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Masonry structures are highly vulnerable to collapse when subjected to blast shock waves. However, existing research primarily concentrates on the response of masonry walls under blast loading, with limited investigation into the response of three-dimensional full-size masonry structures. Therefore, this paper investigates the effects of blast distance and blast equivalent on masonry structure damage using the continuum-discontinuum element method (CDEM). The integration of the HJC element constitutive model, fracture energy contact surface constitutive model, and shock wave fast imposition algorithm into CDEM enables efficient calculation of the damage process of masonry structures under the influence of shock waves. Initially, the blasting process of a masonry wall was numerically simulated, yielding results consistent with experimental findings. Subsequently, the entire damage process of a 3D full-size masonry structure under blast loading was simulated. The findings indicate that at short distances from the blast, the wall may detach directly from the concrete frame due to shock wave overpressure reaching the material's ultimate compressive strength, leading to structural instability. As the distance increases beyond a critical value, the shock wave's effect weakens, and wall damage transitions gradually to bending damage. [ABSTRACT FROM AUTHOR]

Perforated clay brick masonry is a popular and widely used construction, offering both structural and aesthetic benefits. The structural behavior of perforated clay brick masonry walls is a significant topic in the field of civil engineering. However, understanding the compressive and tensile strength of these walls are influenced by various factors such as the quality of mortar joints, the distribution of mortar, and the presence of reinforcement. The purpose of this study is to investigate the compressive behavior of four perforated clay brick masonry walls, using cement-sand mortar, with two different systems under in-plane compression load. The first masonry system is unreinforced with filling joints, and the other system is reinforced by steel bars embedded in the mortar as a low reinforcement ratio. The study provided valuable arguments about how mortar distribution affects wall performance, which is significantly impacted by poor quality of head joints and the fully or partially distributed mortar in the masonry joints. Also, the role of low reinforcement ratio within the construction industry has important effect. The mentioned parameters are investigated through practical case studies demonstrating their effects in the context of ductility and ultimate load capacity. It was found that the compressive strength of the unreinforced masonry system is highly increased to the distribution of the mortar by 35 % and 133% for filling all holes in brick units and the head joints, respectively, due to increasing the bonding between brick units in the masonry wall specimen. In the reinforced masonry system, the utilization of a low reinforcement ratio is increased the ultimate load capacity by 60% and decreased the ultimate displacement by 54%., but it is no longer provided significant changes to the ductility.

Recently, deteriorated masonry structures aged over 30 years have shown serious structural problems. Simple and rapid maintenance plans are urgently needed for aging masonry structures. Polyurea (PU) is an effective retrofitting material for aging structures due to its easy spray application. This process saves time, reduces costs, and allows the structure to remain in use during retrofitting. However, a general PU is not suitable for retrofitting aged masonry and concrete structures due to its low stiffness. In this study, stiff-type polyurea (STPU) was selected as the reinforcement material for masonry structures. It was developed by modifying the chemical mix of general PU to improve stiffness. To evaluate the strengthening effect of STPU on masonry members under static loading, tests were conducted. The flexural load capacity of masonry beams with STPU-sprayed surfaces was assessed. Three different types of STPU applications were used to select the most efficient strengthening method. Reinforcing masonry structures with STPU allows brittle failure modes to achieve ductile behavior. This improves their structural performance under lateral stresses. The experimental data were used to calibrate FEM models for simulation. These models can be used for future parametric studies and masonry structural design. [ABSTRACT FROM AUTHOR]

Copyright of Kufa Journal of Engineering is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Frequent seismic events have demonstrated that building collapse is primarily caused by the loss of load-bearing capacity in vertical structural members. In response to this risk, various national design codes have been established. This study conducted field investigations at an earthquake site in Luding County, Sichuan Province, which was struck at a magnitude of 6.8 on 5 September 2022. In this case, the lower x-direction load-bearing wall of the Tianyi Hotel suffered severe shear damage, and the building was on the verge of collapse. However, no obvious damage was seen in the elementary school dormitory. Numerical simulation analysis revealed that during the earthquake, the buildings primarily experienced y-direction displacement in the x-direction, with significant differences in the stress state among different axes. In the model of Tianyi Hotel, the x-direction load-bearing walls suffered shear damage, while the frame columns were still in the elastic stage. At this point, the shear force of the walls was 6–9 times that of the frame columns. Comparing the damage characteristics of the two buildings during the earthquake, it was found that different structural forms lead to different internal force distributions. This phenomenon is further interpreted through the principle of "deformation saturation", with core structural components being modeled and tested using quasi-static experiments. The results indicated substantial differences in material properties among different structural forms, including variations in lateral stiffness, ultimate load-bearing capacity, and maximum displacement. Moreover, at the same floor level, components with smaller ultimate displacements are decisive of the overall structural stability. To ensure seismic resilience and stability, it is essential to consider not only the load-bearing capacity but also the rational arrangement and cooperative interactions between different components to achieve a balanced distribution of overall stiffness. This approach significantly enhances the building's resistance to collapse. [ABSTRACT FROM AUTHOR]

Arches and vaults are typical elements of ancient buildings. They are formed by voussoirs that resist the pressure they receive and transmit them through compression forces. The transmission of these forces justifies their curved shape. For this reason, arches and vaults are omnipresent elements in ancient constructions, all of them masonry structures. However, when visitors enter the Basilica of the Monastery of El Escorial, they find a narthex with a flat or planar vault. This vault is located under the floor of the choir loft. Its geometric characteristics and its shape, with no curvature, make it an architectural anomaly and a brilliant solution within masonry structures. Therefore, this article tries to analyse the construction process and structural behaviour of this vault, to understand its operation and how it remains standing five hundred years after its construction. [ABSTRACT FROM AUTHOR]

