What is a deflection test?
The primary purpose of deflection testing is to determine the structural adequacy of an existing pavement and to assess its capability of handling future traffic loadings.
How is deflection measured?
Generally, deflection can be calculated by taking the double integral of the Bending Moment Equation, M(x) divided by EI (Young’s Modulus x Moment of Inertia).
What is pavement surface deflection?
Surface deflection is measured as a pavement surface’s vertical deflected distance as a result of an applied (either static or dynamic) load. The more advanced measurement devices record this vertical deflection in multiple locations, which provides a more complete characterization of pavement deflection.
Why is it important to evaluate the deflection of a structure?
Deflection is a crucial consideration in the design of a structure and failure to apply due attention to it can be catastrophic. Different types of load can cause deflections. These include point loads, uniformly distributed loads, wind loads, shear loads as well as ground pressure and earthquakes, to name but a few.
What is deflection testing sewer pipe?
Deflection gauges (mandrels) are used to test flexible sewer pipe for out of roundness or deflection per ASTM specifications D3034 and F679. This testing ensures that flexible pipe has been properly bedded and backfilled to give optimal performance.
Why deflection of beam testing is important?
The beam test provides an effective means to illustrate several important structural engineering concepts. The plot of load vs. deflection provides a direct means to experimentally determine the structural stiffness, K, of the beam as well as the material stiffness, referred to as the modulus of elasticity, E.
What are the types of deflection?
Types of Deflection
- Axial Deflection.
- Lateral Deflection.
- Angular Deflection.
- Combined Deflection.
- Torsional Deflection.
- Cyclic Deflection and Cycle Life.
- Pressure Balancing Examples.
- Hinged or Gimbalpipe Expansion Joints.
Why is deflection a problem?
Deflecting is a psychological defense mechanism that people use to take the blame off of themselves. When they are deflecting, they are trying to make themselves feel less bad for their wrongdoings. This likely happens due to past experiences of being in trouble for things.
Are pavement deflection measurements non-destructive?
Furthermore, pavement deflection measurements are non-destructive. Surface deflection is measured as a pavement surface’s vertical deflected distance as a result of an applied (either static or dynamic) load.
How do you measure deflection on a road?
Figure 1. Deflection measurement schematic. Static deflection equipment measure pavement deflection in response to a static load. The Benkelman Beam (Figure 2), developed at the Western Association of State Highway Organizations (WASHO) Road Test in 1952, is a simple device that operates on the lever arm principle.
What is the Caltrans deflection method for flexible pavement rehabilitation design?
For purpose of flexible pavement rehabilitation design using the Caltrans deflection method, the vibratory loading-based deflection is converted to an equivalent California Deflectometerdeflection by the use of correlation curves previously established between the two devices (discussed in Section E of this test method). 3.
What is a surface deflection measurement?
Pavement surface deflection measurements are the primary means of evaluating a flexible pavement structure and rigid pavement load transfer.