scholarly journals Interpolating spatially varying soil property values from sparse data for facilitating characteristic value selection

2018 ◽  
Vol 55 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Tengyuan Zhao ◽  
Silvana Montoya-Noguera ◽  
Kok-Kwang Phoon ◽  
Yu Wang
Keyword(s):  
Limit State ◽  
Measurement Data ◽  
National Standard ◽  
Resistance Factors ◽  
Characteristic Value ◽  
Individual Judgment ◽  
Data Points ◽  
Geotechnical Design ◽  
Characteristic Values ◽  
Spatially Varying

Limit state design, incorporated into many recent geotechnical design codes, introduces the application of partial or resistance factors to selected characteristic values. Partial or resistance factors are usually set by national standard organizations, while characteristic values of geotechnical parameters are selected by engineers, often based on sparse measurement data combined with subjective engineering experience and judgment. Due to this subjective selection and individual judgment, the characteristic value derived by different engineers from the same dataset may vary greatly, especially when the test data contain significant variability. To address this issue, a new method based on Bayesian compressive sampling (BCS) is proposed in this study. BCS is able to reconstruct a high-resolution geotechnical property profile from sparse measurement data and quantify the uncertainty, e.g., confidence interval (CI) associated with the interpreted profile. The quantified uncertainty in the BCS has a clear statistical meaning: the corresponding confidence level for a CI from the BCS is the expected coverage proportion (i.e., fraction) of the complete profile that falls within the CI, if all data points along depth can be measured to provide the complete profile. This statistical meaning can be used to facilitate objective determination of characteristic values for geotechnical properties.

scholarly journals Applying a Python script to predict the geotechnical properties of the Nasiriyah soil

2022 ◽  
Vol 961 (1) ◽  
pp. 012004
Author(s):  
Haneen Mohammed Ali ◽  
Ressol R Shakir
Keyword(s):  
Soil Properties ◽  
Low Cost ◽  
Measurement Data ◽  
Field Investigation ◽  
Natural Material ◽  
Python Script ◽  
Geotechnical Design ◽  
Spatially Varying ◽  
The City ◽  
Engineering Soil

Abstract Soil is a natural material that suffers from intrinsic spatial variability resulting from natural factors and their influence on the soil. It became controversial and debated how to estimate the characteristic value of soils to obtain a reliable geotechnical design with low cost and less effort. Usually, foundations are not built on the same site as the screening; investigations are carried out to excavate a little at essential sites. In this paper (423), test wells were collected in the study area to be obtained and tabulated in Excel. The kriging statistics is applied using a python script to predict the values of geotechnical site properties and reliability of the method in estimating spatially varying soil properties values based on measurement data and prior knowledge. The program implements probabilistic kriging statistics and predicts the desired value by entering the coordinates of the locations whose properties you want to know and based on the previously prepared Excel file of known points, coordinates, and property values. The program will be used in two soil sites in the city of Nasiriyah to predict its properties. These points were selected from the examination of soil investigation reports to determine the reliability and accuracy of the program in predicting values. To get more reliable probability values using the kriging method and python scripts. A huge database of prepared and analyzed engineering soil properties has been created based on field investigation reports for projects in Nasiriyah.

Anchor rod forces and maximum bending moments in sheet pile walls using the factored strength approach

1996 ◽  
Vol 33 (5) ◽  
pp. 815-821 ◽  
Author(s):  
A B Schriver ◽  
A J Valsangkar
Keyword(s):  
Water Pressure ◽  
Limit State ◽  
Bending Moment ◽  
Ultimate Limit State ◽  
Sheet Pile ◽  
Limit States ◽  
Working Stress ◽  
Geotechnical Design ◽  
Ultimate Limit State Design ◽  
Sheet Pile Wall

Recently, the limit states approach using factored strength has been recommended in geotechnical design. Some recent research has indicated that the application of limit states design using recommended load and strength factors leads to conservative designs compared with the conventional methods. In this study the influence of sheet pile wall geometry, type of water pressure distribution, and different methods of analysis on the maximum bending moment and achor rod force are presented. Recommendations are made to make the factored strength design compatible with conventional design. Key words: factored strength, working stress design, ultimate limit state design, anchored sheet pile wall, bending moment, anchor rod force.

