Introduction

In earthquakes that happened in the past, many of the buildings built using Reinforced Concrete (“RC”) have noted to experience either varied forms of collapse or else damages. With respect to buildings that has been collapsed on account of earthquakes, varied investigations have been undertaken (Totter et al., 2018). Weaker column, stronger beam behaviours, poor quality in concrete, end regions having poor bonds, inadequate form of splice lengths, shorter column behaviours, and design considerations that are incomplete has been noted to some forms of structural level deficiencies. The modern-day building codes has been introduced once the construction concerning most buildings are undertaken (Totter et al., 2018). The required levels of ductility, strength and lateral stiffness can be noted to be much lesser as compared to those that are imposed from modern-day building codes. As these possess lower ductility, the buildings of this nature shall be prone to larger displacement demands on account of deficiency in lateral stiffness as well as strength.

2. Review & Assessments of Potentials to use Modified Framed Shear
It shall be essential for strengthening the concrete structures that are existing with respect to enhanced levels of seismic performances, either post damaging earthquakes or else with respect to preparation concerning the future extent (Basha & Kaushik, 2019). The work shall at all times entails attaching newer concrete or else steel member concerning the structures existing. The epoxy form of grouted dowels shall be ideal with respect to the task that is on account of strength as well as ease in installation with respect to epoxy resins towards threaded rods or else anchor dowels. The shorter term loading over dowels by way of seismic loading shall preclude the creep concerns and as dowels shall be grouted within concrete masses, there shall be sufficient levels of insulation for protecting the epoxy by using heat sources like that of fires (Basha & Kaushik, 2019).

RC-based shear walls can be noted to be widely applied in medium as well as high-rise buildings that is used in varied residential and also commercial purposes for providing the stiffness, lateral strength, as well as capacity for energy dissipation that is required for resisting lateral loads which arise from wind loading or else earthquake (Chase et al., 2019). Over the past decades, considerable modifications shall be adopted within the design concerning RC-based shear walls with respect to newer construction and also with respect to older constructions. The modern-day adopted performances methods of evaluation as well as the principles of capacity design can be considered to be examples for this critical advancements concerning earthquake engineering (Chase et al., 2019). Hence, there shall be mandatory requirement for the enhancement of seismic performances concerning old buildings by use of RC-based shear walls. Hence, they shall meet need concerning the newer performance-based techniques for seismic design.

Study with respect to seismic strengthening concerning RC buildings using exterior form of shear walls can be noted to be undertaken (Abdollahzadeh & Sadeghi, 2018). The structures with respect to the model of two-story frame has been tested as per imposed form of reverse cyclic lateral sways towards simulated seismic loading. It has been observed in that implementation concerning shear walls for structural system having improved capacity pertaining to bare frame in the expected manner (Abdollahzadeh & Sadeghi, 2018). Shear walls refer to structural systems which offer lateral stability towards structures by way of lateral loads akin to earthquake, wind loads. The stated structural systems shall be constructed using reinforced concrete, timber / plywood unreinforced for of masonry, and reinforced masonry in which they shall be sub-divided as coupled shear form of walls, shear wall frame, staggered walls and shear panels (Abdollahzadeh & Sadeghi, 2018).

The study with respect to seismic evaluations as well as strengthening of the prevailing buildings lays emphasis over the identification of components that are most vulnerable with respect to the buildings in risk, as well as in retrofitting them in accordance to risk level for decreasing the risks pertaining to complete or else partial collapse (Ugalde & Lopez-Garcia, 2017). These steps, however, shall not in a necessary manner stop the earthquake damages across strengthened buildings, apart from the procedures employed to strengthen, enhance building performances in case of earthquakes. Using simple terms, it can be stated that the term strengthening shall mean retrofitting or else enhancement to seismic performances. The global strengthening concerning the structure shall be an effective as well as economical form of rehabilitation strategy wherein the seismic evaluation illustrates unacceptable levels of performance on account of overall levels of structural strengthened. The same could be identified while onset of the global level inelastic behaviours take place at the levels in ground shaking which shall be substantially lesser as compared to the levels of code design (Ugalde & Lopez-Garcia, 2017). By way of introducing additional levels of strength in the system of lateral-force resisting, the same shall be possible for raising the overall threshold value concerning ground motion in which occurrence of the damages shall take place. Braced frames as well as shear walls represent elements that shall be used with respect to the stated purpose, and yet they need to possess sufficient levels of stiffness as compared to buildings towards which they shall be supplemented. The same needs their design for providing pretty much complete lateral resistance of the structure (Ugalde & Lopez-Garcia, 2017). The same shall be essential whenever desirable, with existing members shall probably possess very scarce levels of inelastic strength. The addition of newer structural systems within the prevailing buildings shall in an automatic manner transform the overall dynamic behaviour concerning complete building in a considerable manner at the time of earthquakes (Ugalde & Lopez-Garcia, 2017). The specific choice for the element type, their size as well as its number concerning added elements shall depend over the vulnerability concerning the buildings already existing as well as functional layout concerning the buildings. The shear walls, on account of the greater levels of lateral strength as well as stiffness, shall offer most significant element concerning earthquake resistance in the overall building structure (Ugalde & Lopez-Garcia, 2017).

3. Conclusion
On the basis of review, analysis and discussions undertaken, the overall conclusion shall be that the buildings could be strengthened by way of determining overall degree to which susceptibility for weakening, by way of utilising external level shear wall in addition to parallel side in the building as well as connected in an effective manner over shear wall externally as well as existing buildings by use of dowel bar concerning the diameter required , that is, steel bar, for acting in that of homogenous structure while lateral forces shall act on. In using the external-level shear wall structure, the wall structure shall be made to be stiffer, with most of the lateral loads shall be taken using shear wall and hence in the process prevent the structure in being damaged.

References

Abdollahzadeh, G., & Sadeghi, A. (2018). Earthquake recurrence effect on the response reduction factor of steel moment frame. Asian Journal of Civil Engineering, 19(8), 993-1008.

Basha, S. H., & Kaushik, H. B. (2019). A novel macromodel for prediction of shear failure in columns of masonry infilled RC frames under earthquake loading. Bulletin of Earthquake Engineering, 17(4), 2219-2244.

Chase, R. E., Liel, A. B., Luco, N., & Baird, B. W. (2019). Seismic loss and damage in light‐frame wood buildings from sequences of induced earthquakes. Earthquake Engineering & Structural Dynamics, 48(12), 1365-1383.

Totter, E., Formisano, A., Mazzolani, F. M., & Crisafulli, F. (2018). Strip model analysis for steel plate shear walls in earthquake resistant structures. In Key Engineering Materials(Vol. 763, pp. 743-750). Trans Tech Publications Ltd.

Ugalde, D., & Lopez-Garcia, D. (2017). Behavior of reinforced concrete shear wall buildings subjected to large earthquakes. Procedia engineering, 199, 3582-3587.