High Seismic Area Research Articles

Moment Resisting Frames under the light of Japanese and European Codes

AbstractThe aim of the work is to make a comparison between the European and Japanese approaches to design Seismic‐Resistant Steel Frames (MRFs) in high seismicity areas. Therefore, the design rules for both the seismic codes are analyzed and compared. These design rules are applied to design a benchmark structure in DC3 ductility class (according to the new prEN1998) and following the Route 3 procedure (according to the Building Standard Law in Japan, BSL). The examined structural typology is a Spatial Moment Resisting Frames with regularity in plan and elevation configuration. The Japanese approach is divided in two stages. The first one regards the Allowable Stress Design (Elastic analysis) in which all the parts of the structure must be kept elastic; service and damage limitation requirements are in demand. The second stage regards the Ultimate Strength Design (Plastic Analysis) in which no‐collapse requirement and the protection of the human life are in demand. The seismic performance of the designed structures is evaluated by means of pushover analyses.

Ensuring earthquake resistance of hydraulic structures in case of earthquakes

A significant number of hydroelectric power plants (hereinafter referred to as HPPs) are located in areas of high seismicity (7 or more points) in Russia. Ensuring the safety of hydraulic structures (hereinafter – GTS) Hydroelectric power plants in case of earthquakes is an urgent task. The authors of the article point out the lack of sufficient justification for the seismic resistance of the GTS due to the fact that the regulatory regulation of the safety of GTS under seismic impacts was developed in Russia and abroad only at the end of the 20th century, therefore, the GTS that have been in operation for a long time were not designed taking into account seismic impacts. In this regard, there is a risk of their vulnerability to earthquakes. The article provides a brief overview of foreign experience in ensuring earthquake resistance of dams in operation. An overview is given with an assessment of the completeness and sufficiency of the provisions and requirements of the current regulatory framework for ensuring earthquake resistance of hydraulic structures in the Russian Federation, developed at the beginning of the 21st century. The main provisions and mandatory requirements for ensuring earthquake resistance relate to the stages of design and construction. For GTS HPP complexes in long-term operation, the application of these proposed methods requires an individual approach. The authors of the article indicate the need to develop regulatory support for the safety management of GTS in long-term operation in seismically hazardous areas.

New Insight on the Active Fault System in the Halmahera Volcanic Arc, Indonesia, Derived from the 2022 Tobelo Earthquakes

Abstract On 9 January 2022, two shallow earthquakes occurred in the east arm of Halmahera, Indonesia, with magnitudes of Mw 5.2 and 5.4 felt at III–V modified Mercalli intensity. The existence of the causative fault for the earthquakes was unknown. One possible explanation is that the earthquakes were caused by the activity of an inactive fault striking in the southeast–northwest direction, and possibly linked to the volcanic activities in Halmahera. Thus, further analysis of their characteristics is crucial to identify the previously an inactive fault. In this study, we relocated the associated earthquake hypocenters using the double-difference method with an updated velocity model, and determined the focal mechanisms by employing full waveform inversion using moment tensor analysis. The focal parameters were used to analyze the static stress changes. The relocated hypocenters show specific hypocenter clusters, aligning in the north–south direction, associated with left-lateral faulting mechanisms. This north–south alignment differs from the northeast–southwest trend of some other active faults in Halmahera. We propose that the newly found Tobelo fault dips at an angle of around 80° to the west. The seismic stress change from the mainshock and the foreshock of the Tobelo earthquakes corresponds with the distribution of the aftershocks. A detailed analysis of unidentified faults in the high seismicity area is essential to comprehend the tectonic study of Halmahera Island and its seismic hazard assessments.

Site effect influence on the seismic vulnerability of unreinforced masonry buildings in low to moderate seismic urban areas in Algeria

