scholarly journals Numerical and Experimental Investigation on Concrete Splitting Failure of Anchor Channels

CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 502-522
Author(s):  
Anton Bogdanić ◽  
Daniele Casucci ◽  
Joško Ožbolt
Keyword(s):  
Construction Industry ◽  
Failure Mode ◽  
Current Trend ◽  
The United States ◽  
Embedment Depth ◽  
Test Results ◽  
Concrete Members ◽  
Splitting Failure ◽  
Edge Distance ◽  
Numerical Parametric Study

Concrete splitting failure due to tension load can occur when fastening systems are located close to an edge or corner of a concrete member, especially in thin members. This failure mode has not been extensively investigated for anchor channels. Given the current trend in the construction industry towards more slender concrete members, this failure mode will become more and more relevant. In addition, significantly different design rules in the United States and Europe indicate the need for harmonization between codes. Therefore, an extensive numerical parametric study was carried out to evaluate the influence of member thickness, edge distance, and anchor spacing on the capacity of anchor channels in uncracked and unreinforced concrete members. One of the main findings was that the characteristic edge distance depends on the member thickness and can be larger than 3hef (hef = embedment depth) for thin members. Based on the numerical and experimental test results, modifications of the design recommendations for the splitting failure mode are proposed. Overall, the authors recommend performing the splitting verification separately from the concrete breakout to design anchor channels in thin members more accurately.

Behaviour of adhesive steel anchors under impulse-type loading

2009 ◽  
Vol 36 (11) ◽  
pp. 1835-1847 ◽  
Author(s):  
Abass Braimah ◽  
Ettore Contestabile ◽  
Rick Guilbeault
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Dynamic Behaviour ◽  
Stone Masonry ◽  
Experimental Program ◽  
Embedment Depth ◽  
Test Results ◽  
Dynamic Increase Factor ◽  
Adhesive Anchors

The dynamic behaviour of adhesive anchors embedded in concrete is not well established, neither is their behaviour in stone masonry. This paper presents an experimental program designed to study the dynamic behaviour of adhesive anchor – substrate systems under impulse-type loading. The adhesive anchor – substrate systems consisted of steel rods bonded to concrete and limestone with an epoxy-based adhesive. Two steel anchor diameters (6.4 and 9.5 mm), two embedment depths (89 and 114 mm), and two angles of substrate penetration (90° and 45°) were investigated. The predominant failure mode observed for the steel anchor – concrete substrate samples was steel fracture, whereas for the steel anchor – limestone substrate samples, both steel fracture and limestone substrate failure modes were observed. The test results show that in most cases the dynamic increase factor (DIF) of adhesive anchors decreases with an increase in the embedment depth. Also, a substrate penetration angle of 45° increases the DIF in comparison with samples with 90° penetration angle. The DIFs of 1.2 and 2.5 are recommended for adhesive anchors with normal and 45° limestone substrate penetrations, respectively, while for concrete substrate, the recommended DIFs are 1.2 and 3.2 for normal and 45° substrate penetrations, respectively.

Tensile Capacity of Post-Installed Rebars in Concrete Structure

2011 ◽  
Vol 255-260 ◽  
pp. 289-293
Author(s):  
Chi Ping Wang ◽  
Sheng Min Wu ◽  
Chih Kang Wang ◽  
Hong Yu Pan
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Failure Mode ◽  
Concrete Structure ◽  
Tensile Behavior ◽  
Embedment Depth ◽  
Design Procedures ◽  
Spacing Effects ◽  
Edge Distance ◽  
Predicted Values

This paper describes an experimental study on the tensile capacity of post-installed rebars setting with adhesive. Eighty-one specimens containing single or double rebars were tested by an extraction tester to investigate the influence of embedment depth, edge distance and spacing of rebars on the tensile behavior of rebar system. The experimental results show that embedment depth is the most significant factor for rebar capacity and failure mode. The edge distance and the spacing effects are more significant only for the rebars with insufficient embedment depth. This study also attempts to evaluate two available design procedures provided by manufacturers. The comparison between the experimental data and predicted values calculated according to the two design procedures shows that both of the design approaches lay on the conservative side.

