Non-linear finite element modeling of damages in bridge piers subjected to lateral monotonic loading.

Bridges are among the most vulnerable structures to earthquake damage. Most bridges are seismically inadequate due to outdated bridge design codes and poor construction methods in developing countries. Although expensive, experimental studies are useful in evaluating bridge piers. As an alternative, numerical tools are used to evaluate bridge piers, and many numerical techniques can be applied in this context. This study employs Abaqus/Explicit, a finite element program, to model bridge piers nonlinearly and validate the proposed computational method using experimental data. In the finite element program, a single bridge pier having a circular geometry that is being subjected to a monotonic lateral load is simulated. In order to depict damages, Concrete Damage Plasticity (CDP), a damage model based on plasticity, is adopted. Concrete crushing and tensile cracking are the primary failure mechanisms as per CDP. The CDP parameters are determined by employing modified Kent and Park model for concrete compressive behavior and an exponential relation for tension stiffening. The performance of the bridge pier is investigated using an existing evaluation criterion. The influence of the stress-strain relation, the compressive strength of concrete, and geometric configuration are taken into consideration during the parametric analysis. It has been observed that the stress-strain relation, concrete strength, and configuration all have a significant impact on the column response.

Depression in patients on hemodialysis and their caregivers.

Depression is recognized as the most common psychiatric problem in patients with end-stage renal disease. Stress negatively affects the quality of life of not only the patients on hemodialysis but also their caregivers. The objective of this study was to measure and compare the frequency of depression in these patients and their attendants, and to assess the associated risk factors in both groups. A cross-sectional study was conducted at our hemodialysis unit from June to September 2009. A total of 180 patients and 180 caregivers were enrolled and the Beck's Depression Inventory (BDI-II) questionnaire was administered. Of the 360 respondents, 201 (55.8%) were males and 264 (73.3) were married. According to the BDI scoring, 135 (75%) of the patients and 60 (33.4%) of the attendants were found to be moderately to severely depressed. Marriage (OR 1.817), low income status (OR 1.757) and unemployment (OR 4.176) correlated with increased depression grade, while gender and education level did not. Anemia was the only co-morbidity showing positive association with depression scores in the patients' group (P = 0.023). We conclude that the majority of the patients undergoing dialysis were depressed and were twice more likely to be depressed than their caregivers. In both groups, marriage and unemployment were associated with increased depressive symptoms, while household income showed negative association with depression. Gender and education level were not related to the depression scores.