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1

Study on safety management in Turkish earthquakes

Stasiak-Betlejewska Renata, Ömek Gökhan

System Safety : Human - Technical Facility - Environment

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2023

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Vol. 5, iss. 1

224--230

EN

Natural disasters affect not only humans but also all living beings and societal elements. The term "disaster “meaning a Great Calamity. Among these calamities, earthquakes stand out as the most significant in terms of the damages they cause. Internationally, all authorities define earthquakes as the disasters that result in the highest loss of life and property. This paper highlights the urgent need for effective debris management measures, drawing on established scientific knowledge and operational experience from scientific studies authored by universities. By highlighting the challenges faced during earthquake debris management and safety management and the associated threats to public health and the environment, this study was undertaken to raise people's awareness against similar negligence in future catastrophic events.

2

Trzęsienie ziemi w Maroku

Wojnarowicz Michel

Inżynieria Morska i Geotechnika

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2023

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nr 5

217--221

PL

Informacja o tragicznym trzęsieniu ziemi o magnitudzie 6,8 w skali Richtera, do jakiego doszło we wrześniu 2023 roku w Maroku, w prowincji Al Haouz. Przyczyny i skutki trzęsienia ziemi w Maroku. Wytyczne Eurokodu 8 dotyczące klasyfikacji stref zagrożonych trzęsieniem ziemi oraz klas podłoża gruntowego i kategorii podatności budynków pod względem ryzyka sejsmicznego. Zalecenia konstrukcyjne budynków zwiększające bezpieczeństwo podczas trzęsień ziemi.

EN

Information about the tragic earthquake with a magnitude of 6.8 on the Richter scale that occurred in September 2023 in Morocco, in the Al Haouz province. Causes and effects of the earthquake in Morocco. Eurocode 8 guidelines for the classification of earthquake hazard zones and subsoil classes and building vulnerability categories in terms of seismic risk. Building design recommendations to increase earthquake safety.

3

Wstrząs w ogóle i szczególe

Królikowski Jerzy

Geodeta : magazyn geoinformacyjny

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2023

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nr 3

8--9

4

Experimental dynamic damage assessment of PUFJ protected brick infilled RC building during successive shake table tests

Kwiecień Arkadiusz, Rakicevic Zoran, Chełmecki Jarosław, Bogdanovic Aleksandra, Tekieli Marcin, Hojdys Łukasz, Gams Matija, Krajewski Piotr, Manojlovski Filip, Soklarovski Antonio, Halici Omer Faruk, Rousakis Theodoros, Vanian Vachan

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 3

art. no. e144940

EN

It is highly important to determine eigenvalues before and after certain extreme events that may cause damage accumulation, such as earthquake, blasts and mining or seismic tests on research models. Unique experiment design and shake table testing was performed to investigate seismic performance of a 3D RC building model with infill walls and advanced protection with polyurethane-based joints and fiber polymer reinforced light and emergency jackets. For the purpose of wider experimental activities, three methods for determination of the dynamic characteristics were used during multiple successive shake table tests following a dynamic pushover approach, and they are presented in detail. They are: inertance function through impact hammer tests, standard Fourier transformation of measured acceleration time history and digital image correlation. The expected differences in the results are related to the type and intensity of excitation used, the involvement of materials with different mechanical and physical properties, and with the different rate and extent of damage accumulation, as well as to local or global measurements. Y et, all methods lead to reliable results when a consistent methodology is being used, that takes into account locality or globality of measurements, leaving a choice for the most suitable one, depending on the site conditions. The inertance function method presented manifested its high efficiency in analysis of dynamic properties of large-scale structures and in monitoring of their changes caused by the damage and repair process. It offers quite a wide range of useful information, does not require very expensive equipment and its transportation cost is negligible. This method seems to be a proper diagnostic tool for simple experimental modal analysis of real structures and their structural elements, where detection of changes in the structural condition and in dynamic properties is required, also as a non-destructive testing and monitoring method. Digital image correlation proved to be a promising non-contact tool, strongly supporting the conventional instrumentation of shake table testing, while the Fourier transformation was used as a benchmark method yielding the most reliable results.

