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In recent years various studies have explored the seismic behavior of controlled rocking masonry walls (CRMWs) that utilize both gravity loading for self-centering and additional energy dissipation (ED) devices to regulate the response (ED-CRMWs). However, these studies had limitations because ED devices were installed on or within the masonry wall, making repairs difficult or impossible after ED yielding or fracturing. This study presents the testing of two half-scale CRMWs that were constructed with supplemental flexural yielding Energy dissipation devices Accessible in a Steel base (EASt-CRMWs). The proposed EASt-CRMWs simplify the installation of the energy dissipation devices and overall wall construction, while also allowing for easy replacement following damage. The walls were subjected to quasi-static, cyclic loading up to drifts of 2.35%, after which the ED devices were replaced, and the same wall was tested again. Wall 2 was built with a steel plate at the rocking point between the steel base and the foundation interface. All five tests demonstrated a favorable self-centering response, with no significant damage to the walls. The ED devices were easily replaced between tests, and the damage was confined to them. Wall 2 had better performance because of the steel plates, which reduced damage to the mortar at the steel base-foundation interface, resulting in slightly decreased lateral load capacity at lower drift ratios upon retesting for Wall 1. Moreover, residual drifts were below 0.05% for all wall tests. Finally, a numerical model and a damage index proposed previously were validated based on the experimental work presented in this study as well as additional configurations of EASt-CRMWs presented in a previous recent study. The results demonstrate that the model can capture the overall response of the walls, and the damage index can accurately predict the location, type, and severity of the damage. [ABSTRACT FROM AUTHOR]

In this study, a masonry panel under a high compressive stress to strength ratio is considered. The panel is modeled as a composite structure by considering a repeated unit cell of mortar and brick. Load redistributions due to creep in mortar and brick as composite materials are accounted for. A step-by-step in-time analysis is performed to calculate the load redistribution in the composite masonry. Time-dependent system reliability analysis of the masonry panel is performed by defining the component and system limit state functions at each time step. While the reliability index of ductile materials depends on the load level in each part of masonry, the reliability index of brittle materials depends only on the overall load. By proposing the reliability index of quasi-brittle materials being between these two reliability index bounds, the reliability index of quasi-brittle materials depends on both the load level in each part and the overall load. Using the proposed reliability index of quasi-brittle materials, partial safety factors for masonry panel design considering creep and damage are calibrated based on the Hasofer and Lind method. A design example using the proposed partial safety factor is presented. [ABSTRACT FROM AUTHOR]

This paper investigated the lateral resistant behavior of grid-reinforced steel corrugated shear walls (GR-SCSWs), which are applied to shear walls with large width-to-height ratio. By revealing the resistant mechanism, the stiffness requirement of the subgrid, the wall–frame interaction, and the overall lateral resistance were studied. First, compared with ordinary steel corrugated shear walls, the lateral resistant behavior of GR-SCSWs and the bending moment of the boundary column were analyzed. Second, the threshold stiffness ratio was defined for the subgrid, and design suggestions were proposed to ensure that the infill panel has high and stable in-plane lateral resistance. Finally, the yielding development and shear force distribution in GR-SCSWs were explored, and an improved plate–frame interaction (PFI) model and formulas predicting the lateral resistance curve of GR-SCSWs were established by numerical analysis and theoretical derivations. It was found that, due to the full out-of-plane restraining effect of the subgrid, the GR-SCSW with optimized subpanels can achieve an in-plane shear yielding mechanism. GR-SCSWs can resist lateral loading with an appropriate yield sequence from the infill panel to the subgrid and then to the boundary frame. The modified PFI model proposed fully considered the interaction between the infill grid-reinforced panel and the boundary frame, while the theoretical formulas agreed with the FEA results and can be used to predict the lateral resistant curve and shear force distribution of GR-SCSWs. [ABSTRACT FROM AUTHOR]

Recent research has underscored the effectiveness of engineered cementitious composites (ECC) in retrofitting unreinforced masonry (URM) structures. The retrofitting method of embedding ECC in the bed mortar joints is suitable for strengthening historic masonry buildings because the ECC can be concealed within the mortar joints. This study introduces an experimental campaign aimed at understanding the effects of this strengthening method on the in-plane seismic performance of URM walls. Four half-scale masonry walls, one of them unreinforced and the remaining three reinforced with ECC, were built and tested under in-plane cyclic loads. From the test results, it was found that the proposed retrofitting method can mitigate brittle diagonal shear damage and improve the integrity of the masonry walls. Furthermore, the results demonstrated that ECC reinforcement effectively increased the seismic behavior of URM walls in terms of shear bearing capacity, ductile behavior, stiffness degradation, and energy dissipation capacity. The ductility coefficient is defined as the ratio of ultimate displacement to yield displacement. The maximum lateral load and ductility coefficient of the reinforced masonry walls increased by a maximum of 26.08 and 25.77%, respectively, in comparison with the URM wall. Additionally, the lateral bearing capacity of both unreinforced and reinforced specimens was assessed using theoretical models. The results showed that the theoretical model could be used to predict the maximum lateral loads of the specimens, with the error of the calculated and tested maximum lateral loads being within 5%. The hysteresis curves of ECC-reinforced walls were predicted using an idealized trilinear model and a modified Clough model, and the applicability of the hysteresis model was assessed by comparing the force demand history and energy dissipation history of the computed and experimental hysteresis curves. [ABSTRACT FROM AUTHOR]

