In Western countries there has been an increasing interest in adobe constructions, especially for sustainability and comfort reasons. Some billion people live in earth houses all over the world, also in seismic areas. The seismic behaviour of adobe constructions was numerically modelled through the Equivalent Frame method. The static and seismic behaviour of simple adobe buildings was studied with the code RAN and compared with that of low strength masonry buildings. Sardinia is the place in Italy where earth constructions are more widespread, with an important building tradition dating many centuries ago due to the lack of other building materials in the alluvial plain of Campidano. Earth constructions are built in Sardinia especially for comfort and sustainability reasons. For the Italian code in Sardinia, new buildings are to be checked for the seismic action, and existing buildings to be reused with important structural modifications and changes of the loading conditions.
Recent seismic events are a unique opportunity to monitor and collect details of direct repair costs and the downtimes associated with massive reconstruction processes. This paper focuses on the actual repair costs of five RC buildings damaged by the 2009 L'Aquila earthquake. The repair costs for structural and nonstructural components that experienced different types of earthquake damage are discussed and then used as a benchmark for the predictions. The comparison at both the building and component levels revealed that the FEMA P-58 methodology is suitable, in general, for application to different types of building stock. Ad hoc upgrades to the FEMA fragility database for components that are typical of the Mediterranean area are required. When implementing the proposed modifications, a reasonable level of consistency is achieved in terms of actual and predicted repair costs (differences in the range of 30–48%). A discussion on the actual repair costs and the main differences with the predicted costs for infills and partitions, structural subassemblies, floor finishes, and other acceleration-sensitive nonstructural components is provided, along with suggestions for further improving.
Unreinforced masonry (URM) buildings, largely found in Euroasian regions, are particularly vulnerable to in-plane shear failures during seismic events due to the poor shear capacity of masonry walls. In the case of historical masonry buildings, the use of strengthening solutions with polymeric and polymer-modified matrices composites is not recommended since the breathability of the masonry could be reduced, leading to a fast and undesired degradation. In this paper, an innovative fiber-reinforced cementitious mortar (i.e., FRCM) system was used to improve the shear capacity of old-type solid clay brick masonry walls. An experimental program on 24 masonry panels subjected to diagonal compression tests was carried out. The innovative FRCM system consisted of a basalt grid embedded in an improved inorganic matrix, made of lime-based mortar reinforced with short glass fibers (i.e., Fiber-reinforced mortar, FRM). Two sets of specimens were tested, single-leaf masonry panels and double-leaf masonry panels, to investigate the typical configurations of load-bearing walls and partition walls. The effectiveness of the innovative FRCM system was investigated for both a conventional symmetric strengthening configuration and an asymmetric strengthening configuration with anchors, a solution often adopted in the case of internal/external interventions only. Furthermore, the response of masonry panels strengthened with only symmetric FRM with a slightly greater amount of short glass fibers embedded in the matrix was also investigated. The experimental outcomes outlined that panels reinforced with symmetric FRM achieved similar effectiveness in the shear strength increase to panels reinforced with symmetrical FRCM. Conversely, a reduced deformability was observed in FRM panels with respect to those strengthened with FRCM. The experimental results also allowed the quantification of the effectiveness of FRCMs in the case of asymmetric strengthening configurations. Finally, a comparison between experimental results and American Code provisions for FRCM-strengthened systems was reported.
Postearthquake reconnaissance and recent research on seismic risk analysis have shown that nonductile concrete frame structures are much more susceptible to collapse than modern code-conforming frames. The performance-based assessment paradigm has been a persistent research theme over the last decade within the earthquake engineering community in order to estimate seismic fragilities and earthquake loss for these nonductile concrete frames. This paper proposes a nonlinear performance-based methodology to evaluate different retrofit methods considering hazard level, target performance levels, and life-cycle cost estimates. The structural performance is the main parameter considered for the optimization, although a life-cycle cost analysis is also presented. As a case study, the longitudinal frame of an existing building was modeled considering the effect of flexural-shear-axial load interaction in order to capture column shear and axial failures. The presented performance-based procedure identifies the most economic retrofit solution that satisfies structural response requirements for a given performance level.
The seismic assessment of reinforced concrete (RC) structures is commonly carried out neglecting potential previous damage induced by other phenomena, for example those related to the actions of slow-moving settlements. Many efforts are dedicated by the research community in properly considering multi-hazard actions and their inter-relations on the structure, instead of a reductionist approach, to be included in the numerical models adopted for the assessment of the seismic vulnerability. Such a consequences are increasingly becoming an important issue in the structural assessment, since several structures have an age close to, or higher than their design life. In this work, a typological 3D case study RC building, chosen to represent gravity loads designed buildings constructed in Italy from the 1950s to the 1970s, is used. The seismic assessment of the building structural elements, caused by the design seismic action, is initially shown. Then, the seismic assessment is repeated, considering as point zero of the analysis the "damaged" building as consequence of slow-moving settlements, acting in different configurations, potentially due to different causes (e.g., landslides, subsidence). A novel comparison in terms of fragility curves is proposed between the safety condition of the building expected in both cases, with or without the consideration of the precedent induced displacements. The effect of the configuration of the previous slow-moving settlements on the seismic response is investigated, by showing that the application of the horizontal settlements has a stronger effect on the penalization of the seismic response of the building, but also the application of the vertical settlements produces a decreasing of the median seismic capacity.