5

Seismic performance evaluation of a base-isolated steel liquid storage tank with limiting-devices considering soil-structure interaction

Jing Wei, Tian Shuang

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

635--661

EN

Liquid storage tank is widely used in the petrochemical industry, earthquake will lead to structural damage and secondary disasters, and damping control opens up a new way for seismic design of liquid storage tank. Considering soil-structure-fluid interaction, liquid sloshing dynamic behavior and material nonlinearity, a three-dimensional calculation model of shock absorption liquid storage tank is established by combining sliding isolation and displacement-limiting devices. The dynamic responses of the liquid storage tanks under the action of Kobe and El-Centro waves are investigated, and the influence of soil-structure interaction (SSI) on the dynamic response is discussed. The results show that the damping ratio is basically between 30% and 90%. After the SSI is considered, the damping ratio of liquid sloshing wave height is increased, while the damping ratio of the dynamic response of the liquid storage tank is decreased, and the change of elastic modulus has little effect on the damping effect. The sliding isolation with displacement-limiting devices has significant damping control effects on the liquid sloshing wave height and the dynamic responses of the liquid storage tank.

6

Research on the dynamics of lightweight shell and spatial structures with the aid of computational fluid dynamics and a shaking table

Padewska-Jurczak Agnieszka, Cornik Dawid, Walentyński Ryszard, Wiśniowski Maciej, Szczepaniak Piotr

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

379--392

EN

In determining the effects of actions when designing road structures, the influence of the loads caused by the buffeting of the passing vehicles (high-cycle forces) is neglected. Taking into account the fatigue load, they can have a very large impact on the assessment of the load capacity. The subject of analysis is the pressure and velocity distributions around a truck. At the current stage of the work, it can be concluded that the gusts of passing trucks affect the dynamics of the gantry structure and the elements suspended on it, such as platforms or boards. There is a strong suction force. It is possible to simplify the model in such a way that the board and the wind move with the speed of the vehicle while the truck remains stationary. Due to the lack of reliable guidelines for strength calculations of such structures, advanced Computational Fluid Dynamics (CFD) tools were used. This paper also presents a shaking table built by the authors for dynamic loading of structural models. It describes the construction of the shaking table and the kind of movement made by the table deck. It also shows a scheme of the table deck suspension on linear bearings, as well as a scheme of the table motion system.

PL

Przy określaniu skutków oddziaływań przy projektowaniu obiektów drogowych pomija się wpływ obciążeń wywołanych podmuchami od przejeżdżających pojazdów (siły wysokocyklowe). Biorąc pod uwagę również obciążenie zmęczeniowe, mogą one mieć bardzo duży wpływ na ocenę nośności konstrukcji. Przedmiotem analizy są rozkłady ciśnień i prędkości wokół samochodu ciężarowego. Na obecnym etapie prac można stwierdzić, że podmuchy od przejeżdżających ciężarówek wpływają na dynamikę konstrukcji bramownicy i zawieszonych na niej elementów, takich jak pomosty czy tablice. Istnieje duża siła ssąca. Możliwe jest uproszczenie modelu w taki sposób, aby tablica i wiatr poruszały się z prędkością pojazdu, podczas gdy ciężarówka pozostaje nieruchoma. Ze względu na brak rzetelnych wytycznych do obliczeń wytrzymałościowych takich konstrukcji, zastosowano zaawansowane narzędzia obliczeniowej mechaniki płynów (CFD). W artykule przedstawiono również zbudowany przez autorów stół wstrząsowy do dynamicznego obciążania modeli konstrukcyjnych. Opisano w nim konstrukcję stołu oraz rodzaj ruchu, jaki wykonuje płyta stołu. Przedstawiono również schemat zawieszenia płyty stołu na liniowych łożyskach oraz schemat układu ruchu stołu.

7

Probabilistic assessment of the seismic vulnerability of a rammed earth construction: a case study

Jama Balil, Agliz Driss, Abderrahman Atmani, Derife Mina

Archives of Civil Engineering

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2022

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Vol. 68, nr 2

325--335

EN

Rammed earth significantly reduces intrinsic energy compared to concrete construction and has an environmental benefit throughout the life cycle of the building: phases of construction, operation, maintenance, renovation, and demolition. Several studies have recently been carried out to study this material. However, the seismic behavior of rammed earth constructions is still an important topic that needs to be studied in more detail. Through the analysis of non-linear behavior of the rammed earth construction for different wall thicknesses according to the Moroccan earthquake regulation RPS2011, we were able to assess the seismic performance under the corresponding conditions (loads, seismic zone). The results show that the walls studied can have good resistance in areas of seismicity ranging from “very low” to “moderate” and acceptable performance in areas of high seismicity. Furthermore, fragility analysis shows that rammed construction with a wall thickness equal to 50 centimeters exhibits better seismic performance and a low probability of damage, particularly in the case of moderate, severe, and complete damage states.