A novel less-destructive field impression method that overcomes the uncertainties in stability assessments of rock joints in historical monuments, due to material sampling or existing destructive test limitations, has been developed. A thermoplastic resin with low fluidity and a short curing time is used to obtain the surface morphology of rock joints owing to its less destructive nature and wide applicability to the walls and ceilings of historical monuments. However, the insufficient filling of this thermoplastic resin can decrease the geometric accuracy of the impressions. Thus, the geometric accuracy of resin impressions and mortar replicas has been examined through laboratory experiments, and the results have been compared with those obtained using existing silicone-based methods, based on the statistical indicators associated with mechanical replicability. The indicator values of the method developed in this study were comparable to those of the replicas in previous studies that have sufficient geometric accuracy to satisfy mechanical replicability requirements. Furthermore, although roughness-coefficient-based methods underestimate the shear strength because of the insufficient filling of thermoplastic resins, they provide an acceptable safety margin in stability assessments of rock joints. The proposed method is suitable for conducting accurate stability assessments of historical monuments and ensuring their conservation.

Frequent seismic events have demonstrated that building collapse is primarily caused by the loss of load-bearing capacity in vertical structural members. In response to this risk, various national design codes have been established. This study conducted field investigations at an earthquake site in Luding County, Sichuan Province, which was struck at a magnitude of 6.8 on 5 September 2022. In this case, the lower x-direction load-bearing wall of the Tianyi Hotel suffered severe shear damage, and the building was on the verge of collapse. However, no obvious damage was seen in the elementary school dormitory. Numerical simulation analysis revealed that during the earthquake, the buildings primarily experienced y-direction displacement in the x-direction, with significant differences in the stress state among different axes. In the model of Tianyi Hotel, the x-direction load-bearing walls suffered shear damage, while the frame columns were still in the elastic stage. At this point, the shear force of the walls was 6–9 times that of the frame columns. Comparing the damage characteristics of the two buildings during the earthquake, it was found that different structural forms lead to different internal force distributions. This phenomenon is further interpreted through the principle of “deformation saturation”, with core structural components being modeled and tested using quasi-static experiments. The results indicated substantial differences in material properties among different structural forms, including variations in lateral stiffness, ultimate load-bearing capacity, and maximum displacement. Moreover, at the same floor level, components with smaller ultimate displacements are decisive of the overall structural stability. To ensure seismic resilience and stability, it is essential to consider not only the load-bearing capacity but also the rational arrangement and cooperative interactions between different components to achieve a balanced distribution of overall stiffness. This approach significantly enhances the building’s resistance to collapse.

This study presents the most recent development of a nationwide earthquake risk model for non-engineered masonry buildings in Malawi. Due to its location within the East African Rift, Malawi experienced several moderate earthquakes that caused seismic damage and loss. Recently, a new probabilistic seismic hazard model has been developed by considering fault-based seismic sources, in addition to conventional areal sources. The most recent 2018 national census data provide accurate exposure information for Malawian people and their assets at detailed spatial resolutions. To develop seismic fragility functions that are applicable to Malawian housing stocks, building surveys and experimental tests of local construction materials have been conducted. By integrating these new developments of seismic hazard, exposure, and vulnerability modules, a quantitative seismic building collapse risk model for Malawi is developed on a national scale. For the rapid computation of seismic risk curves at individual locations, an efficient statistical approach for approximating the upper tail distribution of a seismic hazard curve is implemented. Using this technique, a seismic risk curve for a single location can be obtained in a few seconds, thereby, this can be easily expanded to the whole country with reasonable computational times. The results from this new quantitative assessment tool for seismic impact will provide a sound basis for risk-based disaster mitigation policies in Malawi. [ABSTRACT FROM AUTHOR]

This study presents the most recent development of a nationwide earthquake risk model for non-engineered masonry buildings in Malawi. Due to its location within the East African Rift, Malawi experienced several moderate earthquakes that caused seismic damage and loss. Recently, a new probabilistic seismic hazard model has been developed by considering fault-based seismic sources, in addition to conventional areal sources. The most recent 2018 national census data provide accurate exposure information for Malawian people and their assets at detailed spatial resolutions. To develop seismic fragility functions that are applicable to Malawian housing stocks, building surveys and experimental tests of local construction materials have been conducted. By integrating these new developments of seismic hazard, exposure, and vulnerability modules, a quantitative seismic building collapse risk model for Malawi is developed on a national scale. For the rapid computation of seismic risk curves at individual locations, an efficient statistical approach for approximating the upper tail distribution of a seismic hazard curve is implemented. Using this technique, a seismic risk curve for a single location can be obtained in a few seconds, thereby, this can be easily expanded to the whole country with reasonable computational times. The results from this new quantitative assessment tool for seismic impact will provide a sound basis for risk-based disaster mitigation policies in Malawi.