Partial Use of Pseudo-Ductile Cementitious Composites in Concrete Components to Resist Concentrated Stress

2006 ◽  
Vol 312 ◽  
pp. 319-324 ◽  
Author(s):  
Christopher K.Y. Leung ◽  
Angus K.F. Cheung ◽  
Xiu Fang Zhang
Keyword(s):  
Load Capacity ◽  
Experimental Program ◽  
Cementitious Composites ◽  
Test Results ◽  
Concrete Members ◽  
Pull Out ◽  
Splitting Failure ◽  
Concrete Blocks ◽  
Ultimate Failure ◽  
Anchor Bolts

The high pseudo-ductility of Engineered Cementitious Composites (ECC) makes it a particularly effective material to resist the propagation of cracks. In applications where failure is due to cracking initiated by localized stresses, the application of ECC around the stress concentrated region should result in significant improvement in the ultimate failure load. In this investigation, we will study the use of ECC in (i) the anchorage zone of post-tensioned concrete members, and (ii) the region around embedded anchor bolts in concrete blocks. For the first application, the replacement of concrete with ECC at the anchorage zone is found to be very effective in increasing the load capacity under concentrated compression. Based on our test results, ECC can actually replace all or part of the conventional steel stirrups in resisting splitting failure at the anchorage zone. For embedded anchor bolts, the placement of a small ECC disc above the steel bolt can effectively delay the propagation of cone-shape failure and increase the pull-out force. Through the present experimental program, we have illustrated the advantage of strategically applying ECC in critical region of structural components, to improve performance without significant increasing the material cost.

A Nationwide Survey of COVID-19 Testing in LGBTQ+ Populations in the United States

2021 ◽  
pp. 003335492110181
Author(s):  
Richard J. Martino ◽  
Kristen D. Krause ◽  
Marybec Griffin ◽  
Caleb LoSchiavo ◽  
Camilla Comer-Carruthers ◽  
...  
Keyword(s):  
United States ◽  
Gay Men ◽  
Antibody Test ◽  
Nationwide Survey ◽  
The United States ◽  
Sociodemographic Characteristics ◽  
Full Time ◽  
Test Results ◽  
Antibody Testing ◽  
And Gender

Objectives Lesbian, gay, bisexual, transgender, or queer and questioning (LGBTQ+) people and populations face myriad health disparities that are likely to be evident during the COVID-19 pandemic. The objectives of our study were to describe patterns of COVID-19 testing among LGBTQ+ people and to differentiate rates of COVID-19 testing and test results by sociodemographic characteristics. Methods Participants residing in the United States and US territories (N = 1090) aged ≥18 completed an internet-based survey from May through July 2020 that assessed COVID-19 testing and test results and sociodemographic characteristics, including sexual orientation and gender identity (SOGI). We analyzed data on receipt and results of polymerase chain reaction (PCR) and antibody testing for SARS-CoV-2 and symptoms of COVID-19 in relation to sociodemographic characteristics. Results Of the 1090 participants, 182 (16.7%) received a PCR test; of these, 16 (8.8%) had a positive test result. Of the 124 (11.4%) who received an antibody test, 45 (36.3%) had antibodies. Rates of PCR testing were higher among participants who were non–US-born (25.4%) versus US-born (16.3%) and employed full-time or part-time (18.5%) versus unemployed (10.8%). Antibody testing rates were higher among gay cisgender men (17.2%) versus other SOGI groups, non–US-born (25.4%) versus US-born participants, employed (12.6%) versus unemployed participants, and participants residing in the Northeast (20.0%) versus other regions. Among SOGI groups with sufficient cell sizes (n > 10), positive PCR results were highest among cisgender gay men (16.1%). Conclusions The differential patterns of testing and positivity, particularly among gay men in our sample, confirm the need to create COVID-19 public health messaging and programming that attend to the LGBTQ+ population.

