A novel control strategy for reproducing the floor motions of high-rise buildings by earthquake-simulating shake tables

To enable the experimental assessment of the seismic performance of full-scale nonstructural elements with multiple engineering parameters(EDPs),a three-layer testbed named Nonstructural Element Simulator on Shake Table(NEST)has been developed.The testbed consists of three consecutive floors of steel structure.The bottom two floors provide a space to accommodate a full-scale room.To fully explore the flexibility of NEST,we propose a novel control strategy to generate the required shake table input time histories for the testbed to track the target floor motions of the buildings of interest with high accuracy.The control strategy contains two parts:an inverse dynamic compensation via simulation of feedback control systems(IDCS)algorithm and an offline iteration procedure based on a refined nonlinear numerical model of the testbed.The key aspects of the control strategy were introduced in this paper.Experimental tests were conducted to simulate the seismic responses of a full-scale office room on the 21^(st)floor of a 42-story high-rise building.The test results show that the proposed control strategy can reproduce the target floor motions of the building of interest with less than 20%errors within the specified frequency range.

Rapid report of seismic damage to buildings in the 2022 M 6.8 Luding earthquake,China

The report summarizes the observed damage to a variety of buildings near the epicenter of the M6.8 Luding earthquake in Sichuan Province,China.They include base-isolated buildings,multi-story reinforced concrete(RC)frame buildings,and masonry buildings.The near-field region is known to be tectonically highly active,and the local intensity level is the highest,that is,0.4g peak ground acceleration(PGA)for the design basis earthquake,in the Chinese zonation of seismic ground motion parameters.The extent of damage ranged from the weak-story collapse that claimed lives to the extensive nonstructural damage that suspended occupancy.The report highlights the first observation of the destruction of rubber bearings and viscous dampers in the isolation layer of Chinese seismically isolated buildings.It also features the rare observation of the brittle shear failure of RC columns in moment-resisting frames in a region of such a high seismic design requirement.Possible reasons that may have attributed to the reported damage are suggested by providing facts observed in the field.However,careful forensic analyses are needed before any conclusive judgment can be made.

Rapid report of seismic damage to hospitals in the 2023 Turkey earthquake sequences

The seismic performance of medical systems is crucial for the seismic resilience of communities.The report summarizes the observed damage to twelve hospital buildings in the area affected by the MW 7.8 and MW 7.5 earthquakes on February 6,2023 in Turkey.They include five base-isolated buildings and seven fixed-base buildings in southcentral Turkey's seven most heavily affected provinces.By relating the post-quake occupancy statuses of the hospitals with the estimated seismic demands during the earthquake doublet,the report offers the following observations:(1)the base-isolated hospital buildings on friction pendulum bearings generally exhibited superior performance of achieving the goal of immediate occupancy and provided better protection for nonstructural elements than fixed-base counterparts did;(2)the fixed-base hospital buildings of reinforced concrete structures constructed after 2001 successfully achieved the goal of collapse prevention even under very high seismic demands;(3)some fixed-base hospitals also remained operational even if they were very close to the fault rupture and were subjected to higher-than-design-level earthquake ground motions.