Abstract Summary
A novel type of structure-dependent integration methods has been developed for time integra-tion and pseudo-dynamic testing. The feasibility of this type of integration methods has been numerically affirmed by numerical tests and experimentally validated by pseudo-dynamic test-ing. It is generally recognized that structure-dependent integration methods can generally com-bine unconditional stability and explicit formulation together. Hence, they are promising for either time integration or pseudo-dynamic testing. An explicit pseudo-dynamic algorithm is generally preferred over an implicit pseudo-dynamic algorithm since the implementation of an implicit pseudo-dynamic algorithm is very complex due to an iteration procedure and it may lead to incorrect results. Both the Chang explicit method and CR explicit method (proposed by Chen and Ricles) have been shown to have desired numerical properties, such as unconditional stability, explicit formulation and second-order accuracy. However, they have a different per-formance in the step-by-step solution of high frequency initial value problems. This is because that Chang explicit method has no weak instability while CRM has this adverse property. It is recognized that a weak instability might lead to inaccurate solutions or numerical explosions. The root cause of weak instability was analytically investigated and numerically illustrated. In addition, a series of pseudo-dynamic tests were conducted by using both integration methods. Several hot-rolled steel beams with the cross section of H 100x100x6x8 and a length of 1.5 m were adopted for the serial tests. The test setup for each steel beam was like a cantilever beam. The steel beam was loaded in its minor axis to avoid any instability or local buckling. In addi-tion, some two-story steel frames were also fabricated for the pseudo-dynamic tests. Test results revealed that Chang explicit method can generally lead to reliable test results while CR explicit methods resulted in incorrect test results if there existed high frequency responses.
