A New Hybrid SPH–FEM Model to Evaluate Seismic Response of TSD Equipped-Structures

Tuned Sloshing Dampers (TSD) are passive devices, working based on shallow liquid sloshing in a rigid tank to suppress the horizontal structural vibrations induced by wind loading or earthquake excitations. The key parameters in design of a TSD could be referred to the natural frequency of the liquid sloshing motion and the inherent damping of the TSD during the excitation. Due to the highly nonlinear behavior of the liquid free-surface occurring in TSDs, accurate prediction of the TSD-structure’s behavior during strong excitations is highly desirable. In the current paper, Weakly Compressible form of Smoothed Particle Hydrodynamic (SPH) method is used to simulate the flow within rectangular TSDs during large movements. Characteristics of the flow such as wave height and sloshing forces acting on the container’s walls are calculated and compared with the existing experimental and numerical data. A hybrid SPH-Finite Element Method (FEM) was developed to investigate the seismic response of MDOF structures equipped with multiple TSDs. The proposed model was employed to evaluate the dynamic response of MDOF structures under severe seismic excitations with different frequency contents. The results showed that depending on the frequency content of the ground motion, having the TSDs tuned to a frequency close to the natural frequency of the structure could significantly alter the seismic response of the structures. The effectiveness of TSD is also related to the higher modes effect for MDOF structures and location of TSDs placed on the structural floors.

Modal Combination in Response Spectrum Analysis of Piping Systems

Modal combination methods in the response spectrum analysis of piping systems have been investiaged. Two particular effects are identified, viz, (i) the residual rigid response, also known as the higher modes effect (HME); (ii) the correlation between the modal response and the rigid response. Gupta’s method accounts for both these effects. It is shown that Gupta’s method gives results which are much closer to the direct integration analysis results than are the results obtained from any other modal combination rules which ignore either one or both of the foregoing effects.