PurposeThis paper aims to develop preliminary damage scenarios for unreinforced masonry buildings located in low to moderate seismic hazard areas in Algeria, taking into account the specific site effects.Design/methodology/approachThree soil types were considered in this analysis according to the definition of the Algerian seismic code (RPA99/2003). Peak ground acceleration values were assigned to each soil type issued from a probabilistic seismic hazard analysis (PSHA). To highlight the effect of soil conditions on the seismic vulnerability analysis of masonry buildings, a site vulnerability increment is carried out, and the macroseismic Risk-UE method has been adopted and applied by developing two main seismic scenarios according to both return periods of the PSHA, 100 and 475 years, respectively.FindingsBased on the preliminary results of rock site condition, it can be outlined that the significant damage obtained for different earthquake scenarios discovered a substantial worldwide seismic risk to the building stock of the study area. Once the site effect is integrated into the analysis, more high values of vulnerability indexes and expected damages are obtained. Moreover, it can be concluded that soft soil (S3) is a little bit more influential than stiff soil (S2) on the final vulnerability index compared to (S1). However, the difference between the soil effect S2 and S3 on the vulnerability index can be neglected.Research limitations/implicationsResearchers are encouraged to test the mechanical approaches for more detailed outcomes of a specific building analysis.Practical implicationsThis research proves to the Algerian decision-makers that due to the site effects and the vulnerability of the masonry buildings, an urgent intervention program is required even for existing buildings located in low to moderate seismic hazard areas.Originality/valueSeveral seismic vulnerability types of research have been conducted in Algeria for the unreinforced masonry buildings in moderate to high seismic areas in which generally the soil effect is neglected. In this context, this research paper proves that due to the site effects and the vulnerability of the masonry buildings, special attention is required even for existing buildings located in low to moderate seismic hazard areas. With this conclusion, the requirement of taking into account the soli effect in the high seismic areas is even more pronounced and should be conducted.

Experimental Investigation on the Seismic Behavior of Ultra-High Performance Concrete Filled Steel Tubular Columns

ABSTRACT In this work, a total of nine ultra-high performance concrete (UHPC) filled steel tubular columns (UHPCFSTs) were fabricated and tested under cyclic loading. The results indicated that UHPCFSTs mainly exhibited flexural failure mode, compression-flexure failure mode and welding line fracture, and it changed from flexural failure mode to compression-flexure failure mode when the axial compression ratios exceeded 0.3. The elastic and ultimate drift ratios of UHPCFSTs were within the ranges of 1.37–2.05% and 2.38–4.32%, respectively, and the equivalent viscous damping coefficients were within the range of 0.197–0.358 when they failed, UHPCFSTs could sever as good choices in high seismic intensity areas.

Development of a novel fire following earthquake probabilistic framework applied to a steel braced frame

This paper describes a novel probabilistic fire following earthquake (FFE) framework to develop FFE fragility functions for steel braced frames. In particular, an 8-storey steel braced frame, located in a high seismic area, was used to demonstrate the framework. An algorithm was formulated to generate fire scenarios based on seismic damage. Damage caused by the earthquake was expressed in terms of inter-storey drift ratio (IDR) and peak floor acceleration (PFA). Damage was captured in structural and non-structural components, such as glazing and partition walls. In particular, floors with IDR and PFA that exceeded pre-defined thresholds were considered to experience ignition after an earthquake. More than 1100 nonlinear FFE analyses were performed by randomly generating values of window widths, fire load densities, earthquake intensities, and yield strength of steel at ambient and at high temperatures. Historic ground motions and natural fire curves were employed to characterize the hazards. Thermomechanical analyses were completed and failure criteria based on displacement and displacement rate were applied to the girders (primary beams) and columns. The results of simulations were processed to generate FFE fragility curves and surfaces for girder and column failures with respect to the time to failure in the FFE scenario and grouped based on spectral acceleration intervals. The results showed that the girder always failed first given the low structural redundancy due to the end conditions. Moreover, the higher the spectral acceleration, the more uniform the damage across the structure with a lower time to reach failure. It was finally found that the fire load density did not have a significant effect on the probability of failure for the case study under consideration.

Seismic isolation analysis and design of a plane irregular building structure in high earthquake intensity area

Taking the large commercial complex building of Changzhou Golden Eagle Plaza as the research object, this paper analyzes various parameters of typical special-shaped space structure under different isolation schemes under the conditions of earthquake protection, rare earthquake and extremely rare earthquake, compares three isolation layer design combinations of rubber isolation bearing, lead isolation bearing, rubber isolation bearing + lead isolation bearing, and studies the influence of different isolation layer arrangement schemes on the steel core and mass center of the building structure. The results show that the reasonable isolation design can obtain the reasonable arrangement pattern and rule of the plane irregular building structure in a high seismic intensity area by comparing and analyzing the arrangement schemes of different types and forms of isolation bearings in the isolation structure model.

