The Second Generation Eurocode 9 Federico M. Mazzolani; Alberto Mandara
Engineering proceedings,
09/2023, Volume:
43, Issue:
1
Journal Article
Peer reviewed
Open access
The paper summarizes the main results achieved in the context of CEN Mandate M/515 for amending and extending existing Eurocodes with regard to Eurocode 9 (EC9) on Aluminium Structures (EN1999). The ...revision process led to introducing additional structural typologies (bridging, roofing and a composite of aluminium–concrete), new connection types, new materials and a new buckling material class and to defining improved buckling curves accordingly. This resulted in the addition of several new annexes to the main text. The new items were mostly planned for Part 1-1, including general upgrading, updating and simplifying, with some new additions where necessary. NDPs were reduced from 89 to 49. A general improvement of editorial aspects was obtained as well.
The progressive collapse of the building structures due to abnormal loads has attracted global attention in recent years. Many studies in the literature have been dedicated to the analysis and design ...procedures for progressive collapse resistance, and several technological solutions have been developed for progressive collapse retrofit. However, many studies are based on simple models and their validity and possibility to generalize the research results to current practice are rather limited. Moreover, there are still not many case studies developed based on full-scale real buildings. The present paper contributes to filling this gap by investigating the robustness of a quite complex real case study, namely a steel braced frame building erected in the early ‘60 s in Naples-Italy to house the Civil Engineering Authority. To this aim, different column removal scenarios have been considered and both nonlinear static and dynamic analyses have been carried out. The results have highlighted that the simple braced frames are susceptible to progressive collapse due to the weak brace connections. However, joint strengthening is not a viable solution, because it would prevent the full functionality of this strategic building during the implementation of the progressive collapse retrofit. As an alternative, an outrigger-belt truss system has been developed that applies the concept of Vierendeel truss system to redistribute the loads due to the column removal. The effectiveness of the proposed retrofit strategy to improve the progressive collapse resistance of the building has been verified through nonlinear dynamic analyses, proving its feasibility for practical applications.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Current seismic codes are based on force-controlled design or capacity design, using the base shear concept. The most important parameter in this approach is the response modification factor, also ...called behaviour factor, which is used to design the structure at the ultimate limit state by taking into account its capacity to dissipate energy by means of plastic deformations. In this paper overstrength, redundancy and ductility response modification factors of steel moment resisting frames are evaluated. In order to cover a wide range of structural characteristics, 12 steel moment-resisting frames (6 regular and 6 irregular in elevation) have been designed and analysed. Both static pushover analyses and nonlinear incremental dynamic analyses have been performed. The investigation focuses on the effects of some parameters influencing the responsemodification factor, including the regularity, the number of spans and the number of storeys. As a conclusion, a local ductility criterion has been proposed to improve the provisions given in the Italian seismic code.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The paper deals with the seismic retrofit of a multiple building structure belonging to the Hospital Centre of Avellino (Italy). At first, the paper presents the preliminary investigations, the in ...situ measurements and laboratory tests, and the seismic assessment of the existing fixed-base structures. Having studied different strategies, base isolation proved to be the more appropriate, also for the possibility offered by the geometry of the building to easily create an isolation interface at the ground level. The paper presents the design project, the construction process, and the details of the isolation intervention. Some specific issues of base isolation for seismic retrofitting of multiple building structures were lightened. Finally, the seismic assessment of the base-isolated building was carried out. The seismic response was evaluated through nonlinear time-history analysis, using the well-known Bouc-Wen model as the constitutive law of the isolation bearings. For reliable dynamic analyses, a suite of natural accelerograms compatible with acceleration spectra of Italian Code was first selected and then applied along both horizontal directions. The results were finally used to address some of the critical issues of the seismic response of the base-isolated multiple building structure: accidental torsional effects and potential poundings during strong earthquakes.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Although the most commonly used isolation systems exhibit nonlinear inelastic behaviour, the equivalent linear elastic analysis is commonly used in the design and assessment of seismic-isolated ...structures. The paper investigates if the linear elastic model is suitable for the analysis of a seismically isolated multiple building structure. To this aim, its computed responses were compared with those calculated by nonlinear dynamic analysis. A common base isolation plane connects the isolation bearings supporting the adjacent structures. In this situation, the conventional equivalent linear elastic analysis may have some problems of accuracy because this method is calibrated on single base-isolated structures. Moreover, the torsional characteristics of the combined system are significantly different from those of separate isolated buildings. A number of numerical simulations and parametric studies under earthquake excitations were performed. The accuracy of the dynamic response obtained by the equivalent linear elastic model was calculated by the magnitude of the error with respect to the corresponding response considering the nonlinear behaviour of the isolation system. The maximum displacements at the isolation level, the maximum interstorey drifts, and the peak absolute acceleration were selected as the most important response measures. The influence of mass eccentricity, torsion, and high-modes effects was finally investigated.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
•Anemometric data from three stations are used to assess the wind climate of a site.•Projected wind velocities at the reference site have been calculated and discussed.•Projected and measured data at ...reference site using a LIDAR anemometer are compared.•Inaccuracies and possibly improvements of projection techniques are finally discussed.
