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Span Load Testing

Span load testing is a method to assess the flexural capacity and overall structural integrity of bridge spans by applying controlled loads and monitoring the structure’s response, such as strains, rotations, deflections, and vibrations.
Here’s a more detailed explanation:
- Purpose:
- To evaluate the true load-bearing capacity and engineering reliability of structures.
- To assess the condition and safety of a bridge, especially when there are concerns about excessive creep deflection, material defects, structural deterioration, or unknown structural strength.
- To verify if the maximum deflection and percentage recovery are within permissible limits.
- How it’s done:
- Loads are applied in stages, often using loaded vehicles or dumpers, on a selected span or part thereof.
- The structure’s response (strains, rotations, deflections, and vibrations) is recorded using appropriate instrumentation.
- The test is conducted in accordance with contract requirements, unless otherwise specified.
- Considerations:
- Types of Structures: Span load tests are used for various structures like metro rail projects, flyovers, industrial slabs, balconies, and bridges.
- Static and Dynamic Loading: Static load tests evaluate the bridge’s response to sustained loads, while dynamic load tests assess its behavior under moving loads and various dynamic conditions.
- Calculations: Calculations after the test are complex and require interaction with structural experts and clients before a report is finalized.
- Types of Load Testing:
- Static Load Testing: Involves applying static loads to the structure to assess its static behavior.
- Dynamic Load Testing: Involves applying dynamic loads (e.g., vehicle loads) to the structure to assess its dynamic behavior.
- Skip-Loading: In the case of continuous multi-span structures, load tests may involve skip-loading (loading spans 1 and 3, for example) to create maximum moments at mid-span, or loading consecutive spans to create maximum moments at support.