scholarly journals Prediction of seasonal patterns of porcine reproductive and respiratory syndrome virus RNA detection in the U.S. swine industry

2020 ◽  
Vol 32 (3) ◽  
pp. 394-400
Author(s):  
Giovani Trevisan ◽  
Leticia C. M. Linhares ◽  
Bret Crim ◽  
Poonam Dubey ◽  
Kent J. Schwartz ◽  
...  
Keyword(s):  
Robust Regression ◽  
Historical Data ◽  
The United States ◽  
Respiratory Syndrome Virus ◽  
Seasonal Patterns ◽  
Test Results ◽  
Swine Industry ◽  
Cyclic Pattern ◽  
Rna Detection ◽  
Virus Rna

We developed a model to predict the cyclic pattern of porcine reproductive and respiratory syndrome virus (PRRSV) RNA detection by reverse-transcription real-time PCR (RT-rtPCR) from 4 major swine-centric veterinary diagnostic laboratories (VDLs) in the United States and to use historical data to forecast the upcoming year’s weekly percentage of positive submissions and issue outbreak signals when the pattern of detection was not as expected. Standardized submission data and test results were used. Historical data (2015–2017) composed of the weekly percentage of PCR-positive submissions were used to fit a cyclic robust regression model. The findings were used to forecast the expected weekly percentage of PCR-positive submissions, with a 95% confidence interval (CI), for 2018. During 2018, the proportion of PRRSV-positive submissions crossed 95% CI boundaries at week 2, 14–25, and 48. The relatively higher detection on week 2 and 48 were mostly from submissions containing samples from wean-to-market pigs, and for week 14–25 originated mostly from samples from adult/sow farms. There was a recurring yearly pattern of detection, wherein an increased proportion of PRRSV RNA detection in submissions originating from wean-to-finish farms was followed by increased detection in samples from adult/sow farms. Results from the model described herein confirm the seasonal cyclic pattern of PRRSV detection using test results consolidated from 4 VDLs. Wave crests occurred consistently during winter, and wave troughs occurred consistently during the summer months. Our model was able to correctly identify statistically significant outbreak signals in PRRSV RNA detection at 3 instances during 2018.

scholarly journals Effect of Fly Ash on Compressive Strength, Drying Shrinkage, and Carbonation Depth of Mortar with Ferronickel-Slag Powder

2021 ◽  
Vol 11 (3) ◽  
pp. 1037
Author(s):  
Se-Jin Choi ◽  
Ji-Hwan Kim ◽  
Sung-Ho Bae ◽  
Tae-Gue Oh
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Construction Industry ◽  
Bituminous Coal ◽  
Raw Materials ◽  
Drying Shrinkage ◽  
The Other ◽  
Test Results ◽  
Slag Powder ◽  
Ferronickel Slag

In recent years, efforts to reduce greenhouse gas emissions have continued worldwide. In the construction industry, a large amount of CO2 is generated during the production of Portland cement, and various studies are being conducted to reduce the amount of cement and enable the use of cement substitutes. Ferronickel slag is a by-product generated by melting materials such as nickel ore and bituminous coal, which are used as raw materials to produce ferronickel at high temperatures. In this study, we investigated the fluidity, microhydration heat, compressive strength, drying shrinkage, and carbonation characteristics of a ternary cement mortar including ferronickel-slag powder and fly ash. According to the test results, the microhydration heat of the FA20FN00 sample was slightly higher than that of the FA00FN20 sample. The 28-day compressive strength of the FA20FN00 mix was approximately 39.6 MPa, which was higher than that of the other samples, whereas the compressive strength of the FA05FN15 mix including 15% of ferronickel-slag powder was approximately 11.6% lower than that of the FA20FN00 mix. The drying shrinkage of the FA20FN00 sample without ferronickel-slag powder was the highest after 56 days, whereas the FA00FN20 sample without fly ash showed the lowest shrinkage compared to the other mixes.

