Reliability Based Design Criteria for Installation of Pipelines in the Bay of Campeche, Mexico: Part 1

2002 ◽  
Author(s):  
Robert Bea ◽  
Tao Xu ◽  
Ernesto Heredia-Zavoni ◽  
Leonel Lara ◽  
Rommel Burbano
Keyword(s):  
Limit State ◽  
Companion Paper ◽  
Design Guidelines ◽  
Design Criteria ◽  
Ultimate Limit State ◽  
Reliability Based Design ◽  
Factor Design ◽  
Load And Resistance Factor ◽  
Ultimate Limit ◽  
Allowable Stress Design

Studies have been performed to propose reliability based design criteria for the installation of pipelines in the Bay of Campeche, Mexico. This paper summarizes the reliability formulations that were used to develop Allowable Stress Design and Load and Resistance Factor Design guidelines for Ultimate Limit State conditions, background on the target reliabilities that were used in the development, and the methods that were used to characterize the demands (loads, displacements) induced in pipelines during their installation. This paper summarizes data that was gathered during the installation of pipelines in the Bay of Campeche to help define the Biases (actual stresses/calculated stresses) associated with the analytical model used to predict installation demands. These results are compared with those published previously based on other field and laboratory tests. A companion paper details the analyses of pipeline Ultimate Limit State capacities and the Biases associated with these capacities.

Reliability Based Design Criteria for Installation of Pipelines in the Bay of Campeche, Mexico: Part 2

2002 ◽  
Author(s):  
Robert Bea ◽  
Tao Xu ◽  
Ernesto Heredia-Zavoni ◽  
Leonel Lara ◽  
Rommel Burbano
Keyword(s):  
Limit State ◽  
Companion Paper ◽  
Design Criteria ◽  
Ultimate Limit State ◽  
Large Database ◽  
Reliability Based Design ◽  
Working Stress ◽  
Factor Design ◽  
Load And Resistance Factor ◽  
Ultimate Limit

Studies have been performed to propose reliability based design criteria for the installation of pipelines in the Bay of Campeche, Mexico. This paper summarizes formulations that were used to characterize the important Ultimate Limit State capacities of the pipelines during the installation period (collapse, bending, tension, combined, and propagating buckling). A large database of laboratory and numerical analysis ‘tests’ (more than 2,000 results) to determine pipeline capacities was assembled to help evaluate the Biases (ratio of measured/predicted capacities) in the analytical methods used to determine pipeline capacities. Given the formulations, target reliabilities, and installation demand characterizations summarized in a companion paper (Part 1), installation design criteria were developed for both Working Stress Design and Load and Resistance Factor Design formats.

Load and resistance factor design of shallow foundations against bearing failure

2008 ◽  
Vol 45 (11) ◽  
pp. 1556-1571 ◽  
Author(s):  
Gordon A. Fenton ◽  
D. V. Griffiths ◽  
Xianyue Zhang
Keyword(s):  
Bearing Capacity ◽  
Limit State ◽  
Resistance Factor ◽  
Shallow Foundation ◽  
Ultimate Limit State ◽  
Full Potential ◽  
Design Codes ◽  
Reliability Based Design ◽  
Factor Design ◽  
Load And Resistance Factor

Shallow foundation designs are typically governed either by settlement, a serviceability limit state, or by bearing capacity, an ultimate limit state. While geotechnical engineers have been designing against these limit states for over half a century, it is only recently that they have begun to migrate towards reliability-based designs. At the moment, reliability-based design codes are generally derived through calibration with traditional working stress designs. To take advantage of the full potential of reliability-based design the profession must go beyond calibration and take geotechnical uncertainties into account in a rational fashion. This paper proposes a load and resistance factor design (LRFD) approach for the bearing capacity design of a strip footing, using load factors as specified by structural codes. The resistance factors required to achieve an acceptable failure probability are estimated as a function of the spatial variability of the soil and by the level of “understanding” of the soil properties in the vicinity of the foundation. The analytical results, validated by simulation, are primarily intended to aid in the development of the next generation of reliability-based geotechnical design codes, but can also be used to assess the reliability of current designs.