The collection of relevant information about the vulnerability of infrastructure damaged by landslides is not an easy task due to the existence of several compounding factors and uncertainties. This makes it difficult to quantitatively estimate their vulnerability to slow-moving landslides. This paper presents a new vulnerability assessment model for masonry buildings on slow-moving landslides based on physical models and field observations. A masonry building model is made of brick and concrete at a scale of 1:10 to physically simulate the damage in structures caused by ground tension cracks commonly developed on slow-moving landslides. The tension crack opening process is simulated through a load-controlled table with an aperture on which the building model is constructed. The strain on the wall and its foundation were measured, and the damage of the model (crack formation and evolution for each loading step) was collected, described, and analyzed. These data were used to develop failure criteria for masonry buildings in rural areas in China in terms of a quantitative vulnerability curve. The quantitative model of vulnerability for masonry structures was established based on fuzzy mathematics and the Weibull function applied on the test data and observations. The vulnerability curve is verified with field cases of masonry buildings damaged by ground tension cracks associated with slow-moving landslides in the Three Gorges Reservoir area. The results support further testing and use of vulnerability curve proposed. [ABSTRACT FROM AUTHOR]

Considering the structural types and construction techniques used in common residential buildings in Xinjiang, the paper proposes a novel masonry structure, i.e., desert-sand AAC blocks constrained by a precast integral construction column. In order to study the seismic performance of the structure, five wall specimens with different constraints are designed and fabricated and further compared and analyzed in terms of failure mode, hysteretic performance, energy dissipation capacity, ductility, stiffness degradation, and other performance indexes. It has been determined from the results that under horizontal low-cycle repeated loading, the main failure cracks of the desert-sand AAC block wall constrained by the precast integral construction column are intersecting oblique cracks, and the cracks in wall failure penetrate along concrete blocks. The stiffness degradation rate of the wall constrained by the water-resistant gypsum construction column gradually decreases with increasing vertical compressive stress. The wall constrained by the water-resistant gypsum construction column with arranged steel bars has a desirable ductility. Under the same vertical compressive stress, the wall constrained by the water-resistant gypsum precast construction column with arranged steel bars has a significant energy dissipation capacity from cracking to the ultimate state. (4) A restoring force model is built for desert-sand AAC block walls constrained by the precast integral construction column using a three-fold line model, offering technical support for the elastoplastic seismic analysis of structures. [ABSTRACT FROM AUTHOR]

The aim of the current study is to evaluate the effectiveness of the watershed management operations by using the quantitative values obtained from the field survey in Khor-Sefidarak, Fashand, and Azimiyeh watersheds, and indicating a clear result of deposited sedimentation rate and vegetation improvement in reservoir tank of the structures. Field evaluation of watershed management structures showed that since 1991, a total of 652 gabion structures, 20 masonry structures, 533 small stone structures, and 15 embankment dams have been implemented in Khor-Sefidarak, Fashand, and Azimiyeh watersheds of Alborz province. A study of the stability of the structures showed that masonry structures had the most stability with the least need for restoration (92% of them). Also, 80% of gabion structures and 83% of small stone structures in the studied watersheds were stable. The study of sediment deposition in reservoirs tanks of structures in the study area showed that a total of 332,100 m3 of sediment has been deposited and stabilized by the structures and has prevented its transferring to rural and urban residential areas. Of this amount, 45960 m3 have been deposited by embankment dams and 286140 m3 by masonry structures, gabion and small stone structures. Sediment volume to structure volume index showed that it was 4.4, 15.3, and 1 for gabion, masonry, and small stone structures, respectively. Evaluation of vegetation and tree cover development of whining reservoirs tanks of watershed structures showed that 4880 trees and seedlings (97% of all them) have been grown and developed in the reservoirs of gabion structures. If the gabion structures are constructed, it is suggested that they be constructed in non-stone beds, and cement cover be used to prevent their destruction.

Rehabilitation and strengthening of existing masonry structures can improve their safety, prolong life and save economic costs. In this study, a total of eighteen masonry column specimens strengthened by ultra-high performance concrete (UHPC) were fabricated and tested in compression. The effects of strengthening method, strengthening thickness and loading eccentricity were investigated. The failure mode, bearing capacity, strain, ductility, and energy dissipation were discussed in before and after strengthening to evaluate the UHPC strengthening effectiveness. A three-dimensional numerical model established using finite element analysis (FEA) was validated with the experimental results. Results indicated that the brittle failure of masonry columns in compression could be significantly avoided using UHPC strengthening. Among three methods of strengthening, hoop strengthening was the most effective in increasing the ultimate load, ductility, and dissipated energy of masonry columns by 185.81%, 49.09%, and 297.12%, respectively. With the strengthening thickness increased from 0 to 20 and 30 mm, the ultimate bearing capacity of masonry columns was respectively increased by 29.17% and 117.26%, while the corresponding lateral displacement was decreased by 32.44% and 37.24%, respectively. The horizontal buckling of masonry columns can be relieved by UHPC, and the increase in eccentricity did not weaken the contribution of UHPC in strengthened masonry columns. The numerical results were in good agreement with the test results, with errors below 7.6%.

Arches and vaults are typical elements of ancient buildings. They are formed by voussoirs that resist the pressure they receive and transmit them through compression forces. The transmission of these forces justifies their curved shape. For this reason, arches and vaults are omnipresent elements in ancient constructions, all of them masonry structures. However, when visitors enter the Basilica of the Monastery of El Escorial, they find a narthex with a flat or planar vault. This vault is located under the floor of the choir loft. Its geometric characteristics and its shape, with no curvature, make it an architectural anomaly and a brilliant solution within masonry structures. Therefore, this article tries to analyse the construction process and structural behaviour of this vault, to understand its operation and how it remains standing five hundred years after its construction.

