Assessment of the performance of steel fibre reinforced self-compacting concrete in elevated slabs

The reinforcement mechanisms at the cross section level assured by fibres bridging the cracks in steel fibre reinforced self-compacting concrete (SFRSCC) can be significantly amplified at structural level when the SFRSCC is applied in structures with high support redundancy, such is the case of elevated slab systems. To evaluate the potentialities of SFRSCC as the fundamental material of elevated slab systems, a ¼ scale SFRSCC prototype of a residential building was designed, built and tested. The extensive experimental program includes material tests for characterizing the relevant properties of SFRSCC, as well as structural tests for assessing the performance of the prototype at serviceability and ultimate limit conditions. Three distinct approaches where adopted to derive the constitutive laws of the SFRSCC in tension that were used in finite element material nonlinear analysis to evaluate the reliability of these approaches in the prediction of the load carrying capacity of the prototype.The study reported in this paper is part of PhD thesis supported by FCT. The first author acknowledges FCT for Grant SFRH/BD/71934/2010. The authors wish to acknowledge inclusive supports provided by Casais Company in this research program for construction of the prototype and for technical supports during the test. The authors also wish to acknowledge CiviTest Company for its collaboration and supports in designing and casting the SFRSCC

Overview of the antibacterial properties of essential oils and extracts of medicinal plants in Iran

Background and aims: With increased resistance resulting from overusing of chemical-synthetic antibiotics, finding alternative medicines that have antibacterial properties and they have the least side effects on human health appears to be necessary. Many studies have been taken into consideration medicinal plants with antimicrobial properties. The aim of this study was to have an overview of the antibacterial properties of medicinal plants. Methods: In this study, by searching key words as: herbs (Medicinal Plants), anti-bacterial properties of medicinal plants in Iran , antimicrobial properties of medicinal plants in Iran, in scientific articles published in databases as: Iranmedx, Magiran, Google scholar, Ebsco, Pubmed, Science direct, and SID, the required data were obtained. Results: Many herbs, including Zataria multifora, Urtica dioical, Crocus sativus L., Artemisia Absinthium, Menta piperita, Eucalyptus globules L., Borago officinalis L., Scrophularia desrti, Cuminum cyminum L., Rosmarinus officinalis L., Allium hirtifolium, Castaneifolia- sativa, Allium sativum, Pycnocycla spinose, Juglans Regia, Salvia officinalis L. have strong antibacterial properties against a variety of pathogenic bacteria. Conclusion: In addition to the various medicinal plants with antimicrobial susceptibility and pathogenic bacteria resistance, antimicrobial properties of these studied medicinal plants could be used as a natural preservative in a variety of foods from these herbs. Thyme and garlic have antibacterial effects on an extensive range of positive and negative gram bacteria through them

A model to simulate the moment-rotation and crack width of FRC members reinforced with longitudinal bars

The present work describes a model for the determination of the moment–rotation relationship of a cross section of fiber reinforced concrete (FRC) elements that also include longitudinal bars for the flexural reinforcement (R/FRC). Since a stress–crack width relationship (σ–w)(σ–w) is used to model the post-cracking behavior of a FRC, the σ–w directly obtained from tensile tests, or derived from inverse analysis applied to the results obtained in three-point notched beam bending tests, can be adopted in this approach. For a more realistic assessment of the crack opening, a bond stress versus slip relationship is assumed to simulate the bond between longitudinal bars and surrounding FRC. To simulate the compression behavior of the FRC, a shear friction model is adopted based on the physical interpretation of the post-peak compression softening behavior registered in experimental tests. By allowing the formation of a compressive FRC wedge delimited by shear band zones, the concept of concrete crushing failure mode in beams failing in bending is reinterpreted. By using the moment–rotation relationship, an algorithm was developed to determine the force–deflection response of statically determinate R/FRC elements. The model is described in detail and its good predictive performance is demonstrated by using available experimental data. Parametric studies were executed to evidence the influence of relevant parameters of the model on the serviceability and ultimate design conditions of R/FRC elements failing in bending.This work is supported by FEDER funds through the Operational Programme for Competitiveness Factors – COMPETE and National Funds through FCT – Portuguese Foundation for Science and Technology under the project PTDC/ECM/105700/2008 – “DURCOST - Innovation in reinforcing systems for sustainable pre-fabricated structures of higher durability and enhanced structural performance”. The second and third author wish to acknowledge the grant provided by this project and FCT (SFRH/BD/71934/2010), respectively

