Nearly Complete Compensation Scheme For Time Delay And Its Application To Real-time Hybrid Testing

Seismic testing methods have been playing an irreplaceable role in promotingengineering seismic techniques and theory. As a new member of seismic testingmethods, Real-time Hybrid Testing (RHT) partitions the structure into experimentalsubstructure which needs to be physically tested and numerical substructure whichneeds to be numerical simulated with the knowledge about the structure. RHT has itsown advantages. It can not only analyze the dynamic performance of complex structuresof large scale with little cost, but also consider rate-dependent properties of specimensdirectly. However, it has high requirements of real-time computation and real-timeloading. Even though numerous studies have been done with relatively simple structuresor components, we will encounter challenges such as, time delay compensation,stability of experiments, real-time computation requirements, and so on when themethod is applied to more complex MDOF structures.The Nearly Complete Compensation Scheme (NCCS) for time delay and itsperformance in RHT are studied in this thesis. The main work and findings aresummarized as follows:(1) The over-prediction strategy in NCCS will bring in larger prediction error. Inorder to reduce the error, a new method for displacement prediction is proposed, whichis based on the information of structure parameters. The analysis of frequency responsefunction shows that it exhibits good prediction accuracy even in larger frequency range.The time history analysis of RHT based on normal compensation schemes for timedelay shows that, with the use of new prediction method, the stability of testing isimproved to some extent, but not that ideal. This reveals the reality that the stability ofnormal compensation schemes cannot be improved significantly and the necessary ofdeveloping novel compensation schemes for time delay.(2) NCCS is endowed with many advantages, such as adaption to the change ofsystem delay, error reduction, and stability improvement. But the numerical simulationreveals that the parameters of the scheme should be chosen carefully prior to tests forbetter results. The principles of parameters determination of the scheme are proved forSDOF and MDOF structures. The principles are confirmed through numericalsimulations. In addition, RHT with a spring specimen also shows good performance ofthe scheme meeting the proposed principles.(3) When the freedom number of numerical substructure increases, Shing methodand EFCM may not satisfy the real-time computation requirements. Besides, theaccuracy of the two methods also reduces with the time delay not completelycompensated for. To solve the problem, the implicit RHT method based on NCCS is proposed. The novel method takes advantage of the character that experimentalsubstructure achieved ahead of numerical substructure to solve nonlinear equationsiteratively. The theory analysis and numerical simulation both show that novel methodhas the advantages as follows: higher calculation accuracy, nearly completecompensation for time delay, higher convergence rate and less time required for singleintegration step computation, which means it can be used in RHT of larger freedomnumber.