| Ancient stone archway as one kind of characteristic structures has significant cultural,historical and artistic value.Each part of archways is connected by mortise and tenon.Under earthquake,archway collapses because of the destructive joint,so it is very important to do seismic response and seismic protection on ancient archway.It is common to do seismic analysis by the finite element method for the existing ancient buildings.When it comes to large deformation problem,the finite element method has some limitations,so it can not analyze the process of collapse of archway accurately and intuitively under earthquake.In this article,taking the Nectar Archway in Ya’an and Longzhong Archway in Xiangyang as objects,two discrete element models for seismic response analysis are established based on investigations and some information about earthquake damage.The main conclusions are as follows:(1)It is concluded that with the increasing of earthquake intensity,the destruction of Nectar Archway increases by analyzing the seismic response at different intensity of Earthquake.The seismic response is weak and the roofs of archway slip slightly only when the seismic intensity isⅥ.There is a greater collapse of archway when seismic intensity isⅦ,ⅧandⅧ.(2)The general rule of earthquake damage of ancient Nectar Archway is obtained by the process of collapse of archway under earthquake.The roofs of archway slip and collapse firstly.The beams which connected whit columns slip until the beams collapse.The earthquake damages of Nectar Archway are consistent with the actual features.(3)The sensitivity of the joint parameters has been studied.A conclusion that the seismic response increases with the increase of the stiffness is obtained by analyzing the seismic response of Nectar Archway at different shear stiffness of joints.The seismic response is weak along the height direction of archway when the joint shear stiffness is less than 2.56×10~3Pa/m.The rigidity become bigger and the attenuation of earthquakes is less than influence of the height direction of archway,when the joint shear stiffness is greater than 2.56×10~8Pa/m.(4)When joint friction angle of Longzhong Archway is small,close to 0°,the surface of joint tends to smooth and the joints do not transfer seismic effect.When joint friction angle varies from 0°to 15°,the effect of earthquake is more obvious,and with the increase of the angle,the greater the dynamic response.When joint friction angle of Longzhong Archway is greater than 45°,the seismic response becomes stable.(5)The base-isolation system of ancient Archways is proposed and verified by discrete element model.The base-isolation system makes a great contribution to attenuation of seismic response under earthquake. |
