Abstract

Unreinforced masonry (URM) buildings, prevalent in seismic-prone regions, have historically demonstrated poor performance during earthquakes due to inherent material and construction deficiencies, heterogeneity, and inadequate seismic detailing. This study presents a comprehensive, performance-based framework for the post-earthquake evaluation and repair of damaged URM structures. It employs a displacement-based methodology to quantify structural behaviour and residual performance accurately. Mechanism-based analytical tools, including capacity-demand ratios, normalized displacement indices, and performance loss metrics, are employed to quantify structural behaviour under intact, damaged, and repaired (or retrofitted) conditions. Crucially, the framework integrates component-level technical assessments with policy-oriented decision-making through three post-earthquake pathways: accepting existing damage, restoring pre-event performance, or upgrading to higher resilience. It bridges the gap between analytical predictions and real field conditions by incorporating empirical observations, mechanism-specific damage indicators, and construction-specific limitations. The framework classifies intervention strategies into cosmetic repairs, structural repairs, and structural enhancements, and summarizes key repair/retrofitting techniques. Each intervention is guided by defined performance objectives, from restoring essential functionality to enhancing seismic capacity. The study emphasizes the need for standardized, mechanism-informed and context-sensitive repair protocols that support efficient and resilient recovery. By promoting transparent, performance-based, and evidence-informed decision-making, the proposed methodology contributes to improving the safety and long-term resilience of masonry buildings in seismic regions.

Abstract

Masonry structures constitute a significant portion of the global built heritage and modern infrastructure. Yet, their assessment poses unique challenges due to material heterogeneity, ageing, and the need for conservation-sensitive approaches. Non-destructive testing (NDT) techniques have emerged as indispensable tools for evaluating the mechanical and physical properties of masonry without impairing its integrity. This paper provides a comprehensive overview of the evolution, principles, and application of NDT methods for masonry structures. It critically examines the working mechanisms, advantages, and limitations of commonly used techniques, including rebound hammer, ultrasonic pulse velocity, flat-jack tests, ground-penetrating radar, infrared thermography, endoscopy and acoustic emission. The role of NDT in condition assessment, strength estimation, seismic vulnerability evaluation, and conservation practices is highlighted. Recent advancements in hybrid and digital diagnostic methods are also discussed, emphasizing the transition towards data-driven, performance-based structural assessment. This review paper summarizes the current challenges associated with the application of NDT methods in masonry diagnostics and presents potential research directions to improve their reliability, standardization, and integration into assessment practices.

Abstract

Natural fibre composites (NFCs) have gained prominence as sustainable, cost-effective alternatives to synthetic fibre reinforcements in masonry structural retrofitting. This paper reviews the extraction, treatment, and fabrication of natural fibres such as jute, flax, sisal, hemp, and basalt into Fibre Reinforced Polymer (FRP) and Textile Reinforced Mortar (TRM) systems suited for masonry appli-cations. Experimental and field studies demonstrate that natural FRP composites improve tensile strength, ductility, and seismic resilience of unreinforced masonry walls, while natural TRM composites offer enhanced environmental compatibil-ity, fire resistance, and vapour permeability, which are essential for heritage ma-sonry preservation. The review assesses mechanical performance, durability chal-lenges related to moisture and ultraviolet (UV) exposure, and sustainability bene-fits, including reduced embodied energy and biodegradability. Practical case stud-ies confirm the feasibility of locally sourced natural fibre retrofits in seismic zones. Challenges such as variability in fibre properties and the need for stand-ardized design codes are discussed alongside future research directions focusing on hybrid composites, bio-based matrices, and sensor integration for structural health monitoring. This review consolidates current advances and prospects, positioning NFCs in form of FRP and TRM composites as viable, eco-friendly retrofit technologies for resilient and sustainable masonry infrastructure.

