Natural Hazards Challenges to Civil Engineering

info:eu-repo/semantics/publishedVersio

Comparison of experimental and analytically predicted out-of-plane behavior of framed-masonry walls containing openings

During an earthquake, structures are loaded in both in-plane and out-of-plane direction. This paper investigates the behaviour of load-bearing frames with infill walls that contain openings. As when they are subjected to out-of-plane, inertial loads. In the experimental campaigns of like structures, it was found that even with openings, the beneficial arching-action was able to develop. However, its effectiveness was limited. Namely, the deformation capabilities in all cases were significantly lowered. Same can not be stated for the load-bearing capacities, as some researches found no reduction while others did. Additionally, this paper analyses the existing equations that can calculate the load-bearing capacity of such structures. Low correlations were found between the experimental and analytical capacities. Hence, further research endeavours should be addressed in order to gain a reliable analytical model

A review of experimental and analytical studies on the out-of-plane behaviour of masonry infilled frames

This paper presents a literature review of research undertaken on the out-of-plane behaviour of masonry infilled frames. This paper also discusses the effects of bidirectional loads, openings, slenderness, boundary conditions etc. As numerous researchers have reported, these effects play a crucial role in achieving arching action cause, as they can bypass or limit its effectiveness. Namely, arching action leads to additional compressive forces which resist traversal ones. This is confirmed by inertial force methods of testing, while the same cannot be claimed for inter-storey drift or dynamical methods. It is to be acknowledged that most experimental tests were carried out using inertial force methods, mostly with the use of airbags. In contrast, only a few were undertaken with dynamical methods and just two with inter-storey drift methods. It was found that inertial force and inter-storey drift methods differ widely. In particular, inertial force methods damage the infill, leaving the frame more or less intact. Conversely, drift heavily damages the frame, while infill only slightly. Openings were investigated, albeit with contrasting results. Namely, in all cases, it was found that openings do lower the deformational but not all load-bearing capacities. Furthermore, analytical models have shown contrasting results between themselves and with experimental data. Models’ stabilities were checked with single- and multi-variable parametric analysis from which governing factors, influences of frame and other parameters were identified

Development and Calibration of a 3D Micromodel for Evaluation of Masonry Infilled RC Frame Structural Vulnerability to Earthquakes

Within the scope of literature, the influence of openings within the infill walls that are bounded by a reinforced concrete frame and excited by seismic drift forces in both in- and out-of-plane direction is still uncharted. Therefore, a 3D micromodel was developed and calibrated thereafter, to gain more insight in the topic. The micromodels were calibrated against their equivalent physical test specimens of in-plane, out-of-plane drift driven tests on frames with and without infill walls and openings, as well as out-of-plane bend test of masonry walls. Micromodels were rectified based on their behavior and damage states. As a result of the calibration process, it was found that micromodels were sensitive and insensitive to various parameters, regarding the model’s behavior and computational stability. It was found that, even within the same material model, some parameters had more effects when attributed to concrete rather than on masonry. Generally, the in-plane behavior of infilled frames was found to be largely governed by the interface material model. The out-of-plane masonry wall simulations were governed by the tensile strength of both the interface and masonry material model. Yet, the out-of-plane drift driven test was governed by the concrete material properties

DOCUMENTATION FOR ENVIRONMENTAL RISK ASSESSMENT AND MITIGATION OF BUILT CULTURAL HERITAGE IN CENTRAL ASIA: THE ERAMCA PROJECT

The ERASMUS+ initiative funded, in 2019, a Capacity Building project named ERAMCA (Environmental Risk Assessment and Mitigation in Central Asia) to build up a study plan at the Master of Science level (120 ECTS in 2 academic years) open to Architects, Civil, Building, and Environmental Engineers to build-up a new generation of professionals able to work in a team with different specialities to document Cultural Heritage assets by considering environmental risks. These new professionals will be able to set up the helpful basic knowledge to plan future actions of preservation and enhancement by following the most recent development in the restoration field at the international level.The ERAMCA project started with a survey of the basic knowledge of architects and engineers in Uzbekistan and Tajikistan on the documentation of natural and anthropic risks.By considering the common knowledge, the Partners of the ERAMCA project (3 European Universities from Italy, Germany, and Croatia and 4 Universities from Uzbekistan and Tajikistan) realised a study plan by concentrating the teaching activity on the following disciplines: Geomatics, Restoration, Structure and Seismic Engineering, Hydrogeology and Geotechnics.ERAMCA project is in its last year of activity, and the final results can be presented and discussed among the Cultural Heritage Documentation community to offer possible suggestions for future actions to diffuse documentation strategies.</p