The Tower of Hercules is an icon of the city where it is located, A Coruña, and it is supposed to be the world's only surviving Roman lighthouse. Its function continues today: it provided a warning to shipping in antiquity and continues to do so now, in the 21st century. Furthermore, it is a paradigmatic case of architectural intervention in an ancient monument: in the 18th century, the Spanish engineer Eustaquio Giannini restored the tower, applying scientific criteria and maintaining the authenticity of the monument. For all these reasons, the Tower of Hercules is an exceptional benchmark through which the development and evolution of the different signaling and navigation aid systems can be studied from the beginning of our era to the present day. [ABSTRACT FROM AUTHOR]

Polyurea elastomer has unique molecular structure, good energy absorption characteristics and excellent mechanical properties in terms of tear strength, tensile strength and breaking elongation. A large number of studies have shown that polyurea elastomer can effectively reduce the destructiveness of the structure under explosive load. Therefore, the research on polyurea elastomer relating to blast protection is becoming more and more extensive. In this paper, the microstructure of polyurea elastomer was briefly introduced, and its mechanical properties at different strain rates were described. Besides, based on the excellent mechanical properties of polyurea elastomer, the research progress of polyurea elastomer relating with blast protection was reviewed from the aspects of masonry structure and steel structure. The analysis showed that polyurea elastomers would become a research hotspot in blast protection field due to their excellent mechanical properties and good energy absorption characteristics and would have broad development prospects in practical engineering applications.

In the case of fire, ordinary mortar as the external plastering layer of masonry structure is prone to explosive peeling at high temperature. Therefore, the hybrid fiber reinforced engineered cementitious composites (HECC) is used to replace the ordinary mortar plastering to strengthen masonry structure, so as to improve the mechanical properties of the masonry structure and the adhesion with the reinforcement layer. In this paper, PB-HECC (mixed with PVA and basalt fibers) and PS-HECC (mixed with PVA and steel fibers) are used to improve the mechanical properties after high temperature, prism compression test and triple shear test are carried out at different temperatures. The test results show that the bonding performance of the engineered cementitious composites (ECC) reinforcement layer is much better than that of ordinary mortar. When the temperature is less than 200°C, the reinforcement layer mixed with basalt fiber (PB group) or steel fiber (PS group) has a higher bearing capacity. PB group has strong energy consumption capacity, but its shear strength decreases the most; When the temperature exceeds 200°C, PS group has the highest compressive capacity, shear bearing capacity and deformation capacity, maintaining relatively good residual mechanical properties. [ABSTRACT FROM AUTHOR]

The report summarizes the observed damage to a variety of buildings near the epicenter of the M6.8 Luding earthquake in Sichuan Province, China. They include base-isolated buildings, multi-story reinforced concrete (RC) frame buildings, and masonry buildings. The near-field region is known to be tectonically highly active, and the local intensity level is the highest, that is, 0.4g peak ground acceleration (PGA) for the design basis earthquake, in the Chinese zonation of seismic ground motion parameters. The extent of damage ranged from the weak-story collapse that claimed lives to the extensive nonstructural damage that suspended occupancy. The report highlights the first observation of the destruction of rubber bearings and viscous dampers in the isolation layer of Chinese seismically isolated buildings. It also features the rare observation of the brittle shear failure of RC columns in moment-resisting frames in a region of such a high seismic design requirement. Possible reasons that may have attributed to the reported damage are suggested by providing facts observed in the field. However, careful forensic analyses are needed before any conclusive judgment can be made.

This paper reports an approach to seismic performance evaluation for masonry structures using linear, nonlinear, and kinematic limit analyses. Considering the analysis results, a retrofitting proposal using fiber-reinforced polymer composites was made. All examinations and strengthening interventions were carried out for a masonry restaurant building currently in use. First, a structural model of the building was prepared based on the current seismic codes. In the second stage, the seismic performance of the building was determined using global and local analysis approaches. The shear force and relative story drift ratios were compared using the limit values given in the seismic code. In addition, local failure mechanisms were determined. Accordingly, the structural strength of the building was found to be insufficient. Therefore, a fiber-reinforced polymer -strengthened design proposal was presented. In order to determine the effectiveness of the proposed strengthening, linear and nonlinear analyses were made based on the strengthened state. In this study, the analysis methods used to assess the seismic performance of a masonry building and strengthening proposal can make significant contributions to construction engineers and architects for the rehabilitation of masonry structures.

Experimental identification of stiffening walls is often limited to studying single-wall models. However, these samples do not reflect many additional effects—torsion of the building and redistribution of internal forces. This paper presents the results of two full-scale buildings made of autoclaved aerated concrete (AAC) masonry elements. The primary purpose of the work was to determine the changes in the stiffness of the shear walls and to attempt the empirical distribution of loads on the stiffening walls. The intermediate goals were: a description of the crack morphology and the mechanism of failure, the designation of the stiffening walls' behavior. It was shown that the first crack formed in the tensile corner of the door opening, and the subsequent cracks formed in the wall without a hole. Based on the changes in the value of the shear deformation angles, the phases of work of the stiffening walls were determined. The presented research results are only a part of an extensive study of stiffening walls in masonry buildings conducted at the Silesian University of Technology. [ABSTRACT FROM AUTHOR]