Abstract

In the Himalayan region, traditional buildings made of masonry have existed for centuries and still make up a sizable portion of the building stock. Many of these buildings have proven records of earthquake resilience. At the same time, the primary cause of fatalities from previous earthquakes is the increasing collapse of unreinforced masonry structures. In various Himalayan locations, local seismic culture has evolved over the past few centuries to improve the seismic capacity of
stone constructions. These areas use wood or other materials with high tensile strength to reinforce their stone masonry. The post-earthquake reconnaissance surveys clearly demonstrate the superior performance of these timber-reinforced masonry constructions. Nevertheless, there is still a lack of scientific investigation, either through numerical modelling or laboratory-based studies, on the behaviour and mechanism of these structures. Furthermore, there are no explicit criteria for evaluating timber-reinforced masonry in the present Indian seismic code. This study examines several distinct traditional masonry building typologies found in the Himalayas, such as 'Thathara', 'Kath-Kuni' or 'Koti-Banal', 'Newari', 'Dhajji Dewari',
'Ikra' or 'Assam-Type House', 'Bhatar' or 'Taq', and 'Dry-stone buildings'. For the majority of these typologies, aside from Dry-stone houses, the masonry walls have embedded horizontal timber bands or lacings that enhance box behaviour, thereby preventing premature failure. Through a thorough analysis of timber-reinforced masonry, including architectural details, earthquake-resilient & vulnerable features, and experimental and numerical investigations, the article presents a unique addition to our understanding of seismic performance and how it might best protect the Himalayan region's traditional heritage. Additionally, the current study contributes to a better understanding of how wood elements give masonry structures greater seismic resilience. This understanding will help with several initiatives: (i) better conservation, preservation, and maintenance of traditional or heritage structures; (ii) seismic codes/standards providing details regarding the assessment of timber-reinforced structures; (iii) supporting and encouraging practitioners to design and build using techniques that have demonstrated superior performance, and (iv) as attempts to lessen the impact of building on our environment increases, provide a way to make safer structures utilizing low-carbon materials.

Abstract

Around the world, there are a lot of unreinforced masonry (URM) buildings situated in seismically active areas. Additionally, the majority of these buildings were not built in accordance with seismic code requirements. Buildings made of URM are seismically unsafe and require strengthening, as demonstrated by previous earthquakes. Masonry material exhibits a great deal of variability in its behaviour, and the tensile or flexural capacity of the structural components is one of the key factors in the seismic susceptibility of masonry buildings. The flexural strength and deformability of URM walls can be increased using a variety of retrofitting methods. These can be loosely divided into two categories: "conventional" and "advanced". The surface treatments (e.g., shotcrete, reinforced plaster, ferrocement overlays, polyurea spray technology), stitching and grout or epoxy injections, re-pointing, reinforced concrete confinement, and post-tensioning fall under the first category. The second category includes the use of seismic wallpaper (i.e., fiber-reinforced polymers--FRP such as epoxy-bonded strips or in situ impregnated fabrics), textile-reinforced mortar composites (mesh/fabric reinforcement in the form of fibre, wire, polypropylene bands, plastic bags, bamboo, etc.), and centre core. The present study reviews the state-of-the-art literature on several methods for reinforcing URM walls subject to lateral earthquake loading. The paper provides a complete overview of retrofitting techniques, including benefits, suitability, applicability, drawbacks, restrictions, sustainability, and consequences on rural communities. In addition, the effectiveness of retrofitting methods is compared using factors including weight, technology (i.e., level of skill required), cost, manpower, and disruption to occupants. The study's findings will help the policymakers, archaeological survey of India (ASI), various government departments owning low-rise masonry buildings, planners, building owners, architects, structural engineers, consultants, and designers, select an appropriate retrofitting system. Further, the design methodology for retrofitting masonry walls using advanced composites like TRM and FRP is also described in detail, using an explanatory example for seismic in-plane and out-of-plane actions.

Abstract

Monuments were built for thousands of years as the most enduring and well-known representations of past civilizations. It is crucial to preserve these because they are national symbols with unique cultural and historical significance. The deterioration of the structures happens as a result of weathering, fire, natural disasters like earthquakes, construction flaws, and numerous other factors. In general, the issue with repairing and reinforcing regular buildings is very different from the issue with restoring monument buildings. The goal of keeping a monumental structure in use may be viewed as secondary in importance and any event as a result of the effort made to fulfil the main task. In the case of monumental buildings, emphasis is placed on the preservation of their aesthetic and historical aspects. Therefore, the restoration strives to protect and highlight the monument's or building's aesthetic and historical aspects. Choosing the appropriate material for the restoration depends on how the original structure looks. New materials must be compatible with those already used in the building. The goal of the present study is to provide an overview of the materials used to restore the structural integrity of historic structures and monuments that have been damaged by seismic activity. All of these buildings need extra attention because of their specific historical or architectural value, or because they are significant because they are still standing examples of a former way of life.

