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On February 6, 2023, two catastrophic earthquakes occurred on the East Anatolian Fault. The earthquakes had magnitudes of Mw = 7.7 and 7.6 and struck Kahramanmaraş-Pazarcık and Kahramanmaraş-Elbistan, respectively. The Kahramanmaraş-Pazarcık earthquake was triggered at 04:17 local time on the Dead Sea Fault (a branch of the East Anatolian Fault). The last earthquake on the addressed fault occurred about 500 years ago. The recorded peak ground acceleration (PGA) at the Pazarcık station reached 2.05g. In addition, the Pazarcık earthquake triggered two independent earthquakes, the Nurdağı and Islahiye earthquakes, which occurred 10 min later than the Pazarcık earthquake. However, the last earthquake, with its epicenter in Kahramanmaraş-Elbistan, struck at 13:24 local time. The recorded PGA for the Elbistan earthquake is 0.68g. This study aims to present the fault rupture mechanism of the February 6, 2023, Kahramanmaraş earthquakes, earthquake characteristics, and to evaluate the performance of masonry dwellings during the Kahramanmaraş earthquake doublet, which affected 10 provinces and numerous towns and villages. This paper also aims to illustrate the damage and failure mechanisms of the masonry dwellings, despite unexpectedly high accelerations that exceeded the design spectrum in the field, specifically in Kahramanmaraş, Gaziantep, Hatay, and Malatya, according to the current earthquake code in use.

The seismic resistance of existing embankments has become a significant issue as embankments fail frequently because of earthquakes. However, there are only a limited number of methods that can improve the seismicity of these existing embankments. In this study, a new improvement method, called the “replacement/counterweight fill method”, is proposed to improve seismic resistance. Two high embankments, of different materials, were constructed on an inclined ground and the replacement/counterweight fill method was applied to them. A seismic response analysis was performed to investigate the effectiveness of the improvement in seismicity. It was found that the replacement/counterweight fill method reduced the area of shear strain by more than 30%, suppressed the deformation of the embankments, and improved the seismic resistance. Along with the increase in the height of the counterweight fill, the effectiveness of this method increased and the seismic resistance was improved even further. Applying the replacement/counterweight fill method contributed to the improvement in seismic resistance by increasing the mean effective stress inside the embankments, decreasing the specific volume, decreasing the stress ratio (q/p’), and reducing the plastic deformation caused by the increase in the overconsolidation ratio due to unloading during the earthquake. Increasing the height of the counterweight fill was seen to be more effective for suppressing embankment deformation than increasing its width because increasing the height meant that the area of the reinforcement effect would be expanded.

This study aims to improve the recovery of bridge columns after being damaged subjected to an earthquake and also proposes a PC column that reduces residual displacement by prestressing. The proposed column has a repairability of the damaged part of the column by arranging a concrete-filled steel tube at the column core. The seismic performance and post-earthquake recovery of the proposed columns were verified by conducting cyclic loading tests. Test results showed that the residual displacement was not reduced enough to improve the post-earthquake recovery. However, after investigating the column core at the end of the test, almost no visible damage, such as fracture or buckling, was found in the steel tube at the core, which means that the concrete-filled steel tube core itself can support the structure above. Therefore, the proposed system can be repaired quickly after being damaged if the residual displacement can be reduced.

A steel dual-core self-centering brace (DC-SCB) is an innovative structural member that provides both energy dissipation and self-centering properties to structures, reducing maximum and residual drifts of structures in earthquakes. The axial deformation capacity of the DC-SCB is doubled by a parallel arrangement of two inner cores, one outer box and two sets of tensioning elements. This paper presents cyclic test results of a DC-SCB component and a fullscale one-story, one-bay steel frame with a DC-SCB. The DC-SCB that was near 8 m-long was tested to evaluate its cyclic behavior and durability. The DC-SCB performed well under a total of three increasing cyclic loading tests and 60 lowcycle fatigue loading tests without failure. The maximum axial load of the DC-SCB was near 1700 kN at an interstory drift of 2.5%. Moreover, a three-story dual-core self-centering braced frame (DC-SCBF) with a single-diagonal DC-SCB was designed and its first-story, one-bay DC-SCBF subassembly specimen was tested in multiple earthquake-type loadings. The one-story, one-bay subassembly frame specimen performed well up to an interstory drift of 2% with yielding at the column base and local buckling in the steel beam; no damage of the DC-SCB was found after all tests. The maximum residual drift of the DC-SCBF caused by beam local buckling was 0.5% in 2.0% drift cycles.