In masonry structures, determination of a structural behavior and load-bearing capacity becomes quite complicated when irregular wall bond patterns and the damages developing in load-bearing elements are considered, as well as the unclear in the material parameters. In these cases, preferring simplified approaches in a numerical analysis allows to obtain solution practically. In this study, in-plane damage developments and load-bearing capacities of masonry structure were tried to be determined using a numerical analysis model consisting of truss elements. In this method, which was proposed as an innovative approach in terms of use in masonry structures, frame elements that only load-bearing in the direction of the longitudinal axis were used. Thus, in the structure, it was aimed to obtain the maximum load-bearing capacity and damages that may occur, under external loads with the nonlinear analyzes performed by the equivalent calculation model. In the study based on masonry structures discussed in the literature previously, the advantages and disadvantages of the method were evaluated comparatively. Although the ductility response of a real structure couldn't be fully represented, it was observed that the maximum load-bearing capacity and damage formation zones could be determined with acceptable accuracy. Consequently, the equivalent truss model approach, which is proposed as an alternative to the commonly preferred detailed modeling procedures, is promising. [ABSTRACT FROM AUTHOR]

Recent years have witnessed increasingly complex circumstances like shield passing buildings and underground structures at close range in urban tunnel design and construction. This paper has analyzed the short-distance side-crossing masonry structure engineering of the shield tunnel of Zhengzhou Metro Line 5. Using field measurement method, surface settlement, settlement and distortion of masonry structure during the construction process of double-line parallel shield tunnels successively superimposed and side-passed through the existing masonry structures, were studied. According to finding, when the construction of the double-line tunnel was completed, the maximum value of surface settlement still occurred near the centerline of the first tunnel. It was expected to make reasonable calculations and assessments for the safety of masonry structures after shield crossing construction and provide reference for similar projects in future.

The shake table test is one of the preferred techniques used to understand the dynamic response of a structure. However, due to the limited number of facilities available to perform such tests and their expensiveness, researchers often must rely on numerical models validated with the results of the static tests only. Moreover, most research papers concerning shake table tests lack details on how the tests were planned and executed. This paper explains the steps used for the preparation and execution of shake table tests on three reduced-scale buildings. These buildings were constructed outside the shake table surface, on a metallic base frame, and later moved to the shake table used for the tests in order to optimize the time of the experimental campaign. This approach enabled us to complete the tests in only 6 days. The approach presented in this paper may be helpful to researchers who want to increase the effectiveness of the available shake table facility and overcome the limitations of time and budget. Moreover, the solution presented in this article helps in the displacement of specimens without the use of a crane or other sophisticated hydraulic machinery. Thus, it could also be useful for testing specimens that have been aged and that are sensitive to displacements. [ABSTRACT FROM AUTHOR]

The Tower of Hercules is an icon of the city where it is located, A Coruña, and it is supposed to be the world’s only surviving Roman lighthouse. Its function continues today: it provided a warning to shipping in antiquity and continues to do so now, in the 21st century. Furthermore, it is a paradigmatic case of architectural intervention in an ancient monument: in the 18th century, the Spanish engineer Eustaquio Giannini restored the tower, applying scientific criteria and maintaining the authenticity of the monument. For all these reasons, the Tower of Hercules is an exceptional benchmark through which the development and evolution of the different signaling and navigation aid systems can be studied from the beginning of our era to the present day.

The seismic performance of indoor water supply pipes plays a significant role during earthquakes, and the failure of pipes causes severe economic losses and other disasters. This paper presents shaking table test research on water supply pipes installed in a full-scale masonry structure. Three different material pipes and three different material fillers were combined to evaluate the difference in seismic performance. In this study, normalized floor response spectra and pipe acceleration amplification factors obtained from experimental data were compared with code provisions. Spectrum analysis was used to evaluate the pipeline seismic response, and the results showed that the combination of pipes and fillers with similar material properties vibrated partially at multiple frequencies. In contrast, the combination of pipes and fillers with very different material properties only vibrated near the predominant structural period. [ABSTRACT FROM AUTHOR]

The impact of floods can be devastating to buildings, especially in countries and villages in mountainous areas. Based on the flood impact risk analysis results, two methods are suggested by authors to improve the flood impact defense capability of rural buildings in this paper: increasing the strength of the mortar used in masonry structures, as well as adding reinforced concrete (RC) columns and circle beams to masonry structures. The impact of floods on the reinforced masonry structures is simulated numerically, and the failure process, stress, and deformation behaviors of masonry structures are analyzed. Compared to the computational results of normal masonry structures, the advantages of the two methods proposed in this manuscript are studied. Increasing the mortar strength slows the rate of damage to the masonry structure but does not improve the deformation or the failure behaviors. Increasing the mortar strength slightly decreases the first principal stress on the mortar and brick elements but has no effect on the third principal stress. Adding the RC frames not only delays the damage to the building and improves the failure behavior of the masonry structure but also decreases the first and third principle stresses of the brick and mortar elements. [ABSTRACT FROM AUTHOR]

The impact of floods can be devastating to buildings, especially in countries and villages in mountainous areas. Based on the flood impact risk analysis results, two methods are suggested by authors to improve the flood impact defense capability of rural buildings in this paper: increasing the strength of the mortar used in masonry structures, as well as adding reinforced concrete (RC) columns and circle beams to masonry structures. The impact of floods on the reinforced masonry structures is simulated numerically, and the failure process, stress, and deformation behaviors of masonry structures are analyzed. Compared to the computational results of normal masonry structures, the advantages of the two methods proposed in this manuscript are studied. Increasing the mortar strength slows the rate of damage to the masonry structure but does not improve the deformation or the failure behaviors. Increasing the mortar strength slightly decreases the first principal stress on the mortar and brick elements but has no effect on the third principal stress. Adding the RC frames not only delays the damage to the building and improves the failure behavior of the masonry structure but also decreases the first and third principle stresses of the brick and mortar elements.