8

Nonlinear analysis of a hoist tower for seismic loads

Pachla Filip, Tatara Tadeusz

Archives of Civil Engineering

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2022

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Vol. 68, nr 3

177--198

EN

In recent years, the intensity of the loads caused by mining activity has increased in Poland. This exploitation is often carried out in urbanized areas, so their operation on structures is not only a social problem, but also a challenge for engineers. Many of the surface facilities safe use affects the failure-free operation of the mine. The paper presents the results of representative measurements of surface vibrations from mining areas in Poland and earthquakes and their comparison. Particular attention was paid to the values of PGA/PGV ratios and the most commonly used methods for dynamic calculation of the structure. The last part of the work presents an experimentally verified dynamical model of the selected RC skip tower. The forced vibrations of the model were analysed by taking representative earthquakes and mining origin tremors. Time history non-linear analysis and push over methods were used. The nonlinear concrete model was adopted in the analyses. The results show that pushover analysis is not able to capture the seismic demands imposed by far-field or near-fault ground motions, especially for short-period systems for which it can lead to significant errors in the estimation of the seismic demands. The results confirmed the qualitative results of the linear analysis. The carried out inventory of cracks to the skip tower also allowed their location in bearing elements of the skip tower. The results of non-linear numerical analyses allowed us to assess the safety of the structure.

PL

Dodatkowym obciążeniem działającym na konstrukcje budowlane są drgania przenoszone przez grunt. Z reguły takie konstrukcje, gdy znajdują się poza obszarami trzęsienia ziemi, nie są przystosowane do takich dodatkowych obciążeń. Na terenach dotkniętych wstrząsami górniczymi konstrukcje nie były projektowane na takie obciążenia. W projekcie uwzględniono tylko obciążenia stałe i ciężar własny, obciążenia technologiczne oraz obciążenia od podmuchów wiatru. W ostatnich latach w Polsce wzrosła intensywność obciążeń powodowanych działalnością górniczą. Eksploatacja ta często prowadzona jest na terenach zurbanizowanych, dlatego ich eksploatacja i wpływ na budynki staje się nie tylko problemem społecznym, ale także wyzwaniem dla inżynierów. Ich zadaniem jest zapewnienie bezpieczeństwa konstrukcji i osób przebywających w tych budynkach. Wiele obiektów naziemnych znajduje się bezpośrednio na terenach kopalni. Ich bezpieczne użytkowanie wpływa na bezawaryjną prace kopalni. Awarie obiektów powierzchniowej infrastruktury budowlanej kopalni prowadzą do dużych strat finansowych i powodują problemy społeczne. W pracy przedstawiono wyniki reprezentatywnych pomiarów drgań powierzchniowych z terenów górniczych w Polsce. Drgania te były spowodowane najintensywniejszymi wstrząsami górniczymi, jakie wystąpiły podczas podziemnej eksploatacji kopalni węgla kamiennego i rud miedzi w Polsce. Wyniki pomiarów in-situ tych drgań porównano z zapisami drgań z wybranych trzęsień ziemi. Szczególną uwagę zwrócono na wartości wskaźnika PGA/PGV, a także różnice charakteryzujące drgania powierzchniowe indukowane podziemną eksploatacją górniczą i wstrząsy sejsmiczne oraz czas trwania intensywnej fazy drgań. Następnie przedstawiono najczęściej stosowane metody obliczeń dynamicznych konstrukcji. W ostatniej części pracy zaprezentowano numeryczny model dynamiczny wybranej żelbetowej konstrukcji wieży wyciągowej.

9

Seismic running safety assessment for stochastic vibration of train–bridge coupled system

