Investigation of Deformation-Based Damage Limits of RC Columns for Different Seismic Codes

The seismic performance of reinforced-concrete columns is related to the expected damage limits under seismic loads and how this damage relates to safety of the structure. In order to assess the performance of reinforced-concrete columns under seismic loads, performance-based deformation and damage limits are proposed by the seismic codes. Adequacy of the deformation and damage limit levels given in the codes such as Seismic Evaluation and Retrofit of Existing Buildings Standard, ASCE/SEI-41 (2017) and Turkish Building Earthquake Code (2018) were evaluated by carrying out parametric studies for RC columns. Reinforced-concrete circular columns are designed in parametric studies to present the effects of various parameters such as concrete compressive strength, axial load levels and spiral reinforcement ratio on performance-based damage limits. Performance limits corresponding to each performance levels obtained by different seismic guidelines were compared. When the results obtained from the analyzes are examined, it has been observed that there are significantly different results in the cross-section damage limits values of ASCE/SEI-41 (2017) and TBEC (2018) regulation, which can change the performance level of the building. TBEC (2018) gives approximately 50% conservative limitations when they are compared with the ASCE/SEI-41 (2017) limitations. As a result, TBDY (2018) seems to offer safer and ductile solutions than ASCE ASCE/SEI-41 (2017).

NEW BEARING STEEL FOR HIGH-SPEED APPLICATIONS

The requirements for speed suitability and fatigue strength of motor spindle bearings are constantly increasing. These challenges can be met by further developing the spindle bearings, e.g. by using higher-performance bearing steels. In the following, the experimental investigation results of a spindle bearing made of a new raceway steel tested on a high-speed rolling bearing test rig are presented. Spindle bearings of the type 7008 (hybrid execution) were tested in an endurance run at a rotational speed of 46 krpm and 3 kN axial load. The operating behaviour was validated based on the bearing outer ring temperature and the vibration behaviour. Microscope analysis of the raceways after the test shows that the new steel has good resistance to micropitting and surface fatigue. The calculated contact pressures, wear parameter and lifetime for the bearings in the tests show that the performance limits of spindle bearings are significantly higher than initially assumed.

The Impact Of Oral Health On Psychological Distress Among Older Adults In California

In California, the population of adults ages 65 and older is projected to increase from 11% in 2010 to 19% in 2030. The aging of the population requires modifications in public health to ensure that people are not only living longer, but also healthier lives. Oral health is an important, but often overlooked factor that affects the overall health of older adults. Poor oral health increases the risk of physical comorbidities, decreases chewing performance, limits food choices, and exacerbates weight loss. Furthermore, poor oral health disrupts social health via decreases in verbal communication and facial expressions, such as smiling. This study examines the effects of oral health, assessed by tooth condition, on psychological distress among adults ages 65 and older in California. The study uses the 2019 California Health Interview Survey (CHIS), an annual survey of a representative sample of the state’s residential, noninstitutionalized population. Logistic regression models are used to determine the association between tooth condition on psychological distress controlling for gender, race, and elderly poverty index. Worsening tooth condition increases the odds of having psychological distress with lower odds among individuals 85+, and higher odds among women, and non-Hispanic whites compared to Hispanics. Public health programs and interventions are required in California to prevent and mitigate the impacts of poor oral health on psychological distress among the increasing and diverse older adult population.