Effects of Barriers on Load Distribution in a Concrete Slab Span Bridge

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UNIVERSIDAD DE ESPECIALIDADES ESPÍRITU SANTO

FACULTY OF ENGINEERING

BRIDGES

THEME:

"Effects of Barriers on Load Distribution in a Concrete Slab Span Bridge"

STUDENT:

MATEO JOSE VÉLEZ VELASCO

TEACHER:

ING. WALEON FERNANDO LAMA CHONG

DATE:

21/03/2024

In the video titled "Effects of Barriers on Load Distribution in a Concrete Slab Span Bridge," Kendall Hill presents a comprehensive study on how barriers influence the load distribution across a slab span bridge. The research was motivated by a specific bridge in Minneapolis, Minnesota, facing restrictions that prevent trucks weighing 80,000 pounds or more from crossing, necessitating a lengthy detour. This bridge, critical for trucking, was built in 1964 and expanded in 1980 but is not scheduled for replacement or significant improvements.

The study aimed to collect field data under known loads and develop a 3D finite element model (FEM) to evaluate the bridge's behavior. The goal was to provide recommendations regarding the impact of barriers on the load distribution, also known as the equivalent width of the bridge. Equivalent width is crucial for determining the live load distribution factor essential for bridge analysis.

Kendall's methodology included sampling materials from the bridge, developing an FEM using these samples along with the bridge's geometry, and then conducting both static and dynamic tests. The tests were designed to analyze the effects of barriers on load distribution, comparing data from near and away from the barrier.

The research uncovered that the barriers indeed have a significant impact on load distribution, particularly for exterior strips of the bridge. Surprisingly, the study found that the compressive strength of the bridge deck and barrier significantly exceeded the design strength, indicating the materials' robustness.

Finite element models, including various scenarios with and without cracks and considering non-linear concrete material properties, were developed to simulate the bridge's conditions closely. These models, along with field data, suggested that barriers might provide additional stiffness, impacting the load distribution.

Comparative analysis using the AASHTO equations for equivalent width showed that current standards might be overly conservative, as the study's findings indicated potential for a higher load rating. The barriers contributed to an increase in load distribution for exterior strips, whereas their impact on interior strips was negligible or slightly negative.

In conclusion, the study advocates for updated modeling approaches and load distribution analyses that consider the specific impacts of barriers. This could lead to optimized bridge designs and load ratings, enhancing efficiency and safety in bridge engineering.

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