Reliability-based design and analysis for internal limit states of steel grid-reinforced mechanically stabilized earth walls

2020 ◽  
Author(s):  
Richard J. Bathurst ◽  
Nezam Bozorgzadeh ◽  
Yoshihisa Miyata ◽  
Tony M. Allen
Keyword(s):  
Tensile Strength ◽  
Reliability Index ◽  
Limit State ◽  
Engineering Practice ◽  
Foundation Engineering ◽  
Mechanically Stabilized Earth ◽  
Limit States ◽  
Reliability Based Design ◽  
Mse Walls ◽  
Mechanically Stabilized

The paper demonstrates reliability-based design (RBD) and analysis for tensile strength (rupture) and pullout limit states for mechanically stabilized earth (MSE) walls constructed with steel grid reinforcement in combination with frictional soils. Five different reinforcement tensile load models for walls under operational conditions are considered in combination with six different pullout models and one tensile strength model. The general approach considers the accuracy of the load and resistance models that appear in each limit state equation plus uncertainty in the choice of nominal values at time of design that is linked to the concept of “level of understanding” that is used in Canadian load and resistance factor design (LRFD) foundation engineering practice. The effect of potential steel corrosion on reliability index for the tensile strength limit state is considered in calculations. A well-documented MSE wall case study is used to demonstrate the general approach. The relationship between nominal factor of safety and reliability index is used to demonstrate how to optimize steel grid member diameters and arrangement to achieve a target reliability index of β = 2.33. The approach described in this paper is an important contribution to next-generation analysis and design using modern concepts of RBD for MSE walls.

scholarly journals Reliability-based design of internal limit states for mechanically stabilized earth walls using geosynthetic reinforcement

2019 ◽  
Vol 56 (6) ◽  
pp. 774-788 ◽  
Author(s):  
Richard J. Bathurst ◽  
Peiyuan Lin ◽  
Tony Allen
Keyword(s):  
Reliability Index ◽  
Limit State ◽  
Closed Form Solution ◽  
Form Solution ◽  
Design Practice ◽  
Mechanically Stabilized Earth ◽  
Limit States ◽  
Reliability Based Design ◽  
Mechanically Stabilized

This paper demonstrates reliability-based design for tensile rupture and pullout limit states for mechanically stabilized earth (MSE) walls constructed with geosynthetic (geogrid) reinforcement. The general approach considers the accuracy of the load and resistance models that appear in each limit state equation plus uncertainty due to the confidence (level of understanding) of the designer at the time of design. The reliability index is computed using a closed-form solution that is easily implemented in a spreadsheet. The general approach provides a quantitative link between nominal factor of safety, which is familiar in allowable stress design practice, and reliability index used in modern civil engineering reliability-based design practice. A well-documented MSE wall case study is used to demonstrate the general approach and to compare margins of safety using different load and resistance model combinations. A practical outcome from the case study example is the observation that the pullout limit state is much less likely to control design than the ultimate tensile rupture state for walls with continuous reinforcement coverage. The more accurate “simplified stiffness method” that is used to compute tensile loads in the reinforcement under operational conditions is shown to generate a more cost-effective reinforcement option than the less accurate American Association of State Highway and Transportation Officials (AASHTO) simplified method.

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.

Experimental analysis of large-scale pullout tests conducted on polyester anchored geogrid reinforcement systems

2017 ◽  
Vol 54 (5) ◽  
pp. 621-630 ◽  
Author(s):  
S.H. Sadat Taghavi ◽  
M. Mosallanezhad
Keyword(s):  
Large Scale ◽  
Mechanically Stabilized Earth ◽  
Height Ratio ◽  
Passive Resistance ◽  
Pullout Resistance ◽  
Pullout Tests ◽  
Mse Walls ◽  
Effective Performance ◽  
Mechanically Stabilized ◽  
New System

The pullout resistance of reinforcement, such as geogrids in mechanically stabilized earth (MSE) walls, includes the skin friction between the soil and solid geogrid surfaces. It also includes the bearing resistance against the transverse ribs, which has a greater influence on the production of pullout resistance. Taking the current limitations involved in producing woven polyester geogrids into consideration (i.e., the limited thickness of the transverse ribs), the amount of bearing resistance developed in front of transverse ribs is limited in the pullout mechanism. Thus, along with introducing an innovative and applied system, this research has endeavoured to demonstrate the effective performance of this new system in increasing the passive resistance — and thereby the pullout resistance — of standard geogrids. This new system, which is formed by adding steel transverse elements (a set of steel equal angles) to the ordinary polyester geogrids by means of nuts and bolts, is called an anchored geogrid (AG). The experimental results show that a spacing-to-height ratio of transversal elements equal to 5 gives the maximum pullout resistance for a polyester AG system in sandy soil used in the study. With an optimum arrangement, this system is capable of increasing the pullout resistance of the ordinary geogrid system by 65%. In addition, based on the plasticity solution, the pullout bearing failure mechanisms of a single isolated transverse element in the polyester AG system depend on overburden pressures.