In unreinforced masonry structures, among the most dangerous events that can occur during earthquakes are the out-of-plane mechanisms. This type of response significantly changes if the wall is restrained by a horizontal element. The collapse, in this case, could take place for slipping/failure of the diaphragm connection or for overturning of the wall, following the formation of a crack at an intermediate height between the base and the top. A specific analytical model is used to capture the complex dynamic behavior of the wall, formed by two stacked rigid bodies (free to rock) with the top one connected to a flexible diaphragm. The model is calibrated using experimental data available in the literature and it is then used to carry out a dynamic parametric analysis. The variation range of relevant parameters refers to the building features surveyed in Emilia-Romagna region, Italy, and their effect on the global response of the system is investigated. Further, the influence of ground motion is considered, using different ground accelerations. The results of the analysis highlight that, for the considered area and return period, the maximum rotations of the system are significant only for large slenderness values. Further, the investigation shows that the diaphragm plays a crucial role in the dynamic response of the system. The stiffness of the diaphragm can significantly reduce the rotations and consequently the risk of overturning. Additionally, the study on the effect of the wall size pointed out how a top spring causes a reverse scale effect. [ABSTRACT FROM AUTHOR]

Several studies have been carried out to assess the building's seismic vulnerability, to mitigate the seismic risk in urban areas, which is one of the most devastating natural hazards causing considerable economic and human losses. These studies must be incorporated to improve the planning of urban areas to have resistant and resilient cities in case of disasters. The seismic feedback has shown that the build-back-better concept has a direct impact on the city's economic growth. In this paper, the existing buildings' resilience is assessed, in order to highlight the capacity of these last to keep the functionality when an earthquake occurs. This building's resilience has been determined for three types of structures: masonry, reinforced concrete and steel, according to the reconstruction time, the reconstruction cost and the damage state. This last has been assessed from empirical fragility curves developed using the log normal distribution for five structures typologies (Unreinforced masonry; reinforced masonry; RC frame; RC shear walls/Mixed RC frame-RC shear walls and steel structures). A seismic resilience scenario was performed using a geographic information system (GIS) and applied for the Blida city (Algeria) classified as a high seismic zone according to Algerian seismic regulations. According to the results found, the old districts of the Blida city, built mainly during the so-called pre-code period, will not be resilient in case of disaster. The other districts built later in the low-code and high-code periods will have, respectively, medium and good functionality. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth analysis of the Kopčić House, a significant example of modernist architecture in Sarajevo, Bosnia and Herzegovina, focusing on its structural-specific features and seismic performance. The Kopčić House embodies a confined masonry structure with innovative construction features, combining load-bearing masonry walls with reinforced concrete elements. This architectural approach was pioneering for its time, combining traditional construction methods with innovative materials and techniques. Detailed analysis using numerical modeling techniques, specifically 3D modeling with the 3Muri software (Vers.14.2.0.4), was conducted to assess the seismic resilience of the structure. The analysis considered different load distributions and eccentricities to comprehensively evaluate the building's response to lateral forces. The findings of this research reveal the structural capacity and potential vulnerabilities of the Kopčić House when subjected to seismic events. While the building demonstrates inherent strength due to its confined masonry design, areas requiring structural strengthening were identified through numerical simulations. This study contributes to the broader understanding of confined masonry construction within the context of modernist architecture. By integrating historical research with advanced structural analysis, this work aims to bridge the gap between architectural heritage and contemporary engineering practices. [ABSTRACT FROM AUTHOR]

Deep faults significantly impact the structural stabilities and deformation behaviors of their overburden rocks, which are key factors in underground engineering and geological hazard research. Considering the problem of deep-fault-overburdened breaking during mining of super-thick coal seams and taking the Yaoqiao Coal Mine as the research object, the mining fracture evolution characteristics and overburden displacement law of the non-structured and fault-bearing overburden corresponding to fully mechanized caving mining are compared and analyzed using numerical simulations and physical similarity simulations. The results of this study show the following: 1) The fracture height of the overlying rock presents a specific change law with advancement of the working face; the initial rapid increase to a maximum height of 74 m is achieved when the working face advances to 90 m; with the development of the plastic zone indicating past yield, the fracture height decreases to 54 m and becomes stable, and the final caving angle of the fracture stabilizes at 70°. 2) In coal mining under normal fault conditions, when the working face advances from the upper to lower walls, the roof forms a masonry beam structure that slows down fault activation and crack development. When moving away from the fault, the overburden movements and water-conducting cracks are fewer, and the crack height is lower than that without faults. When approaching the fault, the influence of the faults in the fracture zone increases, and the height of fracture development reaches the maximum value after crossing the fault, highlighting the significant influence of the fault on fracture development. 3) Through a similarity simulation test, it is shown that the overburden caving zone is further compacted by the overburden rock and that the roof collapses in a large range, resulting in rapid upward development of the overburden rock cracks and separation of the central overburden rock cracks that are gradually compacted and closed. These findings are expected to have important theoretical and practical significance for deep underground engineering design, geological disaster prevention, and fault activity monitoring. [ABSTRACT FROM AUTHOR]