Resistance factors for settlement design

2005 ◽  
Vol 42 (5) ◽  
pp. 1422-1436 ◽  
Author(s):  
Gordon A Fenton ◽  
D V Griffiths ◽  
W Cavers
Keyword(s):  
Random Field ◽  
Limit State ◽  
Three Dimensional ◽  
Site Investigation ◽  
Soil Mass ◽  
Shallow Foundation ◽  
Random Field Theory ◽  
Large Variability ◽  
Resistance Factors ◽  
Settlement Design

To control serviceability problems arising from excessive settlement of shallow footings, geotechnical design codes generally include specifications regarding maximum settlement, which often govern the footing design. Once the footing has been designed and constructed, the actual settlement it experiences on a real three-dimensional soil mass can be quite different than expected, due to the soil's spatial variability. Because of this generally large variability (compared to other engineering materials, such as concrete and steel) and because this particular serviceability limit state often governs the design, it makes sense to consider a reliability-based approach to settlement design. This paper looks in some detail at a load and resistance factor design (LRFD) approach to limiting footing settlement. In particular, the resistance factors required to achieve a certain level of settlement reliability as a function of soil variability and site investigation intensity are determined analytically using random field theory. Simplified approximate relationships are proposed and tested using simulation via the random finite element method. It is found that the simplified relationships are validated both by theory and simulation and so can be used to augment the calibration of geotechnical LRFD code provisions with respect to shallow foundation settlement. Key words: reliability-based design, settlement, geotechnical, shallow foundation, random field, probability.

scholarly journals The ECETOC-Targeted Risk Assessment Tool for Worker Exposure Estimation in REACH Registration Dossiers of Chemical Substances—Current Developments

2020 ◽  
Vol 17 (22) ◽  
pp. 8443
Author(s):  
Jan Urbanus ◽  
Oliver Henschel ◽  
Qiang Li ◽  
Dave Marsh ◽  
Chris Money ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Assessment Tool ◽  
Measurement Data ◽  
Exposure Measurement ◽  
Chemical Substances ◽  
Worker Exposure ◽  
Exposure Estimation ◽  
Measurement Results ◽  
Data Points ◽  
Available Information

(1) Background: The ECETOC Targeted Risk Assessment (TRA) tool is widely used for estimation of worker exposure levels in the development of dossiers for REACH registration of manufactured or imported chemical substances in Europe. A number of studies have been published since 2010 in which the exposure estimates of the tool are compared with workplace exposure measurement results and in some instances an underestimation of exposure was reported. The quality and results of these studies are being reviewed by ECETOC. (2) Methods: Original exposure measurement data from published comparison studies for which six or more data points were available for each workplace scenario and a TRA estimate had been developed to create a curated database to examine under what conditions and for which applications the tool is valid or may need adaptation. (3) Results: The published studies have been reviewed for completeness and clarity and TRA estimates have been constructed based on the available information, following a set of rules. The full review findings are expected to be available in the course of 2021. (4) Conclusions: The ECETOC TRA tool developers periodically review the validity and limitations of their tool, in line with international recommendations.

scholarly journals Development of Rock Embedded Drilled Shaft Resistance Factors in Korea based on Field Tests

2019 ◽  
Vol 9 (11) ◽  
pp. 2201
Author(s):  
Seok Jung KIM ◽  
Sun Yong KWON ◽  
Jin Tae HAN ◽  
Mintaek YOO
Keyword(s):  
Design Method ◽  
Limit State ◽  
Field Tests ◽  
Load Test ◽  
Drilled Shaft ◽  
Displacement Curve ◽  
Base Resistance ◽  
Resistance Factors ◽  
Shaft Resistance ◽  
The Us

Load and resistance factor design (LRFD) is a limit state design method that has been applied worldwide. Because the data for determining LRFD factors in Korea has been insufficient, the resistance factors suggested by American Association of State Highway and Transportation Officials (AASHTO) in the US have been used for design in Korea; however, these resistance factors were defined based on the characteristics of the predominant bedrock types in the U.S. As such, it remains necessary to determine resistance factors that reflect the bedrock conditions in Korea. Accordingly, in this study, LRFD resistance factors were determined using 13 sets of drilled shaft load test data. To obtain accurate resistance factors, calibration of the elastic modulus of the drilled shaft and the equivalent load–displacement curve considering the axial load and elastic settlement was conducted. After determining accurate resistance values, a reliability analysis was performed. The resistance factors were determined to be within 0.13–0.32 of the AASHTO factors for the shaft resistance, 0.19–0.29 for the base resistance, and 0.28–0.42 for the total resistance. This is equivalent to being 30–60% of the AASHTO-recommended values for the shaft resistance and 40–60% of the AASHTO-recommended values for the base resistance. These differences in resistance factors were entirely the result of discrepancies in the conditions of the rock in the US and Korea in which the shafts were founded.

