scholarly journals Reliability of floors under impact vibration

1987 ◽  
Vol 14 (5) ◽  
pp. 683-689 ◽  
Author(s):  
Ricardo O. Foschi ◽  
Ashwani Gupta
Keyword(s):  
Limit State ◽  
Limit States ◽  
Concentrated Load ◽  
Static Loads ◽  
Finite Strip ◽  
Reliability Based Design ◽  
Set Up ◽  
Design Recommendation ◽  
Floor System ◽  
Impact Vibration

Uncomfortable vibrations is a serviceability limit state that must be taken into account in the design of residential floors. A finite strip analysis of a floor system, previously developed for static loads, is extended to dynamic problems. This analysis is applied to the problem of transient vibrations set up by a footfall impact, considering two persons on the floor: an impacter and a receiver. The floor response at the receiver's location is utilized in conjunction with human vibration tolerance data to determine a floor dynamic rating. The variability in this rating is assessed as a function of joist stiffness randomness, and a reliability-based design recommendation is developed: it limits the static deflection produced by a concentrated load of 1 kN, acting at midspan of a joist with the mean modulus of elasticity, to a maximum of 1 mm, independent of span length. Key words: vibrations, impact, floors, reliability, limit states design.

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.

Reliability-Based Tubing and Casing Design: Principles and Approach

1997 ◽  
Vol 119 (4) ◽  
pp. 257-262 ◽  
Author(s):  
M. A. Maes ◽  
K. C. Gulati ◽  
P. R. Brand ◽  
D. B. Lewis ◽  
D. L. McKenna ◽  
...  
Keyword(s):  
Stochastic Modeling ◽  
Oil And Gas ◽  
Limit State ◽  
Design Principles ◽  
Gas Wells ◽  
Limit States ◽  
Risk Levels ◽  
Limit State Design ◽  
Reliability Based Design ◽  
Oil And Gas Wells

This paper describes the development of an LRFD format reliability-based design of tubulars used in oil and gas wells. The approach is based on the principles of limit state design. The paper identifies the applicable limit states of pipe performance, discusses stochastic modeling of the load and resistance variables, and describes calibration of the design check equations. The calibration considers various combinations of hardware configurations, loadings, and tubular application zones with their respective risk levels. Application of the design principles is illustrated with an example problem.

Reliability-Based Casing Design

1995 ◽  
Vol 117 (2) ◽  
pp. 93-100 ◽  
Author(s):  
M. A. Maes ◽  
K. C. Gulati ◽  
D. L. McKenna ◽  
P. R. Brand ◽  
D. B. Lewis ◽  
...  
Keyword(s):  
Risk Analysis ◽  
Stochastic Modeling ◽  
Limit State ◽  
Design Criteria ◽  
Limit States ◽  
Gas Well ◽  
Quantitative Risk Analysis ◽  
Limit State Design ◽  
Reliability Based Design ◽  
Calibration Techniques

The present paper describes the development of reliability-based design criteria for oil and/or gas well casing/tubing. The approach is based on the fundamental principles of limit state design. Limit states for tubulars are discussed and specific techniques for the stochastic modeling of loading and resistance variables are described. Zonation methods and calibration techniques are developed which are geared specifically to the characteristic tubular design for both hydrocarbon drilling and production applications. The application of quantitative risk analysis to the development of risk-consistent design criteria is shown to be a major and necessary step forward in achieving more economic tubular design.

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.

Combined flexure and torsion of I-shaped steel beams

1989 ◽  
Vol 16 (2) ◽  
pp. 124-139 ◽  
Author(s):  
Robert G. Driver ◽  
D. J. Laurie Kennedy
Keyword(s):  
Limit State ◽  
Bending Moment ◽  
Phase Behaviour ◽  
Inelastic Interaction ◽  
Steel Beams ◽  
Ultimate Limit State ◽  
Second Phase ◽  
Design Standards ◽  
Limit States ◽  
Interaction Diagram

Design standards provide little information for the design of I-shaped steel beams not loaded through the shear centre and therefore subjected to combined flexure and torsion. In particular, methods for determining the ultimate capacity, as is required in limit states design standards, are not presented. The literature on elastic analysis is extensive, but only limited experimental and analytical work has been conducted in the inelastic region. No comprehensive design procedures, applicable to limit states design standards, have been developed.From four tests conducted on cantilever beams, with varying moment–torque ratios, it is established that the torsional behaviour has two distinct phases, with the second dominated by second-order geometric effects. This second phase is nonutilizable because the added torsional restraint developed is path dependent and, if deflections had been restricted, would not have been significant. Based on the first-phase behaviour, a normal and shearing stress distribution on the cross section is proposed. From this, a moment–torque ultimate strength interaction diagram is developed, applicable to a number of different end and loading conditions. This ultimate limit state interaction diagram and serviceability limit states, based on first yield and on distortion limitations, provide a comprehensive design approach for these members. Key words: beams, bending moment, flexure, inelastic, interaction diagram, I-shaped, limit states, serviceability, steel, torsion, torque, ultimate.

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.

