Live Load Distribution Factors for Skew Stringer Bridges with High-Performance-Steel Girders under Truck Loads
Abstract
:1. Introduction
2. Finite Element Modeling and Verification
2.1. Bridge Section
2.2. Verification of Finite Element Models
2.2.1. Laboratory Tests at the Turner-Fairbank Highway Research Center
2.2.2. Laboratory Test of a Quarter Scale Model Bridge
3. Bridge Superstructure Database
4. Sensitivity Analysis
4.1. Effect of Span Length
4.2. Effect of Girder Spacing
4.3. Effect of Number of Lane Loads
4.4. Effect of the Skew Angle
5. Development of New Equations for the Live Load Distribution Factors
6. Verification of the Proposed Equations
7. Conclusions and Recommendations
- A good agreement in the structural responses was achieved between the 3-dimensional modeling of the prototype bridges and the results obtained experimentally, confirming that numerical models can reliably predict the responses of slab-on-girder bridges.
- The discrepancy between the finite element results and those calculated using the codified AASHTO LRFD equations revealed that the current LRFD specifications are not suitable for predicting the live load distribution factors for both the bending moment and the shear force for skewed composite bridge with HPS girders. It was therefore necessary to develop a new set of LDF equations for both shear and moment.
- Based on the results of the parametric study on prototype bridges, the span length, girder spacing, number of lane loaded, and skew angle were identified as the key parameters affecting the LDFs of skewed composite bridges. The LDFs for both shear force and bending moment decreased with increasing span length and number of lanes, and increased with increased girder spacing. Increasing the skew angle of the bridge superstructures increased the LDFs for shear force but decreased those for bending moment.
- Based on the statistical analysis, conducted for this study, a set of simplified expressions were developed for the LDFs for both shear force and bending moment. The slightly greater than unity average and low standard deviation and coefficient of variation for each of the proposed expressions indicate high reliabilities for these proposed expressions in estimating the LDFs for shear force and bending moment of skewed composite bridge with HPS girders.
- More studies can be carried to assess the dynamic interaction of these type of bridge and moving load due to traffic conditions. The simplified equations can be derived to determine dynamic impact factor of bridges with HPS steel.
- Analytical and computational approaches to study the seismic response characteristics of bridges are the most economically feasible methods. It is particularly important to investigate the performance of skewed bridges with HPS steel due to vertical ground motions. The study, therefore, would provide comprehensive results through including all the parameters interacting for a wide range of skew angles.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
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Girder | Vertical Defl. (cm) | Web Rotat. (Degree) | ||||
---|---|---|---|---|---|---|
FE | Test | Error | FE | Test | Error | |
G1 | 0.47 | 0.51 | 6.2 | 0.18 | 0.19 | 5.5 |
G2 | 1.51 | 1.63 | 7.9 | 0.21 | 0.20 | 4.7 |
G3 | 2.83 | 2.69 | 4.9 | 0.33 | 0.31 | 6.10 |
Set | L (m) | HPS (w) | L/D | NL | Ng | S (m) | W (m) | θ (Deg.) |
---|---|---|---|---|---|---|---|---|
1 | (30, 45, 60, 75, 90, 105) | (50, 70, 100) | 20 | 2,3 | 3,4,5 | (2, 2.5, 3.0, 3.5, 4) | 9.5 | (0, 15, 30, 45, 60, 75) |
2 | 25 | 2,3 | 3,4 | 13 | ||||
3 | 30 | 2,3 | 3,4 | 13 | ||||
4 | 25 | 2,3,4 | 3,4,5 | 15 |
LDF | Girder Type | AVG. | SD. | COV. |
---|---|---|---|---|
MDFex | External | 1.065 | 0.076 | 0.071 |
MDFin | Internal | 1.045 | 0.069 | 0.067 |
CDFex | External | 1.072 | 0.082 | 0.076 |
CDFin | Internal | 1.059 | 0.094 | 0.085 |
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Mohseni, I.; Cho, Y.K.; Kang, J. Live Load Distribution Factors for Skew Stringer Bridges with High-Performance-Steel Girders under Truck Loads. Appl. Sci. 2018, 8, 1717. https://doi.org/10.3390/app8101717
Mohseni I, Cho YK, Kang J. Live Load Distribution Factors for Skew Stringer Bridges with High-Performance-Steel Girders under Truck Loads. Applied Sciences. 2018; 8(10):1717. https://doi.org/10.3390/app8101717
Chicago/Turabian StyleMohseni, Iman, Yong Kwon Cho, and Junsuk Kang. 2018. "Live Load Distribution Factors for Skew Stringer Bridges with High-Performance-Steel Girders under Truck Loads" Applied Sciences 8, no. 10: 1717. https://doi.org/10.3390/app8101717
APA StyleMohseni, I., Cho, Y. K., & Kang, J. (2018). Live Load Distribution Factors for Skew Stringer Bridges with High-Performance-Steel Girders under Truck Loads. Applied Sciences, 8(10), 1717. https://doi.org/10.3390/app8101717