Development Of Online Hybrid Test System And Its Application To Ring-beam Connection

Earthquakes are among the most destructive natural disasters. The capacity toaccurately simulate the earthquake responses of structures is thus crucial in order toevaluate the level of risk, protect populations and prevent damages and collapses ofbuildings, particularly in a more and more urbanized world. The conventional methodsfor structural analysis, such as experimental test and numerical simulation, are most ofthe time able to provide accurate results, but they have several shortcomings. Theonline hybrid test is appealing because it is an experimental technique able to simulatethe earthquake responses of structures using the benefits of the experimental andnumerical approaches.A new online hybrid test system combined with substructuring techniques andincorporating finite element software is developed. The structure analyzed is dividedinto experimental and analytical substructures. This thesis focuses on the improvementof the analysis of the analytical part. In the proposed system, numerical substructureanalysis is conducted by ABAQUS/Explicit, a finite element analyzer based on anexplicit time integration scheme. An ABAQUS user subroutine VDISP is used as theinterface between the main control program and ABAQUS to impose the targetdisplacements and determine the reaction forces. ABAQUS/Explicit is used instead ofABAQUS/Standard because ABAQUS/Standard employs implicit integration schemeto statically simulate structures, which may lead to convergence issue when thestructures are complex. No iteration is needed in this system, making it suitable forphysical testing. As the approach also avoids the need to modify source code, it will beappealing to a number of real engineering applications. The proposed system adopts aseparated-model framework, Operator-Splitting (OS) integration scheme, and dataexchange through a socket mechanism.The numerical part analysis system is used to simulate the earthquake responsesof simple steel moment-resisting frames. The results obtained from the system arecompared to those obtained from the conventional analysis. It is found that the resultsobtained from the new system are accurate, demonstrating the applicability andefficiency of the proposed approach. A study has been conducted to determine the test parameters giving the most accurate results in the minimum time. The parametersinvestigated are the time increment, loading time, total time step, mass scaling, andmaterial damping. It is found that the loading time should be equal to the total timestep, and the total time step should be equal to two or three times the period of thestructure without damping, and to one-third or one times the period of the structurewith damping. Mass proportional damping is recommended, and mass scaling is usefulbecause it allows the use of a larger time increment.Moreover, the system is applied on a complex steel moment-resisting frame usinga newly developed ring-beam connection. To this end, a finite element model ofring-beam connection is built based on the experimental results provided by cyclicloading tests on test specimens. A parametric study is done in order to obtain furtherinformation on the behavior of this connection and the fulfillment of the strongconnection weak beam requirement. The ring-beam connection achieves all therequirements if the reinforcement is sufficient, demonstrating its applicability andeffectiveness. The results provided by the online hybrid test system are accurate,demonstrating its ability to simulate earthquake response of complex structure.