This study aimed to identify the critical ground motion parameters that lead to structural damage and assess their impact on the nonlinear responses of buildings. The analyses are carried out using a calibrated numerical model that was acquired within the ICONS experimental framework that represents reinforced concrete (RC) structures constructed before seismic design regulations were enforced. For the analysis, 30 seismic records were chosen based on magnitude (M), epicentral distance (R), and peak ground acceleration (PGA) for two high seismic activity areas that were observed. Eleven parameters are categorized, traditional metrics, energy-based, spectrum-based, duration-based, and fundamental metrics, and examined based on their main attributes. The results showed a strong relationship between certain seismic properties and the maximum interstory drifts of building as a damage prediction parameter. Peak ground velocity (PGV), specific energy density (SED), and Housner Intensity (HI) were found to be the most important variables in assessing the correlation with possible structural damage. Therefore, the assessment of structural damage based on nonlinear dynamic analysis should primarily incorporate PGV with the possible addition of energy- and spectrum-based metrics as the most reliable ground motion parameters for the selection of earthquake records for time history analysis.

In this study, the frictional behaviours of three different guide elements—guide rings, labyrinth seals, and hydrostatic bearings—in hydraulic cylinders is investigated experimentally. A modular, double-acting hydraulic cylinder was designed to compare these three different design elements under different pressures (0 bar, 120 bar, and 240 bar), velocities, and radial loads. The results show that the guide rings exhibit the highest friction, especially at high pressures. Labyrinth seals exhibit significantly lower friction and extend the service life of the components. Hydrostatic bearings allow low friction but require precise control of the fluid, which limits their use. The results provide practical guidelines for selecting guide elements and optimising the friction performance, durability, and efficiency of hydraulic systems. We found that the best solution from the points of view of design, friction, and economics is to use labyrinth seals as guiding elements for the fast reciprocal moving rods of hydraulic cylinders.

Fatigue failure remains a key design concern in many mechanical components, particularly in applications where cyclic loading is unavoidable. In experimental practice, uniaxial fatigue testing is still the most widely used approach, mainly because it is simple, cost-effective, and supported by long-established standards. However, many components in service are subjected to combined axial, bending, and torsional loads, for which single-axis tests provide only limited insight. This discrepancy between laboratory testing and real operating conditions has driven the development of multiaxial fatigue testing systems. Existing review studies on multiaxial fatigue largely focus on failure criteria and life prediction models, while the experimental machines required to generate multiaxial loading are seldom examined in a systematic and comparative manner. In this paper, uniaxial and multiaxial fatigue testing machines reported in the literature are reviewed from an experimental perspective, with attention given to mechanical layout, actuation principles, load control, and synchronization. The discussion highlights the trade-offs between loading realism, system complexity, and cost, and illustrates industrial relevance through examples from aerospace and automotive engineering. Recent developments in control, automation, and data analysis are briefly discussed in relation to future experimental fatigue testing strategies.