ABSTRACT The building stock in most historical urban areas in Algeria consists of old masonry buildings which are characterized by the rather high vulnerability. In that respect, to reduce the seismic risk there is a requirement for strategic urban planning and urban management policies. This paper focuses on the assessment of the seismic vulnerability using the RISK-UE methodology, namely the mechanical method LM2, which is adopted and applied to fit the Algerian urban features. In order to implement the RISK-UE LM2 methodology, an old urban center in Annaba city is chosen as a pilot area. Almost, the majority of the structures are unreinforced masonry buildings. In total 226 buildings were assessed, which are typical not only for this region but can be found in many other medium-sized Algerian urban environments. Three scenarios that take into account various values of the peak ground accelerations (PGA) are elaborated. Two scenarios use PGAs issued from an existing probabilistic seismic hazard analysis (PSHA) of Annaba city for 100 and 475 return periods. The third PGA for the last scenario is taken from the Algerian seismic code (RPA99/2003). In order to highlight the degree of vulnerability and risk of the studied masonry buildings, a comparison between the three seismic scenarios is presented in detail for each building’s typology. The obtained seismic vulnerability outcomes offer a great prospect to provide recommendations for making correct decisions to reduce the seismic risk and conduct adequate emergency planning in Algerian urban areas.

Minarets, tall structures, connected or not to the mosque attract attention due to their specific architectural features. Vulnerability to seismic damage has been witnessed throughout history on tall and slender structures after earthquake ground motions. In that respect, it is of the utmost importance to investigate the dynamic characteristics and resilience of historical stone minarets. This paper aims to provide the results of an on-site dynamic investigation of a stone minaret in Mostar and deliver its seismic assessment. The minaret is part of the Tabačica mosque built at the turn of the 16th and 17th century in the City of Mostar, Bosnia and Herzegovina. The on-site investigation comprised dynamic identification of the minaret by ambient vibration testing and qualitative estimation of the masonry wall by sonic pulse velocity testing. Besides the modal analysis a time-history analysis was performed by using the Applied Element Method (AEM), considered an appropriate tool for assessing the behavior of historic masonry structures. A good match is found between the first natural frequency obtained by the on-site investigation and the modal analysis which is a solid basis for further seismic assessment of the minaret as a slender tower-like structure. The concentration of stresses is observed at the transition zones.

Minarets are slender and tall structures that are built from different types of materials. Modern materials are also starting to be used in such structures with the recent developments in material technology. The seismic vulnerability and dynamic behavior of minarets can vary, depending on the material characteristics. Within this study’s scope, thirteen different material types used in minarets in Türkiye were chosen as variables. A sample minaret model was chosen as an example with nine different heights to reveal how material characteristic change affects seismic and dynamic behavior. Information and mechanical characteristics were given for all the material types. Natural fundamental periods, displacements, and base shear forces were attained from structural analyses for each selected material. The empirical period formula for each material is proposed using the obtained periods, depending on the different minaret heights taken into consideration. At the same time, fundamental natural periods for the first ten modes and 13 different types of materials used in the study were estimated with the established Artificial Neural Network (ANN) model. The real periods from the experimental analyses were compared with the values estimated by the ANN using fewer parameters, and 99% of the results were successful. In addition, time history analyses were used to evaluate the seismic performance of the minaret (three different materials were considered). In this specific case, the acceleration record from the 2011 Van (Eastern Turkiye) earthquake (Mw = 7.2) was taken into consideration. Performance levels were determined for the minaret according to the results obtained for each material. It has been concluded that material characteristics significantly affect the dynamic and seismic behavior of the minarets.

Data from past earthquakes is an important tool to reveal the impact of future earthquakes on engineering structures, especially in earthquake-prone regions. These data are important indicators for revealing the seismic loading effects that structures will be exposed to in future earthquakes. Five different earthquakes from six countries with high seismic risk were selected and were within the scope of this study. The measured peak ground acceleration (PGA) for each earthquake was compared with the suggested PGA for the respective region. Structural analyzes were performed for a reinforced-concrete (RC) building model with four different variables, including the number of storeys, local soil types, building importance class and concrete class. Target displacements specified in the Eurocode-8 were obtained for both the suggested and measured PGA values for each earthquake. The main goal of this study is to reveal whether the proposed and measured PGA values are adequately represented in different countries. We tried to reveal whether the seismic risk was taken into account at a sufficient level. In addition, target displacements have been obtained separately in order to demonstrate whether the measured and suggested PGA values for these countries are adequately represented in structural analysis and evaluations. It was concluded that both seismic risk and target displacements were adequately represented for some earthquakes, while not adequately represented for others. Comments were made about the existing building stock of the countries considering the obtained results.

