Controversy prevails over the effect of overglazing on the fracture strength of ceramic materials. Therefore, the effects of different surface finishes on the compressive fracture strength of machinable ceramic materials were investigated in this study. Plates prepared from four commercial brands of ceramic materials were either surface-polished or overglazed (n=10 per ceramic material for each surface finish), and bonded to flat surfaces of human dentin using a resin cement. Loads at failure were determined and statistically analyzed using two-way ANOVA and Bonferroni test. Although no statistical differences in load value were detected between polished and overglazed groups (p>0.05), the fracture load of Vita Mark II was significantly lower than those of ProCAD and IPS Empress CAD, whereas that of IPS e.max CAD was significantly higher than the latter two ceramic materials (p<0.05). It was concluded that overglazed and polished surfaces produced similar compressive fracture strengths irrespective of the machinable ceramic material tested, and that fracture strength was material-dependent.
The damped outrigger system is in widespread in seismic area as a damping modification system. However, the relationships between the exact damping performance and its seismic response reduction effect has not been deeply investigated yet. This paper investigated the non-linear dynamic response characteristic of single-damped outrigger systems with oil dampers or elasto-plastic dampers considering design earthquake levels. The optimal damper design equations to maximize 1st mode damping ratio were proposed, and validated through the application example of a Japanese super-tall building, and a design algorithm to translate the optimized single damped outrigger to quad damped outrigger systems is proposed.
This paper deeply investigated the relation between the modal property and seismic response by the single outrigger system with linear viscous dampers.According to the result, 1) single damped outrigger is efficient particularly for 1st mode control, 2) the optimal outrigger height ratio is 0.5 for maximizing 1st mode damping ratio and 0.6 to 0.8 for minimizing seismic responses, 3) the newly proposed simple equation of optimal damper stiffness ratio is more accurate for the existing equation and 4) a 1st mode control design strategy is proposed and a design example is demonstrated for Japanese 400m height tall building.
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