The attenuation of macroseismic intensity in the volcanic island of Ischia (Gulf of Naples, Italy): comparison between deterministic and probabilistic models and application to seismic scenarios

In this paper, we tackle the problem of the intensity attenuation at Ischia, a critical parameter in a high seismic risk area such as this volcanic island. Starting from the new revised catalogue of local earthquakes, we select a dataset of 118 macroseismic observations related to the four main historical events and analyse the characteristics of the intensity attenuation according to both the deterministic and probabilistic approaches, under the assumption of a point seismic source and isotropic decay (circular spreading). In the deterministic analysis, we derive the attenuation law through an empirical model fitting the average values of ΔI (the difference between epicentral intensity I0 and intensities observed at a site IS) versus the epicentral distances by the least-square method. In the probabilistic approach, the distribution of IS conditioned on the epicentre-site distance is given through a binomial-beta model for each class of I0. In the Bayesian framework, the model parameter p is considered as a random variable to which we assign a Beta probability distribution on the basis of our prior belief derived from investigations on the attenuation in Italy. The mode of the binomial distribution is taken as the intensity expected at that site (Iexp). The entire calculation procedure has been implemented in a python plugin for QGIS® software that, given location and I0 (or magnitude) of the earthquake to be simulated, generates a probabilistic seismic scenario according to the deterministic or probabilistic models of attenuation. This tool may be applied in seismic risk analyses at a local scale or in the seismic surveillance to produce real-time intensity shake-maps for this volcanic area.

Heavy and light masonry walls impact on medium height reinforced concrete frames buildings

The paper studies the influence of light weight aerated autoclaved concrete (AAC) partitioning walls to a medium height reinforced concrete structure, in Bucharest (Romania). The building is designed as a framed structure with non-bearing AAC walls placed in certain bays. There is a bearing full bricks masonry wall in one of the bays. Full bricks are used because of its high strength compared to AAC. The aim is to determine the importance of the masonry walls placement, both full bricks and AAC, for the building’s behavior. The analysis points out the structure’s elastic and plastic behavior and also the efforts developed in the non-bearing walls. The bearing masonry wall’s behavior is very important, because the structure is built in a high seismic area. To extend the study, the full bricks wall is replaced with a reinforced concrete one. This is done to see how it impacts the building’s behavior, for both the elastic and plastic stage. The paper concludes that AAC, full bricks and concrete walls placements have a significant influence on the structure.

Grid Versus Mat Foundations in Areas of High Seismicity: A Case Study in Northern Iran

Grid Versus Mat Foundations in Areas of High Seismicity: A Case Study in Northern Iran

Investigating the effect of using Multi-Level Yielding Pipe Damper dampers in steel structures under earthquake force in the horizontal direction

Multi-level Pipe Damper (MPD) recently proposed by the authors is a passive control device to reduce the seismic vibration. In this research, seismic response of steel structures equipped with MPD is studied. To evaluate the effects of the proposed damper, typical 8 story steel buildings are modeled and their seismic responses under three earthquake excitations are investigated using dynamic nonlinear time-history analyses by ETABS program. Results show the effectiveness of MPD to altering the seismic response of the structures. Moreover, using MPD decreases the structural and nonstructural damages noticeably by limiting the inter story drifts because of the secondary hardening branch of force-displacement respectively proving the effectiveness of the proposed damper as a retrofitting technique for structures at high seismic risk areas.

Comparative study on seismic performance of prefabricated and cast-in-place underground structures under different site conditions

Since the seismic performance of prefabricated underground structures is not yet clear, they not have been constructed in high seismic intensity areas or poor sites. This paper aims to study the applicability of rectangular prefabricated (semi-rigid prefabricated, ASF, and rigid prefabricated, AMT) underground structures in soft soil sites located in high seismic intensity areas. The structures were compared with cast-in-place (CIP) underground structures. Three-dimensional soil-structure interaction advanced finite element models were established to simulate the seismic behavior of the three types of underground structures (ASF, AMT and CIP) constructed in two different sites (soft rock site and soft soil site). The pre-earthquake stress states, dynamic responses, and post-earthquake performance states of the three underground structures were systematically analyzed, considering various static and dynamic conditions. Additionally, the results of dynamic time history were compared with those of the standard procedures available in the literature. The results demonstrated that: i) site conditions have a significant effect on the structures’ static and dynamic responses, ii) the seismic response in soft soil site is much larger than that in soft rock site, but the ratio of response of prefabricated underground structures to that of CIP is almost the same for both soft soil and soft rock sites. Furthermore, as the peak ground acceleration increases, the percentage difference of inter-story displacement ratio (IDR) between ASF, AMT and CIP underground structures in soft soil site decreases, and iii) prefabricated underground structures can be used in both soft rock and soft soil sites. In addition, the seismic performance of ASF is better than that of the AMT structure, which is better than that of the CIP structure. However, when the ASF structure is built in a site with high seismic intensity and poor soil conditions, special consideration must be given to waterproofing measures for wall-slab joints or setting up tongue and groove to improve the connection stiffness and reduce the deformation.

