Effect of Link location, support and joint with Graphene base dampers for Seismic Stability on Metallic Structure

. Hence, it is required to construct such structures which can resist earthquake. The construction of earthquake resistant structures and its effective design is much more required all over the world, particularly, the places where earthquake vulnerability is maximum. This paper is reviewed and tested experimentally for the innovative design of earthquake resistant building which is proposed by engineers and scientists all over the world.in this paper we create multiplex with different link arrangements to minimize the seismic effect and make structure dynamically stable. Other part of the paper concentrates on bolting and busing system with graphene multilayer coting as a vibration isolation and damper.


Introduction
Earthquakes are a natural calamity that occurs every year and are felt by people all over the world.It may occur with a very small magnitude which can be felt by some individuals or the earthquake with great magnitude that can destroy an entire city.Earthquake not only leads to great amount of economic loss for a country/city but also destroys infrastructure of that area which leads to loss of lives in great amount.The shaking of ground, which is a result of earthquake affects the foundation of building and leads to damage of the structure.Every year, approx. 1 lakh earthquake of small and large magnitude earthquake hits the surface all over the world.Some of the biggest and destructive earthquakes of the worlds are Valdivia Earthquake, Chile (1960), Alaska Earthquake (1964), Sumatra Earthquake (2007), Haiti Earthquake (2010), etc.The Indian subcontinent have also faced heavy devastating earthquakes like Bhuj Earthquake (2001), Indian ocean Tsunami (2004), Kashmir Earthquake (2005) which resulted in great loss of citizen and infrastructure of respective nation.Since, earthquake is unavoidable, and the lives are lost not because of earthquake but because of the adverse effects created by earthquake which mainly includes destruction of buildings due to ground shaking [1][2][3][4][5][6][7].The condition of failure of building ICSTCE 2023 https://doi.org/10.1051/e3sconf/202340503019 E3S Web of Conferences 405, 03019 (2023) when earthquake struck the foundation of building, the forces which are generated under the ground because of earthquake, forces are transferred to the building through foundation.As during earthquake, the movement of ground takes place in to and fro motion and hence, as a result the foundations of building will also get affected and tend to move along with the ground.But the upper part of the building i.e., roof will tend to remain in original position.As the walls and columns are connected to the roof, the roof gets dragged by the column, but the motion of the roof is different from that of the ground.It is due to the flexibility of the walls or columns.
The motion of the roof will not be synchronized with the motion of the ground.As the roof's initial position is static and it tends to remain in its original position and this tendency to continue to remain in the initial position is known as inertia.But when the ground moves due to shaking, the building is thrown backwards and the roof experiences force and the whole building experiences to and fro motion.So due to this to and fro motion, the building will start to deform.As the movement is continued for some time, the building will collapse.Hence, it is required to make the building earthquake resisting and for that there are several modifications required to be done at geometrical and structural level.There are several suggestions generated for the building regarding placement of bracing, columns, walls etc. along with the practical implications by showing the real images of failed structures in support of his suggestion which is quite impressive [8][9][10].
The basic idea of a structural engineer to make building earthquake resistant by building it with such procedure that it acts as a rigid layout or the box like structure.Between different components of the structure, the joints must be strong because rigid buildings act as single unit to earthquake forces and to make a building rigid, it is very important to have strong joints.This is a general and most common practice of construction for an earthquake proof building.The three-dimensional model which consists of three floors and by providing displacements in its supports, vibration is created.The analysis is done with the help of piezoelectric accelerometer at different points [11].To compute the behavior of the building and analyze it numerically generating results of frequency, amplitude, admissible load etc.In this paper, the numerical analysis is done for the structure with and without dynamic vibration absorber, but Graphene could be used as coated materials and bushing material as it has a great damping property, so the structure can drastically reduce the vibration amplitudes [3,12].The complex frequency of the viscoelastic SLGS due to changes in the structural damping coefficient (ζ) for diverse ranges of thickness ratio is studied in Figure .1.

