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The effect of blast-induced ground vibration on structures was examined. The aim was to investigate the extent to which the strength attributed by seismic design can resist the effect of mine blasts, as both earthquakes and blasts generate lateral forces. The study was conducted to see whether and how blasts can be controlled such that seismic design of structures may suffice the purpose of withstanding mine blasts. The responses in the elastic and post-elastic regions were compared for implementation of the concept of performance-based design. The responses of structures were investigated for both single and sequential blasts. The results showed that sequential blast events are more damaging than earthquakes. On the other hand, medium- and long-period structures under a single blast event can withstand blast-induced vibration if designed as per seismic provisions. To safeguard structures under sequential blasts, it is recommended that the number of blast events is controlled. The safety of structures under blast can be determined by knowing the additional strength attributed from the seismic effect. This may help to decide whether separate design provisions for blast-induced ground motion are needed. [ABSTRACT FROM AUTHOR]

Seismic engineering, a critical field with significant societal implications, often presents communication challenges due to the complexity of its concepts. This paper explores the role of Artificial Intelligence (AI), specifically OpenAI’s ChatGPT, in bridging these communication gaps. The study delves into how AI can simplify intricate seismic engineering terminologies and concepts, fostering enhanced understanding among students, professionals, and policymakers. It also presents several intuitive case studies to demonstrate the practical application of ChatGPT in seismic engineering. Further, the study contemplates the potential implications of AI, highlighting its potential to transform decision-making processes, augment education, and increase public engagement. While acknowledging the promising future of AI in seismic engineering, the study also considers the inherent challenges and limitations, including data privacy and potential oversimplification of content. It advocates for the collaborative efforts of AI researchers and seismic experts in overcoming these obstacles and enhancing the utility of AI in the field. This exploration provides an insightful perspective on the future of seismic engineering, which could be closely intertwined with the evolution of AI.

Steel corrosion is by far the biggest durability issue for many reinforced concrete bridge structures worldwide. The columns in these bridges can be critical, especially for seismic resistance. In this study, glass-fibre-reinforced-polymer bars were investigated as an alternative to steel for sustainable and resilient bridge construction. As lateral reinforcement is more susceptible to corrosion, and structures fully reinforced with fibreglass bars display softer responses with lower shear and flexural capacity, fibreglass spirals and longitudinal steel reinforcement were used in the tested columns. The experimental programme included the design, construction and seismic testing of full-scale (508 mm diameter) and half-scale (356 mm diameter) columns. The other variables investigated were the axial load and the amount and spacing of spirals. For both column sizes, fibreglass spirals provided increasing confining pressure to the concrete core with increased deformations. For the full-scale columns, no adverse size effects were observed in comparison to the half-scale columns. The columns produced large ductility and energy dissipation. Results from selected representative specimens are presented here to establish the feasibility of using fibreglass spirals in circular bridge columns. Resilience can thus be built into new columns through innovative durable fibreglass lateral reinforcement, with similar if not superior behaviour to steel-reinforced columns. [ABSTRACT FROM AUTHOR]

Multi-span bridges having a bidirectional ductile diaphragm consisting of buckling-restrained braces (BRBs) can provide resilient bridges with damage-free columns, at low cost, while minimising displacement demands to levels that can be easily accommodated. Towards the goal of better understanding the behaviour of this type of bridge and its advantages, a parametric analysis was performed considering regular multi-span simply supported bridges with variations in pier stiffness, BRB target displacement, BRB yield displacement and numbers of spans. The bridges were analysed in the longitudinal direction. BRBs were designed using non-linear response history analysis. The demands of the designed bridges were analysed to understand the influence of the various parameters considered. The proposed system was able to reduce the demands in piers so as to keep them elastic and limit the displacement demands in expansion joints (making it easier to prevent unseating in retrofit situations). It was also found that, according to fatigue damage calculations, it is not necessary to replace BRBs after an earthquake. [ABSTRACT FROM AUTHOR]

Soil–structure interaction can significantly affect the seismic vulnerability of systems through several mechanisms that depend on the mutual effects of the soil properties and the structural characteristics. In this work, a probabilistic-based approach was applied to evaluate such effects on the fragility of an isolated bridge representing a typical Californian highway bridge. Analytical fragility curves were developed using OpenSees, implementing hysteretic materials and advanced plasticity models to represent non-linearity. The mutual non-linear effects of soil deformability and isolation on the system (soil–foundation–structure) were assessed by considering several limit states for the column ductility and the deck displacement. [ABSTRACT FROM AUTHOR]

Bridges are fundamental links for the movement of goods and people and bridge damage can thus have significant impacts on society and the economy. Earthquakes can be extremely destructive and can compromise bridge functionality, which is essential for communities. Evaluation of bridge functionality is thus fundamental in the planning of emergency responses and socioeconomic recovery procedures. It is especially useful to define parameters to assess investments in bridge infrastructure. Resilience is a key parameter that can identify decision making procedures necessary for recovery investments. In this regard, resilience can be defined as the rapidity of a system to return to pre-disaster levels of functionality. This aim of this work was to assess the lack of robust analytical procedures for quantifying systematic restoration for earthquake-damaged bridges, to provide a link between the assessment of resilience and its application in decision making approaches. The proposed methodology (called seismic resilience for recovery investments of bridges) uses functionality–time curves that allow quantification of resilience along with readable findings for a wider range of stakeholders. The results presented in this paper should be of interest to multi-sectorial actors (i.e. bridge owners, transportation authorities and public administrators) and could drive interdisciplinary applications such as the assessment of recovery techniques and solutions. [ABSTRACT FROM AUTHOR]

