Vibration isolator made with scrap car tires and steel rods

Abstract

"Seismic isolator made of scrap tires and steel bars" is a suitable seismic isolator for low-rise buildings in developing countries and the use of this proposed isolator is a suitable solution to reduce the environmental impact of used tire storage. This isolator consists of steel bars with two spherical ends, cup-shaped pieces, rubber layers and upper and lower steel plates. Also, the proposed separator has advantages such as no rotational instability, increased shear strength and energy absorption, effective damping, and horizontal and vertical stiffness compared to rubber separators, providing energy absorption by the frictional performance of replaceable steel rods, reducing the adverse environmental effects of stacked tires, reducing potential loss of life and financial resources in low- and short-lived buildings in rural areas, and simple implementation details compared to common separators.

Description

Description of the invention Title of the invention Seismic isolator made with scrap car tires and steel rods Technical background of the relevant invention This invention is related to the field of seismic isolators made of rubber and in particular has advantages such as low manufacturing cost, increased energy absorption, effective damping, vertical and horizontal stiffness, and consequently reduced earthquake damage in low-rise buildings. Technical problem and stating the objectives of the invention In order to keep the main members of buildings within the elastic behavior range and protect the lives of the occupants from natural disasters such as severe earthquakes, structural engineers consider some predetermined areas of the members or installed dampers to dissipate the incoming seismic energy or use large-deformation base isolators with low shear modulus to prevent the seismic energy from entering the structure. Common conventional base isolators include elastomeric isolators and friction pendulum isolators, which, despite their excellent seismic performance, are too expensive for use in rural or low-span buildings of low importance in developing countries. Therefore, it is necessary to introduce cost-effective seismic isolators for use in low-span buildings. Since the main material used in conventional elastomeric isolators is rubber, an effective solution can be to use alternative rubber materials with low cost.According to a report written for the World Trade Council for Sustainable Development, it is estimated that at a production rate of 1 billion waste tires per year, there are currently 4 billion scrap tires in landfills and warehouses around the world. As scrap tires pile up in landfills, they are exposed to sunlight and release chemicals such as greenhouse gas methane into the air, land and water, and if the tires catch fire, toxic fumes may be released into the atmosphere. In addition, the energy used to produce a new tire and the energy gained from recycling a scrap tire produce 31 kg and 22 kg of CO2, respectively. Therefore, to mitigate the worst effects of global warming and achieve net zero carbon emissions with green and sustainable construction techniques, it is necessary to maximize the use of non-biodegradable waste and residues as a key strategy.In this regard, the use of scrap rubber to manufacture cost-effective and sustainable seismic base isolators appears to be a cost-effective solution to reduce the negative environmental impacts of construction and damage caused by natural disasters in rural areas and low-rise buildings. Following extensive valuable research conducted by various researchers and significant improvements in the performance of low-cost base isolators, it is observed that the use of rubber isolators is a viable sustainable solution for the protection of rural and low-rise buildings. In this regard and in order to improve the behavior of previous isolators, in this research, "Seismic isolator made with scrap car tires and steel bars" has been introduced. The objectives of the present invention are: 1- Using scrap car tires in seismic isolators that can be used in low-rise buildings in rural areas 2- Increasing the energy absorption of the separator by the combined action of rubber and steel bars 3- Interchangeability of energy absorbing components 4- Providing effective damping and greater horizontal and vertical stiffness than the values ​​obtained from existing rubber isolators 5- Fewer implementation details and simplicity of building a seismic isolator compared to common isolators 6- Localization and introduction of this type of seismic isolators to the civil engineering community of the country 7- Presenting new designs to reduce the amount of displacement and increase the amount of energy absorption in the separated level. 8- Reducing the negative environmental impacts of construction and damage caused by natural disasters in rural areas and low-rise buildings 9- Using non-biodegradable waste and residues as a key strategy for separators A description of the state of the prior art and the history of developments related to the claimed invention. A low-cost carbon fiber reinforced strip isolator was introduced and tested by Kelly in 2002 for developing countries, and its vertical stiffness was theoretically evaluated for the flexibility of the reinforcement and the compressibility of the elastomer. In addition, low-cost plates prepared with scrap tires with different properties were investigated for use as seismic base isolators by Ozden in 2006 and Turer and Ozden in 2008, and their performance was successfully evaluated by axial compression and shear tests. Furthermore, it was concluded that the shear stiffness of plates made of scrap tires can be easily adjusted by changing the number of rubber layers, and their size can be changed by placing longer strips together or by a woven structure. In 2012 and 2014, Konstantinidis and Kelly theoretically and experimentally investigated two types of low-cost seismic isolation systems in which thick, inflexible reinforcing steel plate elements were replaced with thin, flexible reinforcements such as carbon fibers and steel filler plates.In 2012–2014, a comprehensive numerical and experimental study on sheets made of scrap rubber with and without interlayer adhesive (STRP) was conducted by Mishra et al. Based on these studies, it