bluuebunny/crossref_metadata_2025 huggingface dataset:
Trading Security Designs Based on Blockchain Techniques
Authors: Liu Chang
Published: May 2023

Contemporarily, digital art has swiftly integrated into human beings’ daily life. While digital art is becoming increasingly popular and significantly influences conventional art, currently it is needed to be more online communities where art enthusiasts and artists may interact and offer a self-sustaining means of payment. Independent art programs based on ideas like reciprocity are what E-Gallery Art aspires to. Its goal is to encourage teamwork and co-creation in the visual arts. This research discusses the way to create decentralized Dapps based on blockchain that are mutually advantageous for platforms, artists, and users. The Dapp follows a process where users reward artists by donating, and the best-case scenario is that the artist is motivated and contributes more to the community. Users can create galleries and display their work for free, which is an important starting point for E-Gallery Art Dapp to start a self-sustainable cycle. These results shed light on guiding further exploration of trading security design based on blockchain techniques.
The Export market of Smartphones: Xiaomi Case Study
Authors: Huo Xiayu
Published: May 2023

The introduction of smartphones over the course of the last decade or so has resulted in a dramatic increase in sales of smartphones all over the world; however, since 2018, the market for smartphones has been experiencing a decline. As a result, this research uses the smartphone manufacturer Xiaomi as a case study to investigate the challenges that the firm confronts, as well as its advantages, and to provide solutions to the problems that have been identified. According to the findings of the research, the most significant challenges for Xiaomi include having strong competition, having poor sales in the Indian market, and not having product patents. Its distinctive advertising approach, cost leadership plan, and the MI community are among its most notable qualities. In addition, minimising the effect that rivals have is made possible by developing a robust three-stream ecology. Concentrating on the millennial generation as a demographic subgroup may be an efficient way to generate sales. Product differentiation will be made possible via the continued development of Xiaomi's proprietary MIUI and the MI Community.
A Comparison of Linear Regression, LSTM model and ARIMA model in Predicting Stock Price A Case Study: HSBC’s Stock Price
Authors: Kuang Shiyue
Published: May 2023

It is widely assumed that the stock market is a key aspect of the financial market and stock price forecasting has become a popular topic of an in-depth study by financial technologists. With the advent of financial markets, stock prices face several analytical and forecasting challenges. In this paper, the stock price trend forecast analysis is carried out and the survey object was the transaction data of HSBC from 2010 to 2019. Linear regression, LSTM model and ARIMA model are used to forecast stock price trends.  The models’ prediction accuracy is demonstrated after the cross-validation process by combining error indicators and trading performance. As a consequence of the analysis, we discover that LSTM has the lowest error value, which implies that it is ideally suited to stock market forecasting.  On the contrary, linear regression holds the largest mean square error, implying that this method has the weakest fitting for the stock market.
A Common Hunger: Land Rights in Canada and South Africa
Authors: Fairweather Joan G.
Published: May 2023

Geographically, demographically, and politically, South Africa and Canada are two countries that are very far apart. What they have in common are Indigenous populations, which, because of their historical and ongoing experience of colonization and dispossession, share a hunger for land and human dignity. Based on extensive research carried out in both countries, A Common Hunger is a comparative work on the history of Indigenous land rights in Canada and post-apartheid South Africa. Joan Fairweather has constructed a balanced examination of the impact of land dispossession on the lives of indigenous peoples in both countries and their response to centuries of European domination. By reclaiming rights to the land and an equitable share in the wealth-producing resources they contain, the first peoples of Canada and South Africa are taking important steps to confront the legacies of poverty that characterize many of their communities. A Common Hunger provides historical context to the current land claim process in these two former British colonies and examines the efforts of governments and the courts to ensure that justice is done.
Capital Market Reactions Analysis in Energy and Non-Cyclical Consumer Issuers During the Russia-Ukraine War
Authors: Richad Richad , Astawa I Gede Bratha , Tonggok Robinson
Published: May 2023

Background: Several shares of energy sector issuers rose amid the war between Russia and Ukraine, this is inversely proportional to the Composite Stock Price Index (JCI) which decreased 1.48 percent to 6,817 at the close of Thursday, February 24, 2022. The share prices of several consumer goods issuers that rely on wheat raw materials fell sharply in the past week.
Aim: This study aims to analyze whether there is a capital market reaction in energy and consumer non-cylical sector stocks in Indonesia to seven different events related to the war between Russia and Ukraine.
Method: Using the event study method, the sample used was 30 issuers, with 15 issuers coming from the energy sector, and 15 other issuers coming from the primary needs sector (consumer non-cyclical). This study obtained secondary data on the list of issuers of energy and primary needs sector stocks on the Composite Stock Price Index, stock prices, daily returns, and trading activity volumes from the website (www.idx.co.id) and (www.finance.yahoo.com).
Findings: The market here is efficient in the form of semi-strong, because the capital market reaction is abnormal returns seen within one to two days after the announcement. In addition, the speed at which the market responds to war-related information that will influence the decision to buy or sell stocks is not seen at the beginning of the war. Overall, the market decisions affected by the war were temporary, as evidenced by the absence of significant stock price differences in the recent events studied.
PEMANFAATAN PUPUK ORGANIK CAIR (URIN KAMBING DAN LIMBAH BUAH) TERHADAP DAUN RUMPUT GAJAH
Authors: Lestari Rika Hari , Ramadani D , Tahyul Tahyul
Published: May 2023

