Vibration resistant reinforcement for buildings

A reinforcement for buildings is provided. The reinforcement is composed of a mixture of a plurality of piezoelectric rods, a plurality of carbon fibers and cement material. The mixture imparts a vibration damping characteristic in the reinforcement.

FIELD OF THE INVENTION

The invention generally relates to reinforcement used in constructing buildings, and more specifically, to reinforcements having capability of damping vibration in buildings.

BACKGROUND OF THE INVENTION

In civil structures which host sensitive equipments, such as measuring and manufacturing equipments, vibration is considered to be a hazardous phenomenon. Occurrence of minimal vibration in the civil structures may hamper performance of sensitive equipments. Therefore, civil structures such as, buildings corresponding to a fabrication lab or a NANO lab, require minimization of the vibration so that sensitive equipments are not affected.

There have been methods for constructing buildings with civil structure blocks which are vibration resistant. These civil structure blocks are manufactured by embedding viscoelastic polymers in cement material of the civil structure blocks. However, addition of a polymer material in the cement results in inclusion of a softening material. Therefore, overall strength and rigidity of the civil structure blocks is reduced.

In another method, plastic reinforcements are used to provide resistance from corrosion and flexibility in the reinforcements. However, such reinforcements are not vibration resistant.

There is therefore a need of a reinforcement which is capable of damping vibration in buildings. Further, there is a need of maintaining strength and rigidity of such reinforcements.

DETAILED DESCRIPTION OF THE INVENTION

Generally speaking, pursuant to various embodiments, the invention provides a reinforcement for buildings. The reinforcement includes a mixture of a plurality of piezoelectric rods, a plurality of conductive fibers, and a plastic matrix. The mixture imparts a vibration damping characteristic to the reinforcement.

FIG. 1illustrates a reinforcement100in accordance with various embodiments of the invention. Examples of reinforcement100include, but are not limited to a rod, a bar, a wire, a rebar, and a cable. Reinforcement100may be used in various civil structures such as, buildings, bridges, tunnels and so forth. Further, a cross-section of reinforcement100may be designed into various shapes such as, square, circle, I shape, triangle, and so forth.

Reinforcement100is composed of a mixture of a plurality of piezoelectric rods102-n, a plurality of conductive fibers104-nand a plastic matrix106. The mixture imparts a vibration damping characteristic to reinforcement100.

Plurality of piezoelectric rods102-nmay be composed of piezoelectric ceramic materials, such as lead zirconate titanate (PZT) or similar materials. While mixing plurality of piezoelectric rods102-nin the mixture, plurality of piezoelectric rods102-nmay be oriented in different directions with respect to reinforcement100. The orientation of piezoelectric rods102-nin the mixture is explained in more detail in conjunction withFIG. 2. Further, plurality of piezoelectric rods102-nare polarized along longitudinal axis of piezoelectric rods102-nprior to mixing plurality of piezoelectric rod102-nto the mixture.

In an embodiment, a piezoelectric rod, such as piezoelectric rod102-1, includes a rod108-1. Rod108-1is composed of a piezoelectric material. Further, piezoelectric rod102-1also includes an electrode110-1and an electrode110-2. Electrode110-1and electrode110-2are placed at each end of rod108-1. In an embodiment, electrode110-nmay be composed of one of a metal material and a piezoelectric material. Further, electrode110-nmay be shaped as an oblate ellipsoid.

In another embodiment, the piezoelectric rod, such as piezoelectric rod102-1, is dumbbell shaped, such that ellipsoid ends of the dumbbell shape of the piezoelectric rods act like electrode110-n. The dumbbell shape enables the piezoelectric rod to efficiently handle and transfer stress which may be developed due to vibration.

Plurality of piezoelectric rods102-nincluded in the mixture exhibits piezoelectric property when reinforcement100is subjected to stress due to vibration. Based on the stress, plurality of piezoelectric rods102-nare deformed and mechanical energy of the stress is converted into electrical charge by plurality of piezoelectric rod102-n.

