Cyclic Performance of Beam-Column Joints with Extended Column Fixed at Base: Part I - Experimental Investigation

http://www.icevirtuallibrary.com/content/journals “Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.”The seismic performance of a non-seismically detailed reinforced concrete (RC) beam–column joint with column pinned and fixed at the base is experimentally investigated in this paper. Six half-scale RC beam–column specimens were tested to study the effect of inflection point on the cyclic behaviour of beam–column sub-assemblages. The specimens were separated into two groups. The shape of specimens in the first group was cruciform; the size of the column in those specimens was varied while the size of beam was kept nearly constant. The dimensions and reinforcing detail of specimens in the second group were identical to those in the first one except that the column was extended to the footing and fixed at the base. The main variable in this study was the relative stiffness between beam and column, which affects the position of the inflection point. The test results demonstrated a significant effect of inflection point position on the load capacity, joint shear stress and failure mode

Machine Learning-Based Prediction of Compressive Performance in Circular Concrete Columns Confined with FRP

This article presents a comprehensive investigation, focusing on the prediction and formulation of the design equation of compressive strength of circular concrete columns confined with Fiber Reinforced Polymer (FRP) using advanced machine learning models. Through an extensive analysis of 170 experimental data specimens, the study examines the effects of six key parameters, including concrete cylinder diameter, concrete cylinder-FRP thickness, compressive strength of concrete without FRP, initial compressive strain of concrete without FRP, elastic modulus and tensile strength of FRP, on the compressive strength of the circular concrete columns confined with FRP. The predictive model and design equation of compressive strength is developed using a machine learning technique, specifically the artificial neural networks (ANN) model. The results demonstrates strong correlations between the compressive strength of the circular concrete columns confined with FRP and certain factors, such as the compressive strength of the concrete and compressive strain of the concrete column without FRP, elastic modulus of FRP, and tensile strength of FRP. The ANN model specifically developed using Neural Designer, exhibits superior predictive accuracy compared to other constitutive models, showcasing its potential for practical implementation. The study's findings contribute valuable insights into accurately predicting the compressive performance of circular concrete columns confined with FRP, which can aid in optimizing and designing civil engineering structures for enhanced performance and efficiency

Stillbirths among Pregnant Women Admitted to the Department of Obstetrics and Gynaecology in a Tertiary Care Centre: A Descriptive Cross-sectional Study

Introduction: Stillbirth is often defined as the death of a foetus in the uterus prior to its birth or during the process of birth. Most of the stillbirths are preventable global health problem. The aim of this study was to find out the prevalence of stillbirths among pregnant women admitted to the Department of Obstetrics and Gynaecology in a tertiary care centre. Methods: A descriptive cross-sectional study was conducted in the Department of Obstetrics and Gynaecology in a tertiary care centre among pregnant women admitted between 14 April 2021 to 13 April 2022. Ethical approval was taken from the Institutional Review Committee (Reference number: 43). Convenience sampling method was used. The data were collected from the medical record section using a proforma. Point estimate and 95% Confidence Interval were calculated. Results: Among 5,118 pregnant women, stillbirths were found in 126 (2.46%) (2.04-2.88, 95% Confidence Interval). Conclusions: The prevalence of stillbirth among pregnant women was higher than in the other studies done in similar settings

Effects of Row Spacings and Varieties on Grain Yield and Economics of Maize

Maize is the second most important crop of Nepal. The yield of the crop is low due to lack of appropriate plant density for the varieties. The field experiment was carried out to study the effect of different row spacings on different maize varieties at Deupur, Lamahi municipality of the dang district in province No. 5, Nepal during the rainy season from June to September, 2018. Four levels of spacings (boardcasting and three row spacings of 45, 60 and 75 cm) and two maize varieties (Rampur Composite and Arun-2) were evaluated using randomized complete block design with three replications. The highest grain yield was found in Rampur Composite and Arun-2 while they were planted with row spacing of 60 cm with plant to plant spacing of 25 cm. The highest grain yield, cob length, cob circumference, number of rows per cob, thousand grain weight  were reported when maize was planted in the  row spacing 60×25cm. Among the maize varieties, Rampur Composite produced the highest grain yield, cob length, cob circumference, number of rows per cob as compared to Arun-2. This study suggested that maize production can be maximized by cultivating maize varieties with row spacing of 60 cm with plant to plant spacing of 25 cm

Effect of top reinforcing on the fire performance of continuous reinforced concrete beams

This paper examines the behaviour of continuous reinforced concrete beams exposed to fire on three sides, in order to investigate the effect of different lengths of the top reinforcing bars over the supports. The study was performed with 2D finite element analysis using SAFIR. The effect of continuity was investigated with rectangular crosssection beams spanning over two and three bays subjected to the ISO 834 fire. Compared to a single span beam, the continuous beams resisted the fire exposure for a longer period of time. It was found that different lengths of the top reinforcing bars resulted in different failure mechanisms, but did not greatly affect the fire resistance of the beams . The influence of the full process of fire development was analysed using the ISO fire for 30, 60 and 90 minutes followed by a decay phase. Structural failure only occurred if the fully developed phase of the fire continued until very close to the failure time reached with no decay phase

Observations on typing from 136 million keystrokes

We report on typing behaviour and performance of 168,000 volunteers in an online study. The large dataset allows detailed statistical analyses of keystroking patterns, linking them to typing performance. Besides reporting distributions and confirming some earlier findings, we report two new findings. First, letter pairs typed by different hands or fingers are more predictive of typing speed than, for example, letter repetitions. Second, rollover-typing, wherein the next key is pressed before the previous one is released, is surprisingly prevalent. Notwithstanding considerable variation in typing patterns, unsupervised clustering using normalised inter-key intervals reveals that most users can be divided into eight groups of typists that differ in performance, accuracy, hand and finger usage, and rollover. The code and dataset are released for scientific use

Field, Frequency, and Temperature Dependencies of the Surface Resistance of Nitrogen Diffused Niobium Superconducting Radio Frequency Cavities

We investigate the rf performance of several single-cell superconducting radio-frequency cavities subjected to low temperature heat treatment in nitrogen environment. The cavities were treated at temperature 120–165 °C for an extended period of time (24–48 h) either in high vacuum or in a low partial pressure of ultrapure nitrogen. The improvement in 0 with a rise was observed when nitrogen gas was injected at ∼300 °C during the cavity cooldown from 800 °C and held at 165 °C, without any degradation in accelerating gradient over the baseline performance. The treatment was applied to several elliptical cavities with frequency ranging from 0.75 to 3.0 GHz, showing an improved quality factor as a result of low temperature nitrogen treatments. The rise feature is similar to that achieved by nitrogen alloying Nb cavities at higher temperature, followed by material removal by electropolishing. The surface modification was confirmed by the change in electronic mean free path and tuned with the temperature and duration of heat treatment. The decrease of the temperature-dependent surface resistance with increasing rf field, resulting in a rise, becomes stronger with increasing frequency and decreasing temperature. The data suggest a crossover frequency of ∼0.95  GHz above that the rise phenomenon occurs at 2 K. Some of these results can be explained qualitatively with an existing model of intrinsic field-dependence of the surface resistance with both equilibrium and nonequilibrium quasiparticle distribution functions. The change in the slope below 0.95 GHz may result from masking contribution of trapped magnetic flux to the residual surface resistance