Dynamic load allowance for capacity rating of prestressed concrete girder bridges based on reliability studies

2012 ◽  
pp. 2267-2274
Author(s):  
L Deng ◽  
C Cai ◽  
M Barbato
Keyword(s):  
Dynamic Load ◽  
Prestressed Concrete ◽  
Girder Bridges ◽  
Dynamic Load Allowance ◽  
Capacity Rating ◽  
Concrete Girder

Dynamic Field Performance of Glued Laminated Timber Bridges

2005 ◽  
Vol 1928 (1) ◽  
pp. 154-164
Author(s):  
Jake Bigelow ◽  
Brent Phares ◽  
Terry Wipf ◽  
Mike Ritter ◽  
Doug Wood
Keyword(s):  
Dynamic Load ◽  
Dynamic Performance ◽  
Field Performance ◽  
Performance Data ◽  
Girder Bridges ◽  
Dynamic Field ◽  
Dynamic Load Allowance ◽  
Glued Laminated Timber ◽  
National Programs ◽  
Timber Bridges

To use and develop timber structures in transportation better, the U.S. government implemented several national programs starting in the early 1990s to address the needs of the timber industry. One need was to investigate the dynamic field performance of timber bridges in relation to vehicular loading. The AASHTO load and resistance factor design specifications recommend a dynamic load allowance of 0.165 for timber bridges. To investigate this codified value, research was needed to determine the dynamic characteristics of timber bridges and to study their dynamic performance. To obtain dynamic performance data, five glued laminated girder bridges and four longitudinal glued laminated panel bridges were selected for testing. The testing involved loading the nine structures to obtain dynamic performance data including deflection and acceleration, as well as to assess the overall condition state of the bridges. The nine bridges tested were found to have fundamental frequencies between 5 Hz and 11 Hz as well as a dynamic load allowance of less than 0.25. The bridges found to have dynamic amplifications above specified code values were also found to have physical characteristics (i.e., rough entrances) that likely caused the higher dynamic amplification values.

Load and resistance factors for prestressed concrete girder bridges

2020 ◽  
Vol 19 (3) ◽  
pp. 103-115
Author(s):  
Andrzej S. Nowak ◽  
Olga Iatsko
Keyword(s):  
Prestressed Concrete ◽  
Theoretical Point ◽  
Design Point ◽  
Resistance Factors ◽  
Girder Bridges ◽  
Load Factors ◽  
Load And Resistance Factors ◽  
The Mean ◽  
Standard Deviations ◽  
Concrete Girder

There has been a considerable progress in the reliability-based code development procedures. The load and resistance factors in the AASHTO bridge design code were determined using the statistical parameters from the 1970's  and early 1980’s. Load and resistance factors were determined by first fixing the load factors and then calculating resistance factors. Load factors were selected so that the factored load corresponds to two standard deviations from the mean value and the resistance factors were calculated so that the reliability index is close to the target value. However, from the theoretical point of view, the load and resistance factors are to be determined as coordinates of the so-called “design point” that corresponds to less than two standard deviations from the mean. Therefore, the optimum load and resistance factors are about 10% lower than what is in the AASHTO LRFD Code. The objective of this paper is to revisit the original calibration and recalculate the load and resistance factors as coordinates of the “design point” for prestressed concrete girder bridges. The recommended new load and resistance factors provide a consistent reliability and a rational safety margin.

Design of Prestressed Concrete Girder Bridges Using Optimization Techniques

2002 ◽  
Vol 1 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Samer Barakat . ◽  
Ali Salem Al Harthy . ◽  
Aouf R. Thamer .
Keyword(s):  
Prestressed Concrete ◽  
Optimization Techniques ◽  
Girder Bridges ◽  
Concrete Girder
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