Unreinforced masonry (URM) buildings in historic urban areas of European countries are generally clustered in an aggregate configuration and are often characterized by façade walls mutually interconnected with adjacent ones. As a result, the seismic performance of buildings in an aggregate configuration can be affected by the mutual interaction between the adjacent units. This interaction, often called the aggregate effect, could significantly influence the level of the seismic vulnerability of URM buildings in aggregate configuration toward in-plane and out-of-plane mechanisms, the latter being the object of the present paper. Traditional methods for assessing the seismic vulnerability of URM buildings neglect the interactions between adjacent buildings, potentially underestimating the actual vulnerability. This study aims to derive fragility curves specific for UMR buildings in aggregate configuration and proposes an innovative methodology that introduces the aggregate effect into an analytical approach, previously developed by the authors for isolated URM buildings. The aggregate effect is modeled by accounting for the friction forces arising among adjacent facades during the development of out-of-plane overturning mechanisms by considering different scenarios, based on how façade walls interact with neighboring structures (e.g., whether they are connected to transverse and/or lateral coplanar ones). The proposed approach is applied to a real case study of an Italian historical center. The obtained results demonstrate that the aggregate effect significantly influences the fragility curves of URM buildings arranged in aggregate configurations. This highlights the importance of considering this effect and the usefulness of the proposed approach for large-scale assessments of seismic vulnerability in historic urban areas, contributing to sustainable disaster risk prevention. [ABSTRACT FROM AUTHOR]

Due to rapid growth in tourism and other economic activities, several small cities and towns in the Indian Himalayan region are facing problems of unplanned construction and extended use of deteriorating old structures. Despite being in the most active zone of seismic activity, significant nonengineered construction is practiced in this region. Hence, it becomes essential to examine the existing engineered and nonengineered building typologies and assess their vulnerabilities against earthquake shaking. This study presents typical engineered and nonengineered construction practices observed through a survey of 1,009 buildings located within Mandi, a small town in the lap of the great Himalayas in the Indian state of Himachal Pradesh. An attempt is made to identify the typical building typologies, visible structural irregular features and their seismic vulnerability. A few building typologies predominantly prevail in the northern zone of the Indian Himalayan region are identified. Rapid visual screening (RVS) of the surveyed buildings is performed using different existing guidelines. It is observed that a substantial number of buildings with hybrid typology (stone masonry mixed with brick masonry or reinforced concrete) prevail in the study area. It is also observed that the seismic vulnerability, as per the adopted RVS guidelines, of the majority of the buildings is high, indicating urgent demand to safeguard the vulnerable built environment and develop the framework for a seismic resilient society. It is further concluded that use of region-specific vulnerability attributes can improve the segregation of buildings based on expected damage. The seismic assessment of large existing building stock through rapid visual screening (RVS) is important for preliminary evaluation. This study presents crucial insights into seismic vulnerability assessment and earthquake-resistant construction practices in the Indian Himalayan region. It identifies new building typologies, prevalent poor construction practices, and critical vulnerable attributes in the case study region. These findings hold significant practical implications for various stakeholders, including engineers, researchers, policymakers, and practitioners. By understanding the ground conditions of construction practices, building typologies, and vulnerability attributes, stakeholders can develop robust RVS methodologies which accurately assess their seismic vulnerability for planning effective seismic risk mitigation strategies and promote earthquake-resistant construction practices. Identifying new building typologies will encourage future research to quantify vulnerability through numerical studies, experimental investigation, and field data. [ABSTRACT FROM AUTHOR]

Predicting the seismic response of masonry-infilled (MI) RC frames holds immense importance due to the significant influence of masonry on the structural performance. Despite numerous studies delving into the seismic behavior of these frames, their complex interaction of masonry infills and RC frame presents ongoing challenges for researchers, designers, and standards committees. Although numerous studies have been conducted to investigate the seismic behavior of masonry-infilled reinforced concrete frames, its complex behavior poses a challenge to researchers, designers, and the specification-making committees. In recent years, several national codes have been revised to include the estimation of the stiffness of reinforced and nonreinforced masonry walls and have provided guidelines for the modeling and analysis of structures considering MI. This article aims to provide a comprehensive review of how infilled masonry walls impact the seismic performance of RC frames, drawing comparisons with codal provisions. The focus lies on scrutinizing experimental, numerical, and analytical studies that explore in-plane and out-of-plane behaviors. Factors like masonry strength, stiffness, area of openings, stiffness degradation, energy dissipation capacity, and damage patterns are thoroughly examined. Key findings with critical implications are highlighted, shedding light on potential future research directions in this crucial field. [ABSTRACT FROM AUTHOR]

