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Several Italian cities are characterized by the presence of centuries-old historic walls, which have a cultural heritage value and, due to their structural role as a retaining wall, often influence the safety of adjacent buildings and infrastructure. Ancient urban walls are increasingly subject to instability and collapse phenomena, because the greater frequency of extreme meteoric events aggravates the static condition of the walls and of the wall–soil system. Since the seismic risk in the contexts in which the historical urban walls are located is often medium-high, it is advisable to evaluate the influence of soil moisture on the seismic response of the soil–structure system. In this paper, the seismic vulnerability of historical urban walls was examined through considering scenarios of both dry and wet soil, in order to evaluate the seismic response of the structure as a function of soil imbibition. Seismic vulnerability analyses were carried out on the case study of the historical urban masonry walls of Volterra (Italy), which have been affected by two major collapses in the last ten years. Seismic vulnerability was assessed by means of the limit equilibrium method and the finite element method, and through adopting proper soil imbibition models. The results highlight which sections of the walls are at greater seismic risk due to the presence of soil moisture, as well as the influence of soil imbibition on the structural safety and failure mechanism. [ABSTRACT FROM AUTHOR]

Featured Application: Non-destructive tests to have a rapid condition assessment of bridges, using the Fast-Falling Weight Deflectometer. In this paper, the use of Fast Falling Weight Deflectometer (Fast-FWD) is analyzed as a non-destructive and quick test procedure to evaluate the efficiency of short-span bridges. The Fast-FWD is an instrument that can produce a broadband dynamic force up to an impact value of 120 KN: The impact is constant and replicable, providing accurate action measures of bridge stiffness in a truly short period (30 ms). In this paper, a single-span reinforced concrete bridge is investigated, using the Fast-FWD. The considered bridge, approximately 12.0 m long and 15.5 m wide, was in critical condition. The bridge is in a suburban principal road near to the City of Cagliari in Sardinia (Italy), with an Annual Average Daily Traffic of 13,500 vehicles/day, and was suddenly closed, creating serious problems for urban mobility. In these conditions, the investigation through other standard techniques is time-consuming and labor intensive. For this reason, it is important to introduce methods that can be rapid, accurate and cost-efficient. In this paper, bridge stiffness values obtained during the in situ experimental campaign were compared with finite element models values. The Fast-FWD has the potential to provide engineering information that can help us to better understand bridge condition, in a rapid and cost-effective procedure. [ABSTRACT FROM AUTHOR]

The present paper deals with the influence ofmaterial variability on the seismic vulnerability assessment of reinforced concrete buildings. Existing r.c. buildings are affected by a strong dispersion of material strengths of both the base materials. This influences the seismic response in linear and nonlinear static analysis. For this reason, it is useful to define a geometrical parameter called "material eccentricity". As a referencemodel, an analysis of a two storey building is presentedwith a symmetrical plan but asymmetrical material distribution. Furthermore, an analysis of two real buildings with a similar issue is performed. Experimental data generate random material distributions to carry out a probabilistic analysis. By rotating the vector that defines the position of the center of strength it is possible to describe a strength domain that is characterized by equipotential lines in terms of the Risk Index. Material eccentricity is related to the Ultimate Shear of non-linear static analyses. This relevant uncertainty, referred to as the variation of the center of strength, is not considered in the current European and Italian Standards. The "material eccentricity" therefore reveals itself to be a relevant parameter to considering how material variability affects such a variation. [ABSTRACT FROM AUTHOR]

The retrofitting of existing masonry buildings is now a crucial problem for Europe. Indeed, structural safety and energy efficiency should represent the target of any renovation. The proposal of a new synthetic performance parameter is presented and discussed. Following this approach, in this paper, after a review of the main studies available in the literature, a proposal of a new performance parameter approach is presented and discussed. It is capable of taking into account both the structural and thermal aspects of masonry retrofitting. An emblematic set of reinforcements and energy improvements for masonry walls is examined. An example, generalized formulas, and a simultaneous evaluation of the role of multiple structural and thermal parameters on masonry buildings are proposed, with a view to optimize several categories of costs related to the intervention. [ABSTRACT FROM AUTHOR]