Tujuan dari penelitian ini adalah untuk mengetahui pengaruh pemberian pupuk organik cair dengan dosis berbeda terhadap daun rumput gajah (Pennisetum purpureum). Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) dengan 4 perlakuan pemberian pupuk dan 3 ulangan. Perlakuan P0= kontrol,  P1 = 150 ml/polybag, P2= 300ml/polybag dan P3= 450ml/polybag. Variabel yang diamati adalah panjang daun, lebar daun dan luas daun. Hasil penelitian menunjukkan bahwa penggunaan pupuk organik cair pada dosis 450 ml/polybag memberikan hasil terbaik pada variabel yang diukur dengan rincian panjang daun (103,33 cm), lebar daun (3,1 cm) dan luas daun (321,33 cm2).
AKTIVITAS PEROKSIDASI LIPID AYAM BROILER DENGAN DAN TANPA PENAMBAHAN GLUTATHIONE DALAM RANSUM
Authors: Yuliandari Mustika , Mushawwir Andi , Permana Ronnie
Published: May 2023

Penelitian ini bertujuan untuk mengetahui  pengaruh pemberian glutation 150 ppm dalam ransum  terhadap peroksidasi lipid ayam broiler. Penelitian ini dilaksanakan di Kandang Produksi Ternak Unggas dan analisis sampel dilaksanakan di Laboratorium Fisiologi dan Biokimia Fakultas Peternakan Universitas Padjadjaran. Objek penelitian ini terdiri dari 60 ekor ayam broiler yang dipelihara sejak doc sampai umur 35 hari. Sebanyak 60 ekor ayam broiler dibagi ke dalam dua kelompok yaitu 30 ekor ayam diberi glutation 150 ppm dan 30 ekor ayam broiler tidak diberi glutation.  Hasil penelitian menunjukkan bahwa penambahan  glutution dalam ransum sebanyak 150 ppm per kg ransum mempengaruhi kadar MDA, kolesterol dan TIBC ayam broiler. Rata-rata kadar MDA, kolesterol dan TIBC ayam broiler yang diberi glutation berturut-turut adalah 2,501 ± 0,033 nm/M-1cm-1, 196,093 ± 2,821b mg/dl, 499,759 ± 2,730b mg/dl. Glutation 150 ppm dalam ransum mampu menekan  konsentrasi MDA dan meningkatkan kadar kolestrol dan TIBC dalam plasma darah ayam broiler.
Primary bedaquiline resistance in Karakalpakstan, Uzbekistan
Authors: Moe S. , Rekart M. L. , Hernandez D. , Sholpan A. , Ismailov A. , Oluya M. , Bayniyazova A. , Zinaida T. , Nargiza P. , Gomez-Restrepo C. , Sitali N. , Sinha A.
Published: May 2023

BACKGROUND: Bedaquiline (BDQ) is widely used in the treatment of rifampicin-resistant TB (RR-TB). However, resistance to BDQ is now emerging. There are no standardised regimens for BDQ-resistant TB. This study aims to share experience in managing primary BDQ-resistant TB.METHODS:
We performed a retrospective study of patients treated for RR-TB in Karakalpakstan, Uzbekistan, from January 2017 to March 2022. We identified patients with resistance to BDQ with no history of BDQ exposure. We describe baseline characteristics, treatment and follow-up of these patients.RESULTS:
Twelve of the 1,930 patients (0.6%) had baseline samples resistant to BDQ with no history of BDQ exposure, 75% (9/12) of whom had been previously treated for TB. Ten (83.3%) were resistant to fluoroquinolones; respectively 66% and 50% had culture conversion by Month 3 and Month 6. The interim
treatment outcomes were as follows: unfavourable treatment outcomes (3/12, 25%), favourable outcomes (2/12, 17%); the remaining seven (58%) were continuing treatment.CONCLUSIONS: A large proportion of the cases had previously been treated for TB and had TB resistant to quinolone.
Both patients who had not experienced culture conversion by Month 3 had an unfavourable treatment outcome. Therefore, we recommend monthly monitoring of culture status for patients on treatment regimens for BDQ resistance.
Best practices for the care of pregnant people living with TB
Authors: Maugans C. , Loveday M. , Hlangu S. , Waitt C. , Van Schalkwyk M. , van de Water B. , Salazar-Austin N. , McKenna L. , Mathad J. S. , Kalk E. , Hurtado R. , Hughes J. , Eke A. C. , Ahmed S. , Furin J.
Published: May 2023

