In the Himalayan region, stone masonry with mud mortar is a widely used construction method for buildings, due to the simplicity of the technique and the abundance of materials. This is particularly applicable in Nepal, where over 80% of the land is mountainous. The 2015 Gorkha Earthquake led to significant damage to 60% of these stone masonry school buildings, thus revealing their seismic vulnerability. This extend of seismic damage poses the urgent need for a comprehensive study of the seismic performance and lateral load capacity of this construction typology, coupled with experimental validation of seismic retrofitting methods to facilitate an increase of the seismic resilience of the existing building inventory. Retrofitting stone masonry using Welded Wire Mesh (WWM) has been incorporated into national-level guidelines as a recommended practice. However, there is a lack of experimental verification on the efficiency of this method for the seismic retrofitting of stone masonry buildings. This research addresses this gap by conducting a series of full-scale wall tests on the out-of-plane load and displacement capacity of stone masonry walls in Kathmandu, under the Seismic Safety and Resilience of Schools in Nepal (SAFER) project, funded by the Global Challenges Research Fund (GCRF) and the Engineering and Physical Sciences Research Council (EPSRC), UK. The study utilized locally available materials, such as galvanized steel wire mesh for the seismic retrofitting of the walls. Three sets of monotonic lateral load tests were performed on stone masonry walls, including two unretrofitted and four retrofitted walls, using a low-cost testing setup. The experimental results demonstrated that the retrofitting increased 3.5 times the out-of-plane lateral load-bearing capacity of the walls, while also doubling their displacement capacity compared to the unretrofitted walls. Furthermore, the failure mode of the walls was substantially modified after retrofitting, with the retrofitted walls exhibiting smaller, more evenly distributed cracks rather than larger, localized ones. Based on the design of the above community-driven testing configurations, this study provides a practical and cost-effective approach for seismic testing and seismic retrofitting of stone masonry walls in developing countries, thus enabling the extraction of valuable experimental data in regions where such information is scarce. The findings facilitate the in-situ experimental validation of low-cost seismic retrofitting techniques and provide design recommendations for their application, thus paving the way for the implementation of seismic risk mitigation strategies in developing countries.

This paper presents the main results of full-scale shaking table tests carried out in an experimental project, funded under the auspices of the SERA project H2020-INFRAIA-2016-2017/H2020-INFRAIA-2016-1. The experimental campaign aim is the evaluation of the seismic performance of three-leaf masonry walls with weak lime-mortar joints. These walls are typically made of two outer leaves made of stones/bricks while the middle leaf is made of weak mortar. The outer leaves are usually not connected. The responses of different walls to a selected natural record, applied with increasing intensity, first with the horizontal component only and then with both the horizontal and vertical components, are reported. Following tests on the as-build specimens, additional walls were tested after applying a retrofitting technique designed to increase the strength of the masonry wall. The retrofitted walls were tested with the same input seismic sequence applied to the un-retrofitted walls. The reported results shed light on the detrimental effects of the earthquake vertical component on the response of the considered masonry, as well as on the beneficial effects of the applied retrofitting system.

This paper examines the effect of soil–structure interaction (SSI) on the seismic demand of cross-laminated timber (CLT) walls, coupled with energy dissipating connectors. The structural system consists of balloon-frame CLT walls with self-centering hold-down connections and coupled with hysteretic steel dampers. To study the effect of SSI on seismic demand, the sub-structure method of analysis in the time domain is used. The numerical SSI model comprises a nonlinear model of the superstructure and an equivalent linear-elastic model of the soil–foundation system. Parametric study with both homogeneous and heterogeneous soil profiles are examined. To account for the frequency-dependence of soil–foundation in the time-domain, a robust Lumped Parameter Model is employed to represent the underlying soil–foundation sub-system. This approach is then compared with the commonly used, simplified Kelvin–Voigt model, which comprises frequency-independent springs and dashpots. It is shown that for low-to moderate intensity ground motions, the SSI increased the maximum inter-story drift ratio and accumulated hysteretic energy demands. Moreover, neglecting the frequency dependence of soil–foundation impedance results into a non-conservative assessment of seismic demand, particularly for heterogeneous soil profiles involving a soft upper layer, for which SSI effects emerge as a critical design consideration.