Experience from past earthquakes has shown that beamtocolumn connections play a critical role in the survival of reinforced concrete momentresisting frame buildings. It is thus important to develop design procedures that will ensure a satisfactory performance of connections during an earthquake. The current practice for the design of connections has evolved from laboratory testing of a large number of beamtocolumn connections subassemblies. However, most of these tests did not include a slab, which, in a real building, is invariably an integral part of the framing system. Recently, some concern has been shown on the effect of the presence of a slab on the behavior of connections. The main objective of this investigation was to study the effect of the presence of a slab on the behavior of exterior beamtocolumn connections. A total of six threequarter scale beamtocolumn connection subassemblies were tested under a simulated earthquaketype loading. The primary test variable was the width of the floor slab. The test results show the slab to have a significant effect on the strength, stiffness, and energy dissipation characteristics of connections and strongly suggest that ignoring the presence of a slab in the design of connections may not be appropriate.

Experience from past earthquakes has shown that beam‐to‐column connections play a critical role in the survival of reinforced concrete momentresisting frame buildings. It is thus important to develop design procedures that will ensure a satisfactory performance of connections during an earthquake. The current practice for the design of connections has evolved from laboratory testing of a large number of beam‐to‐column connections subassemblies. However, most of these tests did not include a slab, which, in a real building, is invariably an integral part of the framing system. Recently, some concern has been shown on the effect of the presence of a slab on the behavior of connections. The main objective of this investigation was to study the effect of the presence of a slab on the behavior of exterior beam‐to‐column connections. A total of six three‐quarter scale beam‐to‐column connection subassemblies were tested under a simulated earthquake‐type loading. The primary test variable was the width of the floor slab. The test results show the slab to have a significant effect on the strength, stiffness, and energy dissipation characteristics of connections and strongly suggest that ignoring the presence of a slab in the design of connections may not be appropriate.

In recent years, seismicity has been increased several times in the Russian Federation. The situation exerts a significant effect on the seismic resistance of existing facilities. It is known that buildings can be reinforced by using various methods among which unconventional seismic protection devices that include seismic isolation and seismic damping hold a special place, being efficiently used not only in newly built buildings, but also in operated ones. Unconventional methods implementation of the seismic resistance increase in operated buildings is shown using specific examples. Rubber-metal supports, dynamic absorber and rubbing friction dampers are used. Recommendations on their specific use to improve buildings seismic resistance are offered.

The article presents higher modes accounting method under estimation of system seismic resistance by nonlinear static method. As part of the study, in order to verify the proposed method for finding the inertial forces modified system a complex of dynamic and static calculations was performed. It is established that proposed inertial forces modified system can significantly reduce system seismic resistance lack.

The purpose of the study is to estimate the coefficient K1, which considers the permissible damage to buildings and structures in a probabilistic formulation. For the study, a flat steel frame was designed in accordance with SP 14.13330.2014 "Construction in seismic regions". The frame calculation was performed in the LS-DYNA software package in a nonlinear dynamic formulation for a set of synthesized accelerograms. The set of accelerograms represents 50 implementations of random earthquake action with a fixed mathematical expectation of the dominant frequency. By gradually increasing the intensity of the action, the frame was brought to fracture in a numerical experiment, the results of which determined the safety margin of load-bearing capacity at each implementation. Further, by considering the safety margin and coefficient K1, their average values were determined. The obtained results showed that the actual coefficient K1 for the structure under study is significantly lower than its standard value, and the steel structure under consideration has a significant margin of seismic resistance. Thus, the developed method enables to estimate the actual value of the coefficient K1.