BACKGROUND: Each year more than 200,000 pregnant people become sick with TB, but little is known about how to optimize their diagnosis and therapy. Although there is a need for further research in this population, it is important to recognize that much can be done to improve
the services they currently receive.METHODS: Following a systematic review of the literature and the input of a global team of health professionals, a series of best practices for the diagnosis, prevention and treatment of TB during pregnancy were developed.RESULTS: Best
practices were developed for each of the following areas: 1) screening and diagnosis; 2) reproductive health services and family planning; 3) treatment of drug-susceptible TB; 4) treatment of rifampicin-resistant/multidrug-resistant TB; 5) compassionate infection control practices; 6) feeding
considerations; 7) counseling and support; 8) treatment of TB infection/TB preventive therapy; and 9) research considerations.CONCLUSION: Effective strategies for the care of pregnant people across the TB spectrum are readily achievable and will greatly improve the lives and health
of this under-served population.
THE ROLE OF DISASTER RISK GOVERNANCE IN POST-DISASTER RECOVERY
Authors: Sigmund Zvonko , Šimić Marko
Published: May 2023

This paper emphasizes the role of decision-making and disaster risk governance in post-disaster recovery on the example of the post-disaster recovery of Croatia after a series of strong seismic events in mainland Croatia. The analysis is based on a thorough review of the national documents of Croatia that overlapped with the national journals reporting on the situation from the affected areas.
SEISMIC RETROFITTING OF BUILDING STRUCTURES AND MONUMENTS IN NORTH MACEDONIA – NECESSITY, SOLUTIONS AND CONSTRUCTION
Authors: Shendova Veronika , Apostolska Roberta , Jekic Goran , Zlateski Aleksandar , Zurovski Aleksandar , Delova Elena
Published: May 2023

The impact of present building code requirements for seismic design of new buildings can readily be acknowledged, however applying regulation to existing buildings is an area less well defined. Presently, there is a diverse list of existing code references which could be interpreted to require seismic upgrades of existing structures. Unfortunately, these references do not provide a clear path toward addressing the hazards, evaluation and retrofitting of existing buildings. And when it comes to existing old buildings and monuments, constructed with low or no seismic consideration, the topic becomes much more complex and challenging. The problem of earthquake protection of historic buildings and monuments is radically different from that of other existing structures, due to the priority given to preservation of aesthetic, architectonic and historic values instead of keeping the structure operational. In providing the protection of these structures in a manner that requires the least intervention and the greatest care to preserve authenticity, the experts are permanently challenged by the fast development and the improved performance of new materials and techniques. This paper presents the integrated multidisciplinary approach to seismic protection of important structures that has been developed by the Institute of Earthquake Engineering and Engineering Seismology, IZIIS, Skopje, and implemented in the process of seismic upgrading or reconstruction of historic buildings and monuments in the country and beyond.
NUMERICAL STUDY ON MECHANICAL PARAMETERS OF NOVEL DRILLED PLATE METALLIC DAMPER (DPMD)
Authors: Heidari Peyman Shadman
Published: May 2023

The purpose of this study is to investigate the seismic performance of a new type of yield metal dampers. Drilled plates are used in these metal dampers. These plates use holes with different diameters. Various drilling arrangement have also used to evaluate and improve the seismic performance of these types of dampers. For this study used a reference sample and 15 proposed models. The overall numerical results show that the proposed metal dampers have similar hysteretic curves. According to the hysteresis curves of drilled plate metallic damper (DPMD) under in-plane seismic loading; obtained mechanical parameters such as ductility ratio, initial stiffness, effective stiffness, total dissipated energy, dissipated energy in the last cycle, elastic strain energy, equivalent viscous damping (EVD) and equivalent plastic strain (EPS). Also, a formula is proposed to estimate the EVD value based on the ductility ratio of the proposed samples. The analytical results showed that the amount of stiffness, ductility ratio and equivalent viscous damping depends on the location and diameter of the holes. Also, the concentration of plastic strain between the holes increases the ductility ratio and EVD value of these types of dampers.
PRELIMINARY EARTHQUAKE SURVEY OF BUILDINGS – CASE STUDY OF SENJ
Authors: Mihaljević Josipa , Grandić Davor , Šćulac Paulo
Published: May 2023

Senj is a medieval town located on the eastern coast of Kvarner. In addition to the destruction caused by World War II, Senj has been hit by strong earthquakes throughout history. The appearance of significant earthquakes in this area is not surprising because, according to the seismic area classification of the Republic of Croatia, Senj is located in an area where the horizontal peak ground acceleration equals 0,24g. Within the historic city center of Senj, some stone masonry buildings date back to the 12th century. Those two facts present a good reason for selecting Senj as a representative research area. In order to evaluate the overall behavior and seismic resistance of existing buildings, it is first necessary to visually establish the characteristics of stone masonry buildings (typology of buildings). The connection of timber floors with stone masonry walls needs to be addressed as well. It needs to be investigated if the timber floor forms a diaphragm or whether it is flexible in its plane because it significantly affects the behavior of masonry buildings during an earthquake. Visual inspection of buildings indicated that most of the buildings were built with mixed materials (which is a result of fast renovation after great destruction in World War II), which implies the use of stone elements, brick parts, and mortar. In almost all stone masonry buildings, a tie system is present as a kind of reinforcement that ensures the integrity of the buildings.
EXPERIMENTAL AND NUMERICAL IN-PLANE SEISMIC BEHAVIOUR OF AN INNOVATIVE STEEL REINFORCEMENT SYSTEM FOR URM WALLS
Authors: Albanesi Luca , Damiani Nicolò , Manzini Carlo Filippo , Morandi Paolo
Published: May 2023

