scholarly journals Calibration of Load and Resistance Factors for Breakwater Foundations under the Earthquake Loading

2021 ◽  
Vol 13 (4) ◽  
pp. 1730
Author(s):  
Nhu Son Doan ◽  
Jungwon Huh ◽  
Van Ha Mac ◽  
Dong Hyawn Kim ◽  
Kiseok Kwak
Keyword(s):  
Sensitivity Analysis ◽  
Failure Probability ◽  
Reliability Index ◽  
System Stability ◽  
Load Factor ◽  
Calibration Process ◽  
Resistance Factors ◽  
Target Reliability Index ◽  
Load And Resistance Factors ◽  
The Stability

This study investigates the system stability of breakwater foundations subjected to earthquakes from a probabilistic point of view. A fully probabilistic approach, i.e., a combination of the Monte Carlo simulation and Bishop’s simplified method, has been developed to evaluate the system failure probability of foundation damage, one of the prevailing failures encountered during earthquakes. Twelve sections of perforated caisson breakwaters located around Korea were chosen as case studies. First, the reliability analysis was performed for all the breakwaters at existing conditions; then, the calibration process involving the estimation of load and resistance factors was conducted for 12 breakwaters at three levels of the target reliability index. As the performance function, used in the stability analysis of breakwater foundations, is defined based on an implicit shape with a high-dimensional space of variables, the calibration process of load and resistance factors becomes cumbersome and complicated. Therefore, this study has proposed a sensitivity analysis to be implemented prior to the calibration process to elicit the effects of variables on the stability of each breakwater, which, thereafter, effectively directs the calibration process. The results of this study indicate that the failures in the foundation of breakwaters frequently occur in different modes. Therefore, the failure probability should be estimated considering all possible failure modes of the foundation. The sensitivity results elucidate that the soil strength parameters are the dominant variables, contributing to the stability of foundations, whereas the seismic coefficient presents the negative effect, causing the insecurity of breakwaters. In particular, the deadweights, though directly contributing to the seismic forces, show a small effect on the stability of foundations. The calibration shows that the load factors slightly vary with an increase in the target reliability index and set 1.10 for three safety levels. In contrast, the resistance factor exhibits an inverse relationship with the specified reliability index. Especially when the load factor equals 1.10, the resistance factors are 0.90, 0.85, and 0.80, corresponding to the reliability index of 2.0, 2.5, and 3.0, respectively. Eventually, it is proved that the sensitivity analysis prior to the calibration process makes the procedure more efficient. Accordingly, the iteration of simulation execution is diminished, and the convergence is quickly accomplished.

Determination of Basic Wind Velocity for Wind Load-Governed Limit State

2019 ◽  
Author(s):  
Ji Hyeon Kim ◽  
Hae-Sung Lee
Keyword(s):  
Wind Velocity ◽  
Reliability Index ◽  
General Procedure ◽  
Limit State ◽  
Wind Load ◽  
Wind Pressure ◽  
Load Factor ◽  
Load Effect ◽  
Design Life ◽  
Target Reliability Index

<p>This paper proposes a general procedure for evaluating a nominal value of wind velocity for a wind load- governed limit state to secure a target reliability index during the design life of a structure. The nominal value of wind velocity, referred to as a basic wind velocity, and wind load factor should be determined so that the factored wind load effect secures a target reliability index for a wind load-governed limit state. In this study, the analytical form of the return period of the basic wind velocity is expressed as a function of the target reliability index, wind load factor, and statistical parameters of wind pressure, which are derived as linear functions of the coefficient of wind velocity. The proposed approach is applied to the Korean Highway Bridge Design Code-Cable supported Bridge, which specifies the design life of a structure as 100- and 200-year.</p>

scholarly journals Squeal Frequency of a Railway Disc Brake Evaluation by FE Analyses

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
F. Cascetta ◽  
F. Caputo ◽  
A. De Luca
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Experimental Tests ◽  
Numerical Approach ◽  
System Stability ◽  
Brake System ◽  
Physical Parameters ◽  
Disc Brake ◽  
Complex Eigenvalues ◽  
The Stability

This paper deals with the development of a numerical model, based on the Finite Element (FE) theory for the prediction of the squeal frequency of a railway disc brake. The analytical background has been discussed and presented, as well as the most efficient methods for evaluating the system stability; the attention has been paid particularly to the complex eigenvalues method, which has been adopted within this paper to investigate the railway disc brake system. Numerical results have been compared with measurements from experimental tests in order to validate the proposed numerical approach. At the end of this work, a sensitivity analysis, aimed at understanding the effects of some physical parameters influencing the stability of the brake system and the squeal propensity, has been carried out.

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 Resistance factor calibration for cold-formed steel compression members

2013 ◽  
Vol 66 (2) ◽  
pp. 233-238
Author(s):  
Marcilio S. R. Freitas ◽  
André L. R. Brandão ◽  
Arlene M. S. Freitas
Keyword(s):  
Reliability Index ◽  
Normal Load ◽  
Load Ratio ◽  
Calibration Procedure ◽  
Resistance Factor ◽  
Steel Columns ◽  
Resistance Factors ◽  
Target Reliability Index ◽  
Cold Formed Steel ◽  
Current Value

The objective of this paper is to provide a review of the calibration procedure of the resistance factor for a target reliability index. Resistance factors for cold-formed steel columns are calculated with a first order second moment reliability approach. A test database of 323 cold-formed steel columns concentrically loaded with plain and lipped C-section was assembled, and test-to-predicted statistics were obtained for the three design methods available in Brazilian cold-formed steel code: the Effective Width Method (EWM), the Effective Section Method (ESM) and the Direct Strength Method (DSM). For the normal load combination, dead-to-live load ratio of 1/3, and target reliability index <img border=0 width=32 height=32 src="../../../../../img/revistas/rem/v66n2/a15for01.jpg" align=absmiddle > or = 2.5, the calculated resistance factors, g, for the three methods are consistent with current value specified by Brazilian code. For all methods, with target reliability index <img border=0 width=32 height=32 src="../../../../../img/revistas/rem/v66n2/a15for01.jpg" align=absmiddle > or = 3.0, the calculated resistance factors, g, are higher than the current value used in Brazilian code.

