Research On Seismic Response Of A Ground Fissure Site Under Earthquake And Parameters Of Its Output Ground-motion

Xi'an is one of the most severely affected cities suffering from disasters caused by ground fissures.Ground fissures can not only destroy the integrity of site,but also damage the engineering buildings constructed aboveit.At present,the principle of space preventing collision is adopted in the current design code.However,many ancient buildings in Xi'an were built across ground fissures,and the same problem will be encountered for the new buildings in urban construction.If the preventing collision principle is always taken,valuable land resources will be wasted.Therefore,it is urgent to study the destructive form of the frame structure across ground fissuresunder earthquake and the law of seismic response of the ground soil.According to the researches,some integrated technical measurescan be taken to make possible buildings crossing ground fissures,which will have a great realistic significance for the urban planning and construction of Xi'an.The shaking table test of a frame structure across ground fissures with a 1:15 scale was carried out in this paper.The simulation of soil boundary conditions and the similitude of scale model were mainly considered,the superstructure of the model is a five-story concrete frame structure,and the substructure is constituted of layered soils with cracks to simulate Xi'an ground fissures.The results are as follows:(1)By sticking rubber membrane and foam board on the shear soil box the test can simulate soil shear deformation very well,and the boundary effect of model's soil box can be reduced effectively.(2)The existing ground fissures made the dynamic response of the model at the hanging wall was lager than that at the footwall;With the increase of earthquake loading's intensity,the natural vibration frequency of structure kept decreasing,and the structural damage was exacerbated;Under the earthquake,the ground fissures in-situ widened and shifted,simultaneous contraction joints expend.(3)Ground fissures has a amplification effect on the soil acceleration.The amplification coefficient decreases with the increase ofseismic intensity.The soil's maximum acceleration is detected at the hanging wall near ground fissures.(4)The main of model's deformation belongs to shear deformation,and the differences between the various story's drifts are significant;The maximum strain of each story happens in the transverse column close to the ground fissures;When the acceleration of the top story is larger than the the underlying story,when the seismic intensity is small,the structure of the overall acceleration response without significant lag,when the seismic intensity is greater,,the acceleration response lag of the overall structure is largest under the bedrock wave,followed by Jiangyou Wave,minimum under El-Centro wave.