An experimental campaign, followed by a numerical research, aimed at evaluating the in-plane seismic behaviour of an innovative steel modular system (named “Resisto 5.9”, designed by Progetto Sisma s.r.l.) for the reinforcement of load-bearing masonry walls, has been performed at the EUCENTRE Foundation in Pavia. Different masonry typologies, selected among the most common solutions in Italian existing buildings, were considered in this study. In this paper, the results related to a solid clay bricks masonry, assembled using lime mortar in “header bond” pattern, are reported. A complete mechanical characterization of units, mortars, masonry typologies and of the strengthening system components (i.e. steel elements and anchors) has been carried out. In-plane cyclic pseudo-static tests were then performed on full-scale specimens to investigate the influence of the proposed reinforcement system on the lateral in-plane response of the walls, compared to their unreinforced conditions. The main parameters which characterized the cyclic behaviour of the masonry piers, i.e. elastic stiffness, lateral strength and displacement capacity, were analysed in relation to the achieved damage mechanism. The numerical study of the research consisted of a series of parametric non-linear analyses on advanced discontinuous models based on the Distinct Element Method (DEM). Different wall dimensions, vertical load levels and boundary conditions, in addition to those tested experimentally, were considered. Moreover, the numerical campaign was also extended varying the bond pattern and the mechanical properties with respect to the experimentally tested solutions. In this paper, the results of the experimental tests on solid brick masonry together with the calibration of the related numerical DEM models were reported.
BEHAVIOUR OF SEISMIC ISOLATED BUILDING DURING CENTRAL ITALY 2016 – 2017 EARTHQUAKES
Authors: Salvatori Antonello
Published: May 2023

The seismic sequence during years 2016 and 2017 involved a great area In Central Italy, involving four regions and more than 100.000 buildings. Many main shock events occurred, namely Amatrice earthquake (Mw 6.0 on August 24th, 2016), Valnerina earthquakes (Mw 5.9 and 5.4 on October 26th, 2016), Norcia earthquake (Mw 6.5 on October 30th 2016), and Montereale – Capitignano earthquakes (Mw 5.0, 5.5 on January 18th 2017) About 80.000 buildings were damaged in the seismic events. In particular, some areas were involved also in the 2009 seismic events (L’Aquila earthquake). After L’Aquila earthquake, during reconstruction period, many buildings with base isolation (both existing and new ones) have been realized in the city area. Furthermore, collapsed buildings, or heavily damaged buildings, were demolished and reconstructed with base isolation (both in foundation and above first elevation columns). The isolation systems were generally composed by both rubber high damping isolators, and plane friction isolators (sliding). Some buildings, which reported less structural damage during 2009 L’Aquila earthquake, were retrofitted with isolation systems, both with rubber high damping isolators, and plane friction isolators. All these isolated buildings were completed before year 2016, that is before the new strong seismic events in Central Italy. Several different dynamic and seismic behaviour were observed in those buildings, depending upon isolation system (noticeable differences have been observed between curved sliding isolators and rubber high damping isolators) and upon soil – structure interaction. Significant displacement has been observed caused by soft soil, and inverse velocity seismic soil profile. Also, frequency response influenced isolated building behaviour. In the work several buildings are examined, analysing the seismic behaviour both in the 2009 earthquake (with no isolation system) and during 2016 – 2017 seismic events (with isolation system).
SEISMIC PERFORMANCE EVALUATION OF EXISTING RC HIGH-RISE BUILDING IN MONTENEGRO
Authors: Popović Nikola , Pejović Jelena
Published: May 2023

Seismic performance evaluation of buildings represents a basis for seismic vulnerability and risk assessment. Considering the importance of seismic risk assessment nowadays, as one of the most actual topics in earthquake engineering, in this paper, a seismic performance evaluation of an existing RC high-rise building with walls on the Montenegrin coast, an area with high seismic risk, is conducted. The aim of the paper is to evaluate the performance of this type of buildings built on the Montenegrin coast and thus contribute to their vulnerability assessment. Two EN 1998-1 fundamental requirements are examined for seismic performance evaluation: non-collapse and damage limitation requirements. A non-linear 3D building model is defined in the PERFORM 3D software. Modelling is performed by taking into account realistic characteristics of used materials, constructed geometry of structural elements and realistic loads. Non-linear time history analyses are performed using 112 ground motion records, from which 56 are used for evaluation of non-collapse requirement and the other 56 for evaluation of damage limitation requirement. Ground motion records were selected and scaled according to EN 1998-1. Peak horizontal ground acceleration of 0.34g for ground motions with a return period of 475 years for checking non-collapse requirement is adopted, and 0.15g for ground motions with a return period of 95 years for checking damage limitation requirement. Inter-storey drift, wall rotations, dilatations in structural elements and shear capacity are the main parameters that are analysed to obtain conclusions on acceptable seismic performance. Useful conclusions related to the seismic performance of existing RC high-rise buildings of structural systems with ductile walls built on the Montenegrin coast are pointed out.
LARGE SCALE SEISMIC ISOLATION FOR A POST-EARTHQUAKE RECONSTRUCTION PRESERVING IDENTITY OF SITES
Authors: Mezzi Marco , Fulco Alessandro , Nodessi Stefano , Fagotti Gianluca , Alemanno Nicola , Rotondi Maurizio
Published: May 2023