A novel less-destructive field impression method that overcomes the uncertainties in stability assessments of rock joints in historical monuments, due to material sampling or existing destructive test limitations, has been developed. A thermoplastic resin with low fluidity and a short curing time is used to obtain the surface morphology of rock joints owing to its less destructive nature and wide applicability to the walls and ceilings of historical monuments. However, the insufficient filling of this thermoplastic resin can decrease the geometric accuracy of the impressions. Thus, the geometric accuracy of resin impressions and mortar replicas has been examined through laboratory experiments, and the results have been compared with those obtained using existing silicone-based methods, based on the statistical indicators associated with mechanical replicability. The indicator values of the method developed in this study were comparable to those of the replicas in previous studies that have sufficient geometric accuracy to satisfy mechanical replicability requirements. Furthermore, although roughness-coefficient-based methods underestimate the shear strength because of the insufficient filling of thermoplastic resins, they provide an acceptable safety margin in stability assessments of rock joints. The proposed method is suitable for conducting accurate stability assessments of historical monuments and ensuring their conservation. [ABSTRACT FROM AUTHOR]

Recent years have witnessed increasingly complex circumstances like shield passing buildings and underground structures at close range in urban tunnel design and construction. This paper has analyzed the short-distance side-crossing masonry structure engineering of the shield tunnel of Zhengzhou Metro Line 5. Using field measurement method, surface settlement, settlement and distortion of masonry structure during the construction process of double-line parallel shield tunnels successively superimposed and side-passed through the existing masonry structures, were studied. According to finding, when the construction of the double-line tunnel was completed, the maximum value of surface settlement still occurred near the centerline of the first tunnel. It was expected to make reasonable calculations and assessments for the safety of masonry structures after shield crossing construction and provide reference for similar projects in future. [ABSTRACT FROM AUTHOR]

The effect of aftershocks on the fragility of single-story masonry structures is investigated using probabilistic seismic demand analysis Finite element models of an unreinforced masonry (URM) structure and a confined masonry (CM) structure are established and their seismic response characteristics when subjected to mainshock, aftershock, and the mainshock-aftershock sequence are then comparatively investigated. The effects of aftershocks and the use of confining members on the seismic response are studied. Probabilistic seismic demand models of the structures are built, and fragility curves under various conditions are derived to investigate the effect of aftershocks on structural fragility. The maximum roof displacement and maximum inter-story drift ratio are lower in the confined masonry model than in the unreinforced masonry model; additionally, the probability of exceedance (PE) values of each damage limit state reduced, and those of the mainshock-damaged models subjected to aftershock significantly increase compared to those directly subjected to a same-intensity aftershock. The probability of severe damage or collapse compared with the mainshock-damaged CM model is greater than when each is subjected to a same intensity aftershock. The use of confining members benefits aftershock resistance and reduces the failure probability of the mainshock-damaged structure. The PE values significantly increase with the aftershock scaling factor δ. Therefore, the effect of aftershocks should be considered in the seismic design and analysis of masonry structures.

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The shake table test is one of the preferred techniques used to understand the dynamic response of a structure. However, due to the limited number of facilities available to perform such tests and their expensiveness, researchers often must rely on numerical models validated with the results of the static tests only. Moreover, most research papers concerning shake table tests lack details on how the tests were planned and executed. This paper explains the steps used for the preparation and execution of shake table tests on three reduced-scale buildings. These buildings were constructed outside the shake table surface, on a metallic base frame, and later moved to the shake table used for the tests in order to optimize the time of the experimental campaign. This approach enabled us to complete the tests in only 6 days. The approach presented in this paper may be helpful to researchers who want to increase the effectiveness of the available shake table facility and overcome the limitations of time and budget. Moreover, the solution presented in this article helps in the displacement of specimens without the use of a crane or other sophisticated hydraulic machinery. Thus, it could also be useful for testing specimens that have been aged and that are sensitive to displacements.

In masonry structures, it is challenging to determine the mechanical parameter values and to determine the structural behavior accordingly. For this purpose, a vaulted masonry structure resting on successive arches was built using solid clay brick and Khorasan mortar under laboratory conditions. Firstly, the Ambient Vibration Test was applied to the structure, and the natural frequency values and mode shapes of the structure were determined. Then, the displacement values due to the load were determined by using linear displacement transducer placed in different regions by applying force in the lateral direction with the incremental loading and unloading method. The structure was modeled with the Finite Element Method in the computer program by macro modeling technique, where mortar and brick were reduced to one element. The graph of change in elastic modulus due to damage ratios in the structure and the graph of change in natural frequency values due to variable elastic modulus were obtained by using the data of the Incremental Cyclic Loading Test in the Finite Element Model. Finally, Finite Element and Ambient Vibration Test analysis results were evaluated comparatively. [ABSTRACT FROM AUTHOR]

The Zagreb 2020 earthquake severely damaged the historic centre of the city. Most of the damage occurred on historic masonry residential buildings, many of which are situated very close to the tram track. Although traffic-induced vibrations generally do not affect surrounding buildings, they can be harmful to buildings damaged by a previous earthquake. Vibrations could contribute to the further propagation of existing cracks. The effect of vibrations depends on many factors, one of the most important being the distance between the track and the building. The vibrations are highest at the source, and the energy loss occurs due to transfer through the soil to the recipients. The impact of tram-induced vibrations on earthquake-damaged buildings in the city of Zagreb is investigated in this paper. The analysis is conducted on a tramway network scale to identify critical locations by performing continuous monitoring on the tramway network and risk analysis based on the distance of buildings from the track, vibration amplitude at source, and building damage. Further investigation is based on the level of buildings to evaluate the influence of vibrations on actual buildings damaged in the Zagreb earthquake. Based on detailed signal analysis, the vibration characterization is performed, and the influence on damaged masonry buildings is evaluated.

