scholarly journals Reliability of Concrete Elements Designed for Alternative Load Combinations Provided in Eurocodes

10.14311/382 ◽  
2003 ◽  
Vol 43 (1) ◽  
Author(s):  
M. Holický ◽  
J. Marková
Keyword(s):  
Structural Design ◽  
Structural Reliability ◽  
Reliability Theory ◽  
Probabilistic Methods ◽  
European Standard ◽  
Limit States ◽  
Design Procedures ◽  
Characteristic Features ◽  
Concrete Elements ◽  
Ultimate Limit

The basic European standard for design of buildings and other engineering works, EN 1990 "Basis of structural design", provides alternative design procedures, for which national choice is allowed. One of the most important questions concerns three fundamental combinations of actions for persistent and transient design situations in the Ultimate limit states. Simple examples of reinforced concrete elements show, that the alternative load combinations may lead to considerably different reliability levels. Probabilistic methods of structural reliability theory are used to identify characteristic features of each combination and to formulate recommendations. However, further calibration studies are urgently needed in order to prepare National annexes to EN 1990 on time.

Seismic Test Methods for Architectural Glazing Systems

1996 ◽  
Vol 12 (1) ◽  
pp. 129-143 ◽  
Author(s):  
Richard A. Behr ◽  
Abdeldjelil Belarbi
Keyword(s):  
Rational Design ◽  
Limit State ◽  
Test Methods ◽  
Test Method ◽  
Ultimate Limit State ◽  
Limit States ◽  
State Data ◽  
Design Procedures ◽  
Seismic Loadings ◽  
Ultimate Limit

An ongoing effort is being made at the University of Missouri-Rolla to develop standard laboratory test methods and codified design procedures for architectural glass under seismic loadings. Recent laboratory work has yielded some promising results regarding the development of an appropriate seismic test method for architectural glass, as well as identifying ultimate limit states that quantify the seismic performance and damage thresholds of various glass types. Specifically, a straightforward “crescendo-like” in-plane dynamic racking test, performed at a constant frequency, has been employed successfully. Two ultimate limit states for architectural glass have been defined: (1) a lower ultimate limit state corresponding to major glass crack pattern formation; and (2) an upper limit state corresponding to significant glass fallout. Early crescendo tests have yielded distinct and repeatable ultimate limit state data for various storefront glass types tested under dynamic racking motions. Crescendo tests will also be used to identify and quantify serviceability limit states for architectural glass and associated glazing components under dynamic loadings. These limit state data will support the development of rational design procedures for architectural glass under seismic loadings.

An Automated Approach for Designing Monopiles Subjected to Lateral Loads

2017 ◽  
Author(s):  
James P. Doherty ◽  
Barry M. Lehane
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Lateral Loads ◽  
Limit States ◽  
Laterally Loaded Piles ◽  
Improve Design ◽  
Design Procedures ◽  
Automated Algorithm ◽  
Laterally Loaded ◽  
Ultimate Limit

This paper describes an automated algorithm for determining the length and diameter of monopile foundations subject to lateral loads with the aim of minimising the pile weight, whilst satisfying both ultimate and serviceability limit states. The algorithm works by wrapping an optimisation routine around a finite element p - y model for laterally loaded piles. The objective function is expressed as a function representing the pile volume, while the ultimate limit state and serviceability limit states are expressed as optimisation constraints. The approach was found to be accurate and near instantaneous when compared to manual design procedures and may improve design outcomes and reduce design time and costs.

Applications of Vector Evaluated Genetic Algorithms (VEGA) in Ultimate Limit State Based Ship Structural Design

2014 ◽  
Author(s):  
Owen Hughes ◽  
Ming Ma ◽  
Jeom Kee Paik
Keyword(s):  
Genetic Algorithms ◽  
Structural Design ◽  
Limit State ◽  
Structural Safety ◽  
Wall Structure ◽  
Ultimate Limit State ◽  
Thin Wall ◽  
Limit States ◽  
Multi Objective ◽  
Ultimate Limit

Ship structural design often deals with multiple objectives such as weight, safety, and cost. These objectives usually conflict with each other, and optimizing a particular solution with respect to a single objective can result in unacceptable results with respect to the other objectives. A reasonable solution to a multi-objective problem is to investigate a set of solutions, each of which satisfies the objectives at an acceptable level without being dominated by any other solution. Genetic algorithms have been demonstrated to be particularly effective to determine excellent solutions to these problems. In this paper a multi-objective GA, called Vector Evaluated Genetic Algorithm (VEGA) is formulated and used to optimize a large and complex thin-wall structure (a complete cargo hold of a 200,000 ton oil tanker) on the basis of weight, safety and cost. The structure weight and cost and all of the stresses are calculated using a realistic finite element model. The structure adequacy is then evaluated using the ALPS/ULSAP computer program (Paik and Thayamballi, 2003) which can efficiently evaluate all six ultimate limit states for stiffened panels and grillages. This example was chosen because the initial design is severely inadequate. The results show that the proposed method can perform ultimate strength based structural optimization with multi-objectives, namely minimization of the structural weight and cost and maximization of structural safety, and also that the method is very robust.