The effects of seismic attacks in oldest parts of hit towns mostly depend on the quality of materials and construction technique even for low and medium intensity earthquakes. The negative consequences of traditional construction approaches appeared in all their evidence in many areas of Central Italy affected by recent seismic sequences of medium intensity (M5-M6) in 2016-17 where entire villages were destroyed. The reconstruction should solve the problem to rebuild with safety but preserving the historical aspect of buildings and landscape. This paper presents a particular application of the known technique of seismic isolation for the reconstruction with integral seismic protection of the worldwide known village of Castelluccio di Norcia in Umbria (Central Italy). The adoption of a seismic isolation system at city scale involves the construction of a large floating platform, having the dimensions of the entire compartment, supported by seismic isolators. In the considered case the platform is stepped due to the site orography, and, above it buildings are built with the aesthetic and constructive characteristics of the collapsed original ones. The solution allows a correct interpretation of the objective to rebuild "as it was, where it was", safeguarding the landscape, prolonging the lifetime, saving the expected cost.
SEISMIC RETROFIT OF R.C. BUILDINGS IN USE THROUGH SEISMIC ISOLATION. THREE CASE STUDIES IN L'AQUILA, ITALY
Authors: Castellano Maria Gabriella , Vetturini Riccardo
Published: May 2023

Seismic isolation (SI) advantages for new buildings are well known: not only it allows to avoid damage of both structural and non structural elements under strong earthquake, but it mantains building functionality as well. This is possible thanks to strong reduction of accelerations and interstorey drift in the superstructure, i.e. the part of structure above the isolation layer. SI offers additional advantages for seismic retrofit of existing buildings. The main advantage is that the works can be limited at one floor (usually the basement, plus the foundation), without any strenghtening on the superstructure. Consequently, the building can be used during the retrofit works. The safety of the retrofitted building increases significantly. Reaching exactly the same safety level of a new building in the same site would be possible, but it would need some strenghtening in the superstructure, and thus is usually avoided in order to keep the building in function during the works. It is worth noting that for the seismic isolation system, the safety is the same than for a new building. The paper presents in detail three case studies of framed r.c. buildings built in the 1980s and now under retrofit with seismic isolation, that could be representative of many other buildings. During 2009 L'Aquila earthquake, those residential buildings were only slightly damaged, and immediately repaired but without any improvement of their seismic performance. Now the retrofit design is carried out for an earthquake stronger than the 2009 earthquake. Despite the buildings are in the same area (ag=0.261g for the Life Safety Limit State earthquake; ag=0.334g for the Collapse Limit State earthquake, used to design the seismic isolation system), the design spectrum is different because of different type of soil. The isolators are inserted in the basement or in the ground floor that host the garages, thus without affecting the apartments. The safety level reached in the three buildings was higher than 70% of that of new buildings in the same site, while before retrofit it was lower than 16%
RELIABILITY ANALYSIS OF REINFORCED CONCRETE FRAME BY FINITE ELEMENT METHOD
Authors: Grubišić Marin , Ivošević Jelena , Grubišić Ante
Published: May 2023

Since the prediction of the seismic response of structures is highly uncertain, the need for the probabilistic approach is clear, especially for the estimation of critical seismic response parameters. Considering the uncertainties present in the material and geometric form of reinforced concrete (RC) structures, reliability analyses using the Finite Element Method (FEM) were performed in the context of Performance-Based Earthquake Engineering (PBEE). This study presented and compared the possibilities of nonlinear modelling of the reinforced concrete (RC) planar frame and its reliability analysis using different numerical methods, Mean-Value First-Order Second-Moment (MVFOSM), First-Order Reliability Method (FORM), Second-Order Reliability Method (SORM) and Monte Carlo simulation (MCS). The calibrated numerical models used were based on the previous experimental test of a planar RC frame subjected to cyclic horizontal load. Numerical models were upgraded by random variable (RV) parameters for reliability analysis purposes, and, using implicit limit state function (LSF), pushover analyses were performed by controlling the horizontal inter-storey drift ratio (IDR). Reliability results were found to be sensitive to the reliability analysis method. The results of reliability analysis reveal that, in a nonlinear region, after exceeding the yield strength of the longitudinal reinforcement, the cross-sectional geometry parameters were of greater importance compared to the parameters of the material characteristics. The results also show that epistemic (knowledge-based) uncertainties significantly affected dispersion and the median estimate parameter response. The MCS sampling method is recommended, but the First-Order Reliability Method (FORM) applied to a response model can be used with good accuracy. Reliability analysis using the FEM proved suitable for directly implementing geometric and material nonlinearities to cover epistemic (knowledge-based) uncertainties.
CRONOS PROJECT: MAIN FEATURES OF SEISMICITY ANALYSIS FOR THE CENTRAL AND SOUTHERN CROATIAN COASTAL AREA
Authors: Lončar Iva , Markušić Snježana , Ivančić Ines
Published: May 2023