Fig.1.
Variation in the structural damping coefficient leads to changes in the complex frequency of simply supported Single-Layer Graphene Sheets (SLGS).Effect of thickness ration to EV, Damping ratio, and Eigen Frequencies [18] Figure 1a illustrates the regions where ξ>1, ξ=1, and ξ<1 for various structural damping coefficients.The findings from Figure 1 indicate that: (1) By increasing the value of the structural damping coefficient, the imaginary part of the eigen frequency decreases until it reaches zero at the critical damping point (ξ=1).
(2) The real part of the eigen frequency exhibits a divergent behavior beyond the critical damping point.
(3) A constant structural damping coefficient, coupled with an increase in thickness ratio, results in a higher damping ratio.
(4) The presence of a structural damping coefficient enhances the damping capacity of thinner graphene structures.
A new type of material has been developed, consisting of alternating layers of metal (copper or nickel) and monolayer graphene in a nano-layered composite.
The copper-graphene composite exhibits an ultra-high strength of 1.5 GPa with a repeat layer spacing of 70 nm, while the nickel-graphene composite achieves a strength of 4.0 GPa with a repeat layer spacing of 100 nm [13][14].These remarkable strengths demonstrate the effectiveness of graphene in blocking the propagation of dislocations across the metal-graphene interface [15][16].
Additionally, when 0.3 wt% Graphene Nanoplatelets (GNP) are evenly distributed within the aluminum matrix, it significantly enhances the tensile, compressive, and hardness properties of the material.This integration of GNP serves as a reinforcing filler, effectively preventing deformation [17][18].

Structural modifications:
Under structural modifications, various types of modifications are proposed to reduce the ill effect of earthquake's shaking over building.Some of the structural modifications can be named as cross bracing, shear walls type etc.Many of the papers have suggested this type of structural modification and is proven to be effective during earthquake [18].Some more modifications which are cheap and affordable, such as making the structure more resisting towards the earthquake like adobe building with earthquake resisting components, rice or wheat straw buildings, bamboo, and wooden houses etc. [19].The response spectrum modal analysis of a three-story model in which natural frequencies, mode shapes and nodal forces are calculated numerically by generating stiffness matrices.Some of the values like peak ground acceleration is taken arbitrary and performed the dynamic analysis.[20] Since, researchers and engineers are not much bother about different configuration of metallic bolted railway structures.Most of them are much concentrated on the concrete structures, which are used for residential purposes.So, bolted metallic structures with graphene base bolted and riveted systems is selected to study.The basic objective of the work is to minimize the amplitude of vibration, which is generated due to the seismic activities and vibration and hence gives base excitation to the structure [21][22][23].To minimize the adverse impact of earthquakes on railway structures, this paper presents several modifications and suggestions aimed at reducing structural deformation caused by such excitations.

Methodology
2.1 The methodology consists of following steps: 1.The recognition of an objective arises from a universal law that states that the elimination of a problem necessitates the establishment of a goal.In this context, our objective is to minimize structural vibration amplitudes by implementing modifications that target the base of the structure, where excitation occurs.2. The modifications primarily focus on the geometric aspects of the building, specifically the faces of the structure.3. Following the implementation of a specific modification, the structures are subjected to excitation, and the resulting values are calculated using the LabVIEW platform.4. Separate values are obtained for each modification and subsequently compared.5.The modification that yields the desired value will be considered optimized and deemed the outcome.The image depicts a scaled-down representation of a building, utilized for conducting experiments.The model is constructed using Plywood and Ingot Iron Bars, specifically Flat Plate Rods and L Sections.Nuts and bolts are employed for easy assembly and disassembly of columns and other components within the structure.The model stands at a height of 6 feet 8 inches, with each floor measuring (3 feet x 2 feet x 2 feet) as illustrated in Figure 2.

Fig. 2. Experimental Analogy of model setup
To fulfill the purpose of base excitation, a mass is suspended from the topmost point of the model and is allowed to hit the side face of the lowest floor of the building.The mass is held at a definite height and is allowed to freely hit the base of the building.Hence, due to this impact, a random vibration is generated and is transferred to the topmost floor of the building where an accelerometer is mounted to acquire the data.This data is then transferred to the National Instrument DAQ and is computed in LabVIEW software as shown in figure 3. The reason behind generation of data in 3 different directions is to know that when vibration is given to the base of building, then which direction gives variation in readings for a particular modification in the building.

2.2.1
Scenario 1: Cross Bracing: In the cross-bracing configuration, the structure includes two diagonal members (braces) connected at each floor.One brace experiences compression, while the other is subjected to tension forces.These braces play a vital role in minimizing the lateral displacement of the building when seismic activity induces excitation at the base.Additionally, they help manage the bending moment and shear force demands imposed on beams and columns within the building.The following depicts the actual structure of a building incorporating cross bracing.

2.2.2
Scenario 2: Chevron Bracing: In addition to cross bracing, Chevron Bracing is another commonly employed technique that effectively mitigates the shear force, bending moment, and axial force demands imposed on the beams and columns of the original structure.