The seismic resilience of structures and infrastructures is affected by damage accumulation phenomena, mainly related to the type of hysteresis. Specifically, pinching drives the cyclic response of several building materials, such as reinforced concrete and masonry. Structural systems affected by pinching phenomena are prone to exhibit a dramatic increment of their displacement response after multiple cycles (e.g. repeated earthquakes). The authors estimate a reinforced concrete pier's response using truncated incremental dynamic analysis by concatenating three earthquake scenarios. The authors adopted a Bouc–Wen class hysteresis model to simulate the reinforced concrete pier's cyclic response, matching its experimental cyclic response. The current analysis proved that ductility and resistance primarily drive the seismic response after a single earthquake. However, the performance after multiple earthquakes strongly depends on the pinching, degradation and drift accumulation, which are generally neglected in standard design practices. [ABSTRACT FROM AUTHOR]

Cyclic resistance curves, derived through undrained element tests, are central to the study of liquefaction. Their use implies that water drainage is negligible during an earthquake. Nevertheless, a growing body of evidence suggests that this hypothesis is not realistic. In proximity to the interface of a liquefiable layer with an overlying lower permeability layer, upwards water flow can lead to localised, co-seismic pore volume increase. The aim of this paper is to quantify the effects of pore volume increase on cyclic resistance curves. Cyclic triaxial experiments are presented, performed under undrained conditions and under conditions of volumetric expansion. A constant inflow rate is chosen for the sake of simplicity. Results show that even small inflow rates have a detrimental effect on cyclic resistance. A simplified methodology is developed, which can estimate cyclic resistance under constant water inflow rates, by assuming a superposition of isotropic unloading and undrained cyclic shearing. The results presented add to increasing evidence on how current liquefaction susceptibility assessments might not be conservative for layered deposits. In addition, they highlight significant aspects of soil response under partially drained conditions. [ABSTRACT FROM AUTHOR]

Foundation scour has been a reason for several cases of river-bridge earthquake-induced failure during recent decades. However, practising engineers often do not consider its direct effect on the seismic design procedure of such structures. The cavity around a bridge foundation is a random phenomenon depending on several uncertain parameters. This study provides a probabilistic platform to investigate the effect of random scouring on the seismic performance of a particular bridge. The procedure is implemented on an existing multi-span reinforced concrete bridge. To this end, the Monte Carlo simulation technique is utilised to generate samples of the random variables of the scour model to develop the scour hazard curve. A common type of reinforced concrete multi-span bridge is considered as a model. The Latin hypercube sampling method is employed to generate random scouring scenarios in the finite-element model, including uniform and non-uniform scour. Then, fragility curves are developed utilising cloud dynamic analysis. The results reveal that the scouring pattern is one of the most crucial sources of uncertainty. In most circumstances, uniform scour scenarios are more effective than the average of non-uniform cases. However, in some specific patterns, the effect of non-uniform scouring is dominant. [ABSTRACT FROM AUTHOR]

Replacing traditional stirrups with high-strength rectangular spiral stirrups can improve the seismic performance of reinforced concrete columns. In order to study the seismic performance of high-strength spiral stirrup confined concrete columns, a validated finite element (FE) method was proposed to establish the FE model of reinforced concrete columns. Combined with the measured data of two existing specimens, parameter analysis was conducted on 19 specimens. The axial compression ratio, shear span ratio, stirrup spacing, and stirrup diameter were variable parameters. Based on a reliable model, internal stress analysis was conducted, and the influence of different variables on the seismic performance of reinforced concrete columns was revealed. The FE results suggest that, when the axial compression ratio is not greater than 0.6, the requirement of ductility greater than 3 in the Chinese Standard GB 50011-2010 can be met. The recommended shear span ratio for optimal ductility was around 4.5. The reinforcement ratio of high-strength spiral stirrups ranges from 1.0% to 2.2%. After completing the simulation of nearly 100 specimens (only calculating the ductility coefficient), a matching relationship between the axial compression ratio limit and the shear span ratio was proposed. [ABSTRACT FROM AUTHOR]

With the ongoing challenges of global climate change and the rapid development of underground engineering, the mechanical behavior of geomaterials under the combined effects of thermal stress and dynamic loading has become a research focus. Underground structures, such as tunnels and foundation pits, often encounter complex stress environments, especially under extreme dynamic loads like earthquakes, where temperature-induced thermal stress may significantly alter the performance of geomaterials. Although previous studies have examined the dynamic response of geomaterials, most methods have primarily focused on the effects of single stresses, with limited attention to the coupling effects of thermal stress and dynamic loads, leading to insufficient predictive accuracy. To address this issue, this paper first selects and establishes a heat transfer model for the dynamic thermal response of geomaterials and systematically explores the stress-strain evolution laws of geomaterials under compound stress conditions, with particular emphasis on the analysis of thermal stress in seismic engineering. This research provides a theoretical basis for optimizing underground structure design and enhancing seismic performance. [ABSTRACT FROM AUTHOR]