Serviceability Limit Verification for Structural Elements of Steel Hall

2017 ◽  
Author(s):  
Izabela Skrzypczak ◽  
Grzegorz Oleniacz
Keyword(s):  
Structural Reliability ◽  
Probabilistic Methods ◽  
Steel Beam ◽  
Structural Elements ◽  
Specific Design ◽  
Limit States ◽  
Time Period ◽  
Reliability Indicator ◽  
Design Requirements ◽  
Probabilistic Measures

In recent years, the importance of assessing structural reliability has increased significantly. This is confirmed by the recommendations of the PN-EN 1990 standard. This standard gives the principles and requirements to ensure the safety, serviceability and durability of the structure. It sets out the basis for calculation and verification of the structure and provides guidance to ensure their reliability. Reliability of structure is its ability to meet specific design requirements, taking into account the planned period of use. The planned period of use should be understood as a time period approved in the project, in which the structure or part of it is to be used for their intended purpose, without the need for major repairs. Typically, reliability is expressed by probabilistic measures as indicator of reliability or probability of failure. The aim of this study is to present the results of of roof girder deflection surveying and modeling their reliability. A general algorithm for determining the value of the reliability indicator for the bending steel beam with FORM method will be presented. Verification of the differences between the indicator of reliability obtained by simplified probabilistic methods and compare them with the values recommended in the Eurocode 0 standard will be also shown. For the analyzed steel beam the serviceability limit states were considered.

Application of Deterministic and Probabilistic Methods in Pipeline Lateral Buckling Design

2012 ◽  
Author(s):  
Hammam Zeitoun ◽  
Maša Branković ◽  
Edwin Shim ◽  
EuJeen Chin ◽  
Benjamin Anderson
Keyword(s):  
Structural Reliability ◽  
Design Guidelines ◽  
Probabilistic Methods ◽  
Design Solution ◽  
Design Parameters ◽  
Pipeline System ◽  
Limit States ◽  
Lateral Buckling ◽  
Current Design ◽  
Subsea Pipelines

Subsea pipelines lateral buckling design has significantly evolved over the last years as more pipeline projects have moved into more challenging environments and into high temperature / high pressure (HT/HP) design application. Knowledge and understanding of pipeline lateral buckling has improved with design application resulting in refined and enhanced design approaches. Using current design approaches, it is now quite acceptable to control lateral buckle formation along the pipeline by using buckle triggers or to allow uncontrolled lateral buckles, provided that the various design limit states are satisfied. A number of design methodologies can be used to check the acceptability of uncontrolled buckling or to design for controlled buckling including deterministic, probabilistic buckle formation and full Structural Reliability Assessment (SRA) methods. Using SRA or probabilistic methods is usually an attractive design option as lateral buckling design involves dealing with a large number of uncertainties and variation in design parameters. These methods help to ensure the reliability of the proposed buckle initiation scheme. However, the use of these methods is also associated with a number of challenges such as the need to identify key parameters influencing the design and quantifying their uncertainties. Deterministic design approaches on the other hand are simpler to apply. However, they do not provide means to quantify the reliability of the proposed buckling scheme or the design risks. The choice of input parameters in a deterministic design is also relatively subjective which can possibly result in an overly conservative or unconservative design solution depending on the adopted design approach, selected design parameters and pipeline system being considered. Design guidelines and recommended practices such as SAFEBUCK (20) offer comprehensive guidelines to design for lateral buckling. However when faced with a range of complex variables, the designer needs to be aware of the effect of these parameters on the overall design. This paper describes the application of Deterministic and Probabilistic design approaches in lateral buckling design. The paper starts by describing these approaches, their advantages and limitations. The paper then explores a number of key uncertainties and variation in design parameters that the designer is faced with and its effect on the pipeline response.