Zhao Han, Wei Biao, Jiang Lizhong, Xiang Ping

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e180, 2022

EN

With the rapid development of high-speed railway, the seismic running safety problem of high-speed train passing on bridge is becoming increasingly prominent. Since different wheel–rail contact states including uplifting, climbing up, detachment, recontact and derailment have been introduced into the simulation of train–bridge coupled (TBC) system, there are many problems arising for the mainstream derailment index in evaluating seismic running safety and stochastic analysis of train. To this end, a seismic running safety assessment for stochastic response of TBC system was first proposed in this paper. In this system, a detailed wheel–rail contact model was built to calculate the time-varying contact point and the contact force, which can be applied to simulate the detachment and recontact between the wheel flange and rail. Meanwhile, a stochastic analysis framework for derailment of the TBC system is developed. The stochastic vibration of a high-speed train traversing a multi-span prestressed simply supported box-girder bridge under earthquake with random magnitude was studied. In addition, an improved train running safety index, lateral wheel–rail relative displacement, was proposed and compared with the derailment factor and the offload factor to verify its feasibility. It shows an intuitive result as a derailment index in a stochastic train running safety analysis under earthquake. Furthermore, the lateral wheel–rail relative displacement and pertinent derailment probability were significantly affected by the intensity of the earthquake. The methodology herein can be helpful in seismic running safety assessment of high-speed train.

10

Meso-scale modelling of size effect on pure torsional-shear of RC columns

Jin Liu, Zhu Huajie, Du Xiuli

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e36, 2022

EN

Under the action of earthquake, the reinforced concrete (RC) columns may subject to torsional moment, and the existence of torsion will change the failure mode of RC columns. Moreover, the torsional fracture of RC columns often presents a brittle fracture pattern, and thus may have an obvious size effect. In this work, a three-dimensional meso-scale simulation approach was utilized to study the torsional failure of RC columns. The influence of structural size, longitudinal reinforcement ratio, stirrup ratio and cross-sectional shape on torsional failure of RC columns was investigated. The results show that: (1) the tested RC columns show brittle failure patterns, the nominal torsional strength presents obvious size effect; (2) the longitudinal reinforcement presents little influence on the size effect; (3) columns with square cross-section present stronger size effect than the ones with circular shape; (4) stirrups can improve the torsional strength, while they would weaken the size effect on torsional strength. In addition, a novel size effect law that can describe the quantitative influence of stirrup ratio was established. Finally, based on the variable angle truss model, the formulas for calculating the pure torsional capacity of RC columns were modified, considering the quantitative influence of the stirrup ratio on the size effect.

11

Clustering analysis of the seismicity of Van Province and its surroundings via spatial autocorrelation techniques filters

Perihanoglu Güzide Miray, Bilginer Ömer, Akyel Elif

Advances in Geodesy and Geoinformation

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2022

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Vol. 71, no. 2

art. no. e24, 2022

EN

Destructive aftershocks such as the M w 7.2 Van earthquake on October 23, 2011, and the Hoy (Iran) earthquake with M w 5.9 on February 23, 2020, occurred in the province of Van and its surroundings. In earthquake studies, the issue of examining the distribution and homogeneity of earthquake incidences with Geographic Information Systems (GIS) based via spatial autocorrelation techniques is frequently investigated. Van province and its surroundings are among the areas with high earthquake risk due to its location on the East Anatolian Compressive Tectonic Block. The aim of this study is to analyze the spatial patterns of earthquakes with magnitude M w 4 and above that occurred in the province of Van and its surroundings during the instrumental period and to determine to cluster. Spatial cluster analyses play an important role in examining the distribution of seismicity. The data used in the study have been taken from the database system of the Earthquake Department of the Republic of Turkey Ministry of Interior Disaster and Emergency Management Presidency. Moran’s I and Getis-Ord Gi methods from spatial autocorrelation techniques were preferred on the earthquake data set to be used in this research. It has aimed to determine the dangerous areas by testing the earthquake distributions in clustered regions via spatial autocorrelation techniques.

12

Seismo-ionospheric anomalies before M7.2 Haiti earthquake of August 14, 2021, from GPS TEC

Thomas Jewel E., Ben Ubong C., Ekanem Aniekan M., George Nyakno J., Nathaniel Ekong U.