The effect of irregularities due to the non-uniform distribution of material properties on structural elements of a significant real case is here investigated. Mechanical tests performed on a typical Italian reinforced concrete (r.c.) school building built in the 1960s showed irregularity in the distribution of compression strength in columns, even though the construction is featured by substantially symmetric distribution of the frames. Extreme scenarios in the distribution of irregularities in compression strength of concrete columns are analyzed, with the hypothesis of rigid or deformable slabs. The seismic analysis showed the influence of the response due to the irregular distributions of concrete strength. A proposal of equivalent "material eccentricity" is shown to account for the mentioned irregularity. Furthermore, the practical solution of reinforcement to mitigate the effects of irregularities is also described. It consists of couple of external r.c. walls stiffened by r.c. buttresses added to the building, connected by transverse slabs. An extensive reduction of material eccentricity is achieved, together with a relevant improvement in seismic capacity. [ABSTRACT FROM AUTHOR]

This article illustrates the production process, the structural calculations and the assembly phases of the wooden walls of the Japan Pavilion at Expo 2015 in Milan, designed by Atsushi Kitagawara Architects (AKA). The pavilion, one of the most popular construction of this international event, was built almost exclusively with precast interlocking. The production process and the assembly phases were optimized to construct the wooden walls (with a height of 4-12 m) in a short time frame and with a high level of quality. Out-of-plane rocking and other aspects of structural safety were considered, to ensure sufficient stability of the walls. [ABSTRACT FROM AUTHOR]

The paper deals with the use of vibro-compressed units with bio-natural components on construction. The proposed mix design of vibrated blocks consist of cork granules and/or hemp shives, with the aim to substitute polymeric elements or expanded clay, together with the use of natural hydraulic lime (NHL) as binder. An experimental campaign is presented, with mechanical tests to evaluate the influence of each component on flexural and compression behavior. The proposal is also investigated from a productive point of view, considering how it can be harmonized in the productive process of lightweight aggregate concrete units without modifications in the productive process. The tested elements could perform a certain reduction of the carbon impact, maintaining interesting mechanical properties. The application of the proposed units in several contexts, as separating elements joined with structural components, is considered to improve rehabilitation or to obtain higher performances in buildings. [ABSTRACT FROM AUTHOR]

Experimental tests and constructive assessments are presented for a simple bamboo framed structure with innovative low-cost and low technology joints, specifically conceived for small buildings in developing countries. Two full scale one-storey bamboo frames have been designed by using the simplest joints solution among three different tested typologies. The entire building process is based on low-technology and natural materials: bamboo canes, wooden cylinders, plywood plates and canapé rods. The first full scale specimen (Unit A) is a one-storey single deck truss structure subjected to monotonic collapse test; the second full scale specimen (Unit B) is a one-storey double deck truss structure used to evaluate the construction time throughout assembling tests. The first full scale specimen showed ductility in collapse and ease in strengthening; the second one showed remarkable ease and speed in assembling structural elements. Finally several constructive solutions are suggested for the design of simple one-storey buildings; they are addressed to four purposes (housing, school, chapel, health center) by the composition of the proposed full scale bamboo frames. Ease of use and maintenance with a low level of technology contribute to application in developing countries although not exclusively. [ABSTRACT FROM AUTHOR]

The combination of structural and thermal efficiency is a new frontier in civil engineering. Indeed, the retrofitting strategies should optimize costs and technical solutions from these two points of view. If a technical solution is able to provide an improvement of both structural and energetic behavior, then the utility of the intervention can better justify the economic investment. In this paper, a meso-scale approach (i.e., façade-scale) for integrated interventions applied on masonry façades is proposed. The structural performance of the façade is evaluated by considering base shear and ductility of the structural element through non-linear static analyses. Moreover, the thermal indicator, that is the thermal transmittance, is computed with a simplified approach in terms of an equivalent wall, taking into account the role of the windows and doors of the façade. As proof of concept, the procedure is applied to a façade of an existing masonry building. Economic and environmental iso-cost curves are obtained to tune the interventions conceived for a real case study, analyzing the benefit offered by different retrofitting solutions. [ABSTRACT FROM AUTHOR]