The paper presents a failure analysis of the bell tower of the church of St. Francis of Assisi on Kaptol in Zagreb subjected to seismic activity using the finite-discrete element method—FDEM. The bell tower is a masonry building, and throughout history it has undergone multiple damages and reconstructions. It was significantly damaged during the earthquake in Zagreb which occurred on 22 March 2020 with a magnitude of 5.5. The analysis was performed on a simplified FDEM 2D numerical model which corresponds to the structure in its current pre-disaster state and the structure after the proposed post-disaster reconstruction. The obtained results showed a good agreement of the crack pattern in the numerical model and the cracks that occurred due to these earthquakes. In addition, the conclusions based on the conducted analysis can provide a better insight into the behaviour and serve as guidelines to engineers for the design of such and similar structures.

Self-supporting surfaces are widely used in contemporary architecture, but their design remains a challenging problem. This paper aims to provide a heuristic strategy for the design of complex self-supporting surfaces. In our method, non-uniform rational B-spline (NURBS) surfaces are used to describe the smooth geometry of the self-supporting surface. The equilibrium state of the surface is derived with membrane shell theory and Airy stresses within the surfaces are used as tunable variables for the proposed heuristic design strategy. The corresponding self-supporting shapes to the given stress states are calculated by the nonlinear isogeometric analysis (IGA) method. Our validation using analytic catenary surfaces shows that the proposed method finds the correct self-supporting shape with a convergence rate one order higher than the degree of the applied NURBS basis function. Tests on boundary conditions show that the boundary's influence propagates along the main stress directions in the surface. Various self-supporting masonry structures, including models with complex topology, are constructed using the presented method. Compared with existing methods such as thrust network analysis and dynamic relaxation, the proposed method benefits from the advantages of NURBS-based IGA, featuring smooth geometric description, good adaption to complex shapes and increased efficiency of computation. • An equilibrium state modeled with IGA is proposed for self-supporting surfaces. Surfaces with complex topology are represented by multi-patch NURBS with high smoothness. • A heuristic strategy to design self-supporting surfaces is provided by tuning the Airy stress of the surfaces. • Newton's iteration is used to solve the nonlinear changes of gravity load caused by shape variation. [ABSTRACT FROM AUTHOR]

With current modern technology, manual on-site inspection can be assisted by automatic inspection, which is cost-effective, efficient and not subjective. In previous work, various image-based techniques have been applied to detect damages in heritage structures based on hand-designed feature extraction and classifiers. A heritage structure is composed of masonry walls, which are the components that are typically subjected to severe damages. This paper proposed a damage detection algorithm for a masonry structure based on Faster Region Convolutional Neural Networks (FRCNN). A labeled dataset for training the damage detection system in heritage masonry structure is created in this study, which is our first contribution as, currently, there is no public dataset available for masonry structures. The second contribution is the creation of a state of the art object detection system based on FRCNN for the detection and localization of damage in masonry structures. The results show that the proposed system performs well and can be used to detect damage in masonry structures with promising computational speed. [ABSTRACT FROM AUTHOR]

• Tensile and shear tests were conducted on stone assembly samples composed of limestone and lime mortar using the acoustic emission technique (AET). • A full-scale test was performed on a shear wall subjected to compression, monitored using digital image correlation (DIC) and the AET. • AET demonstrated a robust performance in damage localization and source discrimination in both stone assembly samples and a full-scale masonry wall. • For the full-scale masonry wall, the AET demonstrated its ability to detect the damage initiation before DIC can. This study evaluated the ability of the acoustic emission technique (AET) to monitor the mechanical damage in masonry structures through multiscale experimental tests ranging from the mesoscopic scale (unit–mortar–unit samples) to the macroscopic scale (shear wall). At the mesoscopic scale, the AET was applied to a series of stone–assembly laboratory specimens subjected to tensile and shear loading. Initially, a mechanical analysis was conducted to characterize two types of cracking, namely mode I (tensile) and mode II (shear). Various acoustic emission (AE) parameters were analyzed in relation to damage accumulation to understand their responses to each type of loading. The representation of AE amplitude versus duration was distinctive in discriminating signals originating from different sources. To validate these findings on the macroscopic scale, we conducted a full-scale test for a shear wall subjected to compression, using both the AET and digital image correlation (DIC). Compared with the DIC results, AET demonstrated a strong performance in damage evaluation and source distinguishment of damage in masonry at the macroscopic scale, which involves more complex failure mechanisms. [ABSTRACT FROM AUTHOR]