The electrical charge generated by plurality of piezoelectric rods102-nis collected at electrodes110-n. From electrodes110-n, the electrical charge is passed through the mixture of plurality of conductive fibers104-nand plastic matrix106. In the mixture, a conductive fiber, such as conductive fiber104-1, is used for creating an electrical path for transferring electrical charge generated by plurality of piezoelectric rods102-n. The conductive fiber is composed of a conductive material such as, carbon. The electrical charge passed through the conductive fiber is dissipated as heat energy due to resistance provided by plastic matrix106.

Plastic matrix106is a binding material for holding plurality of piezoelectric rods102-nand plurality of conductive fibers104-ninto reinforcement100. Plastic matrix106is composed of a plastic material such as, thermoplastic, polyethylene, polyvinyl chloride, polypropylene, polystyrene, and acrylonitrile butadiene styrene. Plastic matrix106provides resistance from corrosion and flexibility in reinforcement100. Further, plastic matrix106provides resistance to the electrical charge flowing in plurality of conductive fibers104-n, which results in dissipation of the electrical charge into heat energy by Joule Effect.

Therefore, the mixture of plurality of piezoelectric rods102-n, plurality of conductive fibers104-nand plastic matrix106enable dissipation of dynamic stress developed due to vibration in reinforcement100, into heat energy. As a result, the mixture imparts a vibration damping characteristic in reinforcement100. A level of the vibration damping characteristic is based on a ratio of plurality of piezoelectric rods102-n, plurality of conductive fibers104-nand plastic matrix106in the mixture. As plurality of piezoelectric rods102-ndirectly convert stress developed due to vibration into electrical charge, the level of vibration damping characteristic is directly proportional to a weight percentage of plurality of piezoelectric rods102-nin the mixture. Thus, a higher weight percentage of plurality of piezoelectric rods102-nin the mixture imparts higher level of vibration damping characteristic in reinforcement100.

Further, the level of vibration damping characteristic is based on a resistance load of reinforcement100. The resistance load is resistance created by plastic matrix106for dissipating the electrical charge conducted by plurality of conductive fibers104-n. The resistance load is increased by decreasing a weight percentage of plurality of conductive fibers104-n. Therefore, the resistance load is inversely proportional to the weight percentage of plurality of conductive fibers104-n. Further, the resistance load is directly proportional to a weight percentage of plastic matrix106. An optimum ratio of weight percentages of plurality of conductive fibers104-nand plastic matrix106is chosen to achieve a required level of resistance load, thereby imparting a required level of vibration damping characteristic in reinforcement100. The optimum ratio of the weight percentage of plurality of conductive fibers104-ndepends on a targeted vibration frequency to be absorbed, because increasing or decreasing the weight percentage of plurality of conductive fibers104-nmay affect damping characteristics of reinforcement100. Therefore, for the targeted vibration frequency, the weight percentage of plurality of conductive fibers104-nis maintained as less as possible.

In addition, the level of vibration damping characteristic is also dependent on shape and size of a piezoelectric rod, such as piezoelectric rod102-1. An aspect ratio, which is length/radius ratio of the piezoelectric rod, is directly proportional to the level of vibration damping characteristic. A higher aspect ratio results in higher conversion of stress developed due to vibration to electrical charge. Hence, the level of vibration damping characteristic of reinforcement100increases. Further, the level of vibration damping characteristic may also be influenced by shape of electrodes110-nof piezoelectric rod102-1. Based on shape of electrodes110-n, the electrical charge is collected at edges of electrodes110-nElectrodes of oblate ellipsoid shape can greatly improve the stress transfer efficiency between the piezoelectric rod and the surrounding matrix (plastic106and conductive fibers104-n) due to anchorage effect; thus, enhancing the damping capability of reinforcement100, thereby improving stress transfer efficiency in the mixture. Therefore the level of vibration damping characteristic of reinforcement100is improved.

Turning now toFIG. 2, a reinforcement202is shown illustrating orientation of a plurality of piezoelectric rods204-nin accordance with an embodiment of the invention. Plurality of piezoelectric rods204-nare oriented along a direction parallel to a longitudinal direction of reinforcement202. As, reinforcement202is generally subjected to tensile stress, the orientation of piezoelectric rods204-nalong the longitudinal direction of reinforcement202supports high tensile vibration damping characteristics in reinforcement202. In an embodiment of the invention, orientation of plurality of piezoelectric rods204-nmay be along a preferential direction reinforcement202. This will enable increasing the vibration damping characteristics along the preferential direction.