In recent years, accelerated bridge construction has led to the substantial application of precast post-tensioned segmental (PPS) bridge piers. However, PPS piers are not widely used in high-seismicity regions due to their low energy-dissipation capacity (EDC). To address this deficiency, a series of shape memory alloy (SMA)–concrete composite PPS piers were examined in this work. Non-linear static and dynamic analyses were performed on experimentally validated finite-element models of the SMA–concrete composite piers and the results were compared with those of piers without SMA bars. It was found that the length, area and post-tensioning ratio of the SMA bars affected the EDC of the piers, and an optimal design of the bars is required to reach the highest EDC possible. The effects of SMA bars on the frequency response functions of piers were investigated for the first time in this study and it was found that, unlike the piers without SMA bars, sub-harmonics and super-harmonics were not seen in the responses of the SMA–concrete composite piers, mainly the drift responses. Furthermore, the SMA–concrete composite piers experienced a significant reduction in drift responses compared with piers without SMA bars. [ABSTRACT FROM AUTHOR]

Seismic engineering, a critical field with significant societal implications, often presents communication challenges due to the complexity of its concepts. This paper explores the role of Artificial Intelligence (AI), specifically OpenAI’s ChatGPT, in bridging these communication gaps. The study delves into how AI can simplify intricate seismic engineering terminologies and concepts, fostering enhanced understanding among students, professionals, and policymakers. It also presents several intuitive case studies to demonstrate the practical application of ChatGPT in seismic engineering. Further, the study contemplates the potential implications of AI, highlighting its potential to transform decision-making processes, augment education, and increase public engagement. While acknowledging the promising future of AI in seismic engineering, the study also considers the inherent challenges and limitations, including data privacy and potential oversimplification of content. It advocates for the collaborative efforts of AI researchers and seismic experts in overcoming these obstacles and enhancing the utility of AI in the field. This exploration provides an insightful perspective on the future of seismic engineering, which could be closely intertwined with the evolution of AI. [ABSTRACT FROM AUTHOR]

This paper presents a generalised Newmark method (GNM) incorporating a displacement hardening mechanism for the prediction of permanent displacements accumulated by diaphragm walls during earthquakes. A key feature of the proposed approach is the adoption of an evolution law for the critical acceleration, which links its current value to the accumulated wall permanent displacements. This displacement hardening mechanism is based on a simplified relation between the average plastic shear deformations experienced by the passive zone of soil below dredge level and the mobilised soil friction angle. This relation is determined indirectly by the evolution of the passive earth-pressure coefficient with wall displacement/rotation, as obtained in quasi-static model wall experiments. The proposed approach has been validated by comparing its predictions with the experimental data obtained in centrifuge model tests of cantilevered and propped walls. In spite of the simplifying assumptions on which it is based, the GNM has demonstrated that it is capable of capturing the essential features of the retaining structures' kinematics and provides realistic predictions of permanent wall displacements. [ABSTRACT FROM AUTHOR]

Most design codes evaluate the non-linear seismic performance of structures using the response reduction/modification factor (R). The value of R is sensitive to a variety of factors in terms of overall ductility and over-strength. In this work, actual R values were assessed for vertical irregularity cases for reinforced concrete bare buildings with moment-resisting frames (MRFs). A significant relationship between R and the vertical irregularity index, calculated from the relative stiffness between adjacent storeys, was derived. Three-dimensional numerical modelling was carried out for soft storey and setback irregularity scenarios using Etabs. Modal pushover analysis was used to obtain the inelastic seismic capacity. It was found that vertically irregular buildings have weak inelastic seismic capacities compared with regular buildings. So, before the design stage, R should be scaled down by 15–40% for single and combined vertical irregularity scenarios. Structures with a combined asymmetric setback with a soft ground storey were found to have the worst R value and R was sensitive to the vertical irregularity index (Vtm) that has R-squared of 80%. So, the vertical irregularity index can be used to specify the allowable vertical irregularity ratio, location and combination of vertical irregularities for each seismic zone. [ABSTRACT FROM AUTHOR]

Long-span structures such as school gyms and sports centres are often used by the Italian Department of Civil Protection as post-catastrophe shelters or headquarters. The Emilia 2012 earthquake drew the attention of the department to this type of structure due to the damage that many of these buildings suffered. In this work, a dataset of 101 timber structures was analysed based on a simplified methodology that detects the major vulnerabilities in long-span timber roofs in order to help plan further investigations and retrofit interventions. Using fast and straightforward approaches, the elements most vulnerable to seismic action were analysed quantitatively and qualitatively. Quantitative evaluation of the vulnerabilities was achieved by applying the Italian Building Code. The aspects not considered in the quantitative evaluation were assessed through qualitative parameters inspired by damage identification forms (e.g. the AeDES form). The analysed structures are located near the epicentres of the last strong earthquakes that struck Italian territory: Abruzzo in 2009, Emilia in 2012 and central Italy in 2016. Damage and retrofits, identified by interviewing owners, designers and builders, showed a good correlation between the real behaviour shown by the surveyed structures and the vulnerabilities detected using the simplified methodology. [ABSTRACT FROM AUTHOR]