Practical Reliability-Based Design Approach for Foundation Engineering

1996 ◽  
Vol 1546 (1) ◽  
pp. 94-99 ◽  
Author(s):  
Kok Kwang Phoon ◽  
Fred H. Kulhawy
Keyword(s):  
Research Study ◽  
Limit State ◽  
Drilled Shafts ◽  
Ultimate Limit State ◽  
Foundation Engineering ◽  
Reliability Level ◽  
Reliability Based Design ◽  
Ultimate Limit State Design ◽  
Ultimate Limit ◽  
Selection Of

A research study was completed recently that was directed toward the development of practical, reliability-based design (RBD) equations specifically for foundation engineering. Some of the key RBD principles used in the study are presented. The important considerations involved in the development of practical and robust RBD criteria are emphasized. In particular, the selection of an appropriate reliability assessment technique and the careful characterization and compilation of geotechnical variabilities are important because of their central role in the calculation of the probability of failure and the assessment of the target reliability level. An overview of a simplified RBD approach is given, and an application of this approach to the ultimate limit state design of drilled shafts under undrained uplift loading is discussed.

scholarly journals Serviceability limit state reliability-based design of augered cast-in-place piles in granular soils

2017 ◽  
Vol 54 (12) ◽  
pp. 1704-1715 ◽  
Author(s):  
Seth C. Reddy ◽  
Armin W. Stuedlein
Keyword(s):  
Lower Bound ◽  
Limit State ◽  
Companion Paper ◽  
Resistance Factor ◽  
Granular Soils ◽  
Serviceability Limit State ◽  
Reliability Based Design ◽  
Wide Range ◽  
Load Displacement ◽  
Load And Resistance Factor

This study proposes a reliability-based design procedure to evaluate the allowable load for augered cast-in-place (ACIP) piles installed in predominately granular soils based on a prescribed level of reliability at the serviceability limit state. The ultimate limit state (ULS) ACIP pile–specific design model proposed in the companion paper is incorporated into a bivariate hyperbolic load–displacement model capable of describing the variability in the load–displacement relationship for a wide range of pile displacements. Following the approach outlined in the companion paper, distributions with truncated lower-bound capacities are incorporated into the reliability analyses. A lumped load-and-resistance factor is calibrated using a suitable performance function and Monte Carlo simulations. The average and conservative 95% lower-bound prediction intervals for the calibrated load-and-resistance factor resulting from the simulations are provided. Although unaccounted for in past studies, the slenderness ratio is shown to have significant influence on foundation reliability. Because of the low uncertainty in the proposed ULS pile capacity prediction model, the use of a truncated distribution has moderate influence on foundation reliability.

Consequence factors in the ultimate limit state design of shallow foundations

2011 ◽  
Vol 48 (2) ◽  
pp. 265-279 ◽  
Author(s):  
Gordon A. Fenton ◽  
D. V. Griffiths ◽  
Olaide O. Ojomo
Keyword(s):  
Limit State ◽  
Shallow Foundations ◽  
Resistance Factor ◽  
Shallow Foundation ◽  
Ultimate Limit State ◽  
Resistance Factors ◽  
Limit State Design ◽  
Reliability Based Design ◽  
Load And Resistance Factors ◽  
Load And Resistance Factor

The reliability-based design of shallow foundations is generally implemented via a load and resistance factor design methodology embedded in a limit state design framework. For any particular limit state, the design proceeds by ensuring that the factored resistance equals or exceeds the factored load effects. Load and resistance factors are determined to ensure that the resulting design is sufficiently safe. Load factors are typically prescribed in structural codes and take into account load uncertainty. Factors applied to resistance depend on both uncertainty in the resistance (accounted for by a resistance factor) and desired target reliability (accounted for by a newly introduced consequence factor). This paper concentrates on how the consequence factor can be defined and specified to adjust the target reliability of a shallow foundation designed to resist bearing capacity failure.

scholarly journals Ultimate limit state reliability-based design of augered cast-in-place piles considering lower-bound capacities

2017 ◽  
Vol 54 (12) ◽  
pp. 1693-1703 ◽  
Author(s):  
Seth C. Reddy ◽  
Armin W. Stuedlein
Keyword(s):  
Lower Bound ◽  
Limit State ◽  
Resistance Factor ◽  
Reasonable Assumption ◽  
Ultimate Limit State ◽  
Design Models ◽  
Resistance Factors ◽  
Reliability Based Design ◽  
The Impact ◽  
Ultimate Limit