In this study, reliable image-based meso-scale damage evolution simulation of concrete can be executed by considering its heterogeneous meso-components. Meso-scale damage evolution of concrete with different meso-components are simulated and analyzed here, which can be used to optimize seismic resistance of concrete. As a case study, seismic damage process of a reinforced concrete (RC) column with different meso-component parameters are simulated. From the simulation results, it can be seen that improvement of the properties of interfacial transition zone (ITZ) can significantly improve the seismic performance of RC columns. The established reliable damage evolution simulation of concrete can supply a useful numerical tool to study the method for improving seismic performance of RC column such as optimizing concrete’s meso-model parameters.

In this article theoretical calculations of the construction of the underground passages under the influence of seismic forces are conducted and refined by a series of experiments. As a result of experimental studies, the authors have clarified the value of the active pressure of the ground on the construction and the active seismic inertial forces, taking into account the design. As a result of theoretical and experimental studies of seismic resistance of underground pedestrian crossings at different ground, areas of stress concentration in these constructions have been determined, which allows these sections to provide anti-seismic beams, which ensures the safety of the constructions to an earthquake or significantly reduce the degree of damage.

The article presents the calculation results for a 12-storey reinforced concrete frame building, which is exposed to fire effects. The results of building calculations are given for different combinations of operating and special loads. The analysis shows that the seismic effect during fire impacts changes the building frame's Stress-strain state: it leads to a change in the dynamic strength and deformation characteristics of the bearing elements of the building, bearing elements, and the fire resistance of the structure is reduced. The reinforced concrete frame calculation of a multi-storey building for seismic load showed that the maximum deformation was: along the X axis, 32.852 mm, along the Y axis - 36.762 mm. According to a building analysis for seismic load (9 degrees intensity) simultaneous with fire impacts, the frequencies of the building's natural oscillations increase by 13.8%. Horizontal movements increase by 1.65 times.

High-strength seismic-resistant rebar is essential in construction engineering, yet balancing its strength, plasticity, seismic resistance, and surface quality poses challenges. This research explores niobium-vanadium-nitrogen composite reinforced steel, examining how cooling bed temperature affects its microstructure, mechanical properties, and surface quality using advanced microscopy techniques. The research reveals that the steel's microstructure primarily consists of ferrite and pearlite. As cooling bed temperatures decrease, both the proportion and colony size of pearlite, along with ferrite size, show a declining trend. Specifically, reducing the cooling bed temperature from 1100 °C to 900 °C results in a decrease in yield strength, tensile strength, and tensile-to-yield strength ratio by 6 MPa, 27 MPa, and 0.03, respectively. Meanwhile, elongation after fracture, total elongation at maximum force, and strength-ductility balance improve by 3.8%, 1.5%, and 1.93%, respectively. At a cooling bed temperature of 1100 °C, significant blistering occurs on the steel surface. Significant blistering at 1100 °C vanishes at 1000 °C and 900 °C, with diminished silicon enrichment in the surface oxide scale. A cooling bed temperature of 1000 °C ± 20 °C is recommended for optimal performance. This study provides a temperature control strategy for the properties of high-strength seismic-resistant rebar rated at 650 MPa and above, contributing valuable insights to the field of advanced construction materials.

Highly ductile cement-based materials have emerged as alternatives to conventional concrete materials to improve the seismic resistance of reinforced concrete (RC) structures. While experimental and numerical research on the behavior of individual components has provided significant knowledge on element-level response, relatively little is known about how ductile cement-based materials influence system-level behavior in seismic applications. This study uses recently developed lumped-plasticity models to simulate the unique failure characteristics and ductility of reinforced ductile-cement-based materials in beam hinges and applies them in the assessment of archetype frame structures. Numerous story heights (four, eight, and twelve), frame configurations (perimeter vs. space), materials (conventional vs. ductile concrete), and replacement mechanisms within the beam hinges are considered in the seismic analysis of the archetype structures. Results and comparisons are made in terms of the probability of collapse at 2% in 50-year ground motion, mean annual frequency of collapse, and adjusted collapse margin ratio (ACMR) across archetype structures. The results show that engineered HPFRCCs in beam plastic-hinge regions can improve the seismic safety of moment frame buildings with higher collapse margin ratios, lower probability of collapse, and the ability to withstand large deformations. Data is also reported on how ductile concrete materials can reduce concrete volume and longitudinal reinforcement tonnage across frame configurations and story heights while maintaining or improving seismic resistance of the structural system. Results demonstrate future research needs to assess life-cycle costs, predict column hinge behavior, and develop code-based design methods for structural systems using highly ductile concrete materials.