This paper presents the results of large-scale uplift tests on pad foundations conducted at the Soil-Foundation-Structure Interaction Laboratory at the University of Bristol, simulating conditions relevant to overhead electrical line infrastructure. Pad foundations with a 1 m & times; 1 m footprint and different geometries were embedded at depths of up to 2 m in manually compacted dry sand. The results complement and validate previous centrifuge tests, and numerical modelling studies aimed at improving current foundation design practices. They confirm: (i) the superiority of theoretical uplift-prediction methods that account for both the weight of the soil wedge and the frictional forces mobilised along the failure planes, both governed by soil dilation; (ii) the potential for optimising foundation geometry through chamfering to increase uplift capacity and reduce concrete volumes; and (iii) that simple projection of the uplift failure wedge to the ground surface can lead to an overestimation of the failure wedge size. Direct comparison with centrifuge tests shows close agreement in maximum uplift capacity, although some discrepancies were observed in the displacement at the peak failure state. Nevertheless, this full-scale validation provides confidence in implementing the novel design methods for pad foundations supporting overhead electrical line infrastructure.

Enhanced seismic hazard assessments are needed to improve codes of practice for use in earthquake-prone regions. In 2020, Nepal published an update to the 1994 building code, which incorporates learning from new research after the 7.8 Mw 2015 Gorkha earthquake and best practices from seismic codes at the international level. In this technical note, the seismic hazard of the latest version of the code is compared with recent probabilistic seismic hazard analysis studies developed for the region including some results from the Seismic Safety and Resilience of Schools (SAFER) project in Nepal. The comparison is contextualized within the overall framework of best performance requirements to effectively improve the building stock at the national level accounting for available resources.

Samos is an island in the Aegean Sea, with rich cultural heritage that suffered significant damage during the Mw 7.0, October 30, 2020, earthquake that was triggered by the rupture of the North Samos fault. The majority of the buildings are masonry ones, constructed during a period of financial wealth from the island’s economic peak in the 19th and early 20th centuries, that is, before the introduction of modern seismic codes. This explains to some extent the damage observed across the island. However, a substantial portion of the building stock, including vernacular architecture and Neoclassical and Venetian-style buildings, exhibited minor to moderate damage. There is an interesting contrast therefore among structures that performed very differently for the same level of ground motion intensity. This paper critically discusses and interprets different damage modes of heritage buildings, drawing lessons for future conservation efforts in seismically active regions. The study concludes with recommendations for simple, pre-earthquake interventions that can enhance the safety of heritage structures.

Over the past decade, building construction has undergone a notable transformation with the advent of additive manufacturing. Indeed, several companies are developing 3D printing systems and buildings worldwide. However, the current literature lacks comprehensive studies, and a significant gap remains in understanding the seismic behaviour of monolithic 3D-printed structures. This paper aims to address this shortcoming by presenting a systematic experimental campaign, beginning with the characterisation of printed materials and culminating in a shake table test on a full-scale 3D-printed housing unit (3m x 4m). To the best of the authors’ knowledge, this is the first seismic shake table test conducted on a 3D-printed building unit. The work proposes a methodological approach developed through a five-step procedure: i) conducting mechanical characterization through a series of preliminary tests, such as diagonal shear tests in 3D printed walls; ii) calibrating a numerical model using preliminary experimental tests to simulate the seismic response of the 3D-printed building unit; iii) designing and dimensioning the 3D-printed building unit, along with its connection to the shake table and the sensor system; iv) implementing the full-scale shake table test on the housing unit, printed directly on the shake table at the SOFSI Lab, University of Bristol; v) refining the numerical model based on the outcomes of the final dynamic test. Preliminary results indicate the potential for establishing foundational design guidelines to support engineers and industry stakeholders adopting this emerging technology. Ultimately, this study enhances seismic risk mitigation strategies and promotes technologically advanced construction solutions. This paper is part of the dissemination activities of the SAFE 3D PRINTED-CS project, funded under HORIZON-INFRA-2021-SERV-01-07, transnational access call 1.

Simulating ground motion (GM) is essential for assessing seismic hazards and evaluating the risks to civil infrastructure in earthquake engineering. The widely used stochastic method achieves temporal nonstationarity in simulated GM by applying a window function to Gaussian white noise. Typically, this window function has a fixed shape due to its constant shape parameters, resulting in uniform waveforms in simulated GMs. This study proposes a novel approach that generates a window function from recorded GMs, rather than one constrained by a specific mathematical form with constant parameters. Here, the relative location of the peak ground acceleration ( P ) and the 5%–75% significant duration ( D 70 ) are selected as shape parameters for the window function. To determine target shape parameters for specific scenarios, this study establishes a probability distribution model for P and applies a well-established predicting model for D 70 . A time series, shaped to meet the target parameters, is generated from recorded GMs, and its normalized envelope, computed using the Hilbert transform, is utilized as the window function. The proposed approach enables the window function’s shape parameters to better align with statistical characteristics, incorporating the temporal nonstationarity of recorded GMs into the simulation. Case studies on the M w 6.9, 2008 Iwate and M w 6.8, 2007 Chuetsu-oki earthquakes illustrate improvements in the envelopes and durations of the simulated GMs.