ASSESSING SEISMIC SOIL LIQUEFACTION POTENTIAL USING MACHINE LEARNING APPROACH

The liquefaction vulnerability of soil is generally related to a few soil parameters which are ordinarily measured by laboratory tests on distributed and undistributed tests under distinctive test conditions. This study uses methods based on a standard penetration test to assess liquefaction criteria to appraise the liquefaction vulnerability for soil deposits of Chalus City placed in a high seismic area. To overcome the deficiencies of these experimental strategies an ANN-based model has been created utilizing the Artificial Intelligence technique to anticipate liquefaction. The proposed model is a function of the plasticity index, liquid limit, water content, and some other geotechnical parameters. Reliability index (β) and probability of liquefaction (PL) have also been determined for both the proposed methods for a superior understanding of their accuracies and strength. First-order second moment (FOSM) reliability analysis has been embraced in the present paper. The observation drawn from the study illustrates a reliable and conventional expectation rate of the regression as compared to the experimental strategy. A strong regression shown for assessing the liquefaction vulnerability, which is based on field test information for preparatory prediction, would be of extraordinary help within the field of geotechnical designing.

Probabilistic seismic risk assessment framework: case study Adapazari, Turkey

While earthquakes can have a devastating impact on the economic growth and social welfare of earthquake prone regions, probabilistic seismic risk assessment can be employed to assess and mitigate such risks from future destructive events. In a previous study (Sianko et al. in Bull Earthq Eng 18:2523–2555, 2020), a probabilistic seismic hazard analysis (PSHA) tool based on the Monte-Carlo approach, was developed to predict the seismic hazard for high seismicity areas. In this study, a seismic risk assessment framework is developed incorporating the previously developed PSHA tool, with vulnerability functions based on various damage criteria, exposures and casualty models. Epistemic uncertainty is addressed using logic trees and distribution functions. The developed seismic risk assessment framework can estimate human and economic losses for particular return periods using an event-based stochastic procedure. The framework is applied to a case study area, the city of Adapazari in Turkey. Seismic risk assessment is carried out for different return periods to identify the most vulnerable areas of the city. The verification of the developed seismic risk framework is performed by comparing the predicted seismic losses to those observed during the 1999 Kocaeli earthquake that severely affected the city of Adapazari. The results of the study indicate that while overall predictions for extensive and complete damage states demonstrate strong correlation with the observed data, accurate risk predictions at the district level are not achievable without microzonation studies.

Seismic Retrofitting of Indonesian Masonry Using Bamboo Strips: An Experimental Study

Unreinforced masonry (UM) is well known as a vulnerable structure against earthquakes. However, it remains a popular structural system for low-rise residential housing in many high-seismicity areas, particularly in developing regions due to its low cost and easy construction. In the present study, a retrofitting strategy using locally available material, bamboo strips, was proposed. In addition to its fast-growing rate, the tensile strength of bamboo is considered high, nearly comparable to its steel counterpart. A series of experimental tests were performed in this study, including the bamboo tensile test, the mortar flexural test, the diagonal compressive shear test on the masonry assemblages, and the in-plane pushover test on masonry wall specimens without and with bamboo reinforcement. The retrofitted specimens with different volumes of bamboo reinforcement were also considered. The results show that the application of bamboo reinforcement, at a proper volume, significantly increases the ultimate strength and the ductility of the masonry wall. Such results indicate that the brittle failure of UM structures can be avoided by means of bamboo retrofitting.

Open Source Data-Based Solutions for Identifying Patterns of Urban Earthquake Systemic Vulnerability in High-Seismicity Areas

Urban settlements located in high-seismicity areas should benefit from comprehensive vulnerability analyses, which are essential for the proper implementation of vulnerability modelling actions. Alas, many developing countries face a shortage of knowledge on seismic vulnerability, particularly concerning its systemic component, as a consequence of a combination of data scarcity and a lack of interest from authorities. This paper aims to identify primary time-independent spatial patterns of earthquake systemic vulnerability based on the accessibility of key emergency management facilities (e.g., medical units, fire stations), focusing on the urban settlements located in the high-seismicity area nearby the Vrancea Seismogenic Zone in Romania. The proposed methodological framework relies on open source data extracted from OpenStreetMap, which are processed via GIS techniques and tools (i.e., Network Analyst, Weighted Overlay Analysis), to compute the service areas of emergency management centres, and to map earthquake systemic vulnerability levels. The analysis shows that accessibility and systemic vulnerability patterns are significantly impacted by a synergy of factors deeply rooted in the urban spatial layout. Although the overall accessibility was estimated to be medium-high, and the overall systemic vulnerability to be low-medium, higher systemic vulnerability levels in certain cities (e.g., Bacău, Onești, Tecuci, Urziceni). The presented findings have multi-scalar utility: they aid in the development of improved, locally tailored seismic vulnerability reduction plans, as well as the allocation of financial and human resources required to manage earthquake-induced crises at regional scale. Further to that, the paper provides a transparent methodological framework that can be replicated to put cities in high-seismicity areas on the map of systemic vulnerability assessments, laying the groundwork for positive change in countries where the challenges associated with high-level seismic risk are often overlooked.