FIG. 3illustrates a hypothetical electrical circuit300depicting vibration damping characteristic of reinforcement100in accordance with an embodiment of the invention. Hypothetical electrical circuit300is formed between plurality of piezoelectric rods102-n, plurality of conductive fibers104-nand plastic matrix106. In hypothetical electrical circuit300, plurality of piezoelectric rods102-nact like a battery by producing electrical charge, plurality of conductive fibers104-nprovide a conductive path for enabling flow of the electrical charge and plastic matrix106provides resistance R in the conductive path.

Hypothetical electrical circuit300is activated when reinforcement100experiences vibration. Vibration results in application of stress on each piezoelectric rod of plurality of piezoelectric rods102-n. As the stress is applied on a piezoelectric rod, such as piezoelectric rod102-1, shape of the piezoelectric rod is deformed. Deformation of the shape results in generation of electrical charge by piezoelectric rod102-1. The electrical charge is gathered at electrodes110-nand then passed through one or more conductive fibers, such as conductive fiber104-1. The one or more conductive fibers may be placed in vicinity of the piezoelectric rod. Further, plastic matrix106around the piezoelectric rod and the one or more conductive fibers provides resistance to the electrical charge. Thereafter, the electrical charge is dissipated into heat energy by Joule Effect. As a result, vibration in reinforcement100is damped.

Therefore, activation of hypothetical electrical circuit300in reinforcement100results in imparting a vibration damping characteristic in reinforcement100. In an embodiment, hypothetical electrical circuit300may be activated between a piezoelectric rod and one or more conductive fibers and plastic matrix106around the piezoelectric rod. In another embodiment, hypothetical electrical circuit300may be activated between a set of piezoelectric rods and one or more conductive fibers and plastic matrix106around the set of piezoelectric rods. Piezoelectric rods in the set of piezoelectric rods are oriented in one direction in such a scenario. Therefore, multiple hypothetical electrical circuits, such as hypothetical electrical circuit300may be formed in reinforcement100, based on orientation of plurality of piezoelectric rods102-n. The orientation of plurality of piezoelectric rods102-n. has been explained in detail in conjunction withFIG. 2.

FIG. 4illustrates a flow diagram of manufacturing reinforcement100in accordance with various embodiments of the invention. At step402, a mixture of plurality of conductive fibers104-n, and plastic matrix106is prepared. Weight percentage of plurality of conductive fibers104-nin the mixture depends on a required level of vibration damping characteristic of reinforcement100. Further, weight percentage of plastic matrix106depends on the required level of vibration damping characteristic of reinforcement100and required shape and size of reinforcement100. In an embodiment, a liquid material, such as a liquid adhesive is also added to the mixture to prepare a paste of the mixture. In another embodiment, plurality of conductive fibers104-nare added in plastic matrix106, which is in a melted state.

Upon preparation of the mixture, plurality of piezoelectric rods102-nare added to the mixture, at step404. Weight percentage of plurality of piezoelectric rods102-nto be added in the mixture is based on the required level of vibration damping characteristic of reinforcement100. While adding plurality of piezoelectric rods102-nto the mixture, each piezoelectric rod is polarized along a longitudinal direction of the piezoelectric rod.

Thereafter, at step406, the mixture is processed to form reinforcement100. Various known processing methods may be implemented to accomplish this. For example, processing may involve pouring the mixture in a mould, and drying the mixture.

Various embodiments of the invention provide a reinforcement for buildings which is capable of damping vibration in the buildings. The vibration damping capability is imparted by a mixture of the reinforcement which includes piezoelectric rods, conductive fibers, and plastic matrix. The mixture enables dissipation of mechanical stress developed due to vibration into heat energy. Further, usage of the piezoelectric rods enables maintaining strength and rigidity of the reinforcement. Moreover, as the piezoelectric rods are shaped like a dumbbell, each piezoelectric rod may effectively support the mechanical stress. Therefore, even high frequency of vibration in a building may be damped by the reinforcement. Such reinforcements may be used in the buildings such as, fabrication lab and NANO lab which host sensitive equipments,

Those skilled in the art will realize that the above recognized advantages and other advantages described herein are merely exemplary and are not meant to be a complete rendering of all of the advantages of the various embodiments of the present invention.