Practical code calibration procedures

1979 ◽  
Vol 6 (1) ◽  
pp. 112-119 ◽  
Author(s):  
Andrzej S. Nowak ◽  
Niels C. Lind
Keyword(s):  
Probability Distributions ◽  
Design Standards ◽  
Limit States ◽  
Safety Level ◽  
Performance Factors ◽  
Code Calibration ◽  
Earthquake Load ◽  
Load Effects ◽  
Safety Indices ◽  
Selection Of

The paper deals with a procedure that can be used by a design standards committee to determine safety indices for structures and calculate optimum performance factors for limit states design. Six load components are considered: dead, sustained live, transient live, snow, wind, and earthquake load effects. The procedure is based on an approximation of the probability distributions by normal distributions in the design point situated on the failure boundary. The objective in selection of performance factors is closeness to a target safety level expressed in terms of the target safety index. A computer program was developed to be used in calibration. The procedure is illustrated by examples.

Cluster analysis as a tool in the classification of structures for safety differentiation

1988 ◽  
Vol 15 (4) ◽  
pp. 601-608
Author(s):  
Carlos Ferregut
Keyword(s):  
Cluster Analysis ◽  
Highway Bridges ◽  
Structural Type ◽  
Limit States ◽  
Safety Level ◽  
Code Calibration ◽  
New Concepts ◽  
Safety Parameters ◽  
The Difference ◽  
Selection Of

Different structures and different structural members should reasonably be assigned different levels of reliability to obtain optimum structural performance. This differential assignment of reliabilities or safety parameters is called "safety level differentiation." Up to the present, no simple practical rationale is available for the selection of safety levels. This paper presents a methodology for the selection of safety levels. Cluster analysis is suggested as a tool in the calibration of limit states design codes. The technique may be used to develop importance factors for the design loadings and resistances, reflecting the difference in consequences of failure. The cluster analysis serves to classify a structure according to various attributes that together reflect its social and economic importance. For code specification purposes, it is fundamental to identify which structures in a set are similar, because it facilitates the specification of a single set of code parameters for each structural type, and permits a more rational selection of importance factors. The acceptable number of structural types and the effect of weighing the attributes are also discussed. Some of the new concepts are illustrated using a sample of highway bridges in southwestern Ontario. Key words: safety differentiation, reliability, cluster analysis, code calibration, bridge classification.

Calibration basis for structural glass design

1987 ◽  
Vol 14 (6) ◽  
pp. 788-794
Author(s):  
Niels C. Lind
Keyword(s):  
Reliability Index ◽  
Limit State ◽  
Structural Response ◽  
Economic Cost ◽  
Structural Glass ◽  
Safety Level ◽  
Design Standard ◽  
Code Calibration ◽  
Importance Factor ◽  
Selection Of

A design standard for structural glass in the limit state design format is currently being developed under the auspices of the Canadian General Standards Board. The standard will be calibrated to a target level of reliability expressed in terms of a reliability index. The selection of this reliability level presents some special problems because the loading is dynamic, the structural response is geometrically nonlinear, and the strength is highly dependent on time, size, and loading history. Selection of safety level so as to achieve a social and economic optimum is described. The optimum reliability index is 3.0, corresponding to a lifetime failure probability of 0.0014, when the social and economic cost of failure is between 15 and 70 times the initial cost. Optimal ranges of applicability over cost for a pair of importance factors (0.8 and 1.25) are also determined. Key words: glass, design, standard, code, calibration, reliability, optimization, importance factor.