The paper reports on the findings of the EU/H2020-funded project REBOND/SERA and investigates, by means of shaking table tests, two key questions on the seismic behaviour of multi-leaf masonry walls. The first one concerns the potential detrimental effects of the vertical component of ground motion on the strength degradation of the wall. The second relates to the effectiveness of a retrofitting scheme based on galvanized steel glass fibres inserted through the wall thickness. Investigating these two issues helps identify cases where the vertical ground motion component should be used in the seismic assessment of both as built and retrofitted masonry structures. It can also indicate cases. The ground motion is incrementally applied with scale factors ranging from 10 % to 120 %, unless collapse is reached at a lower intensity level. These results are compared with those previously published on an identically designed wall tested neglecting the vertical component of the ground motion. The dynamic tests of the retrofitted wall are also comparatively discussed. It is shown that the vertical ground motion component significantly affects the response of the three leaf wall, with more severe cracks and damage levels being observed at lower seismic intensities. With the 100 % scaled record, the consideration of the vertical component caused residual drifts of 0.25 %, corresponding to damage that was not observed under horizontal excitation only. Notably, the first residual vertical displacements were recorded at 75 % of the input earthquake and increased to 2.5 mm at 100 % of the input earthquake. On the other hand, the proposed retrofitting scheme, as anticipated, increased the wall strength and delayed crack formation. The first residual displacements in the retrofitted wall were recorded at 120 % of the earthquake input, which is strong evidence of the effectiveness of the proposed retrofitting scheme.

Recent earthquakes have highlighted the importance of earthquake ground motion recordings and rapid visual inspections (RVSs) of damaged buildings to assess the earthquake impact on the building inventory, prepare recovery plans, and provide valuable findings that could contribute to the preparedness ahead of future earthquake events. The effect of strong earthquake ground motions on the building stock is controlled by a range of interconnected factors. These include the intensity of ground motion, the effects of local soil conditions, the structural design, reinforcement and material properties, as well as the quality control during construction, among others. However, it is important to acknowledge that the earthquake ground motions recorded are dependent on local variables, such as the soil type and potential operational issues. Such an example is the major M6.4 earthquake in Durrës, Albania, in November 2019, the most significant in the region in the past four decades. The strong ground motion recorded at the sole Durrës accelerometric station was interrupted due to a power outage. As a result, the recorded accelerograms (with a PGA of 0.192 g) require thorough analysis and evaluation before they can be reliably used in assessing damage of existing structures. The current paper presents a framework for evaluating the incomplete record to ensure that the strong ground motion pulse is captured in the acceleration series. The latter is achieved by analyzing and comparing the amplitude and frequency contents of the recorded motion against ground motion accelerograms from areas with similar seismotectonic features. Ground motion recordings from stations that have soil conditions resembling those of the Durrës region are used, ensuring that the analysis is relevant to the specific study area. Next, the disrupted ground motion recording is evaluated by comparing the damage of post-earthquake inspected buildings with the results of advanced numerical analysis for the case of a typical 12-storey and a 5-storey building. The effects of pounding, the presence of infills, soil-structure interaction (SSI), and multiple failure modes are taken into consideration. Results indicate that despite the incomplete data, the seismic record retains the essential strong ground motion features and can be used for further studies. The numerical simulations aligned well with observed damage from rapid visual inspections, verifying the record’s integrity. The findings show that factors such as soil-structure interaction, infill panels, and pounding effects significantly influenced building performance. The study concludes that the Durrës record, though incomplete, is reliable for seismic assessment and can aid future risk studies in the region.