The evaluation of the structural behaviour of a masonry Venetian church with a pointed barrel vault is presented in this paper through an analysis following the necessary steps of a monument study. With a detailed geometric model and material estimation, the finite-element method is used to investigate the influence of specific structural parts of the structure, like masonry buttresses and wall connections, on the structural behaviour. The operational modal analysis is used to identify the structure dynamically. The comparison of the eigenfrequencies, which are estimated by in situ measurements and finite-element modal analysis, is used to perform a model identification. The response spectrum analysis, the static analysis after the subsistence of some parts following strengthening proposals, and the transient analysis of specific seismic excitations are used for the evaluation of the structural behaviour. The purpose of the work is to highlight the need for an interdisciplinary approach to the study of a monumental complex structure, regardless of its scale. The coexistence of structural elements of different stiffnesses, such as vaults, elongated walls, buttresses, transverse walls with pediment and belfry, as well as the concha, affects the mechanical behaviour and the pathology of the structure, which is difficult to study with simplifying models. From the analysis, it is concluded that subsidence problems, combined with seismic actions, lead to the cracking of the masonry, while the existence of buttresses limits the extension of the damage and contributes to the stabilization of the structure. [ABSTRACT FROM AUTHOR]

The objectives of this study were to investigate the out-of-plane behavior of unreinforced masonry (URM) infill walls and to identify the effectiveness of tie systems that were proposed to enhance the infill stability under both in- and out-of-plane effects. This study examined three types of tie systems: a full-length tie system (prototype), a staggered tie system and a half-length tie system. For this purpose, four 1/4-scale, single-story, one-bay masonry infilled reinforced concrete (RC) frame specimens with and without the proposed tie systems were sequentially tested under in-plane static cyclic loading and out-of-plane dynamic excitation. In the experimental study, two series of shaking table tests were conducted to investigate the out-of-plane behavior of the infill walls. The first series compared the fundamental out-of-plane performance of three proposed tie systems, and the second series verified the effectiveness of the full-length tie system to prevent infill out-of-plane failure under an excitation simulating the severe floor response in medium-rise buildings. The test results indicated the following: (1) the presence of the tie systems caused minor differences in the in-plane capacity and ductility of each specimen, (2) the effectiveness of the full-length and staggered tie systems was superior to that of the half-length tie system, and (3) the full-length tie system not only prevented the infill out-of-plane failure but also significantly reduced the infill damage under realistic excitation conditions. The above research outcomes provide a useful contribution of the infill to upgrade the seismic resistance of buildings. [ABSTRACT FROM AUTHOR]

An experimental and numerical research, aimed at evaluating the in-plane seismic performance of an innovative external steel modular system for the strengthening of load-bearing masonry walls, is currently underway at the EUCENTRE Foundation in Pavia. This paper presents, in particular, the results of the experimental part of this research campaign. Solid clay brick and hollow clay "doppio UNI" masonry typologies, representing common solutions in Italian existing buildings, were considered. After the mechanical characterization of the masonry and of the components of the reinforcement system, cyclic in-plane pseudo-static tests on full-scale specimens were performed in order to investigate the influence of the proposed system on the in-plane response of the walls, compared to the unreinforced conditions. The main seismic parameters of the masonry walls (i.e. elastic stiffness, lateral resistance, displacement capacity and energy dissipation) were assessed depending on the achieved damage mechanism. The proposed reinforcement system provided very promising results, improving the in-plane seismic performance of masonry walls at serviceability and especially at ultimate conditions, with a significant increase of deformation capacity above all in the case of shear mechanisms. [ABSTRACT FROM AUTHOR]

Historical masonry structures are the most important features that distinguish our cultural heritage, from here comes the importance of protection this type of masonry structures from collapse under earthquakes effect or other dynamic loading such as blast loading. Therefore, Seismic Base Isolation is used to reduce earthquakes damages and protect structures from collapse. This paper aims to study the Effect of Seismic Base Isolation, using High Damping Rubber Bearing (HDRB) on Existing Masonry Structures subjected to dynamic loads such as earthquakes, through utilizing numerical modeling of masonry structures. This paper includes definition of seismic base isolation mechanical characteristics, and definition of numerical modeling approaches for structural masonry analysis. The studied masonry structure is the old AWQAF Directorate Building in Aleppo, which is islamic government building affiliated to the Syrian Ministry of AWQAF; In order to perform the numerical modeling, equivalent masonry properties used for this structure were also determined. This structure was analyzed applying nonlinear dynamic analysis-time history method, and reanalyzing it by using seismic base isolation, type HDRB applying the same method. The results of the two analyses were discussed and compared, and the conclusions of this paper showed reduction in shear force when using seismic base isolation, and reduction in stresses that appear in structure because the stresses are located in the level of base isolation system. [ABSTRACT FROM AUTHOR]

Unreinforced masonry (URM) buildings are quite popular worldwide due to their low construction costs, despite being susceptible to significant damage even from moderate earthquakes. In many cases, reconstruction may not be the most viable option due to financial and time constraints. Among the available retrofit solutions, steel-reinforced shotcrete (SRS) proves to be a cost-effective, straightforward, yet effective method for repair/retrofitting. This paper presents the results of an experimental study aimed at evaluating the effects of various construction conditions on the rebar pullout resistance of steel-reinforced shotcrete used as a retrofit method for URM walls. To achieve this, a total of 46 full-scale URM specimens were manufactured and tested, each consisting of a one-sided 50 mm-thick shotcrete layer with a single 8 mm steel rebar. The variables examined included the condition of the URM surface before the shotcrete application (wet/dry, with/without finishing including plaster/scratched plaster/oil paint), the condition of the rebar surface (rusty/clean), the type of rebar (plain/ribbed), rebar cover in the shotcrete layer (20/25/30 mm), and the URM substrate temperature before application of shotcrete (20 °C/-16 °C). The results indicate that there is an increase in pullout resistance of the specimens under the following conditions: when the wall's finishing is removed, the wall's surface is wetted before shotcrete application, ribbed steel rebar is utilized, and the temperature of URM before shotcrete application is 20 °C, there is an increase in pullout resistance of the specimens by 58 %, 56 %, 32 %, and 13 %, respectively. Additionally, when the steel rebar cover is sufficient, ribbed steel rebar is utilized, and this rebar is rusted, there is an increase in pullout resistance of the specimens by 55 %, 10 %, and 6 %, respectively.