was concluded that these low-cost base isolators can withstand axial pressure as well as existing conventional isolators and these cost-effective isolators can reduce the structural responses to an acceptable level under seismic excitations. Finally, considering the specifications of the relevant design code, it was concluded that both unadhesive and specially bonded STRPs can be used as seismic isolation devices of the structure. Also, Wang and Zhang in 2023 designed 90 STRP samples with different geometric parameters, tire type, and loading conditions to investigate the effect of these factors on the damping ratio, vertical and horizontal stiffness, and concluded that structures equipped with this type of inexpensive base separators can reduce the maximum acceleration of floors by 56% compared to structures with fixed bases. Providing a solution to an existing technical problem along with an accurate, sufficient, and integrated description of the invention One of the main problems of using conventional seismic isolators is their considerable high cost, which makes this effective technology only used in structures with a high coefficient of importance. Therefore, the aim of this invention is to introduce new economical base isolators made by scrap automobile tires. This type of base isolators is suitable for low-rise buildings in developing countries and its use is a sustainable solution to reduce the environmental impact of used tire storage. The following is a detailed and complete description of the "Seismic Isolator Made with Scrap Automobile Tires and Steel Bars". "Seismic isolator made of scrap tires and steel rods" consists of four steel rods with spherical ends (1) movable at the corners of the isolator, which have a friction function (Figure 1 and Figure 2). These steel rods have two spherical ends that are placed inside the bowl-shaped parts (2) so that the spherical parts of the steel rods can move easily during an earthquake and dissipate seismic energy by friction. It should be noted that the bowl-shaped parts are connected to the upper and lower steel plates (3) by welding and the rubber layers (4) and the loading plates by adhesive. In this isolator, 8 layers of rubber with dimensions of 100 x 100 mm and a thickness of approximately 9 mm are used, and the total thickness of the layers is 72 mm. It should be noted that high-strength steel CM5 (MO40) was used for the steel bars and bowl-shaped parts, and common steel St37 was used for the upper and lower steel plates, and native GoldeStone-GS600-165 / 80R13 rubber was used for the rubber separators. In order to compare the performance of the proposed separator with the rubber separator (with rubber layers without adhesive), laboratory studies of two separator samples were conducted using native rubbers in the strong floor laboratory of Tabriz University. It should be noted that the samples were first subjected to a gravity load of 6 MPa and then subjected to lateral quasi-static cyclic loading with amplitudes of 12, 24, 36, 48 and 60 mm, including 3 cycles for each amplitude. According to the cyclic curves obtained from the test results (Figure 3), it is observed that the rubber separator had a lean curve, which indicates a very low energy absorption of this separator, and considering that there was no adhesive between the end rubber layers and the upper and lower steel sheets, the separator rotated. However, the proposed isolator (a seismic isolator made with scrap car tires and steel rods) has higher shear strength, as well as a more solid curve and higher energy absorption.It should be noted that the solid part in the cyclic curve of the proposed separator is due to the frictional performance of the steel rods and is created by the friction between the spherical part of the rods and the bowl part, and it increases the energy absorption in this type of new separator, which indicates the desirable performance of this proposed separator. In order to compare the two samples more accurately, the energy absorption, effective damping, vertical stiffness, horizontal effective stiffness, and shear strength parameters were calculated using cyclic curves (Table 1). It is observed that the "seismic isolator made of scrap tires and steel bars" sample has a higher vertical stiffness than the rubber isolator sample, which is due to the presence of steel bars in the proposed isolator, which prevents excessive vertical deformation of the proposed isolator due to gravity loads. Despite a 54% increase in the horizontal effective stiffness of the proposed isolator compared to the rubber isolator sample, the shear strength, effective damping, vertical stiffness, and energy absorption parameters in the proposed isolator sample increased by 87%, 144%, 200%, and 295%, respectively, compared to the rubber isolator sample. Vertical stiffness plays a very important role in supporting vertical loads and also reducing rocking motion. In addition, the amount of energy absorption and effective damping are key factors in withstanding shear displacements of isolators to ensure compliance with the allowable displacements of design codes.Finally, according to the results obtained, the superior efficiency and performance of the proposed new separator compared to the conventional rubber separator is evident. In addition, the use of scrap tires in the production process helps to reduce the adverse environmental impacts of accumulated tires and at the same time reduces the potential loss of life and financial resources in low-rise buildings in rural areas of developing countries. In addition, the proposed separator is very low-cost and simple in terms of construction and implementation compared to conventional separators, and its energy absorbing members are replaceable. In general, based on the results obtained, it was observed that the proposed separator, while providing simple and low-cost implementation details compared to conventional separators, has higher solid wheel behavior and shear strength, and increased energy absorption, vertical stiffness, horizontal stiffness, and effective damping. The aforementioned separator has the ability to absorb energy with frictional properties to provide stable cyclic behavior to increase the amount of energy absorption. Among the advantages of the proposed separator are the replaceability of energy absorbing components, providing