Prediction of mean and extreme wind climate at a site from historical data contains intrinsic errors; these come from the not necessarily good quality of the original data, from the approximations adopted when defining orography and roughness at the site of interest, from the possible presence of sheltering effects at the site of measurement and from the approximations embedded in the mathematical models used for transferring the measured data to the site of interest. In this paper, first the mean and extreme wind climate evaluated at three neighbouring sites is compared, and an attempt is made to relate the differences to the characteristics of the sites of measurement and to those of the dataset. Then the wind velocities and wind resource projected to a fourth site are compared among each other and with wind LIDAR measurements taken at the site of projection; this was done with the purpose of quantifying inaccuracies and possibly detecting their causes. It is found that the mean wind climate and wind resource predicted at a site of interest is indeed dependent on the original dataset and on the projection technique. In particular, a simple projection technique is proposed, based on interpolation of the data simultaneously measured at the site and at a neighbouring station. The performance of the proposed technique is compared with that obtained using a commercial software, and no evidence was found of one being more accurate than the other. This suggests that the projection technique based on interpolation could be calibrated on short-term on site measurements, and then used to assess the mean and extreme wind climate at the site of interest using long term records from the neighbouring stations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The paper investigates the dynamic characterisation, the numerical model tuning and the seismic risk assessment of two monumental masonry towers located in Italy: the Capua Cathedral bell tower and ...the Aversa Cathedral bell tower. Full-scale ambient vibration tests under environmental loads are performed. The modal identification is carried out using techniques of modal extraction in the frequency domain. The refined 3D finite element model (FEM) is calibrated using the in situ investigation survey. The FEM tuning is carried out by varying the mechanical parameters and accounting for the restraint offered by the neighbouring buildings and the role of soil–structure interaction. The assessment of the seismic performance of the bell towers is carried out through a nonlinear static procedure based on the multi-modal pushover analysis and the capacity spectrum method. Through the discussion of the case studies, the paper shows that the modal identification is a reliable technique that can be used in situ for assessing the dynamic behaviour of monumental buildings. By utilising the tuned FEM of the towers, the theoretical fundamental frequencies are determined, which coincide with the previously determined experimental frequencies. The results from seismic performance assessment through a pushover analysis confirm that the masonry towers in this study are particularly vulnerable to strong damage even when subjected to seismic events of moderate intensity.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The paper deals with a multi-mode pushover procedure that considers higher mode effects, frequency content of response spectra as well as nonlinear interaction between modes. Pushover analyses are ...conducted with story-specific generalized force vectors. Each force vector is calculated through modal analysis and builds up the instantaneous distribution of forces acting on the structure when the interstory drift at each story attains its maximum value during the seismic motion. In order to improve the computational cost effectiveness, both mode truncation and limitation in the number of generalized pushovers are used by checking, however, the accuracy in the evaluation of the interstory drifts at all levels. The target interstory drift is calculated through three different modal combination procedures.
This paper presents the results of the structural performance assessment of an existing masonry tower and the subsequent repair and strengthening intervention. The study deals with an Italian ...architectural heritage building in the Cilento National Park (Southern Italy): the bell tower in Torre Orsaia. The tower has been the subject of on-site diagnostic investigations including geometrical surveys, laser scanning surveys, flat jack tests, endoscopic tests, sonic pulse velocity tests, geognostic surveys, and tie-rods tests. The multilevel assessment path proposed by the Italian Guidelines for the assessment and mitigation of the seismic risk of the cultural heritage is followed and the corresponding results are discussed. The global inelastic behavior of the masonry tower is studied through a macro-model approach using the nonlinear static (pushover) analysis. The local collapse mechanisms are studied through a kinematic limit analysis based on rigid block rotation. The repair and strengthening interventions have shown their effectiveness to close the existing cracks, preventing damage to the belfry, and improving the seismic performance of the tower. Both the compatibility, durability, and reversibility of the interventions and their reliability and monitoring are finally highlighted since the bell tower of Torre Orsaia is a historical heritage building.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The behavior of a submerged floating tunnel (SFT) exposed to a water current of variable velocity is investigated through complex numerical analyses based on the Computational Fluid Dynamics (CFD) ...and the Finite Element Method (FEM) implemented in the ABAQUS code. An accurate modelling of turbulent phenomena is made, based on both Implicit Large Eddy Simulation and the RANS-based Spalart-Allmaras model, followed by a co-simulation procedure in which the fluid dynamics and the structural analysis are carried out separately and interfaced with each other. Circular and elliptical cross sections are considered, each of them fitted for combined railway and motorway services. The analysis is carried out in both static and dynamic way, by varying the current velocity with a given value of the residual buoyancy of the tunnel. The results emphasize the effect of the main parameters investigated, evidencing the great potentials of the adopted calculation tool for carrying out further investigations aimed at achieving useful elements for the design and optimization of the SFT.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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