Unreinforced masonry (URM) structure consisting of bricks and mortar suffers severe damage under impact loading, owing to its poor ductility and brittle failure modes. However, natural nacre with a similar structure to that of masonry exhibits superior mechanical properties through the well-designed assembly process. Therefore, a nacre-inspired design method, which hierarchically assembled bricks and engineered cementitious composites (ECC) into novel masonry walls at the macro-scale, was proposed in present study. The variations of the bionic measurements were experimentally explored. Test results demonstrated that the ductility and toughness of the novel masonry structure were dramatically improved by replacing mortar with ECC as horizontal joint and setting artificial local separations. The energy absorption of masonry wall and masonry beam were improved 5.66 times and 8.05 times, respectively. A theoretical frame model for hierarchically-assembled masonry was established, which considered the randomness of masonry and simulated the crack propagation. Finally, a numerical verification was conducted based on the frame model. This study lays the groundwork for applying the nacre-inspired design method in masonry structure to improve its shear properties in terms of ductility and toughness.

Seismic damage shows that the out-of-plane collapse of unreinforced masonry walls is very common. Especially in the teaching buildings, the out-of-plane collapse of the longitudinal load-bearing walls leads to the disproportionate collapse of the building, which results in serious loss of life and property. It is assumed that the in-plane stiffness of the unreinforced masonry floor system is infinite, and the effect of the integral bending of building on the story drift is ignored. The load-displacement relationship for out-of-plane of unreinforced wall under vertical dead load and horizontal seismic load was deduced with the bilinear constitutive relationship of masonry under compression, the second-order effect of vertical load on deformation being considered. The influence of axial compression ratio and the height-thickness ratio of the wall on the failure model and the load-displacement characteristics in the elastic state, ultimate state and collapse state were also studied. A theoretical method for the collapse mechanism and the aseismic design of the unreinforced masonry structure based on displacement was provided. This study has significant implications for the seismic performance design, post earthquake structural reinforcement, and seismic grade evaluation of unreinforced masonry structures.

Five existing unreinforced masonry buildings, built in different Italian cities in a relatively recent time frame, were selected to study the seismic behaviour of modern existing structures, not designed to withstand seismic actions. The buildings were modelled using an equivalent-frame approach, adopting, and comparing two nonlinear constitutive laws and introducing specific modelling strategies to represent the distinctive features of modern existing URM structures. Nonlinear static analyses were performed to determine capacity and multi-stripe time history analyses to evaluate displacement demand at increasing return periods. Although non-exhaustive, the results show a trend of generally decreasing seismic vulnerability for more recent buildings. [ABSTRACT FROM AUTHOR]

This study assessed the seismic damage to historical masonry towers using a three-dimensional finite element (FE) numerical model. The FE model was validated by comparing the dynamic characteristics and seismic analysis results with experimental data obtained using shaking table tests conducted on a 1/8 scaled tower model. Based on this analysis, a numerical analysis model of the damaged ancient brick masonry tower was established by introducing factors such as initial cracks and inclination, and the damage FE model was validated using experimental data provided by the shaking table tests. Subsequently, the damage index of the wall components were obtained using the modified Park–Ang damage model; these were used to obtain the damage indices of the historical tower floors, which were further used to obtain the overall damage indices of the historical tower. Furthermore, the performance levels of historical towers were proposed, and the damage indices at different performance levels were quantified using various parameters. Finally, the damage to the historical tower model in the shaking table test was analyzed based on the various quantitative results. [ABSTRACT FROM AUTHOR]

Summary: Reinforced concrete (RC) shear wall buildings with unreinforced masonry (URM) infilled moment frames are common in India and neighboring countries. This study assesses the influence of the URM infills on their seismic performance. Fully infilled, open first‐storied, and bare frame versions of a 25‐story shear wall building are considered. Multiple stripe analysis is conducted at five return periods to estimate their performance. Fragility functions for the collapse prevention limit state, which is based on seven engineering demand parameter exceedance thresholds, are generated and compared. The presence of infills (full or partial) is observed to have an overall positive effect on the performance of the RC frame‐shear wall buildings. The performance of the open first‐story building was comparable to that of the fully infilled building. The ratio of story shear carried by the moment frames and shear walls is studied at all return periods to understand the variation in frame shear wall interaction with increased damage for each building. In the case of buildings with infills, the frames carry a higher proportion of story shear at lower return periods. For all three buildings, the fraction of story shear carried by moment frames increases along the height of the building. [ABSTRACT FROM AUTHOR]