scholarly journals The Value of Cognitive Pretesting: Improving Validity and Revealing Blind Spots through the Development of a Newborn Screening Parent Experiences Survey

2021 ◽  
Vol 7 (3) ◽  
pp. 41
Author(s):  
Norma-Jean Simon ◽  
Anne Atkins ◽  
Brianne Miller ◽  
Natasha Bonhomme ◽  
Beth Tarini
Keyword(s):  
Newborn Screening ◽  
The United States ◽  
True Positive ◽  
Test Results ◽  
Parent Experiences ◽  
Survey Questions ◽  
Study Team ◽  
Ages And Stages Questionnaires ◽  
Cognitive Pretesting ◽  
Blind Spots

Surveys are used to gather a range of data on newborn screening (NBS) processes. We describe the development of a survey about parents’ NBS experiences, in the United States, informed by cognitive pretest interviews among parents with varying NBS test results (true-positive, false-positive, normal). Cognitive pretest interviews were conducted following a semi-structured script and notes were taken to identify problematic survey items. The study team met weekly to discuss pretest feedback, draft changes, and generate revised items. Pretests indicated that parent experiences with NBS are varied and NBS screening procedures are not well understood. Substantial modifications were made to survey questions concerning NBS testing and result communication. Pretesters often associated NBS with other tests/exams/scales—APGAR scores, Ages and Stages questionnaires, and genetic testing during pregnancy. Some pretesters recalled receiving NBS blood spot results during their hospital admission, an uncommon practice, and few recalled knowing results would be provided to them or their pediatrician in the first few weeks of life. Thorough explanations regarding NBS procedures and expectations were embedded within the survey to enhance and improve interpretation of survey questions. Future NBS experience surveys should utilize cognitive pretesting to capture divergent experiences and improve response validity.

scholarly journals RISK MANAGEMENT IN MULTI STOREY BUILDING CONSTRUCTION

2018 ◽  
Vol 6 (1) ◽  
pp. 368-376
Author(s):  
Radhakrishnan ◽  
K G Selvan
Keyword(s):  
Risk Management ◽  
Construction Industry ◽  
Current Trend ◽  
Building Construction ◽  
Initial Amount ◽  
Large Numbers ◽  
Proper Perspective ◽  
Total Compliance ◽  
Storey Building

The Construction Industry is the source for widespread employment for people of all walks of life, next only to Agriculture. The industry is picking up very well now after the shake of demonetisation. The builders have also understood the importance of RERA and majority of the builders are ensuring total compliance to it. The GST which was initially looked at as a blow is being viewed in its proper perspective. The current trend in the construction field is to offer “ready to occupy homes”. This is, basically, due to two reasons. Large numbers of builders are in the field doing construction, in almost the entire city and the outskirts. This healthy competition has necessitated offering maximum benefits to customers and whatever possible to retain them in their fold. In a way, the customers are being attracted so nicely that they have to only pay the initial amount at the time of booking, forget about the bother of EMI,

BIM Technology in the Application and Development of China's Construction Industry

2014 ◽  
Vol 519-520 ◽  
pp. 1451-1454 ◽  
Author(s):  
Ya Kun Shi
Keyword(s):  
Project Management ◽  
Construction Industry ◽  
Architectural Design ◽  
Large Scale ◽  
Developed Countries ◽  
The United States ◽  
Status Quo ◽  
Point Of View ◽  
Information Modeling ◽  
Current Status

BIM technology used more widely in construction industry in developed countries in Europe and the United States, the integration of building information modeling (BIM) in the domestic large-scale propulsion was still difficult, and further the trend of widening the gap with foreign advanced level. In order to identify problems and solve the current status quo, and cut into the integrated information from project management point of view of China's architectural design, and analysis the status quo of BIM technology in our project management and developmental disabilities, and BIM-based technology and related parties mutual relations, to explain the development prospects of its application in China.

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