Numerical modelling of the seismic performance of Romanian traditional timber-framed buildings

Traditional architecture made of timber-framed masonry (TFM) system is widespread around the world and has already been recognized as a unique cultural heritage to be preserved. These structures have shown a good seismic performance compared to other typologies because their configuration and construction details were constantly updated as soon as the builders addressed the causes of damage mechanisms when earthquakes occurred. Regarding this typology, Romanian TFM structures can be considered a representative example also because they experienced several seismic events showing their good earthquake-resistance. Although these buildings are still constructed and inhabited nowadays, no recommendation is provided in the Romanian building code and its structural behaviour is not properly characterized yet. Bearing in mind that the building’s global response depends on many parameters such as the performance of its structural elements and their interaction, the calibration of shear walls is crucial to define the non-linear behaviour under cyclic loading. A simplified modelling strategy was chosen to simulate TFM wall response consisting of an equivalent frame with linear elastic elements and non-linearities lumped at the joints by using OpenSees. After calibrating the wall response according to the experimental campaign performed at Technical University of Civil Engineering of Bucharest, the panel was adapted to model a representative Romanian TFM building whose dynamic properties were evaluated by eigenvalue analysis and their potential calibration is proposed based on the ambient vibration tests

Components interaction in timber framed masonry structures subjected to lateral forces

Structures with timber framed masonry represent a special typology that is frequently found in Europe and other countries of the world. They are traditional buildings, non-engineered, which showed an unexpected redundancy during earthquakes where reinforced concrete buildings (improperly constructed) collapsed. In the paper, aspects regarding the interaction between timber elements and masonry are mainly addressed, that were observed both in experimental studies, but also in the in situ seismic behavior of this type of structure during important earthquakes

Seismic loss estimation using experimental fragility and vulnerability functions : case study of Buzau county, Romania

This paper is focused on the seismic risk assessment of Buzau County in Romania. This county overlays the most active seismic source in the region, namely, the Vrancea intermediate-depth seismic source which has produced nine earthquakes with moment magnitude MW≥7.0 in the last two centuries. Over 40% of the population within this county inhabits traditional adobe buildings for which there are very few available fragility or vulnerability functions in the literature. To overcome this shortcoming, in this study, both fragility and vulnerability functions are developed based on recent experimental research performed at the Technical University of Civil Engineering of Bucharest. The seismic risk assessment is performed using two approaches based on both fragility and vulnerability functions. The results of the analyses show considerable differences between the two risk assessment methods and a significant influence of the fragility of the adobe structures on the seismic risk results

A Novel Generation of Polysulfone/Crown Ether-Functionalized Reduced Graphene Oxide Membranes with Potential Applications in Hemodialysis

Heavy metal poisoning is a rare health condition caused by the accumulation of toxic metal ions in the soft tissues of the human body that can be life threatening if left untreated. In the case of severe intoxications, hemodialysis is the most effective method for a rapid clearance of the metal ions from the bloodstream, therefore, the development of hemodialysis membranes with superior metal ions retention ability is of great research interest. In the present study, synthetic polysulfone membranes were modified with reduced graphene oxide functionalized with crown ether, an organic compound with high metal ions complexation capacity. The physico-chemical characteristics of the composite membranes were determined by FT-IR, Raman, XPS and SEM analysis while their efficiency in retaining metal ions was evaluated via ICP-MS analysis. The obtained results showed that the thermal stability of reduced graphene oxide was improved after functionalization with crown ether and that the presence of the carbonaceous filler influenced the membranes morphology in terms of pore dimensions and membrane thickness. Moreover, the ability of Cu2+ ions retention from synthetic feed solution was up to three times higher in the case of the composite membranes compared to the neat ones

Construction Techniques and Detailing for Romanian <i>Paiantă</i> Houses: An Engineering Perspective

Traditional houses represent landmarks of local cultures all over the world. In seismically prone countries, the traditional timber frames with different types of infills have shown quite good earthquake resilience, an essential feature considering their large number, their simplicity and their reduced cost, owing to the use of local materials and workmanship. In fact, their seismic behavior fostered the interest in further scientific research, including that addressing engineering aspects. Because of their diversity in layout and detailing, noticeable even among houses in the same area, developing general methods to preserve and strengthen such buildings is still a difficult task. This paper presents an overview of the traditional building construction techniques in Romania, focusing on the structural configuration and detailing of the so-called paiantă houses. Largely used all over the country, these houses have shown that they can generally withstand earthquakes at least without collapsing and, most frequently, with minor or repairable damage. Their preservation is nowadays a major challenge, as they are being gradually either demolished and replaced, or retrofitted by using invasive techniques. Their cultural and heritage value is undeniable, and there are still many things to be learned from the past craftsmanship and re-valuated in the future. Three case studies of rural buildings located in different areas of the country were chosen among the most widespread paiantă versions, and comprehensive engineering assessments were conducted to identify their detailing and degradations. Based on the most common degradations, the conclusions drawn from this study can be used to substantiate further research aimed at selecting the most appropriate construction and strengthening techniques