amplitude, in order to study the characteristics of dynamic response of structure.3、Through the comparison the law of the steel weight, first order vibration mode corresponding cycle、structural maximum displacement response、curve of maximum displacement of nodes-acceleration amplitude、maximum yield-displacement ratio of nodes and the bearing capacity of the different ratio of rise to span steel arch truss, analysis of how the rise-span ratio Influences the dynamic elastoplastic response of arch truss.Through the comparative analysis, this paper draws the following conclusions:1、The steel weight and the first order vibration mode corresponding cycle are the smallest with0.2rise-span ratio and on both sides to increase under the condition of the same span and the section form. The level maximum displacement response of elastic stage enlarges with the rise-span ratio increasing, and the vertical displacement response reduces with the rise-span ratio increases.2、When the seismic acceleration amplitude is smaller,the response of characteristics indexes linearly increase; with the increasing of the seismic acceleration amplitude, some members turn into plasticity and the equilibrium position of the whole structure comes into being transition; when the acceleration peak reached the critical load, the deformation in the middle members of primary truss is serious and the bucking of the whole structure was taken place.3、When seismic waves is input from the X orientation along the structure, the elastic dividing and elastic-plastic critical peak acceleration reduces with the rise-span ratio increasing, and the vertical orientation is contrary to the horizontal orientation. It means the horizontal bearing capacity of the structure reduces with the rise-span ratio increasing, and the vertical orientation is contrary to the horizontal orientation.4、When seismic wave is on the structure, the vertical displacement ductility coefficient is less than its horizontal displacement ductility coefficient, indicating that the vertical energy dissipation capacity is less than the level of energy dissipation capacity of the structure.