Reliability-based design criteria for timber bridges in Ontario

1986 ◽  
Vol 13 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Andrzej S. Nowak ◽  
Raymond J. Taylor
Keyword(s):  
Reliability Index ◽  
Structural Reliability ◽  
Structural Safety ◽  
Design Code ◽  
Bridge Design ◽  
Limit States ◽  
Acceptance Criterion ◽  
Reliability Based Design ◽  
Load And Resistance Factor ◽  
Timber Bridges

The new Ontario Highway Bridge Design Code (OHBDC) is based on limit states theory and therefore uses a load and resistance factor format. This paper deals with the development of the basis for the timber bridge design provisions (OHBDC). Three structural systems are considered: sawn timber stringers, laminated nailed decks, and prestressed laminated decks. The latter system has been successfully used in Ontario for the last 7 years.The acceptance criterion in calculation of load and resistance factors is structural reliability. It is required that bridges designed using the new code must have a reliability equal to or greater than a preselected target value. Reliability is measured in terms of the reliability index. The safety analysis is performed for a structural system rather than for individual members. The live load model was developed on the basis of available truck survey data. Material properties are based on extensive in-grade test results. Numerical examples are included to demonstrate the presented approach. Key words: bridge deck, design code, prestressed timber, reliability, reliability index, stringers, structural safety, timber bridges.

scholarly journals Mechanically Stabilized Earth with Steel Reinforcement

2021 ◽  
Vol 9 (3) ◽  
pp. 135-141
Author(s):  
Magdi M. E. Zumrawi ◽  
Abubaker B. B. Barakat ◽  
Idris M. I. Abdalla ◽  
Rabab A. A. Altayeb
Keyword(s):  
Retaining Wall ◽  
Soil Reinforcement ◽  
Current Status ◽  
Mechanically Stabilized Earth ◽  
Steel Strips ◽  
Wall Structures ◽  
Backfill Soil ◽  
Mse Walls ◽  
Mechanically Stabilized

This paper presents the Mechanically Stabilized Earth (MSE) technique as a practical option for earth retaining wall structures. The literature pertaining soil reinforcement methods and their application in MSE walls were intensively reviewed. The present work focused on evaluating the performance of MSE walls with backfill soil reinforced by steel strips. Almolid square overpass bridge in Khartoum, which was constructed in 2015 with MSE walls as lateral support of the overpass ramps, was considered as case study. Based on field observations, the current status of the overpass bridge has proven that the use of MSE walls is successful and beneficial for sustainability of the overpass.  

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.

scholarly journals Reliability Analysis of Anchored Geotechnical Structures for the Design Limit States

2020 ◽  
Vol 8 (2) ◽  
pp. 35-47
Author(s):  
Sohaib K Al-Mamoori ◽  
Laheab A. Al-Maliki ◽  
Khaled El-Tawel
Keyword(s):  
Reliability Analysis ◽  
Reliability Index ◽  
Failure Modes ◽  
Limit State ◽  
Tensile Failure ◽  
Limit States ◽  
Geotechnical Parameters ◽  
Retaining Structure ◽  
Geotechnical Structures ◽  
Bending Failure

Reliability has been considered of magnificent importance in engineering design specially in geotechnical engineering due to the unpredictable conditions of soil layers. It is essential to establish well- designed failure modes that could guarantee safety and durability of the proposed structure. This study aims to suggest a reliability analyses procedure for retaining walls by the mean of a reliability index β using the specifications of AASHTO Bridge Design 2002, Eurocode 7, and DIN EN 1993-5 norms. Two failure modes; Tensile failure of tendon (G1) and Failure by bending (G2) were studied and compared by using equation of the Design Limit State (DLS) and by taking some basic geotechnical parameters as Random Variables RV. The analyses demonstrated that the reliability index β and probability of failure Pf are the most important parameter in the reliability analysis. Also, the suitable height (H) for the retaining structure (for all angles ϴ) equals to 6 m and the most critical angle is ϴ= 45º to prevent the failure by tensile of tendon. While the bending failure reliability analysis shows that all heights of retaining structure are suitable. After comparing the two cases it was found that (G1) is more dangerous than (G2).

Sign in / Sign up

Export Citation Format

Share Document