scholarly journals Some relevant aspects of footbridge vibrations

2002 ◽  
Vol 2 (4) ◽  
pp. 281-289
Author(s):  
Ana Spasojevic ◽  
Djordje Djordjevic ◽  
Marija Spasojevic ◽  
Novak Spasojevic
Keyword(s):  
Structural Design ◽  
Natural Frequencies ◽  
Weight Ratio ◽  
Structural Systems ◽  
Live Load ◽  
Limit States ◽  
Codes Of Practice ◽  
Vibration Serviceability ◽  
Bridge Structures ◽  
Ultimate Limit

Considering the contemporary structural inaterials that are becoming more resistant, having higher strength to weight ratio, and the fact that live load of footbridges is low, the design based on static analysis only, respecting ultimate limit states requirements, leads to slender bridge structures for pedestrian and cycle track use. As a consequence, stiffness and masses decrease, facing lively, easy to excite structures, with smaller natural frequencies. The excitation of a footbridge by a pedestrian passing over it can be unpleasant for a person walking or standing on the bridge, but usually not destructive for the structure itself. Recent experiences regarding dynamic behavior of slender footbridges have especially shown that vibration serviceability limit states are very important requirements in any structural design. We are presenting a general algorithm for analytical testing of dynamic parameters of structures, calculation of deflection, thus speed and acceleration of superstructure under human-induced excitation, as predicted by Eurocode, British and Canadian standards in use, since no Yugoslav code deals with the problem. The evaluated system is a footbridge in a system of a simply supported concrete girder. The presented model is used to show correspondence of results, obtained by the algorithm, with the results obtained using the simplified methods suggested by the Codes of Practice, since the latter exists only for certain structural systems.

Application of Probabilistic Methods for the Assessment of Structural Load Bearing Capacity

2015 ◽  
Vol 1106 ◽  
pp. 90-93 ◽  
Author(s):  
Jiří Doležel ◽  
Martina Šomodíková ◽  
David Lehký ◽  
Drahomír Novák
Keyword(s):  
Bearing Capacity ◽  
Fem Analysis ◽  
Latin Hypercube Sampling ◽  
Probabilistic Methods ◽  
Limit States ◽  
Load Bearing Capacity ◽  
The Czech Republic ◽  
Load Bearing ◽  
Current State ◽  
Ultimate Limit

The paper presents the application of methodology for the assessment of reliability and structural load bearing capacity using advanced methods of probabilistic FEM analysis in combination with mathematical modelling of degradation processes of concrete and reinforcement. The durability, serviceability and ultimate limit states are assessed. The authors deal with the validation of load bearing capacity of the bridge on the 3rd class road built in the 1st quarter of 20th century in the Czech Republic. Regarding the reliability requirements according to Standards and, considering the current state of the structure, the actual value of load bearing capacity is assessed. By reason of the time-consuming FEM analyses the stratified Latin Hypercube Sampling (LHS) method is used for generation of input random variables.

scholarly journals Analysis of Partial Factors for New EN 1990 Basis of Design

2017 ◽  
Vol 17 (1) ◽  
pp. 131-136
Author(s):  
Jana Marková
Keyword(s):  
Structural Design ◽  
Structural Glass ◽  
Structural Members ◽  
Limit States ◽  
New Generation ◽  
Ultimate Limit ◽  
Construction Works

Abstract Presently the new generation of Eurocodes is under development. It is expected that the basis of structural design given in current EN 1990 will be considerably revised including the format for load combinations in the Ultimate Limit States and new categorisation of consequence classes for construction works. It is expected that the partial factors for self-weight of structural members could be reduced and factors for variable loads more differentiated. Calibration of partial factors should be performed for actions and materials including also structural glass and FRP polymers.

scholarly journals Credibility of Design Procedures

10.14311/266 ◽  
2001 ◽  
Vol 41 (4-5) ◽  
Author(s):  
J. Marková ◽  
M. Holický
Keyword(s):  
Structural Reliability ◽  
Concrete Slab ◽  
Theoretical Models ◽  
Comprehensive Analysis ◽  
Structural Elements ◽  
Structural Element ◽  
Limit States ◽  
Reinforced Concrete Slab ◽  
Design Procedures ◽  
Design Value

Theory of structural reliability enables comprehensive analysis of structural elements with respect to various limit states, and provides valuable insights into the methodology of applied standards. In addition to reliability analysis of the structural element, a new concept of the credibility of theoretical models used to calculate the design value of basic variables is introduced. The presented example of structural verification for limit states of cracking shows that the credibility of commonly applied formulas and reliability of a reinforced concrete slab have a great scatter and are in some cases inadequate.

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