Abstract

Masonry structures cover a very wide range of monumental works in space and time, covering almost 6,000 years. The structural assessment of the load-carrying capacity of such old structures depends on several parameters such as: (a) material strength; (b) texture of the structure; (c) geometrical form and dimensions; (d) existing loading and constraints; and (e) expected loadings at failure. Detailed calculations are also required for the structural evaluation using most of the above parameters firstly by considering the gravity loads and secondly by the combination of gravity load and lateral action in areas of high seismicity. However, at the same time, it is equally significant for the structural engineer, who is involved in structural restoration design, to know in depth qualitatively the basic forms and their structural behaviour of monumental buildings. The structural engineer in charge must understand from the beginning, qualitatively, the structural behaviour of a building under consideration to various basic actions so that one can make a preliminary diagnosis of the causes that are responsible for the existing damages (cracks, drifts, settlements, splitting etc.). In this way, one will be in a position to focus on the detailed research, in situ and laboratory, to the critical points of the building, and can conduct the analysis and design using suitable models for a credible safety evaluation. Therefore, an effort is made in the present study to give a qualitative approach to the structural behaviour of the basic structural forms of masonry monumental and historical buildings, where the consequences of the seismic action are traumatic now and then. This article gives an outline and creates background information for further structural evaluation of the monuments.

Abstract

Corrosion creates a significant degradation mechanism in reinforced concrete (RC) structures, which would require a high cost of maintenance and repair in affected buildings. The right methods for structural retrofitting are, therefore, quite pivotal. Modification or rectification for any structure is normally categorized under three major categories: (i) Structural rehabilitation, (ii) Structural refurbishment, and (iii) Structural retrofit. All these activities have a thin but predominant line of differentiation. In contrast, the first two activities relate to enhancing the functional life of a structure that has been damaged under an adverse environment or condition. On the other hand, structural retrofit is an activity where the structure is updated in its basic parameters of sharing the load and supporting the superstructure. It improves the safety and durability of the structure. Further, when corrosion hits the structure, it results in a reduction in many important parameters to the extent that they go below their acceptable limits under national and international standards. It is indeed a perfect blend of structural dynamics or design engineering and functionality of the structure in the right proportion when retrofit action for a corrosion-hit structure is conceptualized and crafted. This paper aims to present and discuss various structural retrofitting methods for RC members affected by corrosion, supported by relevant real-world case studies.

Abstract

The majority of the materials that survive from ancient Egyptian material culture are made of stones that were utilized for construction, jewellery, ornamentation, and practical purposes. These primarily originated from the Eastern and Nile Valley Deserts (some from the Western Desert as well), where more than 200 quarries dating from the Late Predynastic to the Late Roman periods have been found. These span around 3500 years. Up until the Late Period, when iron tools took the place of stone tools, the harder stones (almost all volcanic and metamorphic rocks, silicified sandstone, and chert) were mined using stone tools with the help of fire settings and wood levers. During the Dynastic Period, the softer stones (mostly limestone, sandstone, and quartzite) were removed using copper and then bronze picks and chisels; by the end of the Late Period, iron tools had once more taken the place of the earlier ones. The bigger blocks of quarried stone were hauled on sledges, typically over built roads, and possibly pushed by teams of men to the building sites or the Nile River for shipping until the Greco-Roman Period, when appropriate roads and wagons tough enough to carry them appeared. In addition to serving as supplies of stone, old quarries are also important archaeological sites that contain ruins and other cultural artifacts. Their unique viewpoint on life in ancient Egypt makes them worthy of study and preservation. The current study provides a thorough overview of the quarrying techniques used by the ancient Egyptians to differentiate between "soft-stones" (limestone, sandstone, travertine, anhydrite, gypsum, and soapstone) and "hardstones", which are essentially igneous and metamorphic rocks plus silicified sandstone and chert.

Abstract

In the whole procedure of preservation, conservation, and restoration of monuments and historical buildings, structural restoration is considered an undesirable parameter, since it implies interventions on a large scale that might harm the authenticity of a culturally protected building. However, this type of intervention is an inevitable action, because it pertains to the safety of the building and, most importantly, to the safety of the users. In this respect, authenticity and safety are two concepts contradicting each other, and they are ensured by professionals of different origins and philosophies, namely archaeology & architecture on one side and science & technology on the other. In the case of structural restoration, these professionals are required to find a common space of co-existence so that the results of restoration satisfy both concepts, authenticity and safety. The present study gives an overview of thorough knowledge of construction techniques of masonry elements or systems or forms used in the past. In fact, in a period of more than five millennia, various techniques of construction have been developed as a result of big revolutions that have taken place in the history of human civilization. A deep knowledge of all the above is necessary for the suitable selection of present-day techniques and materials that might be used in structural restoration, where principles of reversible or irreversible techniques play a vital role together with the compatibility and durability of intervention materials. The main objective of this study is to guide the structural engineers involved in the structural repair of ancient monuments and buildings of national importance.