Search

A new hybrid system consisting of wood shear walls, concrete columns, bracing system, and viscous damper devices is introduced in this paper. A benchmark wood building is adopted here as a case study, and different configurations of the new hybrid system are applied on it in order to investigate its seismic performance under some near-fault ground motion records. The performance base design method is used to design the considered models. In order to make the models comparable, their performance levels are considered to be identical. Detailed finite element models are built in OpenSees software to conduct nonlinear static and dynamic analyses. The parametric study is done to optimize the viscous damper system parameters. At the end, the damage potential of the models is investigated through their fragilities. The results demonstrate the high potential of the proposed system in improving the seismic performance of the mid-rise wood buildings. It is also observed that the good behavior of the system is achieved when the viscous damper coefficient and its supporting tendon cross-sectional area is dependently increased. [ABSTRACT FROM AUTHOR]

The safety of the built heritage of our cities towards environmental factors and seismic actions is a pressing need for designers and researchers. The actual trend is to setup effective solutions to reduce thermal dispersions through the building envelope. Contrarily, combined systems able to enhance the resistance of constructions to earthquakes, on the one hand, and, on the other hand, to increase the energetic efficiency of existing buildings are scarcely diffused on the market and are rarely investigated in the scientific literature. In this framework, the seismic design of the new envelope DUO system for seismic-environmental requalification of existing masonry constructions is illustrated in the present paper with reference to a case study in the Neapolitan area. After the geometrical and mechanical characterization of the investigated building is performed, an FEM model of the masonry construction is setup by the SAP2000 analysis program, which has allowed performing pushover analyses. Based on the non-linear seismic response of the construction, an appropriate upgrading design mainly based on the innovative seismic envelope DUO system has been made. The static non-linear analyses applied to the upgraded FEM model of the building have shown a clear increase in performance in terms of strength, stiffness and ductility, thus confirming the effectiveness of the proposed envelope system. [ABSTRACT FROM AUTHOR]

A series of simplified approaches are evaluated for their effectiveness to estimate the seismic vulnerability of historical masonry towers. First, collapse loads are evaluated on sixteen “idealized” benchmark cases with different slenderness and shear area. Both analytical and computational approaches are used, namely the analytical procedure proposed by the Italian Guidelines on the Built Heritage and pushover analyses conducted using the commercial codes UDEC and 3Muri. The sixteen towers are representative cases which can be encountered in practice. Their geometry is idealized into parallelepiped blocks with hollow square cross-sections, thus favoring the utilization of 2D approaches, beneficial to drastically reduce the effort required for repeated computations. In addition, a Monte Carlo MC upper bound limit analysis strategy is proposed, in order to have an insight into the possible failure mechanisms for the different cases investigated. Deliberately is avoided the introduction of any form of irregularity and they are supposed isolated from the neighboring buildings, to obtain results exclusively dependent from geometric features. Among all the possible collapse mechanisms, five of them are selected according to the probability of occurrence based on past earthquake experiences. Five million cloud points of collapse accelerations are obtained by carrying the height, slenderness and shear area of the idealized towers. The approach is very fast and allows identifying different regions where single mechanisms are active. The results are confirmed repeating MC simulations with a triangular FE upper bound limit analysis discretization of the idealized towers. A series of equations are provided in order to assist engineers and practitioners to obtain a preliminary estimation of their expected collapse acceleration. For validation purposes, the results obtained previously with refined full 3D FE models of 25 towers located in the Northern Italy are reported. Satisfactory agreement between the predictions provided by simplified methods and sophisticated analyses are obtained. [ABSTRACT FROM AUTHOR]

The paper deals with the numerical calibration of a speedy procedure for large scale seismic vulnerability assessment of masonry building aggregates, which are typical building compounds diffused within historical centres of many Italian towns. First of all, based on several numerical analyses developed with the 3MURI calculation program, this simplified assessment procedure has been implemented, it being derived from the well known vulnerability form for masonry buildings integrated by five parameters accounting for the aggregate conditions among adjacent units. Later on, the set-up procedure has been validated through an application to a single building aggregate in the Vesuvius area. Since the results previously achieved have been again confirmed, subsequently the procedure has been used to investigate a wide area of the historical centre of Torre del Greco, allowing for the knowledge of the buildings most at risk under earthquake. Finally, the methodology has been applied to the historical centre of Poggio Picenze (AQ), damaged by the recent Italian earthquake (2009), in order to prove its effectiveness to foresee the damage level experienced by other types of masonry aggregates under seismic actions. [ABSTRACT FROM AUTHOR]

The proposed study aims at analysing a sub-urban sector in the historic centre of Qualiano, located in the province of Naples (Italy), in order to assess the seismic vulnerability of the main typology classes (masonry and reinforced concrete) in the study area and the consequent expected damage scenarios. The typological and structural characterisation of the investigated area is done through the CARTIS form developed by the PLINIVS research centre together with the Italian Civil Protection Department. Subsequently, the vulnerability simulation analysis is carried out by means of a quick methodology integrated into a GIS tool in order to identify the structural units (S.U.) most susceptible at damage under seismic events. Furthermore, in order to take into account the possible damage scenarios, a parametric analysis is performed using a seismic attenuation law in order to obtain the maximization of the expected urban losses. Finally, the site and topographical local conditions, which negatively influence the severity of the seismic damage on the structures, have been taken into account in order to more correctly foresee the expected damage of the inspected sub-urban sector to be used for appropriate seismic risk mitigation plans. [ABSTRACT FROM AUTHOR]

• Experimental tests have been performed on 57 extruded aluminium bars. • One and two stages Ramberg-Osgood models have been provided for each tested aluminium alloy. • The low cycle fatigue curves have been obtained for 6060, 6082 and 7075 alloys. • Ductility and dissipation have been evaluated in the cyclic tests. • The skeleton curves are derived for each aluminium alloys by means of the incremental cyclic tests. In the present paper an extensive experimental campaign is carried out on 5000, 6000 and 7000 aluminium series through monotonic and cyclic tests. The research is part of a collaboration between the Universities of Salerno and Naples "Federico II" involved for several decades in the development of the Eurocode recommendation regarding the aluminium alloys for structural purposes. The experimental program is composed of 3 monotonic experiments for each aluminium alloy, 29 low-cycle fatigue tests for 6060, 6082 and 7075 alloys and 10 incremental cyclic tests under different loading cycles for all tested alloys. The main purpose of this campaign is the characterization of such alloys not only in terms of the well-known stress–strain curve while in terms of low cycle fatigue, cyclic hardening, dissipated energy and plastic fracture, to achieve more information about the non linear behaviour which can be exhibited, as an example, under seismic loading. In fact, since now, the largest part of the research has been mainly focused on the behaviour of such materials under a large number of cycles in elastic range thus neglecting the potential benefits in exploiting the large dissipative capacity of such alloys. Moreover, the collected information could be of fundamental importance in the framework of the revision of the new Eurocode 8 which presents, for the first time, a section devoted to the seismic design of structures made of aluminium alloys. The accurate knowledge of the random material variability and cyclic hardening could be helpful for the setting up of the coefficients to be used for the application of the hierarchy criteria. [ABSTRACT FROM AUTHOR]