On the role of uncertainty in the limit states design of steel structures

1980 ◽  
Vol 7 (4) ◽  
pp. 588-596 ◽  
Author(s):  
P. Dumonteil
Keyword(s):  
Steel Structures ◽  
Mean Value ◽  
Limit States ◽  
Mean Values ◽  
Code Calibration ◽  
Risk Of Failure ◽  
Load Effects ◽  
Global Uncertainty ◽  
Random Nature

The study of current work on steel code calibration shows that uncertainties in member resistances, load effects, and structural analysis are most usually assumed to have mean values equal to unity. The risk of failure that would result from the apparent safety index is higher than borne out by experience. Perhaps more important is the fact that it is necessary to assume elastic and determinate properties. These restrictions are removed if the various uncertainties are examined separately. It is then shown that their combined effect leads to a global uncertainty of a random nature, whose mean value is less than 1.0. The actual risk of failure is 5–10 times lower than the apparent one.

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.

The Ontario bridge code—Development and implementation

1984 ◽  
Vol 11 (4) ◽  
pp. 824-832
Author(s):  
R. A. Dorton
Keyword(s):  
Highway Bridges ◽  
Safety Index ◽  
Design Code ◽  
Limit States ◽  
Safety Level ◽  
New Development ◽  
Live Loads ◽  
Index Value ◽  
Correct Understanding ◽  
Short Time

The Ontario Highway Bridge Design Code was first issued in 1979 and has since been used for the design and evaluation of most bridges in Ontario. The code is in metric SI units, written in a limit states format, and calibrated to a target safety index value of 3.5. It has produced bridges with a more consistent safety level and capable of carrying design live loads twice those previously prescribed. Feedback from users was obtained and their concerns considered in formulating the provisions of the seeond edition in 1983. New bridge codes can be written in a short time and implemented most readily within a relatively small jurisdiction having control of all highways, bridges, and vehicles. Communications between the writers and potential users are important throughout the preparation and implementation phases. It is essential that a commentary volume be issued with a code to ensure correct understanding and interpretation of new provisions. Computer programs should be available, incorporating the code technology before the use of a new code becomes mandatory. Future code needs and likely areas of new development are outlined in the paper. Key words: calibration, codes, computer systems, highway bridges, loadings, safety, structures.

scholarly journals Integrity Management of Marine Structures; With Emphasis on Design for Structural Robustness

2018 ◽  
Author(s):  
Torgeir Moan
Keyword(s):  
Structural Damage ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Offshore Structures ◽  
Design Standards ◽  
Limit States ◽  
Fabrication Errors ◽  
Integrity Management ◽  
Operational Errors ◽  
And Control

Based on relevant accident experiences with oil and gas platforms, a brief overview of structural integrity management of offshore structures is given; including an account of adequate design criteria, inspection, repair and maintenance as well as quality assurance and control of the engineering processes. The focus is on developing research based design standards for Accidental Collapse Limit States to ensure robustness or damage tolerance in view damage caused by accidental loads due to operational errors and to some extent abnormal structural damage due to fabrication errors. Moreover, it is suggested to provide robustness in cases where the structural performance is sensitive to uncertain parameters. The use of risk assessment to aid decisions in lieu of uncertainties affecting the performance of novel and existing offshore structures, is briefly addressed.

scholarly journals Selección de líneas para formar híbridos de maíz dulce ricos en Lisina l. Probadores.

2016 ◽  
Vol 9 (2) ◽  
pp. 57
Author(s):  
María Cristina Vega ◽  
Enrique Navarro ◽  
José Espinoza ◽  
José Luis Guerrero ◽  
Gustavo A. Burciaga
Keyword(s):  
Inbred Line ◽  
Sweet Corn ◽  
Agronomic Traits ◽  
Average Response ◽  
Performance Factors ◽  
Grain Color ◽  
Color Uniformity ◽  
Ear Height ◽  
And Performance ◽  
Selection Of