On 6 February 2023, two 7.8 magnitude earthquakes consecutively hit south-central Türkiye, causing great concern from all governments, the United Nations, academia, and all sectors of society. Analyses indicate that there is also a high possibility of strong earthquakes with a magnitude of 7.8 or above occurring in the western region of China in the coming years. China is a country that is highly susceptible to catastrophic disasters such as earthquakes, floods, and other natural calamities, which can cause significant damages to both human life and property, as well as widespread impacts on the society. Currently, China’s capacity for disaster prevention and control is still limited. In order to effectively reduce the impact of catastrophic disasters, ensure the safety of people’s lives and property to the greatest extent possible, maintain social stability in high-risk areas, and ensure high-quality and sustainable regional development, it is urgent to improve the seismic resistance level of houses and critical infrastructure in high earthquake risk zones and increase the earthquake-resistant design level of houses in high-risk fault areas with frequent seismic activities; significantly enhance the ability to defend against extreme weather and ocean disasters in economically developed areas along the southeastern coast, as well as the level of fortification in response to extreme meteorological and hydrological disasters of coastal towns/cities and key infrastructure; vigorously enhance the emergency response capacity and disaster risk prevention level in western and ethnic minority regions; comprehensively improve the defense level of residential areas and major infrastructure in high geological hazard risk zones with flash floods, landslides, and mudslides; systematically promote national disaster prevention and mitigation education; and greatly enhance the societal disaster risk reduction ability, including catastrophic insurance.

ABSTRACTParking structures taller than 8 m in height are difficult to design because both fire and seismic resistance must be considered, whereas structures shorter than this threshold are simpler to design and are subject to fewer construction restrictions. Therefore, to optimize the design of these low parking structures, we propose a novel wide, long-span, steel-concrete composite beam that can be applied to reduce their story height. We investigated flexural and shear-bonding performance of the developed composite beams based on experiments, as well as theoretical and analytical research. Seven flexural beams were loaded at two points prior to monotonic bending tests, and four shear bonding beams were tested using compressive loading schemes. The results of the flexural tests indicated that the flexural strength of the wide composite-steel beams increased by approximately 20% as steel thickness increased by 3 mm (from 6 to 9 mm). Shear-bonding tests showed that all specimens without shear connectors exhibited insufficient shear-bonding strength to resist the mechanical bond mechanism; therefore, they should be reinforced with two or more flat bars. As a result, the novel composite beam system can be applied to reduce construction costs and resources by decreasing floor height in systems with long-span beams.

With technological advancements, the seismic resistance of reinforced concrete (RC) buildings has significantly increased. However, as the performance of structural members increases, damage to both structural and non-structural members becomes a severe challenge. To achieve sustainable development goals (SDGs) and a decarbonized society, damaged structures should be reused after large-scale earthquakes. In this study, deep learning (DL) was used for damage assessment in non-structural walls by investigating crack width and spacing. Images captured during previous loading tests for non-structural specimens were used as DL data. First, 12 DL models were designed using the parameters of a pre-trained model, a gradient descent method, and image extension, and these models were examined to determine the optimal model for crack detection. The model that used Xception and stochastic gradient descent method but not image extension performed better than the other models. Subsequently, a crack width measurement method was proposed, and the obtained values were similar to the crack widths measured using a crack gauge. However, the measured values were 1.67 times larger than those of the crack gauge. Additionally, a crack spacing measurement technique was proposed. The measured spacing was similar to that obtained through visual observation. However, when the distance between two cracks was small, the accuracy of the proposed technique decreased. Notwithstanding, the proposed technique was efficient when numerous images were used. Finally, the relationship between the maximum shear force and concrete damage was investigated. The crack width was more affected by the rebar ratio than by the rebar spacing. By contrast, the crack spacing was affected more by the rebar spacing than by the rebar ratio. Additionally, the crack spacing significantly affected the maximum shear force. Therefore, rebar spacing should be considered in shear strength estimation. These results will help in damage assessment and developing a new shear strength equation for RC structural and non-structural walls.