Acta Geophysica

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2022

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Vol. 70, no 6

2621--2627

EN

Satellite-based measurements of total electron content (TEC) have been employed extensively to detect seismo-ionospheric anomalies. In this research, analysis of Global Positioning System (GPS) and TEC data obtained from three stations within seismogenic zone of M7.2 Haiti earthquake (EQ) of August 14, 2021, has been considered. A statistical procedure was used on daily TEC for the detection of anomalous and differential TEC. The study showed both reduction and enhancement in diurnal TEC within the investigative period on days −14,−11,−9,−7,−6, −4, −3, −1, 2, 3, and 4. Based on results, the three stations on days −11, −9, and −6 were concurrently perturbed. The outcomes of the analysis, which were constrained by data of synchronously monitoring geomagnetic indices of Kernnifzer digit (kp), disturbance storm time (Dst), solar indices (sunspot number (SSN) and F10.7 cm), revealed 82% seismic-induced anomalies relating to the EQ. The differential TEC |∆TEC| data were mostly remarkable on −6 and −4 days to the EQ, and this called for spatial mapping of TEC indices for August 8 and 10, 2021, over the epicenter of the EQ in order to check for atypical UT hours. Unusual ionospheric clouds from 16:00 to 20:00 UT enveloped the epicenter. Thus, this study has uncovered strong seismo-ionospheric anomalies from GPS-TEC data related to M7.2 Haiti EQ of August 14, 2021. This work is promising as short-term precursor of EQ in order to alleviate loss of lives and properties associated with this particular seismic event among others.

13

Estimation of local site efects and seismic vulnerability using geotechnical dataset at fyover site Agartala India

Bashir Khalid, Debnath Rajat, Saha Rajib

Acta Geophysica

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2022

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Vol. 70, no 3

1003--1036

EN

Considering future earthquakes, the vulnerability of Agartala city is following an increasing trend mainly due to the recent surge in population density and significant infrastructure developments. The recent moderate intensity earthquake at Tripura, namely the 2017 Dhalai Earthquake (Mw 5.7), with its epicentre being the adjoining district of Agartala, resulted in liquefaction cases, sand blows and lateral spreads, which may be an alarm for the geotechnical engineering fraternity. The present study attempts to evaluate local soil sites’ effect in the form of developing site-specific ground motions using stochastic point-source program SMSIM based on past scenario earthquakes in this region and performing one-dimensional nonlinear ground response analysis (1D GRA) of a recently constructed flyover site of 2.3 km length at Agartala city. Further, the seismic vulnerability of the flyover structure incorporating the local site effect is also assessed herein. The results obtained are explained in terms of surface acceleration time history, the ratio of shear stress to effective vertical stress with depth, acceleration response spectrum, Fourier amplitude ratio with frequency, etc. 1D GRA presented contrasting results with higher values of acceleration in areas with stiffer soils due to attenuation of the seismic waves. In general, the amplification ratio (Af ) evaluated from the present study indicated that the central portion of the flyover yielded high values and a high fundamental frequency value of 6.0 Hz, which might be detrimental for low-lying buildings. The generated synthetic motions of scenario earthquakes will be helpful for researchers and designers for earthquake resistant assessment or design of geotechnical structures in north-eastern India or similar sites in the absence of site-specific data. Finally, this study sheds important observations on seismic design guidelines of the structure located in this region, which may revamp the existing codal procedures.

14

New iterative method of solving nonlinear equations in fluid mechanics

Palivets M., Andreev E., Bakshtanin A., Benin D., Snezhko V.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 3

163--176

EN

This paper presents the results of applying a new iterative method to linear and nonlinear fractional partial differential equations in fluid mechanics. A numerical analysis was performed to find an exact solution of the fractional wave equation and fractional Burgers’ equation, as well as an approximate solution of fractional KdV equation and fractional Boussinesq equation. Fractional derivatives of the order 𝛼 are described using Caputo's definition with 01<α≤ or 12<α≤. A comparative analysis of the results obtained using a new iterative method with those obtained by the Adomian decomposition method showed the first method to be more efficient and simple, providing accurate results in fewer computational operations. Given its flexibility and ability to solve nonlinear equations, the iterative method can be used to solve more complex linear and nonlinear fractional partial differential equations.

15

From Emergency Shelter towards Disaster-relief Housing — Tōhoku’s Reconstruction Case Study

Cosson Camille

Budownictwo i Architektura

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2021

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Vol. 20, no 1

35--46

EN

This paper presents the post-disaster reconstruction of the Tōhoku region. Although Japan has always been one of the most prepared countries because of its long history with natural disasters, the 2011 Great East Japanese Earthquake and tsunami might be one of the most significant disasters recorded in the country’s modern history. This unprecedented disaster that has shaken Japan is a decisive turning point for the entire society as well as for architects and urban planners. Almost ten years later, reconstruction work is still ongoing. This paper introduces specifically Japanese architects’ involvement during the three phases of recovery: emergency shelter, temporary accommodation and permanent housing. After the first stage of perplexity and doubt, architects gradually stepped up and started initiatives to resolve the disaster victims’ precarious situation. This article outlines some of the architects’ actions through the three phases of recovery since the 3.11 disaster. Each of these temporalities has its issues and challenges which the urban planners, architects and designers tried to solve using their know-how to help rebuild devastated communities.