The overall objective of the project “Investigation of seismically vulnerable areas in Croatia and seismic ground motion assessment” – CRONOS – is to make Croatian society more resilient to the impact of destructive earthquakes. The aim of the CRONOS project, funded by Norwegian Financial Mechanism, is to facilitate this through the development and modernization of seismic hazard assessment in Croatia and stimulate the development of seismic risk reduction policies through scientific infrastructure and capacity building, knowledge transfer and international research cooperation. The first step towards the presented goal is to analyse and understand the past seismicity of the given area. Therefore, for the chosen area (42.5 – 44.5 °N, 14.75° – 17.75 °E) an earthquake catalogue CEC-Cronos has been prepared. The chosen area includes the wider area of central and southern Croatian coastal area (Dalmatia) – one of the seismically most prone areas in Croatia. The given catalogue contains almost 48000 earthquakes which occurred between the years 306 and 2020. Those earthquakes, magnitudes up to 6.7 and intensity in the epicentre up to IX °MSK, have been statistically processed and will be presented. Croatia is characterized by a moderate-to-high level of seismicity, highest in its northwestern and coastal parts. More than 145.000 earthquakes from the period before Christ till the end of 2020 are contained in the Croatian Earthquake Catalogue (CEC). There were more than 100 stronger earthquakes, whose computed or estimated magnitudes were more than 5. The majority of the earthquakes on Croatian territory are the result of the strain accumulation caused by the rotation of the Adria microplate towards the Eurasian tectonic plate. Additionally, central Croatia is in a contact zone of three big geological units: The Alps, the Dinarides (or The Dinaric Alps), and the Pannonian Basin.
POWER RESPONSES OF A BUILDING UNDER THE EXCITATION OF PULSE-LIKE GROUND MOTIONS
Authors: Lin Jui-Liang
Published: May 2023

In comparison with far-field (FF) ground motions, near-fault (NF) ground motions with forward directivity or fling-step effect are characterized by large pulses. These pulse-like (PL) ground motions have pronounced coherent pulses in velocity and displacement histories. Even though these prominent pulses generally have very few cycles in a PL ground motion, the destruction they cause to structures is severe and distinctive compared with non-pulse-like (NPL) ground motions. The present study suggests power demand as an alternative engineering demand parameter for reflecting the severity of the risk posed by PL ground motions. The proposed parameter is simply a product of story shears and inter-story velocities. Through an investigation using a three-story building subjected to ensembles of PL and NPL ground motions, this study confirms that power demand satisfactorily elucidates the destructive potential of PL ground motions. In contrast, force demand, which is the cornerstone laid in building seismic design codes, cannot adequately reflect the destructive potential of PL ground motions. In addition to power, power density and normalized power density were introduced to obtain a sense of the magnitude of power demand relative to the degree of structural damage. From the energy response histories of a three-story building, extraordinary increments of kinetic energy under a PL ground motion are closely followed by significant increments of strain energy, indicating large structural deformations. It was found that damping energy is not effectively built up at the first significant increment of strain energy. This implies that inherent or supplemental damping hardly protects building structures against the first crucial strike of PL ground motions, which usually cause the most damage to structures.
PUSHOVER ANALYSIS OF CONFINED MASONRY WALLS USING EQUIVALENT DIAGONAL STRUT MODELS
Authors: Krtinić Nemanja , Gams Matija , Marinković Marko
Published: May 2023

Masonry structures are commonly used for building residential buildings throughout the Balkans and worldwide, in urban and rural areas and areas with seismic risk. For masonry construction in regions with seismic risk, confined masonry (CM) construction offers an appealing alternative to unreinforced masonry (URM) due to its better seismic performance. The numerical simulation of CM is often based on the Equivalent Strut Model (ESM). Such a model provides a very reasonable compromise between accuracy and efficiency and is simple enough for use in design. The purpose of this paper is to compare the results of an experimental shear compression test on a modern CM wall with different ESM models. Five ESM models proposed by various authors are compared. The numerical pushover analyses were performed in the SAP2000 software, and the reference points of the model that gave the best alignment with experimental results were estimated using regression analyses. The results show that the simple modelling of CM walls with an equivalent diagonal strut, which carries load only in compression, can accurately simulate the global seismic response and is suitable for practical applications.
THE CRISIS PLATFORM: A CROSS-BORDER PLATFORM FOR RISK ASSESSMENT AND MANAGEMENT
Authors: Di Meo Antonella , Borzi Barbara , Quaroni Davide , Famà Antonino , Sheshov Vlatko , Apostolska Roberta , Edip Kemal , Vitanova Marija , Bojadjieva Julijana , Bogdanovic Aleksandra , Jekic Goran , Baballëku Markel , Shkodrani Neritan , Qirjazi Genti , Fotopoulou Stavroula , Pedritis Christos , Riga Evi , Pitilakis Dimitris
Published: May 2023