Twenty S5 sweet corn lines containing the opaque-2 gene that increases Iysine  contents as well as the sugary-2 gene were evaluated. The lines were crossed with three testers: one unrelated inbred line, and two related synthetic varieties. Six commercial and three experimental hybrids were used during the trials. Test crosses were evaluated in two locations of Mexico during 1994 using a randomized complete block designo The experiment's goal was to compare lines' performance in combination with three testers, taking into account yield, soundness, uniformity, and corn quality. The average response of lines combined with testers was superior than that of commercial hybrids for traits such as flowering time and plant and ear height. Performance factors analyzed (ear length, grain color, uniformity, soundness, and number of marketable ears) in trial crosses were superior or equal in average to those in experimental hybrids, but this was not the case with sugar percentage. The best results were observed with the unrelated LD tester inbred line for agronomic traits and performance factors. This study made possible the selection of lines for future breeding based on the above mentioned traits, as well as the general combining ability for ear length and number of green flag leaves.

scholarly journals On the Creation of a High-Speed Transport Highway in St. Petersburg

2019 ◽  
Vol 5 (4) ◽  
pp. 73-95
Author(s):  
Nikolai A. Senkin ◽  
Aleksandr S. Filimonov ◽  
Kirill E. Kharitonov ◽  
Vitaliy V. Yakovlev ◽  
Elizaveta O. Bondareva ◽  
...  
Keyword(s):  
Transport System ◽  
Cross Sections ◽  
High Speed ◽  
Tube Steel ◽  
Leningrad Region ◽  
Limit States ◽  
Passenger Traffic ◽  
Rod System ◽  
The Creation ◽  
Selection Of

As part of student research at the St. Petersburg University of architecture and construction, alternative proposals are being developed for the creation of a circumferential high-speed highway with a total length of 147.2 km. Тhe scheme is proposed in the form of a polygon with HUB in the nodes and consists of three main parts: 1 above-ground (62.6 km), 2 above-water (29.6 km) and 3 surface-underground (55.0 km). The main tracks are located in a four-tube steel beam, each tube of which is organized by the technology of vacuum tube transport with a pressure of 10% of the normal for high-speed passenger trains on a magnetic levitation cushion using a linear traction motor (Maglev system). The rail base of the 1520 mm gauge is located along the entire length of the track, both in parking lots, acceleration and braking zones, and on the main high-speed sections for movement with a maximum speed of 500 km per hour. The main direction of research was the development of load-bearing structures that provide the necessary functionality, reliability and safety of structures. In order to reduce the noise impact on the metropolis, overcome numerous artificial and natural obstacles, improve anti-terrorist protection, the main level of the rail track for the above-ground and above-water structures was adopted at +88.00 in the Baltic elevation system. Calculations of variants with determination of internal forces in elements and movements of nodes with use of the program complex SCAD Office 21.1are executed, when accounting for the full range of loads taking into account dynamic effects and non-linearity. The selection of cross-sections of elements according to the method of limit states according to the current norms is carried out. The advantage of the arch-cable-stayed variant with a span of 360 m in strength, stability, stiffness and vertical size (height of supports) is shown. The continuation of research and design work on this topic should lead to the emergence of a district high-speed transport system at the borders of communication between St. Petersburg and the Leningrad region with passenger traffic, quite comparable to the metro line. Aim: To develop a district high-speed transport system at the borders of St. Petersburg and Leningrad region with passenger traffic comparable to the metro line. Materials and Methods: Using the software package "SCAD Office 21.1", the trestle structures are calculated for the combination of operating loads, forces and influences, including the consideration of dynamic aspects and nonlinearity, as well as the selection of cross-sections of elements by the method of limit states. To determine the optimal trestle structures of high-speed highways, namely high-rise and long-length metal structures supporting the overpass beam, calculations with the selection of cross sections of four variants of cable-stayed systems (arch-cable-stayed; cable-stayed rod with inclined cables and steel lattice pylons; the same, steel pipe-concrete pylons; cable-stayed rod system with suspensions according to the patent US5950543 (A). Results: the results of the trial design adopted arch-cable option with a span of 360 m according to the criterion of metal consumption, the consumption of steel amounted to 20.9 tons per 1 m length of highway. Conclusion: the estimated volume of passenger traffic per day for the four-track high-speed line will be 280 thousand passengers, and 102 million passengers per year, which is quite comparable to this figure for the metro line.

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