A new macro model for the finite element modeling of unreinforced masonry (URM) exhibiting in-plane nonlinear cyclic behavior is proposed. The ultimate objective is to predict the seismic response of multi-story URM buildings. The macro model enables the modeling of URM shear walls with a limited number of degrees of freedom (DOF) at low computation times. The macro model consists of a deformable elastic frame supported by diagonal struts with nonlinear behavior aiming to capture all dissipative phenomena occurring during seismic events. The nonlinear constitutive behavior of diagonal struts is inspired by models documented in the literature, ensuring a robust foundation for the proposed approach. This paper first provides a comprehensive review of the principal models currently available for URM analysis. It then articulates the rationale behind the development of this new numerical model, aiming to address the limitations encountered in existing methodologies and to offer a simple and fast tool for predicting the seismic behavior of URM buildings. Afterward, the new model is presented and tested with the simulations of two experimental campaigns performed on different URM walls. The comparison between experimental and numerical results shows that with a limited number of DOF and parameters, it is possible to obtain a prediction of the experimental results with satisfying accuracy. [ABSTRACT FROM AUTHOR]

This paper proposes an effective approach to realise circular construction with concrete, and shows Unreinforced Masonry as a foundational building block for it. The paper outlines the importance of circularity in building structures. It specifically focuses on the impact of circular construction with concrete on improving the sustainability of the built environment in a rapidly urbanising world economy. Subsequently, the relevance of principles of structural design and construction of unreinforced masonry to achieve circularity is articulated. Furthermore, the paper presents and summarises recent developments in the field of Unreinforced Concrete Masonry (URCM) including digital design tools to synthesise structurally efficient shapes, and low-waste digital fabrication techniques using lower-embodied-emission materials to realise the designed shapes. The paper exemplifies these using two physically realised, full-scale URCM footbridge prototypes and a commercially available, mass-customisable building floor element, called the Rippmann Floor System (RFS). The paper also outlines the benefits of mainstream, industrial-scale adoption of the design and construction technologies for URCM, including accelerating the pathway to decarbonise the concrete industry. In summary, the paper argues that URCM provides a solution to significantly mitigate the carbon emissions associated with concrete and reduce the use of virgin resources whilst retaining its benefits such as widespread and cheap availability, endurance, fire safety, low maintenance requirements and recyclability. [ABSTRACT FROM AUTHOR]

Post-seismic assessments have indicated that the responses of masonry walls to seismic forces may be classified into two key categories: in-plane global mechanisms and out-of-plane cyclical actions occurring orthogonally to the wall. The initial phase of this investigation scrutinized the widely accepted shear strength models for in-plane shear resistance, Vn, of reinforced masonry (RM) walls. Subsequently, using a dataset comprising 78 samples of fully grouted hollow concrete block (HCB) RM walls, a detailed examination of the sensitivity of experimental shear strength, V exp , to geometric, mechanical, and reinforcement characteristics of the wall was undertaken. The study's second phase entailed a parametric evaluation using finite element analysis to appraise the sensitivity of lateral drift to wall geometry and bed-joint reinforcement attributes. The third phase of the research introduced an informational model for estimating the lateral drift of partially grouted RM walls, incorporating BJ and vertical reinforcement. The model was established utilizing data from 44 full-scale in-plane cyclic tests on clay brick walls and 32 tests on HCB walls. The investigation further presented a multi-objective optimization methodology to ascertain the optimal vertical and BJR ratios, ρv and ρBJ. A graphical user interface and an accompanying empirical equation were also devised to simplify the analysis and design process for reinforced masonry walls, obviating the need for lengthy analyses. Increasing the BJR size from 6 to 8 mm resulted in a 30% increase in V n for specimens with six BJR rows, while increasing the number of BJR rows from six to ten led to 16% rise in V n , as demonstrated by numerical modeling validated against experimental tests.The findings of the study highlight a notable dependence of the lateral drift capacity of reinforced masonry walls on wall geometry and ρBJ ratio. These revelations provide invaluable insights for designing earthquake-resistant masonry edifices and formulating rehabilitation strategies for existing masonry structures deficient in seismic resilience. [ABSTRACT FROM AUTHOR]

An orthotropic homogenized model is used to investigate the in-plane elastic behavior of coated masonry walls. The homogenization process mainly consists of modeling the elementary cell of a three-layer medium by using suitable designed assemblies of in-parallel springs. On the basis of the latter, the stresses distributed between masonry and reinforcement coatings are analytically assessed after the determination of the average stress acting on the homogeneous medium. The precision of the theoretical outcomes is evaluated through comparisons with finite element (FE) models. Static and dynamic numerical analyses are carried out on both non-homogeneous and homogeneous FE models of sample systems. The homogeneous model is observed to adequately capture both the local and global behavior of reinforced masonry walls. Parametric analyses are also performed to investigate the effectiveness of reinforcement on the overall behavior of the system. [ABSTRACT FROM AUTHOR]