The fiber reinforced resin-based composite materials have the characteristics of high specific modulus and strength, impact resistance, creep resistance, and seismic resistance, which are widely used in the aviation, automotive, and marine industries. As one of the advanced composite material forming technologies, the fiber placement can manufacture the large-curvature composite parts with the high efficiency, high quality, high repeatability and low cost. The rubber compaction roller will deform under the pressure, in which the deformation will increase the contact area between the pressure roller and the substrate, and improve the interlaminar bonding degree. Due to the different deformation of the compaction roller caused by the different laying pressures, the deformation process of the fiber compaction roller was analyzed. By establishing the pressure stress distribution model for the compaction roller, the contact pressure, the downward deformation of the compaction roller and the deformation contact area between the compaction roller and the substrate are obtained. The mapping relationship among the contact curves of the substrate is verified by using the experiments.

The dynamic response of reinforced concrete moment resisting frame (RC-MRF) building structures is mostly altered by the substructure system such as the type of foundations and features of subterranean levels, as well as subsurface soil conditions. The majority of low-to high-rise buildings, in urban areas, are designed with one or multi-level subterranean levels for parking and other services. However, many designers overlooked incorporating these subterranean levels and soils in the seismic resistance analysis assuming that the building is fixed at the ground surface. The present study assessed the effect of the subterranean levels on the dynamic response of RC-MRF buildings. Several two-dimensional (2D) nonlinear finite element seismic response analyses were carried out in ABAQUS software for medium-rise buildings without and with one to multi-level subterranean levels resting on a deep homogenous soft soil profile under the effect of strong seismic input motion. It was observed that the subterranean levels considerably alter the dynamic characteristics and demands of the building structures. Hence, explicitly incorporating the subterranean components and foundation soil during the seismic resistance design of building structures is important.

AbstractEarthquake disaster risk analyses provide significant scientific guidance for reducing earthquake disaster losses etc. The current commonly used method is based on the vulnerability of different types of buildings to evaluate, and may ignore the difference between the seismic resistance of the same type of buildings in different areas. The lethal level considers a series of reasons such as different types of buildings, resulting in different capacities for casualties, the lethal levels of the cities in the same subregion are considerably different and exhibit obvious distribution characteristics. In Yancheng and Suqian, the lethal levels in urban areas are lower than those in rural areas, but the lethal levels in Guangzhou show the opposite trend (the lethal levels are higher in urban areas than in other towns and rural areas). The average lethal level in Guangzhou is 0.3856, that in Suqian is 0.5844, and that in Yancheng is 0.5912. This study based on the lethal levels, conduct a comparative analysis of the earthquake disaster risk of cities throughout eastern China, and a map of the earthquake disaster risk in each city is obtained. The overall lethal level and risk in Guangzhou is much lower than those in Yancheng and Suqian. The main influencing factors in the different cities also diverge. One reason for the lower lethal levels and risk in Guangzhou is that most of the brick-concrete structures are equipped with ring beams and structural columns; conversely, Yancheng and Suqian exhibit higher lethal levels and risk because the brick-concrete structures have ring beams but no structural columns. These maps provide a technical reference and solid scientific and technological support for further earthquake disaster risk analyses and for disaster prevention, mitigation and disaster relief planning, and this method improves the accuracy of rapid postearthquake assessment.