2.2.3
Scenario 3: Frustum Shaped Bracing: A novel and innovative form of bracing, known as frustum shaped bracing, has emerged in building construction.This type of bracing involves joining the braces in a manner that resembles frustum, hence the name frustum shaped bracing.

2.2.4
Scenario 4: Shear Wall: Shear wall bracing in civil metallic structures refers to a structural system that utilizes vertical wall-like elements to resist lateral forces, primarily shear forces, induced by seismic or wind loads.These wall elements, known as shear walls, are typically composed of reinforced concrete or steel, and are strategically positioned within the building to provide stability and reduce the effects of lateral displacements during extreme loading events.Shear wall bracing enhances the structural integrity and overall stiffness of the metallic structure, preventing excessive deformations and ensuring the safety of the building and its occupants.
Where, [M] is a mass matrix [X] is a displacement matrix and [ ̈] is acceleration matrix On solving the determinant given above, we get following equation: Where, = 2 and X=[k]/[M]

Result and Discussion
The primary goal of this paper is to mitigate the amplitude of vibrations generated by seismic activity, which causes excitation at the base of the structure.Such excitation leads to deformations within the structure.Consequently, this paper presents several modifications and suggestions aimed at minimizing the detrimental effects of earthquakes on the structure.To obtain results, a three-floor model of a building with a box-like structure was constructed.Each floor of the model measures 3ft x 2ft x 2ft.The overall height of the building is approximately 7ft.A mass weighing 2kg is suspended from the ceiling of the top floor to provide excitation to the building.The suspended mass is allowed to strike the structure from a height of 2ft, generating an excitation that propagates throughout the building, starting from the top floor.To measure the resulting vibrations within the structure, an accelerometer is mounted on the top floor of the building.The accelerometer's output signal is captured using the National Instrument Data Acquisition (DAQ) system and LabVIEW software.The collected data is then used to generate plots representing the vibrations in the X, Y, and Z directions.Three plots are generated for each modification implemented.The plots obtained during the experiment are presented below.Among the selected configurations, it is observed that cross bracing in metallic structures exhibits significant instability.The amplitude of vibration surpasses 10 volts in both the X and Y directions, which is considerably high in terms of structural considerations.Therefore, it is advisable to avoid the use of cross bracing for maintaining stability in metallic structures.Frustum-shaped bracing structures exhibit lower amplitude of vibration compared to crossbracing structures, but higher compared to conical-shaped bracing.The maximum amplitude for this type of bracing reaches approximately 0.25 volts, with an average value of ±0.17 volts.Therefore, frustum-shaped bracing structures show promising results when compared to other structural configurations.In the case of shear wall bracing, the amplitude of vibration ranges between ±1.0 volts.This value is higher compared to both conical and frustum-shaped bracing, but lower than that of cross-bracing structures.The shear wall bracing does not exhibit promising results in this context.It is worth noting that literature and studies worldwide suggest that the most stable structure involves the incorporation of shear walls; however, these findings are primarily based on concrete structures rather than metallic ones.The seismic activity scenarios considered in our analysis encompassed simple structures, cross bracing, conical bracing, frustum bracing, and shear wall bracing.

Modification and Structural member improvements:
Polyvinyl alcohol-graphene oxide (PVA-GO) and poly (acrylic acid)-grafted-polyvinyl alcohol (PAA-g-PVA) are two bushing materials that can be used for vibration absorbers and dampers in various applications.Here's how they can be applied [24]:

Vibration Absorbers
Vibration absorbers are devices used to reduce or dampen vibrations in mechanical systems.PVA-GO and PAA-g-PVA bushing materials can be utilized in the following ways: a. Automotive Industry: PVA-GO and PAA-g-PVA bushings can be used in vehicles to absorb vibrations and reduce noise.They can be applied in engine mounts, suspension systems, and other components to minimize the transmission of vibrations from the engine and road to the vehicle chassis.b.Industrial Machinery: Vibration absorbers are commonly employed in industrial machinery to improve stability and reduce vibration-induced wear.PVA-GO and PAA-g-PVA bushings can be integrated into machine mounts, bearings, and other mechanical components to dampen vibrations and enhance operational efficiency.c. Construction and Infrastructure: In the construction industry, vibration absorbers are often employed to mitigate the effects of seismic activity, wind-induced vibrations, and machinery-induced vibrations.PVA-GO and PAA-g-PVA bushings can be used in building foundations, bridges, and other structures to absorb and dissipate vibrations, thus enhancing structural integrity.