Analysis of Reliability Calculation and System Analysis of Gravity Retaining Walls

2014 ◽  
Vol 556-562 ◽  
pp. 862-866
Author(s):  
Gui Mei Zhou ◽  
Yan Li ◽  
Fan Zhang
Keyword(s):  
Safety Factor ◽  
Failure Probability ◽  
System Analysis ◽  
Retaining Walls ◽  
System Stability ◽  
Factor Method ◽  
Reliability Calculation ◽  
First Order Second Moment ◽  
Sliding Stability ◽  
The Stability

The reliability indexes of the two unstable modes of the gravity retaining walls were calculated by the first-order second-moment theory through setting up the fundamental model. Results evaluated are compared with the results which is evaluate by the safety factor method, and it shows that there is still a certain degree of probability of failure of gravity retaining walls , even though they meet the checking conditions of "Safety Factor" method .The analysis shows that the failure probability of sliding stability is approximately equal to the failure probability of the entire system stability. And the stability of sliding of the gravity retaining walls should be payed more attention during the process of design checking calculation.

Calibration of the Ontario Bridge Design Code 1983 edition

1984 ◽  
Vol 11 (4) ◽  
pp. 760-770 ◽  
Author(s):  
Hid N. Grouni ◽  
Andrzej S. Nowak
Keyword(s):  
Reliability Index ◽  
Calibration Procedure ◽  
Design Code ◽  
Bridge Design ◽  
Limit States ◽  
Safety Level ◽  
Acceptance Criterion ◽  
Resistance Factors ◽  
Concrete Girders ◽  
Load And Resistance Factors

The paper summarizes the calibration procedure used to calculate load and resistance factors for the Ontario Bridge Design Code 1983 edition. The limit states considered include serviceability and ultimate limit states during service and in construction. The acceptance criterion is closeness to a predetermined target safety level. Safety is measured in terms of a reliability index. The results of calibration are discussed for composite steel–concrete girders, pretensioned concrete girders, post-tensioned concrete decks, and timber decks. The analysis of construction design criteria is demonstrated on segmental bridges. Key words: code calibration, bridges, reliability index, load and resistance factors, limit states.

Calibration of design code for buried structures

2001 ◽  
Vol 28 (4) ◽  
pp. 574-582 ◽  
Author(s):  
Andrzej S Nowak ◽  
Chan-Hee Park ◽  
Peter Ojala
Keyword(s):  
Reinforced Concrete ◽  
Reliability Index ◽  
Water Pressure ◽  
Earth Pressure ◽  
Highway Bridges ◽  
Design Code ◽  
Buried Structures ◽  
Reliability Indices ◽  
Resistance Factors ◽  
Load And Resistance Factors

The reliability-based calibration procedures were applied to develop load and resistance factors for the Ontario Highway Bridge Design Code (1979, 1983, and 1991) and recently the Canadian Highway Bridges Design Code (2000). However, the load components for buried structures were not considered. The development of a statistical model for earth pressure requires a special approach. Therefore, this paper deals with the reliability-based calibration of the design code for buried (cut-and-cover) structures. A typical running structure consists of reinforced concrete walls forming a rectangular box section, while an underground station may have a one- to six-cell box. The major load components include earth pressure, water pressure and weight of the concrete. Other load components such as live load are relatively small. Statistical parameters are derived for representative structures and structural systems. The correlation between load components is estimated based on the available field data. Structural performance is measured in terms of the reliability index. Reliability indices are calculated for a representative spectrum of running structures and stations. In general, the reliability indices for existing buried structures are higher than those for bridges or buildings. The target reliability index has been selected on the basis of calculated reliability indices, comparison with other structures, and cost analysis (consequences of failure). The optimum load and resistance factors are calculated and recommended for the design code to achieve a uniform safety level.Key words: buried structure, code calibration, load models, reinforced concrete, reliability analysis, resistance models.

Foundation Safety of Gravity-Based Systems During Severe Storms

1992 ◽  
Vol 114 (2) ◽  
pp. 104-113
Author(s):  
K. O. Ronold ◽  
S. Haver
Keyword(s):  
Failure Probability ◽  
Load Factor ◽  
Structural System ◽  
Sea State ◽  
First Order Reliability Method ◽  
Severe Storms ◽  
First Order ◽  
Reliability Method ◽  
Northern North Sea ◽  
The Stability

The temporal evolutions of the most important sea state characteristics during storms are presented together with the corresponding uncertainties. Storm data from the Northern North Sea are used for this purpose. The influence of the uncertainties associated with an extreme storm on the foundation safety is demonstrated for a gravity-based structural system founded on a clay. The stability is analyzed with respect to failure in large cyclic displacements accumulated during the storm. The failure probability is estimated by a first-order reliability method and the most important variables concerning their contribution to the failure probability are indicated. In most practical foundation safety investigations, an idealized deterministic storm profile is adopted. The adequacy of this profile is considered by calibrating a “load factor” to be used in connection with the idealized profile.

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

Sign in / Sign up

Export Citation Format

Share Document