2016 New method of structural strengthening based on smart materials to fix and control structural damages in building and civil engineering structures
Development of a new method of structural reinforcement to minimize the effect and repair the structural damage that appears by the action of external forces, such as cracks in beams, columns, etc.
Description
There are mainly two different systems of strengthening to prevent or reduce such cracks: passive strengthening: used to increase the safety of the structure and its strength to actions of forces that haven't yet occurred; and active strengthening: used to recover existing strains in the structure and increase its strength. This type of reinforcement generally requires hydraulic jacks and anchorages, so it’s necessary a large work area to accommodate these auxiliary elements. In this new method, an element of SMA prestrained reinforcement (which may be a bar, wire or similar element) is placed around the structure to be strengthened and then activated by heating, resulting in the activation of said reinforcement. As a result, the reinforcement tries to become shorter, but unsuccessfully because of the wrapped support element, transmitting stresses to the structural element, significantly increasing the shear strength. These stresses are maintained when the material is cooled.
The invention may be useful in cases where the structure may be exposed to accidental events such as earthquakes, explosions, fires, etc. It is applicable to structural elements with shear or punching forces.
Main advantages
- This technology doesn't require a mechanical tensioning process (contrary to conventional active reinforcements) because it uses the shape memory effect of SMA alloys
- If the SMA material is not too ductile (ability to deform plastically without breaking), you can make a preliminary step of rounding the edges of the cross-section of the structure to prevent the existence of vertices of 90º
Innovative aspects
- It doesn't require the accumulation of initial structure damages to be reinforced (contrary to conventional passive reinforcements) because the reinforcement is not based on dilatancy of the structure.
- It can be applied to slabs, beams and columns using the same method.
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