DEVELOPMENT OF A GENERALISED METHOD FOR SEISMIC RETROFITTING OF MASONRY STRUCTURES

Abstract

The URM represent a large portion of buildings around the world. Masonry in construction is being widely used in the country, around 60% of the country amounts to 70% of the masonry construction. The masonry has wide advantages but also have some disadvantages i.e. brittle failure, sudden collapse of the structure in a moderate to strong earthquakes can devastate complete cities or villages resulting in massive death toll and can cause extensive loss. To address contemporary requirements, there are established standards, guidelines, and methodologies that guide the selection of appropriate materials and techniques for both repairing and seismically strengthening buildings damaged by earthquakes. These frameworks also provide recommendations for the design and construction of earthquake-resistant structures, encompassing various construction types such as masonry construction with rectangular masonry units, timber-framed buildings, and structures featuring prefabricated flooring or roofing systems. The method includes the procedure of reconnaissance of structures, visual inspection, collecting data, taking measurements, further the information is fed into the designed module which determines the whether structure is safe/unsafe and depending upon the suitable measures are suggested. The technique described may be useful for all types of masonry buildings and constructions. The proposed method may prove to be effective and efficient in terms of time and cost. Buildings in zone II does not requires special seismic resisting features but the important buildings may be considered for upgrading seismic resistance. Applicable for buildings in seismic zones III to V and are based on damaging seismic intensities VII and more on M.S.K. intensities scales. The objectives are Education Imparting, helping Practicing Engineers/Consultants, can be registered/patented to govt. of India from where it can be accessed to mass application, understanding of code, Pre-earthquake behavior assessment, Useful for surveyor to be used by Insurance company, vi Designers get help for pre – construction, Cost – estimation, Retrofitting cost. Seismic retrofitting of masonry buildings plays a crucial role in reducing the vulnerability of existing structures to earthquake damage. Many of these buildings, especially those made from unreinforced masonry (URM), were not designed with seismic resistance in mind and often lack the flexibility needed to withstand seismic forces. As such, they are particularly susceptible during earthquakes. To address these risks, engineers have developed a range of strengthening methods. These include applying surface reinforcements like shotcrete or fiber-reinforced polymers, using post-tensioning techniques, adding reinforced concrete elements for confinement, and employing advanced systems such as base isolation and energy dissipation devices. These strategies aim to improve the structural behaviour of masonry walls in both in-plane and out-of-plane directions, enhance the connections between walls and floors, and reinforce overall building stability. For heritage or architecturally significant structures, special attention is given to minimizing visual and physical alterations. Comparative evaluations of retrofitting approaches suggest that certain techniques—such as the centre core method and surface reinforcement—offer notable improvements in seismic resistance. These methods vary in terms of cost, complexity, and impact on the existing structure, allowing for flexible application depending on specific project needs. In addition to structural benefits, recent studies highlight the broader value of seismic retrofitting, showing that it can lead to considerable reductions in expected damages, economic losses, and fatalities. This is especially relevant for public-use buildings like schools. Consequently, retrofitting masonry structures has become a key component of disaster risk reduction and heritage conservation strategies in seismically active areas.