To improve the seismic behaviour of cold-formed steel (CFS) walls, a novel infilled CFS wall covered with different wall sheathings (gypsum wallboard, oriented strand board and fibre cement board) was assessed. Four full-scale specimens were tested under cyclic lateral loads to investigate the impacts of the wall sheathings on the seismic performance of the CFS wall. The failure process, failure mode, load–displacement curve, strength degradation, stiffness degradation, energy dissipation, deformation and strain variation of the walls were investigated. The failure modes of the walls were found to be failure of the connections between the CFS frame and the sheathing as well as crushing of the infill material. Compared with a specimen without sheathing, the peak load and lateral stiffness of the walls with sheathing were increased by 1.25–1.72 times, indicating that the sheathings played an important role in the lateral resistance of the wall. An analysis model and formulas for predicting wall lateral stiffness were developed. Comparisons between the calculations and experimental data showed that the proposed theoretical method was able to predict the lateral stiffness of the infilled CFS walls accurately. [ABSTRACT FROM AUTHOR]

In reinforced concrete (RC) buildings, the seismic behaviour of RC beams with flush outside faces of beams and columns has not been verified by experiments. In this study, four large RC beam specimens were fabricated and an experimental verification was conducted. The results showed that all of the specimens (including three beam specimens with flush outside faces of beams and columns) could withstand ultimate drift angles up to 4% rad. In addition, the lateral strength and seismic behaviour of a specimen with a concrete cover of 85 mm were no less than those of the benchmark specimen, so a concrete cover thickness of 85–40 mm should be acceptable for RC beams. The seismic behaviour of two specimens with lateral U-shaped auxiliary transverse reinforcement and a concrete cover of 85 mm was better than that of the benchmark specimen, but the crack width of the latter was wider and the spalling degree of the concrete cover was more serious. Based on the results of this work, the practical recommendation is to adopt lateral U-shaped auxiliary transverse reinforcement in which the two legs extend beyond half the width of the hoop, with two auxiliary longitudinal reinforcements and the same spacing as the hoop. [ABSTRACT FROM AUTHOR]

Many examples of earthquake damage show that liquefied lateral spreading is the main cause of pile foundation failure. Rigid drainage piles (RDPs), with two drainage grooves and plastic drainage plates, are a new type of liquefaction-resistant pile that can take into account the bearing capacity and drainage function. A series of 1g shaking table tests was carried out to analyse the seismic response of an RDP–superstructure–quay wall system subjected to lateral spreading. Three levels of earthquake intensities – small (peak ground acceleration (PGA) of 0.05g), moderate (PGA = 0.1g) and large (PGA = 0.2g) – were investigated. The improvement in the anti-liquefaction performance using RDPs was analysed. The influences of far-field (FF) and near-field (NF) ground motions were also examined. The experimental results showed that RDPs can effectively reduce the liquefaction degree and the horizontal flow of the sand stratum. In addition, the internal force and displacement of the superstructure built on RDPs were small. The seismic response due to NF ground motion was found to be more significant than that of the FF ground motion, but the effects of FF ground motion cannot be disregarded. The results of the tests could provide useful information for the design of RDP groups in a typical pile–superstructure–quay wall system. [ABSTRACT FROM AUTHOR]

Machine Learning (ML) has developed rapidly in recent years, achieving exciting advancements in applications such as data mining, computer vision, natural language processing, data feature extraction, and prediction. ML methods are increasingly being utilized in various aspects of seismic engineering, such as predicting the performance of various construction materials, monitoring the health of building structures or components, forecasting their seismic resistance, predicting potential earthquakes or aftershocks, and evaluating the residual performance of post-earthquake damaged buildings. This study conducts a scientometric-based review on the application of machine learning in seismic engineering. The Scopus database was selected for the data search and retrieval. During the data analysis, the sources of publications relevant to machine learning applications in seismic engineering, relevant keywords, influential authors based on publication count, and significant articles based on citation count were identified. The sources, keywords, and publications in the literature were analyzed and scientifically visualized using the VOSviewer software tool. The analysis results will help researchers understand the trending and latest research topics in the related field, facilitate collaboration among researchers, and promote the exchange of innovative ideas and methods. [ABSTRACT FROM AUTHOR]

The seismic performance of a ring–beam connection system to integrate concrete-filled steel tubular columns and reinforced concrete (RC) frames was studied. Physical experiments on two specimens were conducted under monotonic and cyclic loading. The results showed the connection system had a displacement ductility ratio of 4.68 and an energy dissipation coefficient over 2.0. A finite-element model was established and the numerical and experimental results were compared in terms of skeleton curves and stiffness degradation trends. Parametric studies were then performed to evaluate the effects of the axial compressive force ratio, concrete strength and reinforcement ratio of the ring–beam joint (RBJ) and the reinforcement ratio of the frame beam on the seismic performance of the proposed RBJ connection system. The results showed that an increase in the axial compression ratio or strength of the concrete material improved the initial stiffness and strength of the connection system. The effects of the RBJ reinforcement ratio and the frame beam reinforcement ratio on seismic performance were negligible. [ABSTRACT FROM AUTHOR]

The failure of most reinforced concrete structures is due to inadequate seismic design and detailing, poor construction techniques and/or the use of low-strength concrete (LSC). Retrofitting such structures with fibre-reinforced polymer wrapping rather than traditional concrete or steel jacketing is an emerging popular strengthening technique. In the research reported in this paper, carbon-fibre-reinforced polymer (CFRP) was used for external confinement of LSC bridge pier columns, which resulted in appreciable improvements in flexural strength and load-carrying capacity. Experimental tests and numerical simulations of quarter-size CFRP-wrapped circular columns under quasi-static cyclic loading were performed to evaluate the improvement in lateral load-carrying capacity. The results revealed that the confining action of the CFRP wrapping resulted in significant enhancements in the strength and ductility properties of the columns. It enhanced their energy dissipation capabilities and made them more able to tolerate even larger earthquake forces without an appreciable loss in stiffness. [ABSTRACT FROM AUTHOR]