Geosynthetic-reinforced earth (GRE) retaining walls show a better performance than conventionally-designed walls during destructive earthquakes, due to their capability of redistributing seismic-induced deformations within the reinforced zone. In this paper, a recently-proposed method to design GRE walls is first recalled, where the wall is designed to trigger an internal plastic mechanism in the presence of strong earthquakes. Following a pseudo-static approach, the seismic coefficient kis therefore assumed equal to the internal seismic resistance of the wall kcint. The seismic coefficient is then calibrated against given seismic wall performance, expressed in terms of limit values of earthquake-induced displacements. Permanent displacements are evaluated through empirical relationships that were previously developed on the basis of a parametric integration of an updated Italian seismic database. Effectiveness of the proposed procedure is then demonstrated by assessing, through Finite Difference nonlinear dynamic analyses, the seismic performance of two walls, namely a GRE and a conventional gravity wall, characterised by the same seismic resistance but triggering an internal and external plastic mechanism, respectively. They are both subjected to a real strong motion, capable of activating a plastic mechanism. Results showed that lower permanent displacements are accumulated in the GRE wall where internal mechanisms are triggered.

ABSTRACTBy building the finite-element model before and after strengthening using pre-tensioned prestressed CFRP (carbon fibre-reinforced polymer) textile for different seismic waves, the box beam and pier of a four-span continuation box bridge in Tianshui City are strengthened, and the seismic performance of the prestressed concrete box bridge is studied. Considering the vertical and horizontal seismic loads, the dynamic time history of the entire bridge is modelled, and the effect of the pre-tensioned prestressed CFRP textile on the seismic performance of bridge is examined. The results show that the bending rigidity of the reinforced box girder increases. After strengthening with prestressed carbon fibre textile, the bridge can enhance the seismic resistance from vertical seismic waves by decreasing the vertical acceleration. Obviously, under horizontal seismic waves, after the box girder bridge is strengthened by the prestressed carbon fibre textile, the peak horizontal displacement and acceleration of the top of the pier decrease. Thus, the seismic response of the bridge can be effectively reduced after reinforcement with pre-tensioned prestressed CFRP textile.

The national capital of Nepal is situated on a lacustrine sediment basin. The country has had major seismic events that have resulted in significant damage to structures, human casualties, and substantial economic losses. Mitigating seismic risk is a challenging problem in Nepal due to poor construction practices, no enforcement of seismic safety guidelines, and a lack of awareness in the public. Seismic risk mitigation is essential in improving seismic resistance of buildings, and in reducing the economic loss and casualties in the forthcoming seismic events. The scientific results of earthquake loss estimation studies will lead to improve the policies towards seismic resilience.

The seismic resistance of existing reinforced concrete structures may be inadequate due to weaknesses in the structural system and nonductile detailing. To mitigate the seismic and other natural hazards, existing inadequate or deteriorating structures should be rehabilitated. The evaluation of the seismic resistance of existing structures and their deficiencies is essential before an appropriate repair or upgrade system can be designed. The performance of the structure may be evaluated in terms of its lateral load resistance, global or interstory drift and potential damage. This review presents the state-of-the-art, concepts, philosophy and approaches for the seismic assessment of existing reinforced concrete structures. The state of practice in the evaluation of the performance of structures, methods of analysis, and limitations are discussed.

As a result of experimental and analytical research in seismic behaviour of masonry structures in the last few decades, new methods for seismic resistance analysis and design, as well as new, seismic resistant technologies and construction systems have been developed. After many centuries of traditional use, and decades of allowable stresses verification, clear concepts for limit states verification of seismic resistance of masonry structures have been introduced in the seismic codes. In this review, some basic aspects of seismic resistance verification of masonry walls and buildings are discussed, and some suggestions for future research are given.

Given the unpredictability of the occurrence of the earthquake and other potential disasters into consideration, the nuclear power plant may be confronted with beyond design-basis earthquake load in the future. The containment structure may be severely damaged under such severe earthquake loading, increasing the risk of containment concrete cracking and potential radioactive materials leaking. Moreover, initial damage caused by the earthquake may significantly alter the pressure performance of the containment under follow-up internal pressure. To compromise the dangers of beyond design-basis earthquake to the containment, an alternative of replacing the conventional concrete with fiber-reinforced concrete (FRC) to upgrade the seismic resistance capacity of the containment is attempted and thoroughly researched. In this study, the influence of various fiber types such as rigid fiber and mixed fiber is regarded to constitute fiber-reinforced PCCVs. The physical properties of traditional and fiber-reinforced PCCVs under earthquake ground motions are scientifically compared and identified by using traditional and proposed evaluation indices. The results indicate that both the traditional evaluation index (i.e. top displacement, stress, strain) and the proposed damage index are greatly reduced by the practice of fiber strengthening under earthquake ground motions.