This paper aims to describe the CRISIS web-based platform (WBP) in all its parts and functionalities. The platform is the main result of the two-year EU-funded project CRISIS (Comprehensive RISk assessment of basic services and transport InfraStructure). It has been developed by EUCENTRE (European Centre for Training and Research in Earthquake Engineering) using the most up-to-date web programming frameworks and technologies. The CRISIS WBP is a user-friendly tool intended to support disaster and emergency management authorities in case of earthquakes and/or seismo-induced landslides in the cross-border region of Albania, North Macedonia, and Greece. It has been designed to collect, organise, and visualise for the project target area: i) the exposure data of educational facilities, health facilities, and bridges; ii) the seismic and landslide hazard data; iii) the earthquake damage scenarios (calculated both for selected historical events and in real-time); and iv) the landslide risk scenarios related to the considered exposure dataset. The tool also allows the identification of alternative routes to the nearest available safe facilities, if the main one cannot be used due to damage to the transport infrastructure following a seismic event. This feature can be particularly useful for rescuers who have to intervene promptly after damaging earthquakes. In addition to supporting emergency management, the CRISIS platform can also be used to identify the most vulnerable assets and prioritise actions to increase the resilience of the project target area. As a case study, two earthquakes that affected the cities of Ohrid and Valandovo in 1911 and 1931, respectively, have been simulated. The results of these simulations, also in terms of emergency management (e.g., how to get to the nearest hospitals in the cross-border areas), are presented in detail hereinafter.
SEISMIC INTERFEROMETRY FOR DAMAGE IDENTIFICATION OF LARGE SCALE MODEL OF RC SHEAR WALL STRUCTURE
Authors: Zhurovski Aleksandar , Gjorgjiev Igor
Published: May 2023

Structural Health Monitoring is essential when it comes to damage detection and quantification of civil infrastructure under dynamic excitations. Lately, seismic interferometry has been frequently used for damage identification of structures under earthquake excitations. The method uses data from vibrational sensors to detect changes in travel times of seismic waves propagating trough the structure. The propagating waves’ travel time between pairs of sensors (and consequently their velocity) is related to the local stiffness of the structure enabling to follow possible degradation caused by damage during an extreme event. In this study an analytical uniform Timoshenko beam model that accounts for dispersion due to bending deformation, was implemented for system definition and damage identification of a 3 storey, 1:2 large scale shaking table model. The model is coupled wall RC structure and it was tested in the dynamic testing laboratory in IZIIS, in the frames of SERA project. A full testing programme consisted of random excitation and shaking table tests with gradually increasing intensity of the input excitation. We collected the data consisted of accelerograms from the distributed accelerometers of all tests and recorded damages of the model after each test, defining four damage states. In our research we focus on fitting uniform Timoshenko beam model in the recorded response of the shaking table model after each test. The structure was modelled with large shear stiffness and its compressional wave velocity, cL, was identified and analyzed. We monitored the change in cL after each damage state and compared it with the shift in the fundamental frequency of vibration f1 as well as the observed damage to discuss on the effectiveness of the method. We concluded that it is possible to detect and quantify damages of the structure induced by the increasing earthquake amplitude in each test by wave propagation analysis.
EXPERIMENTAL AND NUMERICAL ANALYSIS OF DAMAGED MASONRY BUILDING
Authors: Duvnjak Ivan , Frančić Smrkić Marina , Damjanović Domagoj , Grgić Karla
Published: May 2023

Recent seismic activity in Croatia has caused significant damage to a large number of old masonry buildings. Since the post-earthquake condition and mechanical properties are not known, on-site experimental testing is an important segment of the maintenance and repair of old masonry buildings. In this paper, the results of experimental determination of the mechanical properties and dynamic parameters on the damaged maisonette building of Sisak highschool are presented. In order to confirm and validate the experimental results, a numerical analysis of the building was performed. After making the initial FE model, the comparison between the natural frequencies obtained from the model and the experimental results revealed unsatisfactory outcomes. Therefore, the FE model was calibrated through a whole series of iterations: modification of the boundary conditions, modelling of partition walls, modelling of the damages and modification of the global stiffness of the structure. After a series of iterations, the global stiffness was significantly reduced by nearly 50% of the experimental results, ultimately leading to a satisfactory result. Apart from the reliability of the numerical model and the calibration of the numerical model analyzed here, by repeating the test after the future renovation (considering changes in building mass), the experimentally determined dynamic parameters of the structure can be used to verify the effects of the renovation of the building.
DETERMINATION OF THE DYNAMIC BEHAVIOR OF A BRIDGE STRENGTHENED WITH SHOCK TRANSMISSION UNITS
Authors: Pajan Jurica , Duvnjak Ivan , Damjanović Domagoj , Brozović Tomislav , Ereiz Suzana
Published: May 2023

Shock Transmission Units (STU), also known as Temporary Connection Devices (TCD) or Lock-up Devices (LUD), are mechanical devices that provide a simple and economical way to improve the resistance of existing bridges. They are mainly used for retrofitting existing bridges to accommodate higher-intensity earthquakes and breaking loads defined by new design codes for which the existing bridges do not have sufficient load-bearing capacity. The basic idea of a shock transmission unit is to distribute seismic or other sudden impact loads only to different substructure elements of the bridge so that the bridge behaves as a rigidly connected structure. In the case of slowly acting loads such as temperature, creep, and shrinkage, the shock transmission units are not activated, so that the different parts of the bridge-bearing structure can move independently of each other. They behave like "seatbelts for bridges" because they restrain bridge movement for sudden dynamic loads but allow free movement under slowly acting static loads. To determine the real contribution of STU to the bridge stiffness and consequently, to the global dynamic behavior of the bridge in regular operating conditions, modal parameters such as natural frequency, mode shapes, and damping were determined on the pedestrian bridge, which had been strengthened with shock transmission units. The modal parameters were determined using operational modal analysis and the numerical model. This paper shows the difference between the experimental and numerical modal parameters and draws conclusions about the impact of the shock transmission units on global bridge stiffness. A proposal is also given for the numerical modeling of shock transmission units and their influence on the overall seismic action.
PHYSICAL AND VIRTUAL EXPERIMENTAL INVESTIGATION OF SELF-CENTRING CONCENTRICALLY BRACED FRAMES
Authors: Petreski Borjan , Gjorgjiev Igor
Published: May 2023