In the semiconductor and liquid crystal display (LCD) industries, suspended ceilings are widely used in wafer and LCD panel fabrication plants (fabs). Despite several preventive measures having been taken, substantial financial losses have been incurred in past earthquakes, with one of the main causes attributed to damage or collapse of ceilings due to excessive ceiling sway during earthquakes. A practical approach of incorporating customised viscous dampers into suspended ceilings to mitigate their seismic response is described in this article. Unlike the convention in most fabs, where diagonal bracing rods are added between suspended ceilings and the structural floor slab to mitigate ceiling vibration, this new approach installs customised viscous dampers in between the ceiling and the column/wall. An analytical model to simulate the vibration of a suspended ceiling was developed. Shake table tests of the ceiling–structure model were then conducted to verify the effectiveness and feasibility of the proposed approach. The results indicated that, when equipped with viscous dampers, the displacement responses of a suspended ceiling can be significantly reduced. Incorporating the dampers into the ceiling with added bracing rods was found to give the best seismic performance. [ABSTRACT FROM AUTHOR]

The post-fire performance of slag-based geopolymer materials in structures under cyclic loading has yet to be reported and the condition of the rebars inside such structures remains unexplored. In the present work, cyclic tests were conducted on exterior beam–column joints made with a slag-based geopolymer after exposing the specimens to natural fire. The mechanical properties of the reinforcement embedded in fire-exposed specimens were also determined and analysed. The cyclic test results indicated that deterioration of the geopolymer and rebar altered the failure pattern of the fire-exposed specimen from the desired beam-end hinging to joint shear failure. The peak load, stiffness, ductility and energy dissipation reduced significantly in the fire-exposed specimens compared with the unheated control specimens. [ABSTRACT FROM AUTHOR]

Continuous-curved-beam (CCB) bridges are often used in earthquake-prone areas, but their design characteristics make it difficult to predict structural damage during an earthquake. A large-scale model of a CCB overpass that was damaged during the 2008 Wenchuan earthquake was created and tested on a shaking table. After one pier suffered seismic damage, it was reinforced using polyurethane cement (PUC) and retested. The results showed that the PUC repair improved the structural performance of the bridge. The use of PUC is thus a new and valid method for the quick repair of earthquake-damaged bridge piers. [ABSTRACT FROM AUTHOR]

Random variables introduced in modelling of seismic engineering are often the result of cognitive limitations and the unpredictability of structures, leading to uncertainties in the field. A practical method for dealing with them is to develop sensitivity analysis in the framework of data and probability statistics. Of existing non-structural components, cable tray systems are characterized by a number of uncertainties which may influence their bearing capacity drastically. In this research, the main characteristics of material, geometry, member layout along with the connection stiffness in cable tray are considered as random variables using global sensitivity analysis, with their results relative importance of these potential uncertainties on the seismic performance of cable tray. The sensitivity analysis method developed especially for cable tray under seismic excitation is constructed based on modal analysis and equivalent inertia force method combined with the Latin hypercube sampling method. The final results demonstrate the need to consider the effects of random variables in modeling assumption in seismic performance analyses of cable tray and can be further used in optimization design. [ABSTRACT FROM AUTHOR]

Random variables introduced in modelling of seismic engineering are often the result of cognitive limitations and the unpredictability of structures, leading to uncertainties in the field. A practical method for dealing with them is to develop sensitivity analysis in the framework of data and probability statistics. Of existing non-structural components, cable tray systems are characterized by a number of uncertainties which may influence their bearing capacity drastically. In this research, the main characteristics of material, geometry, member layout along with the connection stiffness in cable tray are considered as random variables using global sensitivity analysis, with their results relative importance of these potential uncertainties on the seismic performance of cable tray. The sensitivity analysis method developed especially for cable tray under seismic excitation is constructed based on modal analysis and equivalent inertia force method combined with the Latin hypercube sampling method. The final results demonstrate the need to consider the effects of random variables in modeling assumption in seismic performance analyses of cable tray and can be further used in optimization design.

With daily traffic of 260 000 vehicles, the San Francisco–Oakland Bay Bridge is a major connection in the San Francisco Bay area (CA, USA). The new bridge is a designated lifeline structure (to remain open for emergency traffic after a major seismic event) with a design life of 150 years. The new bridge is 3.6 km long and consists of four distinct structures: a low-rise post-tensioned concrete box girder near the Oakland shore; a 2.4 km long segmental concrete box girder (skyway); a first-of-its-kind self-anchored suspension (SAS) bridge with a 385 m main span over the navigational channel; and a post-tensioned concrete box girder that connects to the east portal of the Yerba Buena Island tunnel. Opened in 2013, the signature span of the bridge is the SAS bridge with a length of 624 m and a total deck width of 79 m accommodating ten lanes of traffic in addition to a bike/pedestrian path. The US$6.4 billion megaproject was procured under multiple contracts and was delivered using the traditional design–bid–build method. This paper describes the key design innovations and construction methods which address the unique challenges on this project. [ABSTRACT FROM AUTHOR]