Experimental study of CFST embedded precast concrete bridge column-foundation connection with studs

Accelerated bridge construction (ABC) is increasingly gained attention worldwide based on its advantage of high-quality precast elements, less environmental effect, quick construction speed, and minimum traffic block. The seismic performance of prefabricated bridge structures is mainly dependent on the feasibility of connections. To efficiently bear the load from the gravity of other elements and deformation ability in high seismic areas, in this study, an innovative contrete-filled steel tube (CFST) embedded precast concrete bridge column-foundation connection with studs was put forwards. Two 1:2 scale specimens were designed to verify the seismic performance of the proposed connection type. One is a precast specimen with the bridge column-foundation connection, the other is the conventional cast-in-place (CIP) specimen as a reference. The experimental observations and seismic properties were analyzed and compared with those of the CIP specimen, such as failure mode, load-displacement curves, energy dissipation, etc. The finite element model of the precast specimen with bridge column-foundation connection was established and the validated model was used to conduct the parametric study. The precast specimen with bridge column-foundation connection has a larger capacity, ductility, energy dissipation, and equivalent viscous damping ratio than the CIP specimen. Axial compression ratio, embedded depth, and concrete strength affect the seismic performance of the precast specimen with the bridge column-foundation connection. The proposed CFST embedded precast concrete bridge column-foundation connection can be applied to ABC technology in high seismic areas.

Development of the Algorithmic Basis of the FCAZ Method for Earthquake-Prone Area Recognition

The present paper continues the series of publications by the authors devoted to solving the problem of recognition regions with potential high seismicity. It is aimed at the development of the mathematical apparatus and the algorithmic base of the FCAZ method, designed for effective recognition of earthquake-prone areas. A detailed description of both the mathematical algorithms included in the FCAZ in its original form and those developed in this paper is given. Using California as an example, it is shown that a significantly developed algorithmic FCAZ base makes it possible to increase the reliability and accuracy of FCAZ recognition. In particular, a number of small zones located at a fairly small distance from each other but having a close “internal” connection are being connected into single large, high-seismicity areas.

Determination of Vs_30 from existing geophysical investigation data

The Vs_30 refers to the velocity of transversal seismic waves in the upper earth crust (surface shallow depths) in the 0-30 m interval. This parameter reflects the integral ground properties and is used in almost all seismic hazard assessment software. The determination of Vs_30 is important, especially in the case of urban territories, where in-situ measurements are very difficult and sometimes impossible due to dense urban areas, large anthropogenic noise and the need of expensive boreholes. The paper presents a methodology for extracting necessary data and information from archival sources, mainly geophysical measurements frequently executed for different prospecting purposes. The methodology for assessment of the integral values of Vs_30 is proposed for the definition of seismic hazard maps in Bulgaria. The methodology proposed, based primarily on archive data, represents an effective approach with significant results, especially for the intensive urbanized town territories located in high seismic areas.

Experimental study of vibrations of cross-rod spatial structures

This article explores a technique for studying the dynamic characteristics of cross-rod spatial structures (CRSS) using small-scale models, including the developed nodal connection of spatial frame rods protected by copyright. Using a nodal connection makes it possible to regulate the construction lifting of large-span structures and increases their strength and reliability. The developed nodal connection of the structure can be used for any spatial frames of buildings and structures and is especially effective for the frames erected in areas of high seismicity. Choosing methods for excitation of free and forced vibrations is being investigated, equipment for recording and recording vibrations is selected, and a layout of vibration sensors and sources of excitation of free and forced vibrations is being developed. Natural vertical oscillations of the structure model were caused by removing it from the state of equilibrium by concentrated loads applied in the middle and a quarter of the span with their subsequent removal. The test results and their analysis are analyzed. The experimental models' elements at all loading stages worked in the elastic stage. The tests showed that the structure has sufficient strength, stability, rigidity, and seismic resistance. Based on the results obtained, recommendations were made for their use in calculating and designing CRSS for seismic regions.