The demand for advanced nonlinear time‐history and seismic collapse simulations of old unreinforced masonry (URM) constructions to support informed risk evaluation and mitigation plans is rapidly increasing in the structural engineering profession. On one hand, offering cutting‐edge solutions based on the latest advances is challenging for practitioners, given the reduced timeframe usually available for projects and the specialized knowledge required. On the other hand, researchers frequently face difficulties in accessing old buildings and gathering key data required in complex numerical collapse analysis strategies. In this work, a pragmatic approach for evaluation of the earthquake collapse response of vulnerable old URM churches typical of the Northern Netherlands, now exposed to low‐magnitude induced seismicity due to gas extraction, is presented. To bridge the gap between academic and industry applications, an integrated framework is proposed that combines archival and onsite research, code‐based prescriptions, geometrical characterization and simplified discrete element modeling. Main outcomes include the identification of recurrent damage patterns for five old URM churches erected during the 11th, 13th, 14th, and 19th centuries, representative of key traditional multi‐leaf and cavity‐wall structural types, as well as relevant failure mechanisms and collapsed debris distributions for seismic signals of varying intensities. Produced results constitute a solid foundation of data on which to base the design of ad‐hoc retrofits and development of tailored risk assessment models. This study opens a new line of inquiry while discussing practical challenges and research questions which arose, to be of interest to both applied researchers and structural engineering professionals. [ABSTRACT FROM AUTHOR]

The present paper adopts a sophisticated numerical modeling technique using a plasticity-based simplified micro-model method and the extended finite element method for simulating the nonlinear behaviour of unreinforced masonry (URM) walls with different types of sizes and positions of openings. The validity of this model has been proven by comparing the results subjected to a similar loading obtained by the experimental approach. Thereafter, the validated computational model is used to study the behaviour of the 3D URM wall model with different opening percentages. The effect of the position of the openings is also studied. Further, the load–displacement curves are drawn to provide a clear idea about the load-carrying capacity of the same URM walls. The hysteretic behaviour obtained in each model under cyclic loading gives an idea about the energy dissipation capacity of each of the models studied. The same walls are analyzed by strengthening the walls with two cost-effective materials, wire mesh and polypropylene bands. Since the study on lateral behaviour of masonry walls, particularly regarding the effect of area and the position of the opening, is very rarely available, the present detailed study is believed to be helpful in reducing the seismic vulnerability of actual masonry structures, which always have openings with different sizes and positions. [ABSTRACT FROM AUTHOR]

Assessing the seismic vulnerability of existing buildings is an essential task for the management of earthquake disasters. For this purpose, the seismic behaviour of buildings is usually determined under the assumption of isolated conditions, although aggregate structures are one of the most common typologies found in urban centres. This study aims to investigate the nonlinear static behaviour of aggregate dwellings consisting of grouted reinforced concrete block configurations commonly observed in San José, Costa Rica. This research investigates the use of several strategies to model connections between adjacent buildings which are typically found in modern building practises in this country. The methodology used here to analyse the seismic behaviour of isolated and row-aggregated dwellings reveals significant differences in their response under seismic loads, especially when acting perpendicular to the aggregate. The study reveals that the type of interaction considered between adjacent buildings has a very important impact on the seismic capacity and failure mechanisms of the aggregated structures. This procedure can also be applied to the vulnerability assessment and retrofit of existing aggregates. [ABSTRACT FROM AUTHOR]

In recent years, Fabric-Reinforced Cementitious Mortar (FRCM) has gained widespread application for strengthening reinforced concrete and masonry structures. This research investigated the influence of microfibre parameters on the tensile characteristics of FRCM, focusing on the fibre type, length, and volume fraction. Three distinct types of microfibres were scrutinized: amorphous metallic (AM) fibres, polyvinyl alcohol (PVA) fibres, and nylon fibres. FRCM coupons were designed and fabricated based on the AC434 standard. A tensile experimental program, following RILEM TC232-TDT, revealed the pronounced advantage of employing AM fibres in the pre-cracking stage by significantly improving the crack stress up to 226% and pre-cracking stiffness of FRCM. Conversely, synthetic fibres such as nylon and PVA were beneficial in the post-cracking stage by enhancing cracked stiffness, peak stress, and tensile toughness. Additionally, it was found that using fibres with shorter lengths improved the tensile behavior of FRCM composites in the post-cracking stage due to better random distribution in the cement-based matrix. Finally, an artificial neural network (ANN) model was proposed to predict the tensile parameters of the FRCM composites incorporating microfibres. [ABSTRACT FROM AUTHOR]

Following recent earthquakes, precast buildings exhibited a strong seismic vulnerability related to the presence of closure external panels. The aim of this work is to simulate the seismic response of existing single-storey precast buildings in the case of explicit modelling of external panels. The considered case studies are precast buildings representative of the Italian building stock in the 1970s and 1990s, characterised by two different cladding systems, namely, masonry infills and reinforced concrete precast panels, respectively. The explicit modelling of infills and panels, typically introduced solely as participating masses, provided insights into their actual contribution on the global structural behavior. [ABSTRACT FROM AUTHOR]