Multi-storey masonry structures are popular structural systems for residential buildings in China in the 1970 s, which need strengthening urgently due to poor seismic performance. To save construction time and achieve minimum disturbance, a single-sided engineered cementitious composites (ECC) strengthened method for masonry structures was proposed. To investigate the effectiveness of the strengthening method, two 1/4-scaled 5-storey masonry structures, including a reference unreinforced structure (US) model and a corresponding retrofitted structure (RS) model, were designed and tested by shake table tests. The comparisons between the US model and the RS model were analyzed in terms of the natural frequency, acceleration amplification factor, acceleration response, and storey drift response. The results show that the strengthening method can improve the seismic performance of the masonry structure. The connection method can ensure that the existing masonry walls and ECC layers work together. The initial natural frequency of the RS model is 1.3 times that of the US model. The maximum storey drift of the US model is 3.0 times that of the RS model at PGA = 0.550 g. To ensure the strengthening efficiency, the acceptable structural aspect ratio range for the strengthening method was suggested, and an improved strengthening method was proposed. • An ECC-strengthened method based on minimum disturbance was proposed. • Two structure models were tested on a shaking table. • The masonry walls were well connected to the ECC layers under seismic load. • The acceptable aspect ratio for the strengthening method under different PGA was studied. • A more rigid strengthening method was developed. [ABSTRACT FROM AUTHOR]

The integration of visible and thermal images has demonstrated the potential ability to enhance crack segmentation accuracy. However, due to the intricate texture of masonry structures and the challenges posed in precisely aligning these cross-modality images, it is necessary to explore pixel-level alignment and develop a comprehensive dataset to enable deep-learning based methods. Therefore, a dataset, Crack900, including five image types, is developed together with a proposed two-step registration to achieve highly accurate pixel-level alignment. In addition, both Train from Scratch and Transfer Learning (TL) strategies are applied on eleven models to investigate the impact of different fused image types. Our findings reveal that the concatenation strategy markedly improves segmentation accuracy, and the performance of TL depends on the compatibility of channel numbers and domain difference between pre-trained and target models. These findings pave the way for further development of cross-modality in masonry crack segmentation methodologies for structural health monitorin. • A large labeled dataset including visible and thermal infrared images • A new registration method for accurate alignment of visible and infrared images • A fusion strategy to create a "multispectral" input image to keep raw information • Six CNN-based models and five transformer-based models are trained and evaluated. • Both Train From Scratch and Transfer Learning training strategies are considered. [ABSTRACT FROM AUTHOR]

• A FE model for seismic analysis of triple-arched masonry structures is presented. • The seismic capacity was assessed by means of time-history analysis. • The geometry of the structure was found to affect its behavior and performance. • Bending failure of the foundations caused failure of the structure. The seismic response of three multi-span masonry structures has been investigated through an advanced macro and micro-modeling FE-based approach. The structures with 1.27, 2.25 and 3.3 vault-to-spring ratios (L/B) are selected. Detailed three-dimensional FE models with a damage plasticity behavior for masonry have been developed, and non-linear dynamic analyses were done. The studies have highlighted the effects of geometrical features on the seismic behavior of the nine structures. The structures were subjected to six near-fault and far-fault accelerations. The structure with a square plan has a lower earthquake coefficient. But, in a rectangular plan with the length of one longer side, the earthquake coefficient increases significantly. It shows that a square plan has more ductility than a rectangular plan. The structure with the square plan showed the best stability. Changing the plan from square to rectangle, the structure's stiffness increases significantly with the increase the number of spans. On the other hand, the one to two-span structures with a rectangular plan have the highest increase in stiffness of about 56 %, which becomes about 23 % with the increase of the third span. The vertical component in near-field accelerations can increase displacement and damage by 83 %. The beginning of the damage process in the structures with the square plan is from the connection of the vault and spring to the roof, but in structures with a rectangular plan, the plastic strain starts from the connection of the spring to the roof. Some far-fault accelerations could have destructive effects, like did near-fault accelerations in the horizontal direction. It is better to state that the remoteness of the accelerations is not the reason for reducing the damage to the structure. [ABSTRACT FROM AUTHOR]

Due to the radical political, economic and social changes of the 19th century Belgrade saw a complete transformation from a ruined Ottoman town into a modern European one. Liberation from Turkish rule and stabilisation of political and economic conditions influenced the population growth and intensified building activity. Like other European capitals, Belgrade was being transformed architecturally and in its urban plan, gradually losing traits of an Oriental town. The adoption of new building techniques in the 19th century was a way for local civil engineering to harmonise with engineering practices of the developed Central European countries which had by then already adopted masonry structure. The article studies the transition in building forms from Oriental ones, largely charatcterised by timber-framed systems, to a brick-based construction system. This paper is part of a wider, more comprehensive research on building techniques in Belgrade’s residential architecture, undertaken to define the typology of construction systems, in order to evaluate the quality of residential comfort in the buildings of Belgrade.

The current seismic strengthening methods for masonry structures usually require the removal of wall decoration and superficial mortar, and the wet work during indoor construction takes a long time, which seriously interferes with the normal life of residents. To realize the low-interference construction in the seismic strengthening process of masonry residences, a new seismic strengthening method was proposed in this study. The reinforcement was performed by adding the ring beam and constructional column into the exterior wall and the ring beam into the interior transverse wall. Based on field detection and appraisal, the following three seismic strengthening methods were compared: steel mesh mortar splint, sticking carbon fiber reinforced plastic composite materials, and the addition of constructional column and ring beam. The seismic behavior of the building was investigated by using the JGJD module of PKPM structure design software. The following parameters were calculated: average seismic capacity index (ASCI), compound seismic capacity index (CSCI) of the floor, the resistance to load effect ratio (RLER) of the wall. Results show that the ASCI and CSCI of the floor after reinforcement are both >1.0 and the RLER of the wall is >1.0. Thus, the seismic behavior of the building is improved and meets the grade-2 appraisal requirements in the Standard for Seismic Appraisal of Buildings. Moreover, low-interference construction is achieved. This study provides references for the new low-inference seismic strengthening design of masonry structures. [ABSTRACT FROM AUTHOR]