Mechanical properties of confirmat screws corner joints made of native wood and wood-based composites

2019 ◽  
Vol 105 ◽  
pp. 76-84
Author(s):  
NADEŽDA LANGOVÁ ◽  
PAVOL JOŠČÁK
Keyword(s):  
Mechanical Properties ◽  
Carrying Capacity ◽  
Limit State ◽  
Calculated Data ◽  
Statistical Processing ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Characteristic Values ◽  
State Method

Mechanical Properties of Confirmat Screws Corner Joints Made of Native Wood and Wood-Based Composites. The aim of this investigation was to design and determine the mechanical properties of confirmat screws corner joints made of native wood and wood-based composites. The objective of the study was to ascertain the stiffness and load carrying capacity of joints that differed in the diameter and length of confirmat type screw, as well as in the kind of materials. The results include statistical processing of measured and calculated data, and evaluation of the influence of selected factors on mechanical properties. The results are applied to the calculation of the characteristic values of the properties and to the determination of the equations for their calculation for other values of the selected factors. The characteristic values are used for the evaluation of the joints according to the limit state method.

scholarly journals Load and resistance factor design of drilled shafts subjected to lateral loading at service limit state

2018 ◽  
Author(s):  
◽  
Minh Dinh Uong
Keyword(s):  
Limit State ◽  
Design Procedure ◽  
Drilled Shafts ◽  
Resistance Factor ◽  
Lateral Loading ◽  
Drilled Shaft ◽  
Resistance Factors ◽  
Service Limit State ◽  
Load And Resistance Factor ◽  
Aashto Lrfd

Since 2007, the American Association of State Highway Administration Officials (AASHTO) has made utilization of Load and Resistance Factor Design (LRFD) mandatory on all federally-funded new bridge projects (AASHTO, 2007). However, currently, there are no guidelines implementing LRFD techniques for design of drilled shaft subjected to lateral loads using reliability-based analysis. On a national level, the AASHTO LRFD Bridge Design Specifications (AASHTO, 2012) specify that a resistance factor of 1.0 be used for design of drilled shafts subjected to lateral loading at service limit state, which means reliability-based analyses for calibration of resistance factors have not been performed. Therefore, there is a need to create a LRFD procedure for drilled shafts subjected to lateral loading at service limit state that has reliability-based calibrated resistance factors applicable for future projects. The research focuses on the reliability-based analysis of drilled shaft subjected to lateral loading, characterize lateral load transfer model of drilled shafts in shale, probabilistic calibrate resistance factor and contribute to the development of design procedure using LRFD. The objective of this work is to improve the design of drilled shaft subjected to lateral loading using LRFD at service limit state by providing a more reliable design procedure than the current AASHTO LRFD procedure for drilled shafts subjected to lateral loading at service limit state.

scholarly journals Reliability Estimation for Highway Bridges

2020 ◽  
Author(s):  
Nafiseh Kiani
Keyword(s):  
Reliability Index ◽  
Structural Reliability ◽  
Limit State ◽  
Highway Bridges ◽  
Reliability Estimation ◽  
State Function ◽  
Limit States ◽  
Resistance Factors ◽  
Load And Resistance Factors ◽  
Reliability Methods

Structural reliability analysis is necessary to predict the uncertainties which may endanger the safety of structures during their lifetime. Structural uncertainties are associated with design, construction and operation stages. In design of structures, different limit states or failure functions are suggested to be considered by design specifications. Load and resistance factors are two essential parameters which have significant impact on evaluating the uncertainties. These load and resistance factors are commonly determined using structural reliability methods. The purpose of this study is to determine the reliability index for a typical highway bridge by considering the maximum moment generated by vehicle live loads on the bridge as a random variable. The limit state function was formulated and reliability index was determined using the First Order Reliability Methods (FORM) method.

Sign in / Sign up

Export Citation Format

Share Document