Moisture in historic built heritage is one of the main degenerative agents, because it supports or manifests itself through multiple pathologies. Current knowledge allows for the diagnosis and assessment of the problem, but there are deficiencies in the evaluation of corrective systems due to the time it takes for moisture to become significant. In response, this study proposes an experimental methodology that aims to reproduce the accelerated aging of real scale specimens under laboratory conditions. Thereby improving the understanding of the impact of moisture related deterioration on masonry structures. To achive this, eight masonry walls were constructed and subjected to eight cycles of sulfate crystallization. They were saturated with different sulfate concentrations (5% or 10%) and exposed to different drying conditions (outdoor or solar dehydrator) in order to identify the factors favoring sulfate crystallization and the resulting deterioration. The progress of the experiments was monitored using a hygrometer, a thermographic camera and photogrammetry. The results indicate that it is possible to induce efflorescence in real scale specimens. Temperature and moisture monitoring helped identify the solar dehydrator as a more effective drying treatment. While digital photogrammetry was considered inefficient for quantifying volumetric damage, since this technique can present errors greater than 2%, a value exceeding the observed wear. Reason why the weight of material detached at the end of the experiment was recorded and a positive correlation between the increase in sulfate concentration and the use of the dehydrator was observed. Finally, pertinent considerations are made to improve the experimental conditions. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of a range of timber-based solutions for the seismic and energy retrofitting of existing masonry buildings. These solutions are designed not only to prevent structural collapse during earthquakes but also to create integrated interventions that enhance thermo-physical performance and reduce emissions in existing buildings. Various case scenarios were considered and both mechanical and energetic behaviour post-intervention were evaluated. Timber-engineered products serve as foundational components for the retrofit approach, encompassing one-dimensional vertical elements (strong-backs) and various types of panels (cross-laminated timber panels, laminated veneer lumber panels, and oriented strand board panels). The analyzed retrofit techniques share a common principle involving the attachment of these timber-based elements to the building's wall surfaces through mechanical point-to-point connections. The proposed solutions integrate strong-backs and timber panels with membranes and insulation layers, yielding cohesive, and highly effective interventions. Finite element modeling was employed to analyze the mechanical and thermal responses of the retrofitted walls. A comprehensive comparative analysis of various techniques was conducted to determine the most effective solution for each specific scenario. [ABSTRACT FROM AUTHOR]

Unreinforced masonry (URM) walls are common load-bearing structural elements in most existing buildings, consisting of masonry units (bricks) and mortar joints. They indicate a highly nonlinear and complex behaviour when subjected to combined compression–shear loading influenced by different factors, such as pre-compression load and boundary conditions, among many others, which makes predicting their structural response challenging. To this end, the present study offers a discontinuum-based modelling strategy based on the discrete element method (DEM) to investigate the in-plane cyclic response of URM panels under different vertical pressures with and without a damp-proof course (DPC) membrane. The adopted modelling strategy represents URM walls as a group of discrete rigid block systems interacting along their boundaries through the contact points. A novel contact constitutive model addressing the elasto-softening stress–displacement behaviour of unit–mortar interfaces and the associated stiffness degradation in tension–compression regimes is adopted within the implemented discontinuum-based modelling framework. The proposed modelling strategy is validated by comparing a recent experimental campaign where the essential data regarding geometrical features, material properties and loading histories are obtained. The results show that while the proposed computational modelling strategy can accurately capture the hysteric response of URM walls without a DPC membrane, it may underestimate the load-carrying capacity of URM walls with a DPC membrane. [ABSTRACT FROM AUTHOR]

Carbon fibre-reinforced polymer (CFRP) emerges as a viable solution for reinforcing unreinforced masonry (URM) walls subjected to shear loads. While masonry structures are straightforward to construct, the complexity of the construction materials, especially in terms of their mechanical properties, poses challenges for numerical studies of their structural behaviour. Walls, being fundamental components in masonry construction, play a crucial role in transferring both horizontal and vertical lateral forces. This study investigates the enhancement of masonry wall behaviour through the reinforcement of CFRP. CFRP reinforcement increases ductility and strength, reducing the risk of failure under shear conditions. Additionally, CFRP composites present a practical solution to strengthening masonry structures compared to traditional reinforcement. However, brick, mortar, and CFRP have not been thoroughly investigated. Experimental tests on the bond behaviour of different configurations of CFRP-retrofitted masonry triplets have not been performed before and are therefore presented in this paper. Triplet specimens, comprising three bricks and two mortar joints, both with and without CFRP strengthening, were subjected to bond testing. The study affirms that masonry triplets strengthened with CFRP under shear loads exhibit strength levels at least four to six times greater than those without CFRP. The experimental work was carried out with eight different CFRP configurations on triplet masonry, and each test was repeated four times. Further, the bond stress-slip relationship in the case of masonry triplets with and without CFRP was predicted with new mathematical equations based on the conducted test results. These equations were included in the commercial finite element software ANSYS and used to conduct simulations of CFRP-reinforced masonry triplets. The numerical results indicate good agreement between the finite element model and the test results. The outcome of this research improves the current knowledge on the use of CFRP to reinforce masonry walls with brick and mortar, which will contribute to the understanding of the effect of CFRP on masonry structures. [ABSTRACT FROM AUTHOR]

Seismic loads pose a great risk to existing masonry buildings. Modern seismic control methods that are being increasingly used today, rather than various traditional strengthening methods, appear in the retrofit of existing masonry structures. The use of seismic control in existing masonry buildings increases the functionality of the building and obviates the need for additional structural requirements. Particularly, seismic control methods are superior because they contain the least possible interventions to architectural details. On the other hand, these methods are a unique option in sensitive structures such as historical masonry structures. In this research, base isolation systems, energy-damping systems, and hybrid systems as well as architectural application details of seismic control methods in masonry structures are discussed in the context of architectural details. [ABSTRACT FROM AUTHOR]