PL

W artykule przedstawiono odbudowę regionu Tōhoku po katastrofie naturalnej. Chociaż Japonia zawsze była postrzegana jako jeden z najlepiej przygotowanych krajów na klęski żywiołowe ze względu na ich długą historię występowania, trzęsienie ziemi i tsunami, które uderzyły w pacyficzne wybrzeże regionu Tōhoku w 2011 roku było prawdopodobnie jedną z najbardziej znaczących katastrof odnotowanych we współczesnej historii tego kraju. Ten bezprecedensowy kataklizm, który wstrząsnął Japonią, stanowi decydujący punkt zwrotny dla całego społeczeństwa, a także dla architektów i urbanistów. Prawie dziesięć lat później odbudowa wciąż trwa. Niniejszy artykuł przedstawia pracę japońskich architektów podczas trzech faz odbudowy: schronów bezpieczeństwa, tymczasowego zakwaterowania i stałego zamieszkania. Po pierwszym etapie niepewności i zwątpienia, architekci zaczęli podejmować inicjatywy mające na celu poprawę trudnej sytuacji ofiar katastrofy. Ten artykuł przedstawia niektóre działania architektów w trzech fazach odbudowy po kataklizmie z marca 2011. Każdy z tych okresów ma swoje problemy i wyzwania, które urbaniści, architekci i projektanci starali się rozwiązać, wykorzystując swoją wiedzę, aby pomóc w odbudowie zniszczonych społeczności.

16

Seismic rocking effects on a mine tower under induced and natural earthquakes

Bońkowski Piotr Adam, Kuś Juliusz, Zembaty Zbigniew

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

410--420

EN

Recent research in engineering seismology demonstrated that in addition to three translational seismic excitations along x, y and z axes, one should also consider rotational components about these axes when calculating design seismic loads for structures. The objective of this paper is to present the results of a seismic response numerical analysis of a mine tower (also called in the literature a headframe or a pit frame). These structures are used in deep mining on the ground surface to hoist output (e.g. copper ore or coal). The mine towers belong to the tall, slender structures, for which rocking excitations may be important. In the numerical example, a typical steel headframe 64 m high is analysed under two records of simultaneous rocking and horizontal seismic action of an induced mine shock and a natural earthquake. As a result, a complicated interaction of rocking seismic effects with horizontal excitations is observed. The contribution of the rocking component may sometimes reduce the overall seismic response, but in most cases, it substantially increases the seismic response of the analysed headframe. It is concluded that in the analysed case of the 64 m mining tower, the seismic response, including the rocking ground motion effects, may increase up to 31% (for natural earthquake ground motion) or even up to 135% (for mining-induced, rockburst seismic effects). This means that not only in the case of the design of very tall buildings or industrial chimneys but also for specific yet very common structures like mine towers, including the rotational seismic effects may play an important role.

17

Real-time hybrid test of a LNG storage tank with a variable curvature friction pendulum system

Lin Shu-chao, Wang Jingxuan, Gao Shan, Zhao Hong-tie

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

44--62

EN

To accurately reproduce the seismic response of the liquefied natural gas (LNG) storage tank equipped with the variable curvature friction pendulum system (VCFPS), a real-time hybrid (RTH) experiment, also known as a real-time substructure experiment, is conducted on it in this study. A typical LNG storage tank with a capacity of 160,000 m3 is employed as the numerical substructure simulated using the MATLAB/Simulink, while the variable curvature friction pendulum bearing (VCFPB) is utilized as the experimental substructure tested using the compression-shear equipment. Thereafter, the validity and feasibility of the RTH experiment are verified using the SAP2000 results. Finally, the working performance of the VCFPB is evaluated scientifically, comprehensively, reasonably, and efficiently. The results show that the VCFPB is very effective in avoiding the resonance phenomenon. It can be seen from the displacement of isolation layer that the VCFPB meets the design requirement. The maximum relative deviations between the RTH test results and the SAP2000 results are 3.45% for the displacement of isolation layer, 4.27% for the base shear, and 1.49% for the liquid sloshing height, respectively. The RTH test is stable and reliable and the predicted results are highly accurate and effective. The RTH test method proves to be accurate in the prediction of the seismic response of the LNG storage tank equipped with the VCFPBs.