A passive shape-memory-alloy–rubber-bearing isolator has been developed for seismic protection of offshore jacket platforms. Mathematical modelling of an offshore jacket platform subjected to earthquake ground motions was undertaken, after which a systematic study of the key parameters of the isolator was undertaken to investigate its efficiency and to improve its performance. Dynamic time history analyses were carried out for both isolated and non-isolated jacket platforms using scaled ground motions. These clearly indicated the effectiveness of the isolator in controlling the overall responses of the jacket platform. It was better at mitigating structural displacement than structural acceleration, and its performance was dependent on the duration of ground motion. [ABSTRACT FROM AUTHOR]

The aim of the proposed work is to clarify the dynamic behaviour of asymmetric bodies in the case of rocking behaviour. The proposed algorithm is based on Housner theory and the integration of the equations of motion is evaluated with the Runge–Kutta–Fehlberg (RKF45) method. The significant accumulation of numerical errors is evaluated during the integration between two consecutive acceleration points where the rotation sign changes owing to the adoption of an equation that is wrong. An iterative calculation is developed to reduce numerical error depending on a specific tolerance and, therefore, the algorithm accuracy is investigated. In addition, the reduction of energy due to the impact at the point of change of the sign of rotation is analysed by means of a restitution coefficient. It is important to note that this is highly dependent on the rigid block properties, and experimental programmes are required to calibrate the restitution coefficient properly. Sensitivity analyses are performed in order to clarify the effects of convergence parameters and tolerances on the results, due to high numerical instabilities. Furthermore, fragility curves are retrieved based on far-field and near-field sets of accelerograms proposed by the Applied Technology Council in 2008, ATC-63, and a critical discussion is provided concerning the most efficient intensity measure parameters. [ABSTRACT FROM AUTHOR]

The tuned mass damper is a passive control technique, which is used in high-rise building structures for mitigation of the vibration produced as a result of wind and earthquake loadings. Irregularity in structure increases the chances of vibrations produced from these loadings. In this paper, detailed experimental work was carried out for vibration mitigation of an irregular four-storey structure having mass irregularity at its fourth floor using a single tuned mass damper (STMD) and multiple tuned mass dampers (MTMDs), against different harmonic and seismic loadings; such work has never been carried out before. The positions of STMD and MTMDs were varied along each floor and all possible configurations of STMD and MTMDs were tested against these loadings. For comparison, the acceleration responses of each storey for all configurations of STMD and MTMDs were compared with that of the uncontrolled structure. It was found that under all types of loadings, the STMD reduces the acceleration response of all floors of the uncontrolled structure; similarly, all configurations of MTMDs show further reduction in acceleration response, demonstrating the efficiency of MTMDs over a STMD in irregular structures. [ABSTRACT FROM AUTHOR]

The influence of shape memory alloy (SMA) reinforcement on the non-linear static and dynamic responses of hollow-section concrete columns to earthquakes was investigated. The seismic performance of concrete columns reinforced with steel and with a mix of SMA and steel was compared by assessing their ductility ratios, dissipated energies, strain recovery capacities and collapse drifts. The influence of near- and far-field ground motions on the static and dynamic responses of the test columns was also investigated. To verify the results, the columns were subjected to a near-field ground motion related to an existing earthquake and the relative displacement response history was compared with experimental results. Compared with the steel-reinforced column, it was found that the use of the hybrid SMA–steel reinforcement was more effective at recovering strains and reduced the residual deflections. On the other hand, the steel-reinforced column had a greater ductility ratio and energy dissipation capacity. It is therefore important to find an optimal combination length for the two types of reinforcement in a concrete column. The results indicated that the optimum reinforcement configuration involves replacing steel with SMA at 15–20% of column height, which includes the probable plastic hinge length. [ABSTRACT FROM AUTHOR]

Existing earthquake damage reconnaissance reports indicate that many tunnels have suffered noticeable damage. During seismic excitation, ignoring the rock–concrete interaction may affect the accuracy of research results. In this study the influence of rock–concrete interaction on the response of a tunnel under seismic excitation was systemically investigated. A finite-difference method (FDM) model of the tunnel was constructed and full dynamic time history calculations were performed. The rock–tunnel interface was built using the FDM, with interface elements defined by a linear Coulomb shear strength criterion. The reliability of the numerical simulation of the interface was verified by comparisons with direct shear test results. Based on a real engineering case (Xianglushan water conveyance tunnel), two models with different rock–tunnel interactions were established and their seismic responses evaluated. The mechanical properties of the interface were compared. The seismic responses of the tunnel were assessed in terms of displacements, stresses and lining dynamic internal forces. The results indicated that rock–concrete interaction may have a significant effect on a tunnel's seismic response, and that effect has a certain pattern. The influences of the mechanical parameters of the interface on the seismic response of tunnels are complex and the stiffness of the interface plays a significant role. [ABSTRACT FROM AUTHOR]

The north of the state of Baja California (BC) is located in one of the regions of Mexico with a high seismic risk. The predominant infrastructure in the city of Tijuana consists of reinforced masonry housing structures, making it crucial to understand the dynamic behavior of this type of structure. Using the "Vulnerability Modeller'sToolKit" (VMTK), fragility functions were obtained for low, medium, and high levels of seismic design. It was found that the probability of achieving or surpassing the different damage states (light, moderate, extensive, and complete) is high in low-height housing (1–3 floors) for an expected value of 0.50 g of PGA and in medium-height housing (4–7 floors) for an expected value of 0.5 g of SA (T = 0.5 s).Vulnerability functions were derived, and it was determined that, for a low seismic design level, low-height and medium-height structures, respectively presented loss probability rates of 30% and 44% for an expected value of 0.50 g of PGA and SA (T = 0.5 s). These fragility and vulnerability functions can be used to estimate damage and losses in future risk scenarios, thereby reducing uncertainty in the risk analysis calculations for the city of Tijuana. [ABSTRACT FROM AUTHOR]

