Modified Portland Cement Association Stress Analysis and Thickness Design Procedures

1997 ◽  
Vol 1568 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Ying-Haur Lee ◽  
Jean-Hwa Bair ◽  
Chao-Tsung Lee ◽  
Shao-Tang Yen ◽  
Ying-Ming Lee
Keyword(s):  
Portland Cement ◽  
Stress Analysis ◽  
Prediction Models ◽  
Equivalent Stress ◽  
Design Procedure ◽  
Concrete Pavements ◽  
Spreadsheet Program ◽  
Practical Trial ◽  
Portland Cement Association ◽  
User Friendly

A new stress analysis and thickness design procedure for jointed concrete pavements was developed. On the basis of Westergaard’s edge stress solution and several prediction models for stress adjustments for a variety of loading and environmental (i.e., thermal curling) conditions, a modified Portland Cement Association (PCA) equivalent stress analysis and thickness design procedure was proposed and implemented in a highly user-friendly, Windows-based program, TKUPAV, for practical trial applications. The proposed approach has been further verified by reproducing results very close to the PCA’s equivalent stresses and fatigue damages using a spreadsheet program and the TKUPAV program. The possible detrimental effect of loading plus daytime curling has been illustrated in a case study, which also indicated that the effect of thermal curling should be considered in the thickness design of concrete pavements.

Reliability Design of Flexible Airfield Pavements: Elastic Layered Method

1997 ◽  
Vol 1568 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Yu T. Chou
Keyword(s):  
Prediction Models ◽  
Design Procedure ◽  
Design System ◽  
Mean Values ◽  
Reliability Design ◽  
Reliability Level ◽  
Lack Of Fit ◽  
User Friendly ◽  
Pavement Thickness ◽  
Independent Parameters

A design procedure was developed for layered elastic flexible airfield pavement systems in terms of probability and reliability. A user-friendly computer program, RELIFLEX, was prepared to carry out the computations. The Rosenblueth method is used to estimate the expected value and variance of the computed strains (dependent parameters) on the basis of the input mean values of independent parameters (i.e., aircraft load, layer thicknesses, and material moduli). RELIFLEX has the capability of considering the strain distribution to be normal, lognormal, or beta, and a capacity-demand analysis is included. Only normal distribution is presented. Environmental effects and the lack of fit of the prediction models are not considered in RELIFLEX. The relationships between the reliability level and the allowable strain repetition of the designed system, established using RELIFLEX, provide a decision-making tool for engineers to design pavement at the desired reliability level. For a desired reliability level of the design system, pavement thickness can be varied to agree with the designed coverage or the allowable coverage can be modified for a given pavement thickness.

Measuring As-Constructed Smoothness of Portland Cement Concrete Pavements with Lightweight Profilometers

2001 ◽  
Vol 1764 (1) ◽  
pp. 189-200
Author(s):  
Mahmuda Akhter ◽  
Mustaque Hossain ◽  
Jeffrey Hancock ◽  
John Boyer ◽  
William J. Parcells
Keyword(s):  
Portland Cement ◽  
Concrete Pavements ◽  
Portland Cement Concrete ◽  
Cement Concrete

scholarly journals Portland clinker with civil construction waste: influence of pellet geometry on the formation of crystalline phases

2020 ◽  
Vol 20 (4) ◽  
pp. 205-223
Author(s):  
Fernanda Nepomuceno Costa ◽  
Daniel Véras Ribeiro ◽  
Cléber Marcos Ribeiro Dias
Keyword(s):  
Sustainable Development ◽  
Portland Cement ◽  
Rietveld Method ◽  
Industrial Process ◽  
3D Printer ◽  
New Materials ◽  
X Ray Diffraction ◽  
Construction Waste ◽  
X Ray ◽  
Portland Cement Association

Abstract Efforts to reduce greenhouse gas emissions in the context of sustainable development have intensified, with the development of research aimed at the production of new materials and binders for construction. This article analyzes the influence of pellet geometry in the production of clinkers, with the incorporation of construction waste (CCW). Procedures adapted from the method proposed by Brazilian Portland Cement Association were adopted in studies of laboratory clinkers, in an attempt to simulate the stages of the industrial process. Pellets were prepared with the same formulation, however, with four different geometries: spherical, with diameters of 1 cm, 2 cm and 3 cm, with manual molding, and semi-spherical, with a diameter of 2 cm, using molds of PLA (polylactic acid) printed on a 3D printer to facilitate the molding of the clinkers in a standardized way. Clinkers were characterized mineralogically by x-ray diffraction (XRD) and the Rietveld method was used to quantify the phases. Variations in the quantities of the alite and belite phases were observed depending on the geometry of the pellets, although the same calcination conditions were used. This is probably due to the variation in the surface area (exposure area) and the gradients of the cooling rate.

scholarly journals Covid19Risk.ai: An open source repository and online calculator of prediction models for early diagnosis and prognosis of Covid-19

2021 ◽  
Author(s):  
Iva Halilaj ◽  
Avishek Chatterjee ◽  
Yvonka van Wijk ◽  
Guangyao Wu ◽  
Brice van Eeckhout ◽  
...  
Keyword(s):  
Open Source ◽  
Predictive Models ◽  
Prediction Models ◽  
Patient Specific ◽  
Diagnosis And Prognosis ◽  
Online Calculator ◽  
User Friendly ◽  
Type 3 ◽  
Proof Of Principle