18

Mitigating the seismic pounding of multi-story buildings in series using linear and nonlinear fluid viscous dampers

Elwardany Hytham, Jankowski Robert, Seleemah Ayman

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

1--16

EN

Seismic-induced pounding between adjacent buildings may have serious consequences, ranging from minor damage up to total collapse. Therefore, researchers try to mitigate the pounding problem using different methods, such as coupling the adjacent buildings with stiff beams, connecting them using viscoelastic links, and installing damping devices in each building individually. In the current paper, the effect of using linear and nonlinear fluid viscous dampers to mitigate the mutual pounding between a series of structures is investigated. Nonlinear finite-element analysis of a series of adjacent steel buildings equipped with damping devices was conducted. Contact surfaces with both contactor and target were used to model the mutual pounding. The results indicate that the use of linear or nonlinear dampers leads to the significant reduction in the response of adjacent buildings in series. Moreover, the substantial improvement of the performance of buildings has been observed for almost all stories. From the design point of view, it is concluded that dampers implemented in adjacent buildings should be designed to resist maximum force of 6.20 or 1.90 times the design independent force in the case of using linear or nonlinear fluid viscous dampers, respectively. Also, designers should pay attention to the design of the structural elements surrounding dampers, because considerable forces due to pounding may occur in the dampers at the maximum displaced position of the structure.

19

Simulation of the MW =7.9 Gulf of Alaska earthquake on January 23, 2018, by the stochastic fnite fault model

Qicheng Li, Shupeng Yuan, Xinjuan Zheng

Acta Geophysica

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2021

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Vol. 69, no. 2

415--425

EN

On the premise of constraining the seismogenic fault structure of a future large earthquake, we proposed using empirical equations to determine the length, width, seismic moment and slip distribution of a large seismogenic fault plane and using the stochastic fnite fault model to predict future large earthquakes. The ground motion time histories and response spectra recorded by 12 seismic stations on bedrock during the MW =7.9 Gulf of Alaska earthquake on January 23, 2018, were simulated. The simulation error determined by the average ratio of the simulated spectrum amplitude to the recorded spectrum amplitude varied between 1.08 and 0.92 in the period range of 0–10 s, and the standard deviation of the simulation error at diferent frequencies did not exceed 1; the 95% confdence interval also did not change signifcantly with the period. The above analyses show that our simulation results refect the mean ground motion. To further discuss the reliability of predicting future large earthquakes by the stochastic fnite fault model, we redistributed the initial rupture point and slip distribution on the seismogenic fault plane by the quasi-random method, and the simulation errors and simulation results of the redistribution model were similar to those of the previous model. Further research confrmed that our method for obtaining the seismic source parameters is viable and that the stochastic fnite fault model for the prediction of future large earthquakes is reliable, especially for large far-feld earthquakes. The seismic stations that we used are all situated on bedrock on one side of the fault and do not involve rupture directivity, i.e., the seismic wave pathways may be similar, so the simulation results are ideal. However, if the rupture directivity, diferent site conditions, surface topography and basin efects are considered, it will be necessary to amend the proposed method.

20

Scaling properties of the Mw7.0 Samos (Greece), 2020 aftershock sequence

Vallianatos Filippos, Pavlou Kyriaki

Acta Geophysica

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2021

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Vol. 69, no. 3

1067--1084

EN

On October 30, 2020, a strong and shallow earthquake (Mw=7.0) hit Samos, an island on the eastern edge of the Aegean Sea (Greece). The epicenter was located on the north ofshore of the Greek island of Samos. The goal of our work is to provide a frst analysis of the scaling properties observed in the aftershock sequence as reported until December 31, 2020, as numerous seismic clusters activated. Our analysis is focused on the main of the clusters observed in the East area of the activated fault zone and strongly related with the mainshock’s fault. The aftershock sequence follows the Omori law with a value of p ≈ 1.01 for the main cluster which is remarkably close to a logarithmic evolution. The analysis of interevent times distribution, based on non-extensive statistical physics indicates a system in an anomalous equilibrium with a crossover from anomalous (q>1) to normal (q=1) statistical mechanics, as great interevent times approached. A discussion of the crossover observed, is given in terms of superstatistics. In addition, the obtained value q ≈ 1.67 suggests a system with one degree of freedom. Furthermore, a scaling of the migration of aftershock zone as a function of the logarithm of time is discussed in terms of rate strengthening rheology that govern the evolution of afterslip process.