With a unique architecture and a very tight site, the vertical elements that transfer the gravity loads of a 26-story residential building to the foundation required several transfer elements that needed to remain elastic in case of a maximum considered event (MCE) earthquake. To allow for this, composite construction was used to maximize strength, and complex temporary works were erected, supporting the concrete cantilever system with steel columns during construction. Because of the additional lateral stiffness provided by the transfer elements, additional earthquake stresses needed to be controlled. The strategy was to maximize the lateral stiffness of the building and the energy dissipation of the coupling beams. The strategies successfully achieved the desired behavior, delivering a seismic response with low lateral interstory drift, and key transfer elements with an elastic performance and reserve strength, in case the seismic demand is greater than anticipated. [ABSTRACT FROM AUTHOR]

Machine Learning (ML) has developed rapidly in recent years, achieving exciting advancements in applications such as data mining, computer vision, natural language processing, data feature extraction, and prediction. ML methods are increasingly being utilized in various aspects of seismic engineering, such as predicting the performance of various construction materials, monitoring the health of building structures or components, forecasting their seismic resistance, predicting potential earthquakes or aftershocks, and evaluating the residual performance of post-earthquake damaged buildings. This study conducts a scientometric-based review on the application of machine learning in seismic engineering. The Scopus database was selected for the data search and retrieval. During the data analysis, the sources of publications relevant to machine learning applications in seismic engineering, relevant keywords, influential authors based on publication count, and significant articles based on citation count were identified. The sources, keywords, and publications in the literature were analyzed and scientifically visualized using the VOSviewer software tool. The analysis results will help researchers understand the trending and latest research topics in the related field, facilitate collaboration among researchers, and promote the exchange of innovative ideas and methods.

Panel zones (PZs) can be proportioned to be weak, balanced or strong. Damage to steel special moment frames (SMFs) in past earthquakes has highlighted the limitations of weak PZ design, leading to its discontinuation from design practice. Balanced and strong PZ approaches remained acceptable, but the shear demand and capacity for which PZs need to be proportioned to achieve a balanced or strong PZ still remain ambiguous. In this work, three different PZ design approaches were investigated (named PZ-I, PZ-II and PZ-III) by incorporating them in seismic design of selected study buildings. The shearing behaviour of the PZs was evaluated using the results of non-linear analyses, which indicated that PZ-I, PZ-II and PZ-III led to weak, balanced and strong PZ behaviour, respectively. In particular, PZ-I design was found to lead to excessive shearing distortions in the PZ. Thus, in order to either limit or entirely eliminate inelasticity in the PZs of steel SMF buildings, it is appropriate to adopt PZ-II or PZ-III design. It is recommended that adopting the PZ-II design approach would suffice for moment frame buildings in regions of moderate seismicity. [ABSTRACT FROM AUTHOR]

The seismic design of new structures in Iran is currently based on earthquake hazard maps for a fixed return period of 475 years. However, this can lead to an unequal level of risk due to uncertainty in collapse capacity and differences in hazard curves in different locations. In the work reported in this paper, a risk-targeted approach was used to determine the peak ground acceleration (PGA) for designing reinforced concrete moment-resisting-frame (RC MRF) buildings in four important port cities in southern Iran. The three main parameters considered for determining risk-targeted PGA were the structural fragility curve, the seismic hazard curve and the target annual collapse probability. Nine RC MRF buildings with different geometrical characteristics were evaluated and their fragility curves were extracted. Then, using a risk integral, the annual collapse probability and PGA of the frames were obtained for the studied cities. Comparison of the results showed that an approach proposed in the literature for Europe is in accordance with the results of the approach proposed in this paper. [ABSTRACT FROM AUTHOR]

In recent decades, one of the most interesting innovations has undoubtedly been the application of resilience principles to the study and mitigation of seismic risk. However, although new rigorous mathematical models have become available in the context of seismic resilience assessment, their applications to real case studies focus on a local scale, or even single structures. Consequently, new models and procedures are absolutely necessary to adopt resilience measurements in the formulation of mitigation strategies on a national or subnational scale. Given the crucial role of residential buildings in the global resilience of Italian cities against major earthquakes, a new framework for large-scale applications is proposed to roughly measure the seismic resilience of communities through the integration of an empirical recovery function based on the reconstruction process of housing systems in the aftermath of the 2012 Northern Italy Earthquake. As a first attempt, the framework is applied to housing systems in the southern regions of Italy by modelling their physical damage with vulnerability curves defined on the basis of macroseismic approaches. The main results are presented and discussed in terms of average functionality levels over time in order to compare and understand the recovery capacity of the considered housing systems. [ABSTRACT FROM AUTHOR]

