Energy capacity and seismic resistance of loess cave structures under field ground motions

Abstract

A shake table test studied the seismic response of a loess cave structure subjected to ground motions. The test specimen was a reduced-scale structure designed under current building codes and located in a region of moderate seismicity of the Asia area. The specimen was subjected to a sequence of increasing acceleration amplitude tests that represented frequent, design, rare, and very rare earthquakes at the site. The test structure performed well (basically in the elastic domain) under frequent and design earthquakes, approached the boundary between the performance levels of life safety and near collapse under the rare earthquake, and collapsed under the very rare earthquake. Damage concentrated covering at cave face and arch top at inner cave hole. The covering layer energy dissipated about 49.4% of the total energy that contributes to damage, and the rest was dissipated by the arch and cave leg layers. The total energy input on the structure until collapse under the very rare earthquake action was very close to the value obtained in a rare earthquake. The seismic capacity of the loess cave meets the seismic fortification index.