How to check bridges

Tells ammo:

As you know, I work in an organization dedicated to inspection and test bridges. For the first five years of work at the Institute IMIDIS I had a chance to look at everything with my own eyes.

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Each new bridge should be examined, and even non-standard bridges and tested under load.



A survey of the bridge begins with a visual inspection of the bridge structure.



Many bridges have a metal box-shaped supporting structures. Engineers extends from the beginning to the end of the bridge to these boxes, and check the quality of welding, bolting, the color quality. Detected deficiencies are photographed and recorded in the statement of defects.



Checking the strength of concrete piers.



Sclerometry shows the strength of the concrete as a result of several measurements.



Using a special scanner is determined by the depth of the reinforcement in concrete.



So check all pillars of the bridge.



The quality of the painting is determined adgezimetrom. First, the paint adheres to a special fungus, then adgezimetr separates it from a coat of paint and measures breakout force.

According to a survey prepared a report containing a description and photographs of the bridge, all measured parameters, the statement of defects.



When tested on the bridge located load - laden dump trucks and through a variety of instruments measured the deformation of the bridge under load.



The test begins with the layout of the bridge. With curvimeter label applied to the locations of poles and fourth spans between supports.



Inside the box, a bridge or between the boxes are installed strain gauges. The sensor is attached to the metal bridge with powerful magnets and measure the distance between two points within a tenth of a micron. When the bridge is loaded, the metal is stretched or compressed.



Each surveyed area established a group of four or six sensors (top and bottom on both sides of the box), can be connected to the radio module.



Such groups with their transmitters can be up to ten. The server is connected to the radio netbook running the program, interrogating the sensors and performs the calculation of the stress of the metal.



Radio communication with sensors sided. This makes it possible to install the sensors in advance (the radios are in standby mode with low power consumption) and activate them as needed, and in each dimension are queried only the desired sensor. The equipment and the monitoring program "CIS-IMIDIS" developed in our institute.



The same system and other sensors are connected. Strain gauges mounted on the railing of the bridge gap and is used to measure the vibration of the bridge under dynamic loads.



The laser range finder can measure the displacement of the bridge vertically using the original engineering solution - the goal is at an angle of 45 degrees, and the motion of the beam up and down, changing the length of the beam.



Profile of the bridge is measured using the total station - the device accurately measured the coordinates of a point in space on the deflection of the laser beam on the target-range pole and the distance to the target.



Once the instruments are installed, testing begin. First, the static load. On the bridge are driven laden dump trucks (20 to 40 tons each). The measurements were made on each the span of the bridge.



The deflection at the center of the span metal bridge under the weight of trucks can reach 1/400 span length that hundred-meter span is as much as 25 centimeters. In addition to the device memory, the amount of deflection is recorded in the journal test.



Additional tests are made with unbalanced load.



Then the dynamic tests carried out bridge. First measured vibrations of the bridge when driving a laden truck at different speeds. Then, with the help of the board simulates rough road on which the truck bounces on speed.



According to test results the decision on the suitability for use of the bridge.

Examinations and tests carried out periodically throughout the life of the bridge. This independent control allows you to make bridges safer.

That's all I wanted to say!



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