| Development of high performance seismic isolated buildings to meet the needs of seismic resilience defence has become an academic frontier and an engineering challenge in China and abroad.The Regulations on Anti-seismic Management of Construction Projects clearly states that newly built schools in high-intensity regions should be guaranteed to meet normal use requirements during design basis earthquake,and at the same time,as the functions of school buildings continue to develop,higher requirements for space utilization and functional integration among multiple buildings are put forward,and large chassis base isolation technology is expected to meet the needs of seismic resilience defense and functional integration of schools.This paper relies on a real large chassis base isolated school construction project in a region of 8degrees(0.3g),firstly,the large chassis base isolation design was carried out for the project,then the seismic resilience assessment of the structure was carried out,the key response parameters affecting its resilience level were identified,and then the influence of the key design parameters of the isolation system on the seismic resilience of the structure is analyzed.,the yield ratio value of the newly built large chassis base isolation frame structure oriented to the resilience target is proposed,which can provide an important reference for the seismic isolation design of such structures.The main work and conclusions of this study are as follows:(1)The large chassis base isolation design of the project was completed.The yield ratio of the seismic isolation system was 3.0%,and the analytical model of the project was established by ETABS and the design indexes were evaluated,the results show that the horizontal seismic reduction coefficient was 0.26,the maximum story drift under maximum considered earthquakes was 1/435(0.23%),the maximum surface pressure of the seismic isolator was 15.32 MPa,and the minimum value was 0 MPa.The maximum displacement of the seismic isolator is 352 mm,all of which meet standard requirements.(2)The elastoplasticity analysis model of this large chassis base isolated school was established using Perform-3D,and the elastoplasticity analysis under design basis earthquake and maximum considered earthquake was carried out to obtain the seismic response of the three towers T1,T2 and T3,and the repair cost,repair time and casualty rate were obtained from the resilience assessment according to Chinese standard,towers T1 and T2 had high floor accelerations under maximum considered earthquakes,and under these conditions the elevator produced a corresponding repair time of 13.1days,resulting in a two-star resilience level for T1 and T2.The floor accelerations of T3 were better controlled,the repair time is 3.1 days,resulting in a three-star resilience level for the overall assessment.(3)Three large chassis isolation schemes are designed,and the corresponding yield ratios are 2.0 %,3.0 % and 4.0% respectively.With the decrease of yield ratio,the story drift and floor acceleration of the three towers decrease.When the yield ratio is 2.0%,up to 22.86% reduction in structural story drift and up to 34.50% reduction in floor acceleration compared with other options.For the tower T1 and T2,when the yield ratio is 3.0% and 4.0%,the structural resilience level is two stars,and when the yield ratio is2.0%,the structural resilience level is raised to three stars;for tower T3,when the yield ratio is 4.0%,the structural resilience level is two stars,and when the yield ratio is 2.0%and 3.0%,the structural resilience level is three stars.Controlling the damage of acceleration-sensitive non-structural components is the key to improving structural resilience levels.A reduction in the yield ratio can effectively control floor accelerations,thereby improving structural resilience levels.Under the design conditions of this design basis intensity(0.3g),the recommended value of yield ratio is 2.0%. |
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