The use of augered cast-in-place (ACIP) piles for transportation infrastructure requires an appropriate reliability-based design (RBD) procedure. In an effort to improve the accuracy of an existing design model and calibrate appropriate resistance factors, this study presents a significantly revised RBD methodology for estimating the shaft and toe bearing capacity of ACIP piles using a large database consisting of static loading tests in predominately granular soils. The proposed design models are unbiased, as opposed to those currently recommended. Based on the reasonable assumption that a finite lower-bound resistance limit exists, lower-bound design lines are developed for shaft and toe bearing resistance by applying a constant ratio to the proposed design models. Resistance factors are calibrated at the strength or ultimate limit state (ULS) for ACIP piles loaded in compression and tension for two commonly used target probabilities of failure with and without lower-bound limits. For piles loaded in compression, separate resistance factors are calibrated for the proposed shaft and toe bearing resistance models. The inclusion of a lower-bound limit for piles loaded in tension results in a 24%–50% increase in the calibrated resistance factor. For piles loaded in compression, the application of a lower-bound limit results in a 20%–150% increase in the calibrated resistance factor, and represents a significant increase in useable pile capacity. Although the impact of a lower-bound limit on resistance factor calibration is directly dependent on the degree of uncertainty in the distribution of resistance, this effect is outweighed by the type of distribution selected (i.e., normal, lognormal) at more stringent target probabilities of failure due to differences in distribution shape at the location of the lower-bound limit. A companion paper explores the use of the revised ULS model in a reliability-based serviceability limit state design framework.

Combined Reinforced Concrete Columns Strengthening with Steel Clipping and Concrete Surfacing

2021 ◽  
pp. 11-22
Author(s):  
Ю. Г. Москалькова ◽  
С. В. Данилов ◽  
В. А. Ржевуцкая
Keyword(s):  
Reinforced Concrete ◽  
Load Transfer ◽  
Limit State ◽  
Concrete Columns ◽  
Ultimate Limit State ◽  
Concrete Core ◽  
Reinforced Concrete Columns ◽  
Entire Height ◽  
Complex Structural ◽  
Ultimate Limit

Постановка задачи. Исследуется метод усиления железобетонных колонн устройством стальной обоймы с обетонированием, который позволяет восстанавливать эксплуатационные показатели колонн, имеющих значительные дефекты и повреждения. Предпосылкой настоящих исследований явилось предположение о том, что усиление стальной обоймой с обетонированием является эффективным способом повышения несущей способности железобетонных колонн, причем вариант приложения нагрузки - только на бетонное ядро или ко всему сечению - существенно на эффективность усиления не влияет. В связи с этим целью исследования является определение необходимости устройства стального оголовка и включения в работу ветвей стальной обоймы при условии обетонирования стержня колонны по всей высоте. Результаты и выводы. Рациональным признан способ передачи нагрузки только на бетонное ядро усиленных колонн, поскольку устройство оголовка стальной обоймы требует применения сложных конструктивно-технологических решений, но при этом дополнительно увеличивает несущую способность незначительно (согласно проведенным исследованиям менее чем на 10 %). Ввиду отсутствия необходимости устройства конструкций стального оголовка снижаются трудоемкость и сроки производства работ по усилению колонн. Statement of the problem. The method of strengthening reinforced concrete columns with a steel clipping and the concrete surfacing is investigated. This method allows one to repair the columns with significant defects and damage. The prerequisite for this study was the assumption of strengthening with a steel clipping and the concrete surfacing is an effective way to increase the ultimate limit state of reinforced concrete columns, furthermore, the option of applying the load (only to the concrete core or to the entire section) does not significantly affect the strengthening effectiveness. In this regard, the purpose of the investigation was to identify the need to include the steel jacketing in the work, on the condition the column is coated with concrete along with the entire height. Results and conclusions. The load transfer method only to the concrete core of the strengthened columns is recognized as rational since the device of the steel clipping head requires the use of complex structural and technological solutions, but at the same time additionally increases the ultimate limit state insignificantly (according to the studies by less than 10 %). Due to the absence of the need to establish structures of the steel jacketing head, the labor intensiveness and terms of work production on strengthening the columns are reduced.

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