Evaluation of the influence of post-cracking response of steel fibre reinforced concrete (SFRC) on load carrying capacity of SFRC panels

To develop a reliable methodology for the design of steel fibre reinforced concrete (SFRC) slabs, an extensive experimental program was carried out with SFRC square panels simply supported in their contour. By adopting a moment-rotation approach, a numerical model was developed capable of taking into account the constitutive laws of the SFRC for the prediction of the force-deflection response of variety of panel tests recommended in the international standards. The predictive performance of the model was assessed by considering results available in the bibliography and those obtained on the experimental program. The proposed model was utilized in a parametric study to assess the influence of toughness classes of SFRC on the behaviour at serviceability limit conditions, on the load carrying capacity, and on the deformational response of SFRC round panels.This work is supported by the FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT - Portuguese Foundation for Science and Technology under the project SlabSys-HFRC-PTDC/ECM/120394/2010. The first author acknowledges the FCT PhD Grant SFRH/BD/71934/2010. The authors would like to acknowledge the materials supplied by Maccaferri (fibres), SECIL (cement), SIKA and BASF (superplasticizers), OmyaComital (limestone filler), and Pegop (Fly ash). Special thanks for CiviTest Company that developed the SFRCs and executed the specimens of the experimental program.Fundação para a Ciência e a Tecnologia (FCT

A design-based approach to estimate the moment-curvature relationship of fiber reinforced elements failing in bending

Relatório A0.T0.UM.

The comparison of the acupressure and pyridoxine effect on severity of both nausea and vomiting in primigravida women

زمینه و هدف:اختلالات دستگاه گوارش به ویژه تهوع و استفراغ، شایع ترین شکایات دوران بارداری می باشند. بررسی های انجام شده نشان داده که در مراقبت های بارداری تقریباً 20 درصد زنان باردار به علت شدت این مشکلات در جستجوی خدمات پزشکی هستند. هدف از این پژوهش مقایسه اثر دو روش درمانی طب فشاری و پیریدوکسین (ویتامینB6 ) بر روی شدت تهوع و استفراغ خانم های باردار نخست زا می باشد. روش بررسی: در یک کارآزمایی بالینی، پژوهشگر با حضور در مراکز بهداشتی - درمانی شهرستان اهواز از میان زنان نخست حامله ای که در زمان انجام پژوهش جهت دریافت خدمات دوران بارداری به مراکز مربوطه مراجعه کرده و دارای تهوع و استفراغ بودند، تعداد 100 نفر بصورت مبتنی بر هدف انتخاب و بطور تصادفی در دو گروه 50 نفره قرار گرفتند. جهت درمان تهوع و استفراغ گروه اول تحت تأثیر طب فشاری با استفاده از نواری بنام سی باند قرار گرفت و گروه دوم روزانه 40 میلی گرم ویتامین B6 دریافت کردند و درمان به مدت 4 روز برای هر دو گروه انجام شد. برای هرکدام از نمونه ها پرسشنامه ای تکمیل و به کلیه افراد برگه هایی جهت ثبت وضعیت روزانه برای مدت 4 روز داده شد و داده های بدست آمده با استفاده از آزمون آماری کای دو، تی تست، من ویتنی و ویل کاکسون تجزیه و تحلیل شدند. یافته ها: نتایج نشان داد که استفاده از ویتامینB6 و سی باند باعث کاهش شدت تهوع و دفعات استفراغ می شود (001/0

A design model for strain-softening and strain-hardening fiber reinforced elements reinforced longitudinally with steel and FRP bars