After a long period of no excessive ground shaking in Croatia and the region of ex-Yugoslavia, an earthquake that woke up the entire region was the one that shook Croatia on 22 March 2020. More than 25,000 buildings were severely damaged. A process of reconstruction and strengthening of existing damaged buildings is underway. This paper presents proposed strengthening measures to be conducted on a cultural-historical building located in the city of Zagreb, which is under protection and located in zone A. After a detailed visual inspection and on-site experimental investigations, modeling of the existing and strengthened structure was performed in 3Muri. It is an old unreinforced masonry building typical not only for this region but for relevant parts of Europe (north, central, and east). The aim was to strengthen the building to Level 3 while respecting the ICOMOS recommendations and Venice Charter. Some non-completely conservative concessions had to be made, to fully retrofit the building as requested. The structural strengthening consisted of a series of organic interventions relying on—in the weakest direction—a new steel frame, new steel-ring frames, and FRCM materials, besides fillings the cracks. Such intervention resulted in increasing the ultimate load in the X and Y directions, respectively, more than 650 and 175% with reference to the unstrengthened structure. Good consistency was obtained between the numerical modeling, visual inspection, and on-site testing.

The European building stock presents pertinent issues needing suitable strategies to be solved. In detail, this regards seismic safety and energy efficiency of buildings to ensure more liveable and safe cities, which represents an important goal for modern societies. Energy performance includes both comfort and saving, the latter required for a more responsible resource consumption within the building sector, having a considerable contribution to the total demand. Current strategies do not seem to be able to simultaneously solve such aspects satisfactorily, both for higher economic requirements and poor technical feasibility implied by separated and disharmonious interventions. Thus, a holistic perspective should be adopted to pursue such an ambitious objective, which has recently gained increasing attention among researchers. Current requirements are firstly highlighted to show the need for an integrated approach to building retrofit. Secondly, a critical review of integrated strategies combining seismic and energy refurbishment proposed in the literature is reported. Then, special issues are discussed, including the feasibility of an integrated approach applied to heritage buildings. This study revealed that a fully efficient strategy for integrated retrofit has not still been proposed in the literature and there are several open issues to be solved. However, current solutions may be further developed to improve them and the several options currently available demonstrated the increasing attention and importance of the topic. Finally, concluding remarks on this research topic have been drawn to promote future studies.

Conservation of historical centres is a pressing need for Mediterranean countries, that are characterized by masonry aggregates representing the most typical construction type within cities. Masonry clustered buildings were usually designed without seismic design criteria. Moreover, the current seismic standard codes do not foresee a clear calculation method to predict their non-linear behaviour. For this reason, in this paper, a wide overview on the seismic response of masonry aggregates has been done considering analysis at different levels, from simplified large-scale evaluations to sophisticated non-linear analyses. In the former investigation kind, a vulnerability form appropriately conceived for clustered buildings has been applied to different historical centres with the aim to perform risk analysis considering both empirical approaches and real data deriving from occurred past earthquakes. In the second evaluation type, the macro-elements analysis method has been examined with reference to typical clustered buildings of the Italian territory. In particular, global assessments, performed using the 3Muri non-linear analysis program, have been performed with the final goal to derive fragility curves of structural units of masonry aggregates considering their plan position in the clustered building (end of row, internal, and corner).

Tekija (tekke, khanqah) is an Islamic institution where dervishes (Sufis) gather, reside, and perform religious rites. The word tekke is of Persian origin. In Bosnia and Herzegovina, tekkes appeared with the advent of Islam in the 15th century. However, some were built before the arrival of the Ottomans, such as the Mevlevi tekke in Bentbaša built by Isa-beg Ishaković in 1461 in Sarajevo. Tekkes were usually the first buildings that were constructed and located at the entrance of the city. Usually, they were built by dervishes, most often sheiks. Besides religious purposes, they also served as resting places or lodgings for casual travelers. There are numerous tekkes throughout Bosnia and Herzegovina from west to east, from north to south. Some of the most famous tekkes in Bosnia and Herzegovina are the tekke at the Buna spring in Blagaj, the Hadži Sinan’s tekke, Nadmlini tekke in Sarajevo, tekke in Kaćuni, tekke in Jajce, tekke in Živčići, and others. Among these, one of the most distinguished tekke in Bosnia and Herzegovina is the one at the Buna spring in the city of Blagaj. The paper aims to elaborate on the most important characteristics and main features of this tekke and other structures within this complex.

One way to improve a structure’s total load-bearing capacity during an earthquake is to apply fiber-reinforced polymers (FRP) to unreinforced walls. The study discusses the use of FRP to strengthen unreinforced masonry (URM) structures. Although, many studies were conducted on the FRP strengthening of URM buildings, most of them were experiments to investigate the success of retrofitting approaches, rather than developing a successful design model. A database of 120 FRP-reinforced wall samples was created based on the current literature. Various approaches for calculating the bearing capacity of FRP-reinforced masonry are presented and detailed. The findings of the experiments, which were compiled into a database, were compared to those derived using formulas from the literature and/or building codes, and the model’s limitations are discussed.