The objective of this research is to assess the seismic performance of different types of electrical cabinets in nuclear power plants. The cabinets under investigation are: (a) Case 1: a short single cabinet; (b) Case 2: a tall single cabinet; (c) Case 3: separated cabinets; and (d) Case 4: a combined cabinet with coupling effects. To accurately capture the real behavior of the cabinet, three-dimensional finite element models are developed using ANSYS with connection non-linearity. Frequency-domain decomposition (FDD) is used to determine the dynamic properties of the cabinets from shaking table testing data, and these results are utilized to validate the numerical model. The close match between the experimental and numerical results obtained from the modal analysis demonstrates the accuracy of the numerical model. Subsequently, transient structural analysis is performed on the validated models to explore seismic performance. The results show that the acceleration response of the combined cabinet is lower than the single cabinet and the separated cabinet. This observation suggests that top anchors used to combine two different types of cabinets play a crucial role in assessing the efficiency and seismic resistance of electrical cabinets in a nuclear power plant.

The shaking table model test was conducted to investigate earthquake resistant behavior of stone columns under the intensity of an earthquake resistance of buildings is VIII. The test results show that when acceleration is less than 0.20 g, composite foundation is not liquefied, settlement is also small and pile dislocation is not observed; when acceleration is 0.3g, ground outside embankment’s slope toe is liquefied and ground within stone column composite foundation is not. It is suggesting that reinforcement scale of stone column foundation should be widened properly. The designed stone column composite foundation meets the requirements for seismic resistance.

There is a growing interest in plausible reuse of wastewater and solid waste materials for compressed earth bricks (CEBs) production due to their sustainability benefits, affordability, and they are considered relatively ubiquitous raw materials. However, a study of the behavior of CEBs produced from soil and injected wastewater from oilfields has not been well documented in the literature. This study aimed at employing an experimental testing program to assess structural and thermal properties of masonry units, mainly prism’s compressive strength, masonry wall’s behavior, and thermal properties of CEBs rooms made with produced water and soil obtained from two oilfields in Oman: namely Marmoul and Nimr oilfields. It was found that prism strength decreases with increasing prism height, with Marmoul CEBs (2.4–3.9 MPa) showing slightly better performance compared to that Nimr (1.8–3.8 MPa). The masonry prism efficiency factor, which was estimated based on the ratio between the prism and block strength, was in the range of 52.3–59% for Marmoul CEBs, whereas for Nimr blocks, it ranged from 39.2% to 57.9%. The results of the masonry wall test showed that the wall reached an ultimate load of 386 kN at a deformation of 8.0 mm and the mode of failure was deformation of the wall due to overall buckling. The CEBs rooms have shown enhanced thermal performance compared to the reference room built with hollow concrete blocks. The CEBs rooms provided 1–7 h of time lags and achieved between 0.15 and 0.23 lower decrement factors than the reference room due to their high thermal mass and thermal resistance, respectively. While the CEBs under this study have shown good structural and thermal insulation potential as a sustainable building material, other factors, including indoor air quality emissions, acoustic properties, seismic resistance, and cost-benefit analysis, need to be considered in future studies.

Structural walls made of solid brick masonry have been used for centuries in old buildings, which are vulnerable to earthquakes. Reinforcing this type of walls may increase the overall building seismic strength. In this paper, the in-plane behaviour of these types of walls, both plain and reinforced, was experimentally assessed through triplets shear tests. The reinforcement considered, with near surface mounted (NSF) steel bars, has already been studied in the scope of a broader ongoing research project. The in-plane strength of brick masonry walls is of utmost relevance for seismic resistance and strongly depends on their resistance to sliding that may occur along the horizontal mortar interfaces. The bricks and the laying mortars tested correspond to walls of buildings built between 1920 and 1950 that may be found in Lisbon and other cities. Triplet specimens (made of three stacked bricks connected by a laying mortar) were built and tested. Two types of mortar compositions were used, of an earlier and a later phase within the period referred above. Both types included unreinforced specimens and specimens reinforced with steel bars of different types. The specimens were subjected to direct horizontal shear tests to determine the relevant properties of the assemblage, namely the cohesion and friction angle of the brick mortar joints. The results obtained in this study may be used in the numerical modelling of ancient buildings with brick masonry walls granting a better correlation with real behaviour.

