Research On Substructural Shake Table Testing Method For Non-structural Elements In Buildings

Experimental tests on non-structural elements present two distinct features when compared to the tests on structural elements.Firstly,non-structural elements are attached to the primary structure,and their seismic behaviors are closely correlated to the seismic response characteristics of the primary structure.Secondly,the seismic damage incurred by non-structural elements is primarily governed by floor acceleration or velocity,exhibiting complex sensitivity to multiple engineering demand parameters.This stands in contrast to the seismic damage observed in general structural elements,which is primarily determined by structural deformations,such as inter-story drift.This dissertation take the building structure as the research object.To address the above-mentioned first feature of the experimental tests on non-structural elements,a standardized dynamic loading protocol is proposed to obtain the seismic performance of non-structural elements,which takes into consideration the seismic response characteristics of the primary structures.This will establish a unified standard for evaluating the seismic behaviors of non-structural elements.Basd on the proposed loading protocol and to address the second feature,a substructural shake table testing method is proposed to simulate the seismic responses of a full-scale room with multiple engineering demand parameters in the archetype building.It serves as an innovative experimental testing method for replicating the seismic responses of different types of non-structural elements located on different floors of different buildings.The main research achievements of the dissertation are summarized as follows.(1)This dissertation presents a standardized dynamic loading protocol for nonstructural elements,considering the seismic response characteristics of the primary structure.The proposed loading protocol is an amplitude-varying sinusoidal wave,composed of five closed-loop functions.It is designed to effectively match the target response spectrum,which is controlled by the dual-frequency segments of the shortperiod range and natural period range of the primary structure.By accounting for the fundamental-period characteristics,the target response spectrum accurately reflects the influence on the seismic behavior of non-structural elements from a specific building.(2)This dissertation introduces an estimation method,based on modal response spectrum analysis,for determining the peak floor acceleration which is a crucial reference point in the target response spectrum.The proposed method addresses the issue commonly encountered in general modal combination methods,where the maximum absolute acceleration responses tend to be zero at the bottom of the structure.To rectify this,the method incorporates a complementary mode in the modal combination that considers the contribution of the ground motion excitation.This approach proves to be appropriate for the peak floor acceleration estimation for both linear and moderately nonlinear multi-story and high-rise buildings.(3)A substructural shake table testing method has been proposed in this dissertation that can simultaneously simulate the seismic response time histories in the horizontal directions of both the ceiling and floor level of a full-scale room.On the one hand,a design method based on the first two mode matching is established for determining the design parameters of the substructure testing frame.On the other hand,an open-loop nonlinear control algorithm based on optimal control theory and offline iteration has been proposed to generate the input of the shake table.This method allows the substructure testing frame to accurately reproduce the target responses at a specific floor of the archetype building.Consequently,this method not only facilitates the simulation of seismic responses of the archetype building but also allows for the replication of the standardized dynamic loading protocol proposed in this dissertation.(4)Taking a typical 42-story high-rise reinforced concrete frame-core building as the archetype structure,a substructure shake table test was conducted for simulating the seismic responses of a full-scale room situated at the middle elevation of the archetype building and verified the feasibility and accuracy of the proposed substructural shake table testing method.The test successfully simulated the horizontal acceleration time histories of both the bottom and roof level of the room,as well as their inter-story drift.Additionally,the test accurately reproduced the seismic responses of various nonstructural elements,including suspended ceilings,bookshelves,swivel chairs,and partition walls that were arranged in the room.