Safety of RC highway bridges strengthened with CFRP; flexural and shear limit states

2011 ◽  
pp. 593-606
Author(s):  
O Ali ◽  
D Bigaud
Keyword(s):  
Highway Bridges ◽  
Limit States

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 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.

Analytical Fragility Curves for Ordinary Highway Bridges in Turkey

2011 ◽  
Vol 27 (4) ◽  
pp. 971-996 ◽  
Author(s):  
Özgür Avşar ◽  
Ahmet Yakut ◽  
Alp Caner
Keyword(s):  
Nonlinear Response ◽  
Fragility Curves ◽  
Ground Motions ◽  
Limit State ◽  
Highway Bridges ◽  
Skew Angle ◽  
Limit States ◽  
Point Estimates ◽  
Single Column ◽  
Skew Angles

This study focuses on the development of analytical fragility curves for the ordinary highway bridges constructed after the 1990s. Four major bridge classes were employed based on skew angle, number of columns per bent, and span number (only multispan bridges). Nonlinear response-history analyses (NRHA) were conducted for each bridge sample using a detailed 3-D analytical model subjected to earthquake ground motions of varying seismic intensities. A component-based approach that uses several engineering demand parameters was employed to determine the seismic response of critical bridge components. Corresponding damage limit states were defined either in terms of member capacities or excessive bearing displacements. Lognormal fragility curves were obtained by curve fitting the point estimates of the probability of exceeding each specified damage limit state for each major bridge class. Bridges with larger skew angles or single-column bents were found to be the most seismically vulnerable.

Resistance factors for steel highway bridges

1984 ◽  
Vol 11 (2) ◽  
pp. 324-334 ◽  
Author(s):  
D. J. Laurie Kennedy ◽  
Karen A. Baker
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Highway Bridges ◽  
Limit States ◽  
Welded Steel ◽  
Mean Values ◽  
Resistance Factors ◽  
Performance Factors ◽  
Simulation Performance ◽  
Girder Bridges

Resistance (performance) factors for bridge members composed of rolled and welded steel sections are developed consistent with the live and dead load factors given in the Ontario Highway Bridge Design Code (OHBDC).Ratios of the load components of seven different spans of plate and box girder bridges are used with the statistical data for loads used in the development of the OHBDC. Monte Carlo simulation techniques are used to compose distribution curves for the various resistance functions from distribution curves describing the appropriate geometric properties, material properties, and test/predicted ratios. Using the 0.001 and 0.05 fractiles of the distribution curves so obtained for the resistances, mean values and coefficients of variation are obtained for equivalent lognormal distribution curves.Resistance factors are then developed for the fully plastic moment resistance, the yield moment, the inelastic buckling moment resistance, the elastic buckling moment resistance, the moment resistance of composite sections, and column resistances for slenderness parameter values of 0.8, 1.0, and 1.2. A general resistance factor of 0.93 is recommended for all the resistances and bridges studied. Resistance factors of 0.95 and 0.98 are considered appropriate for the flexural resistance of bridges composed of welded and rolled sections, respectively. Key words: bridges, limit states, Monte Carlo simulation, performance factors, resistance factors, steel, rolled sections, welded sections.

Load and Resistance Factor Design of Driven Piles

1996 ◽  
Vol 1546 (1) ◽  
pp. 88-93 ◽  
Author(s):  
George G. Goble
Keyword(s):  
Quality Control ◽  
Highway Bridges ◽  
The United States ◽  
Resistance Factor ◽  
Limit States ◽  
Resistance Factors ◽  
Nominal Strength ◽  
Factor Design ◽  
Load And Resistance Factor ◽  
Driven Pile

A load and resistance factor design (LRFD) bridge specification has been accepted by the AASHTO Bridge Committee. This design approach is now being implemented for highway bridges in the United States, including the design of driven pile foundations. To test the new specification's practicality and usefulness, an example problem has been solved using it. In the example, a pipe pile was designed to be driven into a granular soil to support a bridge column subjected to a factored axial compression load of 10 MN. The nominal strength selected for the pile was 1.58 MN with an estimated length of 25 m. Since the resistance factors are defined by the specified quality control procedures, the number of piles required in the foundation also depends on the quality control. In this example, the number of piles required varied from 15 to 8 with improved quality control, for a savings of almost half of the piles. This example indicated that the new AASHTO LRFD specification for driven pile design can be used effectively to produce a more rationally designed foundation. Some modifications should be made to include additional serviceability limit states, and additional research may indicate that changes should be made in some of the resistance factors.