Dampers
are devices designed to dissipate or absorb energy from vibrations, resulting in the reduction of motion amplitudes.PVA-GO and PAA-g-PVA bushings can be applied in the following damper applications [25]: a. Aerospace and Aviation: Vibration dampers are crucial in aerospace and aviation applications to improve stability, reduce structural fatigue, and enhance passenger comfort.PVA-GO and PAA-g-PVA bushings can be utilized in aircraft landing gears, engine mounts, and control surfaces to dampen vibrations induced by engine operation, aerodynamic forces, and landing impacts.b.Power Generation: Power plants, including nuclear, fossil fuel, and renewable energy facilities, often utilize large rotating machinery such as turbines and generators.Vibration dampers are employed to reduce the transmission of vibrations to the structures.PVA-GO and PAA-g-PVA bushings can be used in turbine mounts, generator bearings, and other critical components to dampen vibrations and prevent equipment damage.
c. Consumer Electronics: Vibration dampers are also used in consumer electronics to reduce the transmission of vibrations and improve device performance.PVA-GO and PAAg-PVA bushings can be applied in smartphones, laptops, and other electronic devices to absorb vibrations generated by motors, cooling fans, and other moving parts.Overall, PVA-GO and PAA-g-PVA bushings offer excellent vibration absorption and damping properties, making them suitable for a wide range of applications in different industries where vibration control is crucial.

X-ray powder diffraction (XRD)
X-ray Diffraction (XRD) proves to be a valuable technique for examining changes in the inner layers, grain size, and crystalline properties of the synthesized material.Figure 11 (a,  b, and c) displays the XRD patterns of pristine graphite, native TRGO (Thermally Reduced Graphene Oxide), and TRGO-incorporated film of poly (Vinyl Alcohol-g-Acrylic Acid) nanocomposites, respectively [26].
To determine the grain size of pure graphite, TRGO, and TRGO-incorporated film of (PVA-g-PAA) nanocomposites, the Debye-Scherrer equation was employed for calculation purposes.
= / In Figure 11 (a), the X-ray diffraction pattern of pristine graphite prior to reduction is depicted.The pattern exhibits a distinct diffraction peak at 26.5°, corresponding to the (002) reflection of the hexagonal graphite structure.By utilizing the Debye-Scherrer equation, the average grain size of graphite flakes was determined to be 10.30nm.Additionally, the percentage crystallinity (Xc) was found to be 93.2%.The X-ray diffraction (XRD) analysis of TRGO (Thermally Reduced Graphene Oxide) after reduction is presented in Figure 11 (b).It confirms that the interlayer distance derived from graphene oxide measures 7.22Å (2θ= 12.2°), which is expected to contract due to the removal of functional groups.Notably, the appearance of a peak at 3.356 to 3.61Å (2θ=26.5°)indicates the significant elimination of most functional groups, resulting in an XRD pattern resembling that of graphite.Furthermore, a peak is observed at 26.7°, 2θ (002), suggesting a similarity to the d-spacing of pristine graphite [27].The average size of TRGO nanosheets is determined to be 9.28 nm, and the percentage crystallinity (Xc) is calculated to be 94.4%. Figure 11(c) presents the X-ray diffraction pattern of TRGO-incorporated film of (PVA-g-PAA) nanocomposites.The appearance of peaks at 9.7°, 12.4°, 20.3°, 25.7°, and 26.2°, 2θ suggests the presence of both TRGO and the polymer matrix.This indicates that the TRGO particles are not uniformly dispersed in the PVA matrix but rather exist as platelets consisting of a few layers [28].The broadening of the peak at 20.2°, 2θ is attributed to PVA in the nanocomposites, while the peak at 28.8° signifies an interlayer distance of 0.316 nm, confirming the successful reduction of graphene oxide.Utilizing the Scherrer's formula, the estimated grain size is approximately 0.87 nm, while the Xc value indicates a crystallinity of 23%, highlighting the nanostructured nature of PVA-grafted TRGO nanocomposites.