cyclic behavior without rotational instability, providing effective damping and horizontal and vertical stiffness greater than the values ​​obtained from rubber separators, and fewer implementation details and simplicity of construction of the separator compared to conventional expensive separators, as well as reducing the adverse environmental effects of accumulated tires by using scrap tires and reducing the potential loss of life and financial resources in low-rise buildings in rural areas of developing countries. Explanation of shapes, maps and diagrams Figure 1) This figure shows the component details and assembled model of "Seismic Isolator Made with Scrap Car Tires and Steel Rods". (1- Steel rod with spherical end, 2- Bowl-shaped pieces, 3- Steel plates, 4- Rubber layers) Figure 2) This figure shows the details of the proposed separator: a) steel rods, b) bowl-shaped pieces, c) rubber layers, d) steel plates (dimensions are in millimeters). Figure 3) This figure shows the wheel curves of the laboratory samples. Table 1) This table shows the shear strength, energy absorption, effective damping, vertical stiffness, and horizontal effective stiffness parameters of the isolators. A clear and precise statement of the advantages of the claimed invention over prior inventions. Among the advantages of the proposed tool are the following: 1- Rotational instability of the proposed separator 2- Higher shear resistance than rubber separator 3- Fuller cyclic curve and higher energy absorption than rubber separator 4-Providing energy absorption by the frictional action of the steel rods and the friction between the spherical part of the rods and the bowl part 5- Higher vertical stiffness compared to the rubber separator sample due to the presence of steel rods in the proposed separator. 6-Preventing excessive vertical deformation of the proposed isolator due to gravity loads and reducing rocking motion due to increased vertical stiffness. 7-Increase in effective damping, vertical stiffness, and energy absorption in the proposed isolator sample compared to the rubber isolator sample. 8- Increasing the shear displacement tolerance of isolators to ensure compliance with the permissible displacements of design regulations by increasing energy absorption and effective damping. 9- Superior efficiency and performance of the proposed new separator compared to the rubber separator 10-Reducing the adverse environmental impacts of accumulated tires by using scrap tires in the proposed separator production process 11-Reducing the potential loss of life and financial resources in low-rise buildings in rural areas of developing countries 12- Energy absorption by steel bars with frictional performance (replaceable members) to provide stable cyclic behavior to increase energy absorption. 13- Interchangeability of energy absorbing components (steel rods with frictional function) 14-Simple and low-cost implementation details compared to common separators 15- Usability in rural buildings 16- Facilitates the replacement of damaged separator elements Description of at least one implementation method for implementing the invention The method of making this separator is as follows: first, steel rods, bowl-shaped pieces, and steel plates are cut and prepared in the required dimensions, and also layers of scrap tires are prepared in the required dimensions and number. Then, one of the steel plates is placed at the bottom and horizontally, and a layer of rubber is attached to the steel plate with glue, and after that, the remaining rubber layers are attached to each other with glue. The lower bowl-shaped pieces are welded to the lower steel plate, and the upper bowl-shaped pieces are welded to the upper steel plate. After that, the uppermost rubber layer is also attached to the upper plate with glue, and the steel rods are also placed in their positions, and the separator components are completed. It should be noted that in order to place the steel rods in their positions, one of the four legs of each bowl piece must be welded after the rod is placed in its place. In order to use this separator in the construction industry, first, after the foundation is built, pedestals are constructed to house the separators, and then the separators are installed in place. After that, a reinforced concrete diaphragm is placed on the separators in the intended location and the desired structure is built on it. Explicit mention of the industrial application of the invention Among the industrial applications of this invention can be mentioned in the construction industry, especially in the construction of low-value structures. Considering that due to the high cost of seismic isolators, isolators are usually used in high-value structures, therefore, this proposed isolator is less expensive due to the use of scrap tires and is suitable for use in short buildings in rural areas in developing countries. In addition to providing positive environmental effects in the use of scrap tires and reducing their accumulation, it plays a significant role in protecting the health and lives of people (residents of buildings) in rural and short buildings during severe earthquakes. It should also be noted that the proposed isolator has energy absorption properties, effective damping, shear resistance, and higher vertical and horizontal stiffness than rubber isolators.

Claims

Claim What is claimed: Claim 1) What is claimed is a rubber isolator called "seismic isolator made with scrap tires and steel rods" which can be used in rural low-rise buildings by using a combination of scrap tires and steel rods and consists of the following components: - rubber layers between upper and lower steel plates; - upper and lower steel plates; - bowl-shaped pieces connected to the steel plates at the four corners of the isolator; - steel rods with two spherical ends placed inside the bowl-shaped pieces. Claim 2) According to claim 1, steel bars are placed inside the bowl-shaped pieces at the four corners of the separator to withstand vertical loads and provide vertical stiffness of the proposed separator and reduce the rocking motion of the separator. Claim 3) According to claim 1, the steel rods have two spherical ends so that during an earthquake, rotation can easily occur inside the bowl-shaped parts and provide a frictional isolating function against earthquake loads.

Images