The self-centring concentrically braced frames (SC-CBF) present an innovative structural typology for improved behaviour of the steel structures to earthquake loading. Namely, the SC-CBFs present an advanced technological solution for minimization of the residual drifts at concentrically braced frames which are quite substantial following high intensity seismic action. This structural type’s main characteristic is the re-centring of the frame following the earthquake loading in the initial vertical position, thus reducing the post-earthquake cost and time for retrofitting. It also reduces the material used for repair since the only elements needing retrofitting remain the diagonal braces that undergo many cyclic loadings under the earthquake excitation and develop plastic hinges. However, in order to validate this behaviour, many experimental investigations are required. For that purpose, this study addresses previous, current and future experimental testing considerations and shows the results and potential findings. Firstly, the previous experimental studies involving quasi-static and shake table testing are presented. Then, a virtual experimental procedure is presented in order to tackle the most demanding aspects of calibration and parameter estimation for the simulation of dynamic structural response. The various types of experimental procedures are then combined in order to form a complete methodology for estimation of the main characteristics of the novel system and proceeding to a code conforming evaluation procedure. A combination of these experimental methodologies is the ultimate method for developing reliable numerical simulation model, as well. The calibrated model is subjected to reliability analysis in order to estimate the probability of failure for predefined failure scenarios. Finally, the numerical model is used for developing several archetype structures and thorough parametric study for EC conform design procedure.
EFFECTS OF CORE STRUCTURE IN MULTIPHASE SIMULATION OF AN EARTH DAM
Authors: Edip Kemal , Sheshov Vlatko , Bojadjieva Julijana , Kitanovski Toni , Ivanovski Dejan , Gjorgjeska Irena
Published: May 2023

One of the most popular themes in earthquake geotechnical engineering is the simulation considering the phase interaction among different phases inside the soil medium. The present article aims at providing numerical simulations of an earth fill dam composed of multiphase material models. Moreover, the assessment of liquefaction potential is investigated considering the presence of core structure inside the dam body which obviously has great implications for the results. The formulation of the coupled approach is presented as a mixture of three constituents – soil grains, water and air in the pores. Mixture theory is considered including the concept of volume fractions in defining of the coupled approach. An earth dam has a trapezoidal cross section with the presence of core structure inside the dam body. The flow of water is different and simulations are more time consuming for which results from literature are used in verification process. The simulation considers a nonlinear behavior with respect to the water retention curves and material model for the solid state. The hydrostatic distribution of water pressured at steady state conditions show obvious differences in saturation of the earth filled dam and are in accordance with the results from literature. The dam is assumed to be situated above a hard rock formation. The soil material of the dam body is simulated as hypoplastic material model which is nonlinear even for the small deformations. The usage of hypoplastic model and the accumulation of strain in each cycle of the stress – strain relation makes the model advantageous. Results are compared accordingly, and conclusions provide directions for further usage of the multiphase model in simulation of this type of structures
FRIBAS: A PARAMETRIC DATABASE OF BUILDING AND SOIL FEATURES INCLUDING THE FUNDAMENTAL FREQUENCY OF RESONANCE
Authors: Scaini Chiara , Petrovic Bojana , Gallipoli Maria Rosaria , Calamita Giuseppe , Tragni Nicola , Barnaba Carla , Vona Marco , Parolai Stefano
Published: May 2023

The FRIBAS database collects information on the characteristics of more than 300 buildings located in southern and northeastern Italy. The characteristics comprise age, construction material, storey number and other data such as geometrical features (e.g. shape) and construction details (e.g. roof type, floor types). Such characteristics were inferred based on external and sometimes internal building inspection, combined with information provided by residents. In addition, FRIBAS includes the fundamental frequencies of buildings and foundation soil, estimated empirically using single station ambient noise measurements. The database was assembled based on data collected separately in northeastern and southern Italy on different building types (including both low to mid-rise historical and modern masonry and low to high-rise reinforced concrete buildings). The buildings were chosen also based on the possibility of accessing the interior and performing measurements. Data were harmonized into 37 fields which provide a generalized classification of building and soil parameters. FRIBAS is the first database that collects several buildings characteristics, including structural and geometrical features, together with the fundamental frequencies of buildings of and foundation soil. FRIBAS was assembled with the specific purpose of analyzing how different building parameters influence structural behavior (in particular, the fundamental period). The database is available online in open access mode under the CC 4.0 license. The collected data support the definition of different period-height relationships based on construction material and soil types. The analysis can be extended to other parameters associated with specific building types. We discuss the relevance of empirical building and soil characterization for seismic damage/risk assessment and propose potential applications of the FRIBAS database.