The macroecology of phylogenetically structured hummingbird-plant networks

Aim To investigate the association between species richness, species' phylogenetic signal, insularity and historical and current climate with hummingbird-plant network structure. Location 54 communities along a c. 10,000 kilometer latitudinal gradient across the Americas (39ºN - 32ºS), ranging from sea level to c. 3700 m asl, located on the mainland and on islands, and covering a wide range of climate regimes. Methods We measured null-modeled corrected complementary specialization and bipartite modularity (compartmentalization) in networks of quantitative interactions between hummingbird and plant species. Using an ordinary least squares multi-model approach, we examined the influence of species richness, phylogenetic signal, insularity, and current and historical climate conditions on network structure. Results Phylogenetically-related species, especially plants, showed a tendency to interact with a similar array of partners. The spatial variation in network structure exhibited a constant association with species' phylogeny (R2=0.18-0.19). Species richness and environmental factors showed the strongest associations with network structure (R2=0.20-0.44; R2138 =0.32-0.45, respectively). Specifically, higher levels of complementary specialization and modularity were associated to species-rich communities and communities in which closely-related hummingbirds visited distinct sets of flowering species. On the mainland, warmer temperatures and higher historical temperature stability associated to higher levels of complementary specialization. Main conclusions Previous macroecological studies of interaction networks have highlighted the importance of environment and species richness in determining network structure. Here, for the first time, we report an association between species phylogenetic signal and network structure at macroecological scale. Specifically, null model corrected complementary specialization and modularity exhibited a positive association with species richness and a negative association with hummingbird phylogenetic signal, indicating that both high richness and high inter-specific competition among closely-related 150 hummingbirds exhibit important relationships with specialization in hummingbird-plant networks. Our results document how species richness, phylogenetic signal and climate associate with network structure in complex ways at macroecological scale

The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project

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A building classification scheme of housing stock in Malawi for earthquake risk assessment

This study presents a building classification scheme for residential houses in Malawi by focusing upon informal construction, which accounts for more than 90% of housing in the country, which has the highest urbanisation rate in the world. The proposed classification is compatible with the Prompt Assessment of Global Earthquakes for Response (PAGER) method and can be used for seismic vulnerability assessments of building stock in Malawi. To obtain realistic proportions of the building classes that are prevalent in Malawi, a building survey was conducted in Central and Southern Malawi between 10th and 20th July 2017. The results from the survey are used to modify the PAGER-based proportions of main housing typologies by reflecting actual housing construction in the surveyed areas. The results clearly highlight the importance of using realistic building stock data for seismic risk assessment in Malawi; relying on global building stock information can result in significant bias of earthquake impact assessment

Ecological filtering shapes the impacts of agricultural deforestation on biodiversity

Funding: This project was funded by the National Natural Science Foundation of China (Grants 32122057 and 3198810 to FH) and the Ministry of Science and Technology of China (Grant 2022YFF0802300 to FH), and received further support from Tsinghua University Initiative Scientific Research Program (Grant 20223080017 to LY).The biodiversity impacts of agricultural deforestation vary widely across regions. Previous efforts to explain this variation have focused exclusively on the landscape features and management regimes of agricultural systems, neglecting the potentially critical role of ecological filtering in shaping deforestation tolerance of extant species assemblages at large geographical scales via selection for functional traits. Here we provide a large-scale test of this role using a global database of species abundance ratios between matched agricultural and native forest sites that comprises 71 avian assemblages reported in 44 primary studies, and a companion database of 10 functional traits for all 2,647 species involved. Using meta-analytic, phylogenetic and multivariate methods, we show that beyond agricultural features, filtering by the extent of natural environmental variability and the severity of historical anthropogenic deforestation shapes the varying deforestation impacts across species assemblages. For assemblages under greater environmental variability—proxied by drier and more seasonal climates under a greater disturbance regime—and longer deforestation histories, filtering has attenuated the negative impacts of current deforestation by selecting for functional traits linked to stronger deforestation tolerance. Our study provides a previously largely missing piece of knowledge in understanding and managing the biodiversity consequences of deforestation by agricultural deforestation.Peer reviewe