Dynamic Field Test For A Base-Isolated High-Rise Steel Building Structure

Dynamic field test is one of the most effective means to verify thedynamical characteristics of real engineering structures. However, due tolimitations of loading facilities and loading circumstances, it is difficult torealize the dynamic field test for a real huge building structure. In recentyears, more and more researches emphasize interests to dynamic field testswith developing of the modern loading technology and computingtechnology, as well as the increasing accuracy demand on structural FEManalysis model. Our research team has successfully implemented thedynamic field tests on a15-storey (51.3meters) base-isolated officebuilding with steel structure, which provides valuabledata for studies ondynamic characteristics and the seismic behavior of base-isolated steelstructure. Following tasks have been completed in this thesis:1. Literature review onthe study advance of base-isolated buildingstructures and dynamic field tests for buildings. The study historiesas wellas the characteristics of the dynamic field tests on base-isolated buildingstructures are summarized briefly. The advantages and disadvantages ofbase-isolated steel building are also commented.2. Design and implementation of the dynamic field tests tothebase-isolated15-storey office building of Yunnan Province DesignInstitute. Test purposes, design details, measurement plans, loadingprotocols and test cases are introduced respectively.3. Comprehensive analyses on the test results data for totally71casesofdynamic field tests. In all71test cases, ambient vibration tests, free dampingvibration tests, sinusoidal vibration test and displacement controlled one-dimensional low-level earthquake simulation tests were completed one byone respectively.The acceleration and displacement responses on each floorwere measured. The relative displacement, story drift and absoluteaccelerationresponse at each floor are analyzed. As well, equivalent lateralstiffness of the base isolation story, the natural frequency and damping ratioof the base-isolated structural system are evaluated.Results demonstrate thatthe overall elastic deformation capacity of the isolation layer has beenunderestimated in the design phase.And it causes the underestimation to thestory shear-force demand in force-controlled design for minor earthquakecases.4. Comparative analysesbetween the numerical results of finite elementmodel (FEM) and the field test results. On the basis of the ambient vibrationtest for the real building, SAP2000finite element model is developed for thetested base-isolated high-rise steel structure.Key field test cases are simulated with the FEM analyses. The accuracy and reasonability of thefinite element model are verified, and the earthquake resistant advantages ofbase-isolated structure are explained correspondingly. By comparing thefield test results and the SAP2000results with the numerical results of theETABS modelused in the design phase discloses the fact that theunderestimation to the equivalent stiffness of the base isolation story and thecorresponding consequence about the underestimation to the story shearforce demand in design phase.