Frost damage to concrete can make concrete beams more vulnerable under seismic forces. However, research on the seismic performance of frost-damaged reinforced concrete (RC) beams is still in its infancy. In this paper, the effects of freeze–thaw cycles (FTCs) and concrete strength on the seismic performance of frost-damaged RC beams are studied using an artificial rapid freeze–thaw climate and pseudo–static test in sequence. The seismic resistance of frost-damaged RC beams is assessed in the following respects: general damage behavior and failure pattern, hysteresis response, displacement, strength, cumulative energy consumption, and shear component. It turns out that, with the increase in the number of FTCs (NFTCs), the load and displacement under different characteristic states, ductility ratio, and cumulative energy consumption decrease stage by stage, while the shear distortion and the contribution of shear displacement under the entire cyclic loading process are progressively enhanced. Simultaneously, the strength of the cracking point is more susceptible to FTC action than to yield and peak points, and the declining rate of strength under different characteristic points gradually increases. Based on the test results, a calculation formula for the skeleton curve of frost-damaged RC beam–column is established, taking the influences of the pristine concrete strength, NFTCs, and axial force ratio into account.

Central columns have long been demonstrated to play a vital role in withstanding not only static gravity loads but also seismic loads like earthquakes. A series of modeling tests are implemented on shaking table instrument to reflect the mechanism of soil — structure interaction and examine the validity of method of uplifting underground structural seismic resistance through strengthening central columns. An innovative method of enhancing central columns by adhering carbon fiber cloth onto column’s peripheral surface is introduced into a series of shaking table modeling tests, in which two two-layer underground model structures are constructed for comparison, one without any column remedy acts as a benchmark for reference and the other is amended with carbon fiber cloth adhered on column surface. Test results show that soft round model box adopted in tests serves well in simulating earthquake actions with negligible boundary effects on wave transfer; soil dynamic characteristics and the relative stiffness of structure to surrounding soil will interactively limit mutual motion and deformation. Racking deformation assumption may be not applicable for overall two-layer underground structure deformation analysis, but may be suitable for inter-layer displacement calculation for single layer in multi-layer rectangular underground structures. The adopted column enhancement measure could not only greatly increase the stiffness ratio of model structure to soil, reducing structure deformation, but also improve the integrity of underground structure by narrowing down the deformation difference between two structural layers, certifying that such a measure could be validly used in improving the seismic resistance capacity for already built underground structures without enough aseismic consideration when designed.

After the Hanshin Awaji Earthquake disaster, the seismic resistance of embankments was evaluated, and design principles were changed from specification-based to performance-based. However, compaction properties and the mechanical behavior of compacted soil were not sufficiently considered in the Manual of Highway Earthworks on Embankments.

Building facades play an important role in creating the urban landscape and they can be used effectively to reduce energy usage and environmental impacts, while also incorporating structural seismic-resistant elements in the building perimeter zone. To address these opportunities, the authors propose an integrated facade concept which satisfies architectural facade and environmental design requirements. In Europe, remarkable facade engineering developments have taken place over the last two decades resulting in elegant facades and a reduction in environmental impact; however modifications are needed in Japan to take account of the different seismic and environmental situations. To satisfy these requirements, this paper proposes the use of a diagonally disposed louver system. Diagonally arranged louvers have the potential to provide both seismic resistance and environment adaptation. In many cases, louvers have been designed but not installed due to concerns relating to restricted external sight lines and low levels of natural lighting in the building interior. To overcome these problems, full-scale diagonally arranged louver mock-ups were created to evaluate illumination levels, the quality of the internal daylight environment and external appearance. Interior illumination levels resulting from a series of mock-up experiments were evaluated and correlated with results from a daylight analysis tool.