Integral abutment bridges (IABs) are widely used worldwide when the crossing span is short-to-moderate. Due to the elimination of bearings and joints, the seasonal expansions and contractions of IABs are absorbed by the backfill and foundation. However, during the cyclic expansion and contraction of the bridge deck caused by temperature variation, the abutment-backfill-embankment system significantly interacts with the superstructure in a way that is difficult to predict analytically. In the context of the EPSRC-funded PLEXUS project, a 1g small-scale experiment was conducted to assess the distribution of the earth pressures behind the abutment. The experiment comprised a soil box filled with sand. A hinged moveable wall was set against the soil to simulate the integral bridge's abutment-backfill interaction, and the thermal-induced deformation was introduced by cyclic movements of the wall. This study aims to numerically model the PLEXUS experiments using OpenSees and its visual toolkit STKO, carrying out a numerical-to-experimental comparison as well as a numerical-to-numerical comparison between different finite element (FE) software packages (i.e. OpenSees and PLAXIS, ABAQUS). In the OpenSees model, the soil-wall interaction interface is represented by "EqualDOF" links, and the backfill is considered a discrete domain with "PressureDependMultiYield02" material. The results indicate good agreement between the numerically predicted and the experimentally measured response when the soil is modelled as nonlinear in OpenSees while highlighting specific differences with respect to the different software packages considered. The strategy using "EqualDOF" for modelling abutment-soil interface and plastic "PressureDependMultiYield02" material showed a relatively satisfactory agreement with experimental results.

We investigate abutment–backfill interaction in integral bridges (IBs) under thermal loading over a large number of cycles for a 120-year life span as specified by modern design codes. To better understand the associated mechanisms and assess the performance of IBs within their entire life cycle, a large-scale (1 g) physical model, comprising a 3 m tall concrete wall retaining 35 m 3 of dry uniform sand, was built and tested in the soil pit of the Soil Foundation Structure Interaction laboratory at the University of Bristol. The thermal load was modelled as a cyclic displacement history of constant amplitude imposed via a hydraulic actuator, corresponding to a maximum drift of 4.8 × 10 –3 . The maximum passive soil resistance increases monotonically, especially during the first 40 loading cycles, at a decreasing rate. Motivated by the inability of available design formulae to capture the pressure built-up over the entire life cycle of the bridge, an adaptive numerical spring model is developed, employed first for the design of the experiment and subsequently for the numerical simulation of the test; the model has shown to capture reasonably well the densification of sand and successfully mimic the observed lateral earth pressure and bending moment distribution with number of cycles.

Timber construction is rapidly advancing in structural engineering due to its benefits, such as light weight, ease of prefabrication, and contribution to societal goals. With an increase in building height, however, knowledge garnered by coupling advance modelling and experimental testing will enable designers to push the boundary further. The ERIES-HYSTERESIS project will use geographically distributed hybrid testing to investigate energy dissipation characteristics and soil-structure interaction (SSI) responses of multi-story buildings constructed with mass timber. Testing large-scale timber structures with SSI considerations poses unique challenges, requiring an innovative hybrid testing methodology. Geographically distributed hybrid simulation involves designing a representative pilot structure and dividing it into subcomponents for simultaneous testing. This paper details the 3D design of the pilot structure, considering constraints required for hybrid testing. SSI is addressed as a critical factor, with the objective of identifying the hierarchy of failure between the soil, the wall-foundation connection and the hold-downs. A balance has been achieved between maintaining a realistic design and ensuring the experimental requirements remain within the capabilities of the involved laboratories.

Integral abutment bridges (IABs) generate strong soil-structure interaction (SSI) effects due to their high structural stiffness and transmission of inertial and thermal loads generated at the deck directly to the abutments. Despite an increasing number of experimental and numerical studies available in the literature, there is a lack of consolidated methodologies to model dynamic SSI phenomena for IABs, particularly in seismic regions where uncertainties associated with the induced ground motions render the problem harder to tackle. This study proposes an advanced strategy to model the seismic response of IABs, accounting for dynamic interaction between the structure, the abutment and the foundation, including piles and earth retaining walls. To this end, detailed finite-element studies were carried out employing OpenSees to simulate a recent experimental campaign on a scaled IAB model in a soil container (SERENA) carried out at EQUALS Lab, University of Bristol, in the framework of SERA/H2020 project. An extensive dataset in terms of recorded accelerations, displacements, strains and settlements are available from these tests, including earth pressures which are back-calculated from bending strain measurements. The objectives of this paper are threefold: firstly, the model parameters are explored and assessed critically by comparing the results from the numerical simulations against the experimental data; secondly, once the model is deemed sufficiently representative of the experiments, earth pressures are obtained numerically, as these are not directly measured in the tests; thirdly, the estimated static and dynamic earth pressures on the abutment wall are compared with the predictions of two simplified analytical procedures currently under consideration for inclusion in the new Eurocode 8. The results indicate that records and predictions match well for frequencies of up to 40 Hz at model scale (about 8 Hz in prototype scale) and confirm that the proposed modelling strategy can be used in practical applications. The quasi-elastic model proposed in this study is shown to provide dependable predictions for cases involving moderate strains in real-life applications.

