Strategies for numerical simulation of cast-in-place piles under axial loading

peer reviewedPile foundations are constructed using a variety of installation methods, which can significantly influence their behavior under axial loading. In this study, numerical simulations of a bored pile, a full-displacement pile and a full-displacement pile with attached expander body have been carried out using standard finite-element analysis where constitutive model parameters are estimated based on various geotechnical field measurements. Considering variations of in situ test measurements, conservative, best estimate and optimistic sets of the calibrated model parameters have been used for the subsurface soil. In order to capture the effect of pile installation method, different numerical strategies have been examined and their applicability to each of the installation methods evaluated. By studying the load-movement response and load distributions along the pile under head-down loading tests, results of the numerical simulations have been evaluated and compared to those obtained from a monitored field study. Finally, local and global sensitivity analyses, as well as a parameter identification procedure have been, respectively, used to find out the most contributing model parameters and to improve model predictions. Results of the numerical simulations signify the importance of a verified staged procedure for modeling the bored and full-displacement piles, as well as the expander body to best capture the pile bearing capacity and load-movement behavior. Furthermore, the parametric study undertaken reveals that acceptable predictions can only be achieved if the most contributing model parameters are identified and calibrated adequately

The efficacy of articaine infiltration versus lidocaine inferior alveolar nerve block for pulpotomy in mandibular primary second molars: randomized clinical trial

Background. Successful anesthesia is a major concern during pulpotomy treatment. The aim of this study was to compare the anesthetic efficacy of inferior alveolar nerve block using 2% lidocaine and buccal infiltration using 4% articaine for pulpotomy of mandibular primary second molars. Methods. This randomized cross-over clinical trial was performed on 23 children (5‒8 years of age) from July through November 2016, referred to the Department of Pediatric Dentistry, Tehran University of Medical Sciences, who needed pulpotomy treatment in both mandibular primary second molars. The patients’ feeling during injection and their behavior during pulpotomy and postoperative complications were registered. Wilcoxon signed ranks test was used for analysis of data. A significant level of differences was taken as P≤0.05. Results. Patients’ feeling during injection and postoperative complications did not significantly differ between the two groups (P>0.05). Patients’ behavior during pulpotomy was significantly better in the articaine group (P=0.004). Conclusion. Articaine buccal infiltration can be used successfully in pulpotomy of mandibular primary second molars

On the role of topographic amplification in seismic slope instabilities

Surface wave generation due to body wave propagation near ground surface has been discussed in the literature. This phenomenon, typically occurring in topographic changing areas, along with its interaction with body waves (SV), decreases precision of formulas for evaluation of slope displacement. This significant fact caused the researchers not only to investigate the combined surface and SV waves motion pattern, but also to consider its effect on structures built on the slopes. In order to reveal the phenomenon, several finite element numerical studies have been performed by ABAQUS programme. Besides, two physical model slopes simulating the landslide occurrence have been constructed and tested by shaking table device. The results of induced and calculated accelerations obtained by two approaches have been compared and Rayleigh wave generation has been proved. Furthermore, the slope displacements have been calculated by various empirical methods and the results were compared with numerical ones. The results proved that in order to increase the precision of empirical formulas for displacement prediction, surface wave effect should be taken into account. Finally, a concept of “effective depth of surficial amplification” is introduced and its effect on dynamic slope stability is analysed

Relationship Between Different Types and Forms of Anti-Asthmatic Medications and Dental Caries in Three to 12 Year Olds

Objectives: Asthma is a common chronic disease. Asthma and anti-asthmatic medications have been suggested as risk factors for increased susceptibility to caries. This study was conducted to evaluate the effects of different types and forms of antihistaminic medications and the duration of drug consumption on the severity of dental caries in asthmatic children. Materials and Methods: This cross-sectional study was conducted in Asthma and Allergy Department of Children’s Medical Center in Tehran, Iran. Eighty-five children between three to 12 years who had been diagnosed with asthma, by means of taking medical history, clinical examination and spirometry were chosen by non-simple random sampling. The participants and their parents were interviewed. Oral examination was performed by a qualified dentist. The data were collected by use of questionnaires and analyzed by the stepwise multivariate linear regression analysis, using SPSS version 16. P<0.05 was considered statistically significant. Results: There was a significant correlation between the number of cetirizine and ketotifen tablets taken and decayed/missing/filled (dmf/DMF) teeth score (P=0.006). There were no correlations between the number of consumed sprays and dmf/DMF score (P=0.923), the duration of drug therapy (P=0.907) or the type of medication taken including ß2 agonists, antihistamines, steroids or a combination of them (P=0.907). Conclusions: The present study showed that the tablet form of medications significantly increased the severity of dental caries even in presence of confounders (sex, age, duration of disease, tooth brushing, sugar consumption, fluoride therapy, mouth dryness).