A close form solution is developed for the prediction of the moment-curvature relationship of cross sections of fiber reinforced concrete (FRC) elements failing in bending, and reinforced longitudinally with steel and fiber reinforced polymer (FRP) bars. The FRP bars are installed with the largest possible internal arm, e.g. with the minimum concrete cover that assures the bond conditions for a sound stress transfer from FRC to the FRP bars. The model is also able of simulating the flexural strengthening contribution provided by FRP bars installed according to the Near Surface Mounted (NSM) technique. To have good protection conditions against corrosion, the steel bars are applied with a relatively thick FRC cover. Since steel stirrups are the reinforcement with the smaller concrete cover thickness, they are the most susceptible to corrosion. In the reinforcement concept to be developed in the present research program, steel stirrups are replaced with discrete fibers. This hybrid reinforcement aims to develop high durable pre-fabricated elements that fail in bending. The proposed analytical formulation can simulate FRC with strain softening or strain hardening behavior. In the present work, the formulation is described and its predictive performance is appraised.The study reported in this paper is part of the research programs "DURCOST", PTDC/ECM/105700/2008, supported by FCT, and "PONTALUMIS", QREN, Project No. 3456. The first and third authors wish to acknowledge the support provided by project PONTALUMIS, while the second author acknowledges the support of DURCOST

Prediction of the load carrying capacity of elevated steel fibre reinforced concrete slabs

A novel methodology is developed for predicting the load carrying capacity of elevated steel fibre reinforced concrete (E-SFRC) slab systems. In the proposed approach the depth of slab’s cross section is discretized into several layers, and the number of steel fibres per each layer is determined by considering the distribution of fibres along the depth of cross section. This information, together with the one obtained from the threepoint notched beam bending tests performed on four series of SFRC made of different concrete strength class and content of fibres, have provided the stress-crack width laws for defining the post-cracking behaviour of each layer. These constitutive laws are implemented in a numerical model developed based on the moment-rotation approach for determining the positive and negative resisting bending moment of the slab’s unit width cross section. By using the yield line theory, the load carrying capacity of ESFRC slab is predicted for the most current load conditions. Predictive performance of the proposed methodology is assessed comparing to the results recorded in experiment and the ones obtained by the numerical simulation. Finally the developed model is utilised in a parametric study to evaluate the influence of parameters that affect the load-carrying capacity of E-SFRC slabs.This work is supported by FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT - Portuguese Foundation for Science and Technology under the project “SlabSys – HFRC – Flat slabs for multi-storey buildings using hybrid reinforced self-compacting concrete: an innovative structural system” PTDC/ECM/120394/2010. The first author also acknowledges the financial supports provided by Seismic Geotechnical and High Performance Concrete Research Centre of Semnan Branch, Islamic Azad University.info:eu-repo/semantics/publishedVersio

Comparison of the effects of gum chewing with those of early initiation of oral feeding and routine regimen on recovery of bowel function in primiparous women after cesarean section

Background and Aim: Ileuses is one of the most common problems after abdominal surgery including cesarean section (CS) which leads to inability to start feeding. Several studies have been performed on the effects of liquid diet in the postoperative period on the recovery of bowel movement but there has been no perfect study on the effect of gum chewing on this subject. The aim of this study was to compare the effect of early oral feeding with liquid diet on the recovery of bowel movements with that of gum chewing in primiparous women after (CS) in Hajar Hospitral in Shahrekord in 2007. Materials and Methods: In this randomized clinical trial, 180 patients scheduled for elective cesarean section were randomly divided into three groups: gum-chewing group (n=30), early feeding group (n=30) and control group (n=30) postoperatively. The patients in the gum-chewing group chewed postoperatively sugar free gum four times daily, each time for 15 minutes, as soon as they recovered from anesthesia. In the early oral feeding group the women received a liquid diet within six hours after surgery, and control group received routine post operative dietary regimen. Data were analyzed by x2, paired and independent t tests and one way ANOVA. p<0.05 was considered significant. Results: Recovery of bowel movements in the gum chewing and early oral feeding groups was significantly faster than that of control group and was faster in gum chewing group in comparison to early oral feeding group (P<0.05). Conclusions: Gum chewing after CS is safe, inexpensive and beneficial which is well tolerated by the patients and associated with rapid resumption of intestinal function and rapid recovery of the patients after cesarean-section