Inelastic Displacement Ratios of SSI Systems

This paper presents the effect of soil-structure interaction on seismic inelastic displacement ratios of Single Degree of Freedom (SDOF) systems. Existing methods used in the past assumes the soil to be rigid. Through simplified equivalent fixed-base methods, the effect of soil-structure interaction (SSI) on the inelastic behaviour of structures is evaluated for different soil parameters using effective period and damping values. Using a degrading modified Clough model, the influence of different types of degradation is accounted for, for SDOF systems with periods ranging from 0.2 to 1.4 s. In total 300 different earthquake motions recorded on firm soil condition with magnitudes greater than 5 and peak ground acceleration (PGA) values greater than 0.08 g were selected. These records were scaled to the same hazard level and applied on five experimentally-tested reinforced concrete columns selected from the Pacific Earthquake Engineering Research Centre database. A total of 384,000 dynamic analyses were conducted. The results of the soil interacting systems are compared with the fixed-base case for different strength reduction factors (R) and foundation aspect ratios (h/r) for a range of NEHRP soil types C and D properties. These results show that the maximum inelastic displacements for soil type D are greater than those of soil type C and the fixed-base case. Particularly for periods less than 0.6 s with large aspect ratios, the effects of soil-structure interaction should be accounted for. Finally, the collected data was used to derive mathematical expressions for inelastic displacement ratios of SSI systems, suitable for use in performance-based seismic evaluation of structures

Comparative Assessment of Soil-Structure Interaction Regulations of ASCE 7-16 and ASCE 7-10

This paper evaluates the consequences of practicing soil structure interaction (SSI) regulations of ASCE 7-16 on seismic performance of building structures. The motivation for this research stems from the significant changes in the new SSI provisions of ASCE 7-16 compared to the previous 2010 edition. Generally, ASCE 7 considers SSI as a beneficial effect, and allows designer to reduce the design base shear. However, literature shows that this idea cannot properly capture the SSI effects on nonlinear systems. ASCE 7-16 is the first edition of ASCE 7 that considers the SSI effect on yielding systems. This study investigates the consequences of practicing the new provisions on a wide range of buildings with different dynamic characteristics on different soil types. Ductility demand of the structure forms the performance metric of this study, and the probability that practicing SSI provisions, in lieu of fixed-base provisions, increases the ductility demand of the structure is computed. The analyses are conducted within a probabilistic framework which considers the uncertainties in the ground motion and in the properties of the soil-structure system. It is concluded that, for structures with surface foundation on moderate to soft soils, SSI regulations of both ASCE 7-10 and ASCE 7-16 are fairly likely to result in a similar and larger structural responses than those obtained by practicing the fixed-base design regulations. However, for squat and ordinary stiff structures on soft soil or structures with embedded foundation on moderate to soft soils, the SSI provisions of ASCE 7-16 result in performance levels that are closer to those obtained by practicing the fixed-base regulations. Finally, for structures on very soft soils, the new SSI provisions of ASCE 7-16 are likely to rather conservative designs.Comment: ASCE Structures Congress, Fort Worth, TX, USA, April 19-21 (2018

ESR1, ESR2 and FSH Receptor Gene Polymorphisms in Combination: A Useful Genetic Tool for the Prediction of Poor Responders

Purpose: Previous studies in humans concluded that a multigenic model including specific FSHR, ESR1 and ESR2 genotype patterns may partially explain the poor response to FSH. The aim of our study is to analyse three different loci -polymorphisms in ESR1 Pvu II, ESR2 Rsa I and Ser680Asn FSH receptor gene-in a Greek population and their involvement in stimulation outcome and pregnancy rates. Methods: Each locus was studied alone, and in combination with the others. We performed both restriction fragment length polymorphism analysis and real-time polymerase chain reaction. A total of 109 normally ovulating female patients underwent IVF or ICSI. Results: Studying each locus alone, no significant results were drawn for ESR1 and ESR2 genes. Concerning the FSHR polymorphism, the women carrying the AA variant presented higher total amount of gonadotrophins used (P=0,048) and tended to have higher number of stimulation days (P=0,057). Considering the ESR1 and FSHR gene polymorphisms in combination, the TC/SA combination presents the highest number of pregnancies in poor responders group (3/4 pregnancies carried this genotype), in good responders group (4/12 pregnancies carried this genotype) and in the total population (10/26 pregnancies carried this genotype). Except the CC/AA combination, all other genotype combinations presented incidence of pregnancy, with TC/SA having the highest incidence. The CC/AA genotype presents the worst profile of ovulation induction, confirming a poor responder profile: the total amount of gonadotrophins used was highest in CC/AA group (P<0,05). The peak E2, the number of follicles and of retrieved oocytes and the pregnancy rate were significantly lower (P<0,05). This genotype combination seems to be over-presented in the poor responders group in a statistically significant way (P=0,038). Women with CC/AA combination have 1,5-2,4 times more risk to be poor responders in comparison with women that do not carry that combination. Conclusion: This study supports the hypothesis that a multigenic model, including the well studied ESR1 and FSHR genes is involved in the controlled ovarian stimulation outcome indicating that the CC/AA genotype presents the worst ovulation induction profile, while the TC/SA genotype presents the higher number of pregnancies in our population

The inSIGHT study: costs and effects of routine hysteroscopy prior to a first IVF treatment cycle. A randomised controlled trial.

Contains fulltext : 109856.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: In in vitro fertilization (IVF) and intracytoplasmatic sperm injection (ICSI) treatment a large drop is present between embryo transfer and occurrence of pregnancy. The implantation rate per embryo transferred is only 30%. Studies have shown that minor intrauterine abnormalities can be found in 11-45% of infertile women with a normal transvaginal sonography or hysterosalpingography. Two randomised controlled trials have indicated that detection and treatment of these abnormalities by office hysteroscopy after two failed IVF cycles leads to a 9-13% increase in pregnancy rate. Therefore, screening of all infertile women for intracavitary pathology prior to the start of IVF/ICSI is increasingly advocated. In absence of a scientific basis for such a policy, this study will assess the effects and costs of screening for and treatment of unsuspected intrauterine abnormalities by routine office hysteroscopy, with or without saline infusion sonography (SIS), prior to a first IVF/ICSI cycle. METHODS/DESIGN: Multicenter randomised controlled trial in asymptomatic subfertile women, indicated for a first IVF/ICSI treatment cycle, with normal findings at transvaginal sonography. Women with recurrent miscarriages, prior hysteroscopy treatment and intermenstrual blood loss will not be included. Participants will be randomised for a routine fertility work-up with additional (SIS and) hysteroscopy with on-the-spot-treatment of predefined intrauterine abnormalities versus the regular fertility work-up without additional diagnostic tests. The primary study outcome is the cumulative ongoing pregnancy rate resulting in live birth achieved within 18 months of IVF/ICSI treatment after randomisation. Secondary study outcome parameters are the cumulative implantation rate; cumulative miscarriage rate; patient preference and patient tolerance of a SIS and hysteroscopy procedure. All data will be analysed according to the intention-to-treat principle, using univariate and multivariate logistic regression and cox regression. Cost-effectiveness analysis will be performed to evaluate the costs of the additional tests as routine procedure. In total 700 patients will be included in this study. DISCUSSION: The results of this study will help to clarify the significance of hysteroscopy prior to IVF treatment. TRIAL REGISTRATION: NCT01242852