scholarly journals Long-term loss assessment of coastal bridges from hurricanes incorporating overturning failure mode

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Deming Zhu ◽  
Yaohan Li ◽  
You Dong ◽  
Peng Yuan
Keyword(s):  
Fragility Curves ◽  
Highway Bridges ◽  
Wave Force ◽  
Fe Model ◽  
Loss Assessment ◽  
Limit States ◽  
Coastal Bridges ◽  
Structural Capacity ◽  
Structural Demand

AbstractCoastal highway bridge is an essential component of the transportation system but threatened by natural hazards such as hurricanes. Damaged highway bridges result in not only transportation disruption, but also tremendous financial, societal, and life loss. Therefore, vulnerability and loss assessments of bridges under hurricane events are becoming primary concerns for decision-makers. This study provides an elaborate framework to assess the vulnerability and long-term loss of coastal bridges subjected to hurricane hazards based on three-dimensional (3D) numerical analyses. A 3D Computational Fluid Dynamics (CFD) numerical model is established to investigate wave-bridge interaction and a Finite Element (FE) model is established for the bridge to calculate structural responses under wave impacts. Based on the numerical results, the effects of wave force and overturning moment on structural capacity are studied and a probabilistic vulnerability model is developed. Structural demand, capacity, and limit states are determined, respectively. Uncertainties associated with wave parameters, structural capacity, and material properties, and the resulting consequences are considered. Then, fragility curves are calculated, and long-term damage loss is assessed. The proposed approach can benefit the management and design of coastal bridges against the impacts of hurricane hazards.

Development of loading-truck model and live-load factor for the Canadian Standards Association CSA-S6 code

1987 ◽  
Vol 14 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Akhilesh C. Agarwal ◽  
Moe S. Cheung
Keyword(s):  
Highway Bridges ◽  
Load Level ◽  
Load Factor ◽  
Live Load ◽  
Limit States ◽  
Load Factors ◽  
Loading System ◽  
Using Data ◽  
Council Of Ministers ◽  
Level Loading

Studies have shown that the MS-200 loading model in the Canadian Standards Association standard CAN3-S6-M78 for design of highway bridges no longer represents modern-day heavy trucks in Canada. For the new edition of the CSA-S6 code, based on the limit states philosophy, a new loading-truck model was developed based on the Council of Ministers' loading, which is the legal load limit for interprovincial transportation in Canada. The loading model, designated as the "CS-W loading truck," provides the flexibility to adopt a multiple-level loading system appropriate to various jurisdictions.The live-load factor was determined from a statistical approach using data from a truck survey conducted across Canada in seven provinces. Responses in simple-span bridges were determined by running one or more trucks from the survey across the bridge. Based on this study, a live-load factor of 1.60 was determined and CS-600, with a gross weight of 600 kN, was selected as the standard load level. As well, the validity of the truck model and the live-load factors were checked for continuous-span bridges. Key words: highway bridges, design loads, codes and standards, live-load models, load factors, load surveys, vehicle weight regulations.

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.

Reliability assessment in highway bridge design

2002 ◽  
Vol 29 (5) ◽  
pp. 799-805 ◽  
Author(s):  
M S Cheung ◽  
W C Li
Keyword(s):  
Reliability Assessment ◽  
Highway Bridges ◽  
Highway Bridge ◽  
Design Code ◽  
Bridge Design ◽  
Limit States ◽  
Safety Level ◽  
Reliability Design ◽  
Finite Strip Method ◽  
Standard Design

The current practice of highway bridge design in Canada is based on limit states design. Ideally, by means of the properly calibrated load and resistance factors specified in the applicable design code, limit states design will yield a consistent and uniform safety level for all designed bridge structures. Some factors neglected in the standard design procedures, however, may have unexpected effects on the reliability of a particular design. In this case, to follow a design code exactly may still lead to a certain degree of underdesign or overdesign. Therefore, the reliability assessment is recommended for each particular design, and a simulation-based approach for this assessment is proposed in this study. Examples are presented to support the afore-mentioned recommendation.Key words: highway bridges, reliability, design code, simulation, finite strip method.

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