Reliability-Based Criteria for Load and Resistance Factor Design Code for Wood Bridges

2000 ◽  
Vol 1696 (1) ◽  
pp. 316-322
Author(s):  
Chris Eamon ◽  
Andrzej S. Nowak ◽  
Michael A. Ritter ◽  
Joe Murphy
Keyword(s):  
Rational Design ◽  
Structural Reliability ◽  
Highway Bridges ◽  
Resistance Factor ◽  
Rational Basis ◽  
Design Code ◽  
Good Tool ◽  
Bridge Structures ◽  
Factor Design ◽  
Load And Resistance Factor

Recently AASHTO adopted a load and resistance factor design code for highway bridges. The new code provides a rational basis for the design of steel and concrete structures. However, the calibration was not done for wood bridges. Therefore, there is a need to fill this gap. The development of statistical models for wood bridge structures is discussed. Recent test results provided a considerable amount of new data for sawed wood and glulam components. Statistical methods provide a good tool for development of rational models for loads and resistance. Because of the random nature of load and resistance, reliability is a convenient measure of structural performance that also provides a rational basis for comparison of wood and other structural materials. The results of a recent project that led to development of rational design criteria for wood bridges are presented. The structural reliability of selected wooden bridges designed by the AASHTO codes are determined, and inadequacies in load distribution and material resistance in the current specifications are identified.

AASHTO’s Load and Resistance Factor Design Specifications for Transverse Braces: Adverse Effects on Integrity and Durability of Reinforced Concrete Deck Slabs

2000 ◽  
Vol 1740 (1) ◽  
pp. 118-125 ◽  
Author(s):  
Martin P. Burke ◽  
Joseph S. Seif
Keyword(s):  
Reinforced Concrete ◽  
Highway Bridges ◽  
Resistance Factor ◽  
Structural Systems ◽  
Steel Bridge ◽  
Design Specifications ◽  
Deck Slabs ◽  
Factor Design ◽  
Load And Resistance Factor ◽  
Concrete Deck

The transverse bracing provisions (diaphragms, cross-braces, crossframes, and so on) of the 1998 AASHTO load and resistance factor design (LRFD) bridge design specifications for the design of deck-type highway bridges are examined. This examination suggests that implementation of these provisions not only will have an adverse effect on the integrity and durability of reinforced concrete deck slabs, and consequently on life-cycle bridge costs; implementation of such provisions also has the potential to affect the desirability of steel bridge construction adversely. Instead of avoiding the use of midspan braces, as implied by LRFD provisions, it is urged that midspan braces be more generally recognized as primary elements of complex superstructure structural systems and thus be sized and spaced to function not only as transverse flange braces but also integrally with concrete deck slabs to distribute vehicular loads laterally. Such a practice not only will yield more efficient higher-quality structural systems capable of functioning effectively for 100 years or more, thus doubling their presently expected lives, but it will also help extend the service lives of the more vulnerable reinforced concrete deck slabs.

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.

Structural Integrity for Nuclear Power Plant Against Excessive Load on Design Extension Condition

2013 ◽  
Author(s):  
Daigo Watanabe ◽  
Kiminobu Hojo
Keyword(s):  
Nuclear Power ◽  
Structural Integrity ◽  
Safety Factors ◽  
Design Code ◽  
Acceptance Criteria ◽  
Integrity Assessment ◽  
Current Design ◽  
Factor Design ◽  
Excessive Load ◽  
Load And Resistance Factor

This paper introduces an example of structural integrity evaluation for Light Water Reactor (LWR) against excessive loads on the Design Extension Condition (DEC). In order to assess the design acceptance level of DEC, three acceptance criteria which are the stress basis limit of the current design code, the strain basis limit of the current design code and the strain basis limit by using Load and Resistance Factor Design (LRFD) method were applied. As a result the allowable stress was increased by changing the acceptance criteria from the stress basis limit to the strain basis limit. It is shown that the practical margin of the LWR’s components still keeps even on DEC by introducing an appropriate criterion for integrity assessment and safety factors.

Load and Resistance Factor Design Criteria for Connectors

1978 ◽  
Vol 104 (9) ◽  
pp. 1427-1441
Author(s):  
John W. Fisher ◽  
Theodore V. Galambos ◽  
Geoffrey L. Kulak ◽  
Mayasandra K. Ravindra
Keyword(s):  
Resistance Factor ◽  
Design Criteria ◽  
Factor Design ◽  
Load And Resistance Factor

Closure to “Load and Resistance Factor Design Criteria for Connectors”

1980 ◽  
Vol 106 (9) ◽  
pp. 1985-1986
Author(s):  
John W. Fisher ◽  
Theodore V. Galambos ◽  
Geoffrey L. Kulak ◽  
Mayasandra K. Ravindra
Keyword(s):  
Resistance Factor ◽  
Design Criteria ◽  
Factor Design ◽  
Load And Resistance Factor
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