AbstractObjectiveThe current pandemic has led to a proliferation of predictive models being developed to address various aspects of COVID-19 patient care. We aimed to develop an online platform that would serve as an open source repository for a curated subset of such models, and provide a simple interface for included models to allow for online calculation. This platform would support doctors during decision-making regarding diagnoses, prognoses, and follow-up of COVID-19 patients, expediting the models’ transition from research to clinical practice.MethodsIn this proof-of-principle study, we performed a literature search in PubMed and WHO database to find suitable models for implementation on our platform. All selected models were publicly available (peer reviewed publications or open source repository) and had been validated (TRIPOD type 3 or 2b). We created a method for obtaining the regression coefficients if only the nomogram was available in the original publication. All predictive models were transcribed on a practical graphical user interface using PHP 8.0.0, and published online together with supporting documentation and links to the associated articles.ResultsThe open source website https://covid19risk.ai/ currently incorporates nine models from six different research groups, evaluated on datasets from different countries. The website will continue to be populated with other models related to COVID-19 prediction as these become available. This dynamic platform allows COVID-19 researchers to contact us to have their model curated and included on our website, thereby increasing the reach and real-world impact of their work.ConclusionWe have successfully demonstrated in this proof-of-principle study that our website provides an inclusive platform for predictive models related to COVID-19. It enables doctors to supplement their judgment with patient-specific predictions from externally-validated models in a user-friendly format. Additionally, this platform supports researchers in showcasing their work, which will increase the visibility and use of their models.

Modeling of Gear Hobbing: Part II — A Computer Supported Experimental-Analytical Determination of the Wear Progress to Optimize the Tool Life Time

1999 ◽  
Author(s):  
Konstantinos D. Bouzakis ◽  
Spiros Kombogiannis ◽  
Aristomenis Antoniadis ◽  
Nectarios Vidakis
Keyword(s):  
Tool Wear ◽  
Prediction Models ◽  
Digital Simulation ◽  
Life Time ◽  
Analytical Determination ◽  
Tool Wear Prediction ◽  
Gear Hobbing ◽  
User Friendly ◽  
Continuous Enrichment

Abstract Tool wear prediction models for gear hobbing were presented in the first part of this paper. To determine the constants of the equations used in these models, fly hobbing experiments with uncoated and coated HSS tools were conducted. Hereby, it was necessary to modify the fly hobbing kinematics from continuous tangential feed to continuous axial feed. The experimental data were evaluated, and correlated to the analytical ones, elaborated through the described digital simulation of the cutting process. The determined constants of the wear laws for the investigated tools were used in a further developed user friendly software, enabling the prediction of the tool wear accomplishment in gear hobbing. On that account the wear development can be precisely foreseen and the tangential shift of the tool is optimized. The open and modular structure of the developed code enables the continuous enrichment of its database with other type of coating and workpiece materials. With the aid of the aforementioned techniques, the superiority of coated HSS tools in comparison to uncoated ones is also quantitatively exhibited.

Fertilized Midrotation-Aged Slash Pine Plantations—Stand Structure and Yield Prediction Models

1989 ◽  
Vol 13 (2) ◽  
pp. 76-80 ◽  
Author(s):  
Robert L. Bailey ◽  
Thomas M. Burgan ◽  
Eric J. Jokela
Keyword(s):  
Prediction Models ◽  
Stand Structure ◽  
Basal Area ◽  
Slash Pine ◽  
Pine Plantations ◽  
Individual Tree ◽  
Investment Opportunities ◽  
User Friendly ◽  
Volume Equations ◽  
Soil Groups

Abstract Data from 263 plots in a regional fertilization study of midrotation-aged slash pine plantations were used to fit prediction equations for basal area, trees per acre, stand average dominant height, diameter distributions, and individual tree heights. The equations include N and P fertilizationrates and CRIFF soil groups as predictor variables. The survival model also accounts for the accelerating effect of fusiform rust on mortality rate. Using published tree volume equations, the prediction of volumes by dbh class for fertilized slash pine plantations is now possible. This integratedsystem of equations is available as a user-friendly computer program that can calculate expected yields by diameter class and aid the forester in evaluating investment opportunities that include forest fertilization. South. J. Appl. For. 13(2):76-80.

Design aids for rectangular reinforced concrete sections under combined bending and axial forces

1988 ◽  
Vol 15 (5) ◽  
pp. 916-928 ◽  
Author(s):  
P. Riva ◽  
M. Z. Cohn
Keyword(s):  
Reinforced Concrete ◽  
Portland Cement ◽  
Key Words ◽  
Axial Compression ◽  
Strength Analysis ◽  
Short Columns ◽  
Axial Forces ◽  
Portland Cement Association

Design interaction diagrams, Pr–Mr, for rectangular reinforced concrete sections under combined bending and axial compression or tension forces in accordance with the current Canadian code are presented. The interest of the note is that the interaction diagrams eliminate the limitations of those in the Canadian Portland Cement Association Handbook. Their format can be extended to other section shapes and reinforcement layouts. Key words: Combined bending, design aids, interaction diagrams, rectangular sections, reinforced concrete, short columns, strength analysis.

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