A dual structural system for low-to-medium-rise buildings is examined, comprising light-timber frames (LTF) coupled with a cross-laminated timber (CLT) wall. To enhance the energy-dissipating capacity of LTF featuring pinching behavior, friction sheathing-to-frame connections have been proposed in place of conventional nail connectors. The resulting friction LTFs (FLTF) exhibit sustainably rich hysteresis loops that significantly enhance energy dissipation capacity. Nevertheless, the friction-dissipating mechanism leads to nonuniform story drift distributions and residual drifts in multistory FLTF buildings. To address this issue, a CLT wall with self-centering hold-down connections is coupled to the multistory FLTF building for imposing uniform story drifts and for reducing residual drifts. A direct displacement-based design (DDBD) approach is employed to design the dual CLT-FLTF system and ensure (i.e., impose) uniform seismic demand across the height of the building. Nonlinear-time-history analysis (NTHA) and incremental dynamic analysis (IDA) show that the DDBD approach can lead to safe designs and effectively control the displacements of the proposed dual system.

Modern research often involves the collection or analysis of data and the use of specialized computer algorithms. Traditional text articles thus provide only partial documentation of a research study. Readers have limited ability to reproduce or utilize work if the source data are not available or if it relies on an algorithm that is described, but code is not provided. Fortunately, a wide variety of tools are now available to support the publication of research data and code. The effort required to publish data is now relatively small, and the benefits can be immense. This opinion article discusses trends toward increased sharing in academic publishing. It describes opportunities and resources to support data and code sharing and describes the benefits for both authors and readers. Finally, it discusses how Earthquake Spectra is providing resources and enhancing its policies to establish the sharing of data as the default procedure when publishing in the journal, and encourage the sharing of code and other resources.

The complexity of design, the high transportation cost and the use of materials of high carbon footprint inhibit the sustainable implementation of response modification strategies, such as seismic isolation systems and tuned mass dampers to a large number of countries worldwide.This study presents novel, low-cost response modification strategies that are constructed based on materials, which can be easily resourced.These strategies comprise low-cost engineering measures for the protection of the superstructure from seismic damage at the design hazard level and low-cost seismic isolation techniques for the seismic protection of structures for intensities that exceed the design one.These methods are based on the inclusion of a thin layer of sand or roller bearings between two rigid and smooth surfaces in a sandwich configuration, which facilitates the sliding of the upper surface against the bottom surface at an attractively low, yet reasonably configurable, friction coefficient.The efficiency of the aforementioned response modification strategies is demonstrated based on large-scale testing performed at University of Bristol that paved the way for the design and construction of a new building.

This study establishes a multi‐hazard probabilistic assessment framework for assessing the integrity of monopile offshore wind turbines (OWT) under the stochastic coupled effect of wind, wave and earthquake loading. The procedure deals with the entire operational range of inflow wind speed (i.e., 3–25 m/s), for which the probability of failure under multi‐hazard excitations is found to be non‐negligible. Numerical analysis is performed by implementing nonlinear finite‐element models of the OWT developed in OpenSees. The dynamic response of the OWT system under wind‐ and wave‐load combinations is individually validated against those obtained from the aero‐hydro‐servo‐elastic simulator OpenFAST. Following the Latin‐hypercube approach, a cloud‐based assessment procedure is then performed with an ensemble of 300 earthquake ground motions, from which the multi‐hazard performance of the OWT regarding the serviceability limit state (SLS) and the ultimate limit state (ULS) can be evaluated. The epistemic uncertainty associated with various loads, structural properties, and soil conditions is also accounted for. Based on this probabilistic assessment framework, the sensitivity of the resulting OWT fragility surfaces to different statistical regression methods and wind—ground motion intensity measure pairs (IM‐pairs) is further scrutinised. Regression methods are comparatively evaluated. The efficiency, practicality, proficiency and sufficiency of various IM‐pairs are examined for the purpose of assessing operating OWT multi‐hazard fragility functions. The optimum IM‐pair is then employed in a trained Gaussian Process Regression (GPR) scheme for cloud data regression to assess the multi‐hazard fragility of the system. The derived multi‐hazard fragility function shows that the contribution of seismic forces in structural demand for a design‐level earthquake is comparable to those caused by operational‐level wind and wave loads.