Raman spectroscopy analysis
Raman spectral analysis is an invaluable technique for obtaining detailed molecular-level information regarding the chemical bonds and symmetry of the material being studied.Figure 12(a, b, c) displays the Raman spectra of pristine graphite, native TRGO (Thermally Reduced Graphene Oxide), and TRGO-incorporated film of (PVA-g-PAA) nanocomposites, respectively.The spectrum obtained in Figure 12(a) exhibits the Raman bands associated with pristine graphite.Among these bands, the most prominent features are the G band at 1580 cm -1 , which corresponds to the in-phase vibration of graphite lattice, and the D band at 1350 cm -1 , which can be attributed to the presence of edge planes and a disordered structure [26].In Figure 12(b), the spectra obtained from the native TRGO nanosheets confirm the energy shift of the Stokes phonon due to laser excitation.This shift is evident in the two main peaks observed in the Raman spectrum: the G band (1580 cm -1 ), representing the primary in-phase vibrational mode, and the D band (1340 cm -1 ), corresponding to a second-order overtone of a different in-plane vibration.The positions of the D and 2D peaks vary depending on the laser excitation energy, and the spectra consistently show a prominent G band at 1580 cm -1 [27].
Figure 12(c) illustrates the Raman spectra of nanocomposites comprising TRGO incorporated film (PVA-g-PAA).These spectra exhibit two significant peaks observed at 1358 and 1585 cm -1 , which could be associated with local defects located at the edges of TRGO nanosheets [28].Additionally, in these spectra, both the G and D bands are present, with the D band exhibiting higher intensity than the G band.This intensity ratio suggests the presence of sp 3 carbon resulting from the amorphization of graphite during the oxidation process [29][30].

Structure with PVA-g-PAA and Graphene Bushing, Joints and Damping films
As we are discussing earlier that the graphene polymers are very high damping coefficient and we used graphene polymers as vibration isolation.We Synthesis of PVA nanocomposite containing Graphene Oxide and make film of Graphene base PVA.Cut them in the appropriate shapes line bushing and rectangular damper film, applied at the junction of the structure to act as vibration isolation.These joints are act as a damper to reduce the vibration and stabilized the structure.We are comparing the results with or without bushing and damper for the cross bracing, conical bracing, and frustum bracing as quantified in table 1 and shown in Figure 13.
Table 1.Structural cases with or without Graphene-PVA bushing Fig. 13.Effect of Graphene-PVA bushing and isolation effect briefly.

Design consideration and structural suggestions for earthquake resistant building:
Based on the design principles outlined in IS 1893(Part 1): 2002, the standards for structural design are as follows: 1. Structural Integrity: The structure should be able to withstand major earthquakes without collapsing.2. Damage Resistance: The structure should be able to resist moderate or minimal magnitude earthquakes without significant damage.While some minimal damage may occur during moderate earthquakes, it should remain within permissible limits.3. Resilience to Frequent Earthquakes: The structure should have sufficient strength to withstand minimal but frequent earthquakes without incurring significant damage.
The principle of earthquake-resistant building design is based on three main pillars: 1. Reduction of Earthquake Forces: There are two approaches to prevent structures from being damaged by earthquake forces.Firstly, reducing the force of seismic waves can be achieved by using lightweight construction materials, which decreases the magnitude of seismic forces and enhances the safety of the structure.Secondly, non-conventional design methods can be employed to divert or absorb the energy of seismic forces.Examples of such designs include base isolation techniques and incorporating energy-absorbing or dissipating devices into the structure.2. Enhanced Structural By implementing earthquake-resistant features in building design, the overall resistance capacity of the structure can be increased.3. Planning Considerations: During the design phase, careful considerations should be given to the materials, configuration, and framing of the structure in order to improve seismic safety and achieve an economically feasible design.Some important considerations include: a. Selecting a suitable construction site that minimizes vulnerability to earthquakes, ensuring future safety.b.Choosing lightweight materials with high mechanical properties, such as strength and durability.c.Designing a structurally simple configuration that can resist torsion, maintaining symmetry with regard to mass and rigidity.d.Ensuring continuous and well-connected construction to prevent separation due to earthquake forces.By incorporating these principles and considerations, structures can be designed to withstand seismic events while minimizing damage and ensuring the safety of occupants.

Conclusions
From the above testing and the plot generated based on data generated on the LabVIEW software, the bracing which shows best results and is appropriate according to the reading generated is the conical and frustum shaped bracing and the unstable structure according to the data generated is the cross-bracing structure.The results are generated by testing on the metallic structure and hence, we can conclude based on results that the best structure is the conical and frustum structure.But according to the literature and the studies, the best structure is shearing wall bracing but that is for the concrete structure and our results are generated based on metallic structure.The seismic vibration and structural vibration are reduced critically using PVA-Graphene base bushing and vibration isolation films.Another advantage of PVA-Graphene bushing, and films are rust resistive.So, for the seismic regions it is recommended that trusses, frames and metallic structures are incorporated these bushing and damping for structural stability.

For a single
modification, 3 sets of data are generated which comprises of: Data generated in X-Y-& Z Direction.