Near-field (NF) and far-field (FF) ground motion records were used to develop seismic fragility curves at different damage states for a multi-span reinforced concrete bridge using incremental dynamic analysis (IDA). The use of different methods for the prediction of the fragility curves, including truncated IDA, was also investigated. The results indicated that the median spectral acceleration causing different states of earthquake damage was lower for the NF records than for the FF records. In other words, the studied bridge was more vulnerable when subjected to NF records. The significantly larger probabilities of failure at different damage states, especially at the bar buckling damage state, for the case of NF records was attributed to the significantly larger variability of the results compared with the case of FF records. The results also showed that the probability of failure at different damage levels was relatively low for the case of the FF ground motions. It was also found that truncated IDA could be used to predict the fragility curves with sufficient accuracy for the cases studied. [ABSTRACT FROM AUTHOR]

Attention should be paid to tunnels' seismic behaviour since many of them have been damaged by earthquakes. The paper presented a seismic study of a shallow circular tunnel by physical modelling on shaking table test. A small scale tunnel model of the Hanoi pilot metro line's underground segment was placed in the middle of a rigid soil container and buried in Red River sand (Vietnam). The table was vibrated along the soil container's long wall, with a simulated seismic wave created from the 1788 Tolmezzo (Italia) accelerogram. Five testing campaigns were executed, and the model's acceleration data were studied. The uni-directional vibration created by the shaking table caused the three-directional vibration of the physical model. The Fast Fourier Transform (FFT) frequency spectrum analyses were performed. The vibration characteristics of the model (i.e., frequency graph's structure, maximal acceleration, dominant frequency, strong-motion duration) in three orthogonal directions under the artificial earthquake action were compared. The obtained results proved the complicated seismic impacts on a shallow tunnel.

Lateral torsional coupling of asymmetric buildings governs their seismic response. Other than building eccentricity, the extent of this impact depends on the interaction of the building foundation with the surrounding soil – soil–structure interaction (SSI). This study investigates the seismic response of a representative asymmetric building, equipped with semi-active dampers, by accounting for the effect of SSI. Two semi-active damping schemes – friction-type and two-step viscous – are considered and their relative efficiencies are measured when compared with passive dampers. All analyses, including building eccentricity, SSI and dampers, are performed under ten earthquakes with different characteristics and peak intensities. Results obtained imply that SSI can have a significant impact on the lateral torsional coupling of the building if not realistically considered, and thus can greatly influence the seismic response of an asymmetric building. Comparative assessment between semi-active and passive dampers, with respective optimal damping parameters and placement, reveals the superiority of friction-type dampers over the others in reducing the response of the asymmetric building during seismic shaking. Nevertheless, all dampers are found to be efficient in regulating the seismic response of the asymmetric building–SSI system by lowering the adverse effect of lateral torsional coupling on the seismic response of the building. [ABSTRACT FROM AUTHOR]

Accurate long-term risk and resilience assessments of bridges are of paramount importance to aid rational decision making under seismic hazards. Both earthquakes and structural deterioration exhibit time-varying features. It has been found that the occurrence of large earthquakes is dependent on time, due to energy accumulation, whereas the widely adopted homogeneous Poisson process assumes a time-independent hazard occurrence. Bridges can deteriorate over time due to environmental exposure, resulting in increased seismic vulnerability. The time-varying characteristics associated with earthquakes and deterioration, which have compound effects on structures, should thus be incorporated in long-term seismic risk and resilience assessments. An approach for assessing the long-term resilience of bridges incorporating the time-varying characteristics of earthquakes and deterioration is presented. The Brownian passage time model, capturing energy accumulation and release, is used to model the time-varying characteristics of earthquakes. Bridge seismic vulnerability is computed in a time-varying manner considering deterioration. Subsequently, long-term bridge resilience loss is computed by considering earthquakes and deterioration over the entire service life of the bridge. The proposed approach is illustrated on a highway bridge subjected to time-dependent seismic hazard and structural deterioration. [ABSTRACT FROM AUTHOR]

An experimental study was performed to investigate the effect of external prestressed truss steel-bar units installed on an unreinforced masonry (URM) wall under out-of-plane loadings. The key components of this new retrofitting method are prestressed vertical and diagonal bars. The prestressed vertical bars induce a prestressing force onto the horizontal section of the URM wall and the diagonal bars resist lateral loadings. Reverse cyclic tests were conducted on a full-scale URM wall as a control specimen and URM walls retrofitted in-plane and/or out-of-plane (parallel to short intersecting walls). The test results showed that the specimen strengthened using the new technique was superior to the control specimen in terms of seismic performance, including lateral load resistance, stiffness, energy dissipation and restrained slip of the entire specimen. Two units installed on short intersecting walls exhibited the same shear strength as four units installed on the in-plane and in-plane retrofitted masonry walls. The out-of-plane masonry specimen demonstrated the best performance. It was confirmed that aligning the retrofitting method based on the loading direction was effective, despite the lower axial load level. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic response and assesses the safety of a propylene tower subjected to blasting vibrations. A group of monitoring experiments on the response of the tower to blasting vibrations was carried out to this end. A model of a cantilever beam was used for the response along the horizontal direction and that of a strut for along the vertical direction. The theoretical and measured displacements were consistent in terms of time history curves and peak values. The design spectrum of the tower suitable for sustaining blasting vibrations was then proposed and verified, and its safety was assessed in combination with local requirements on seismic design. The results show that the first six modes of response should be considered under blasting vibrations in the horizontal direction, instead of the first three modes as in the case of an earthquake. The first three modes should be considered under blasting vibrations in the vertical direction. Owing to the importance higher modes in this scenario, the shear should be taken as the primary object of evaluation when assessing the safety of a tall propylene tower subjected to blasting vibrations. [ABSTRACT FROM AUTHOR]