Influence of Human Error on Structural Reliability

2017 ◽  
Author(s):  
Eric Brehm ◽  
Robert Hertle ◽  
Markus Wetzel
Keyword(s):  
Human Error ◽  
Structural Reliability ◽  
Failure Modes ◽  
Structural Model ◽  
Limit State ◽  
Design Procedure ◽  
Material Strength ◽  
Limit States ◽  
The Impact

In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

scholarly journals Probability Calibration Of Load Duration Modification Factor For Timber Roofs In The Polish Mountain Zones

2014 ◽  
Vol 60 (2) ◽  
pp. 195-208
Author(s):  
T. Domański
Keyword(s):  
Limit State ◽  
High Stress ◽  
Life Time ◽  
Probabilistic Methods ◽  
Limit States ◽  
Term Limit ◽  
Load Duration ◽  
Maximum Likelihood Methods ◽  
Short And Long Term

Abstract The resistance parameters of timber structures decrease with time. It depends on the type of load and timber classes. Strength reduction effects, referred to as creep-rupture effects, due to long term loading at high stress ratio levels are known for many materials. Timber materials are highly affected by this reduction in strength with duration of load. Characteristic values of load duration and load duration factors are calibrated by means of using probabilistic methods. Three damage accumulation models are considered, that is Gerhard [1] model, Barret, Foschi[2] and Foshi Yao [3] models. The reliability is estimated by means of using representative short- and long-term limit states. Time variant reliability aspects are taken into account using a simple representative limit state with time variant strength and simulation of whole life time load processes. The parameters in these models are fitted by the Maximum Likelihood Methods using the data relevant for Polish structural timber. Based on Polish snow data over 45 years from mountain zone in: Zakopane – Tatra, Świeradów – Karkonosze, Lesko – Bieszczady, the snow load process parameters have been estimated. The reliability is evaluated using representative short – and long –term limit states, load duration factor kmod is obtained using the probabilistic model.

OPERATIONAL ASSESSMENT OF THE LIMIT STATE OF TRACTOR UNITS WITH THE USE OF INDICATOR COUNTERS

2021 ◽  
Vol 3 (144) ◽  
pp. 12-21
Author(s):  
Nikolay A. Petrishchev ◽  
◽  
Mikhail N. Kostomakhin ◽  
Aleksandr S. Sayapin ◽  
Igor’ M. Makarkin ◽  
...  
Keyword(s):  
Limit State ◽  
Technical Condition ◽  
Point Of View ◽  
Research Purpose ◽  
Diagnostic Tools ◽  
Diagnostic Process ◽  
Technical Documentation ◽  
Limit States ◽  
Limit Condition ◽  
Reliability Indicators

In accordance with GOST 20793-2009, the tractor and its components are subjected to resource diagnostics before maintenance. The technical condition of the components of the tractor or machine should be checked with the use of control and diagnostic equipment. Currently, the criteria for the limit state are significantly outdated and require revision from the point of view of tightening modern requirements for operational and economic characteristics and reliability indicators. (Research purpose) The research purpose is in analyzing the state of the issue and the current regulatory documentation and making proposals for remote monitoring of the criteria for the limit states of individual components and aggregates. (Materials and methods) The article presents an analysis of scientific and technical documentation, State standards of the Russian Federation and scientific papers on the problems of minimizing technological risks, diagnostics and control suitability for determining the maximum technical condition, and staged studies on the possibility of monitoring the operation of individual components and units online. The article notes the need to adjust the criteria for the maximum technical condition in accordance with the new designs of resource-determining units, aggregates and existing technical regulations. (Results and discussion). The article presents the justification of the diagnostic process and identified contradictions in the design of tractors and existing scientific and technical documentation and standards, and proposed option of using meters-identifiers when upgrading tractors as a system of built-in online diagnostic tools. (Conclusions) Timely, automated monitoring of the technical condition of tractors, which is based on comparing data with the criteria of the limit condition, serves as a justification for the effective operation of equipment with built-in devices for diagnostics, which allows minimizing agrotechnological risks.

Limit State of Torsion of Ship Hulls with Large Hatch Openings

2001 ◽  
Vol 45 (02) ◽  
pp. 95-102
Author(s):  
Yuren Hu ◽  
Bozhen Chen
Keyword(s):  
Cross Section ◽  
Structural Reliability ◽  
Limit State ◽  
Safety Margin ◽  
Plastic Shear ◽  
Torsional Moment ◽  
Limit States ◽  
Ship Hulls ◽  
Design Values ◽  
Bound Theorem

The limit state of torsion of ship hulls with large hatch openings is studied. A method to determine the distribution of the plastic shear flow on the hull cross section in the limit state by using the lower-bound theorem is presented together with the corresponding linear programming problem. The limit torsional moment of the hull cross section is obtained based on the distribution of the shear stress in the limit state. Three example limit states for typical containerships of different sizes with large hatch openings are calculated. The calculated limit torsional moments are compared with the design values of wave torque calculated by using the equations given by main classification societies in their rules. A rough estimate of the safety margin is obtained. The results show that for large containerships, it is necessary to pay attention to the safety with respect to torsion. The present method can serve as an effective tool in structural reliability analysis of ships with large hatch openings when the failure mode of torsion is taken into account.

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