1,721,172 research outputs found
Chairman della "S14 Seismic Design Optimization" in sostituzione del Prof. T. Trombetti alla 14th World Conference on Earthquake Engineering, October 12-17, 2008, Beijing, China
No full textChairman della "S14 Seismic Design Optimization" (Oct.14 Tuesday, 13:30-15:20) in sostituzione del Prof. T. Trombetti alla 14th World Conference on Earthquake Engineering, October 12-17, 2008, Beijing, China
Session S14 Seismic Design Optimization
Co-Chairmen: Silvestri S., Gasparini G.
in substitution of
Salajegheh, E.; Trombetti, T.
Meeting Room No.111
S14-038 Stiffness-Strength-Ductility-Design for C
Braces
rescent Shaped Trombetti, Tomaso Trombetti, Tomaso; Silvestri, Stefano;
Gasparini, Giada
S14-012 Passive Control System of a Steel Truss
Bridge
Girder Cable-Stayed Wang, Kehai Wang, Ke
S14-018 Cost Modeling of Foundations of Reinfo
Buildings Designed for Seismic Effects
rced Concrete Thiruvengadam,
Vellaichamy
Thiruvengadam, Vellaichamy; Wason, J.C.;
Praseeda, K.I.
S14-021 Cost-Effectiveness of Tuned Mass Damper and Base Isolation Hong, Han Ping Lee, C.S.; Goda, Katsuichiro; Hong, Han
Ping
S14-040 Risk-Based Multi-Hazard Optimization o
Structures Using Evolutiounary Algorith
f Passsively Damped
ms
Dogruel, Seda Dogruel, Seda; Dargush, Gary F.
S14-050 Risk Based Minimum Life-Cycle Cost D
Structures
esign of Aseismic Lu, Dagang Lu, Dagang; Wang, Guangyuan
S14-053 Sensitivity Analysis of SDOF Structure P
Damage Ratio Coefficient
arameters on Hadzima-Nyarko,
Marijana
Hadzima-Nyarko, Marijana; Nyarko,
Emmanuel; Moric, Draga
An approach for the mechanical characterisation of the Asinelli Tower (Bologna) in presence of insufficient experimental data
No full textThe Asinelli Tower, built at the end of the 12th century, is one of the main symbol of the town of Bolognaand a valuable historical heritage of the Medieval age of the entire Italy. For its structural configuration,the tower appears prone to seismic damages and, therefore, an assessment of its dynamic properties is ofprimary importance to predict its seismic response. In the present paper, based on the results of limitedmaterial tests, the mechanical and dynamic properties of the tower are analysed through the developmentof models of increasing complexity. First, models for the evaluation of the main materials mechanicalproperties are compared to validate the experimental results. Then, different structural models of thetower (from simple continuum analytical models to more complex finite element models) are developed.The analytical and numerical results obtained from the different models are finally compared to somerecent experimental measurements of the free vibration response of the tower conducted by the ItalianNational Institute of Geophysics and Volcanology (the INGV). The preliminary results indicate that theexperimental frequencies are in good agreement with the values obtained from the models. However,additional studies are necessary to better understand the torsional response of the tower
ANALYSIS AND INTERPRETATION OF THE STRUCTURAL BEHAVIOR OF THE ROSE WINDOW OF THE CATHEDRAL OF MODENA (ITALY)
Full text linkThe rose window is a peculiar character of the main facade of Romanesque cathedrals. A beautiful example of rose window can be found in the Cathedral of Modena, Italy. The faced of the Cathedral, built at the end of the XI century, and declared as UNESCO heritage sites in the 1997, was originally built without the great rose window which was added during the XIII cen-tury, together with some lateral doors, to increase the brightness inside the building. It is made of various stones typologies which are arranged in order to suggest the shape of a rose. Due to the quite slender shapes of the stones forming the spokes, the rose could be subjected to high stress and susceptible to instability.
In this paper a preliminary assessment of the structural safety of the rose window is carried out. The structural behavior is studied considering both the in-plane and out-of plane actions. The in-plane analyses are developed through limit schematizations. The out-of-plane analyses are carried out through finite element models which are compared with simple hand calculations. The analyses results indicate that the rose window is in a safety state
Seismic Modal Contribution Factors
No full textOver the years, the belief that the first mode of vibration governs the seismic
response of shear-type frame structures has been widely accepted and proved to be effective
for preliminary structural design. Indeed, most of the actual seismic design procedures are
based on drift profiles which are typically an approximation of the shape of the fundamental
mode of vibration. In this paper, an analytical study on the dynamic properties of multi-storey
shear-type frames is carried out with the purpose of precisely identifying the contribution of
the modes of vibration to the seismic response of such structures, both in terms of maximum
inter-storey displacement profiles (which govern the beams and columns maximum actions)
and maximum inter-storey velocity profiles (which govern the viscous dampers maximum
forces, of fundamental importance for building structures equipped with additional viscous
dampers). A new parameter, referred to as Seismic Modal Contribution Factor, which represents
the contribution of the generic mode to the seismic response of the structure, is
introduced. With respect to the well-known Modal Contribution Factor, grounded on the
concept of modal static response, the Seismic Modal Contribution Factor explicitly takes into
account also the dynamic nature of the response due to earthquake excitation. The Seismic
Modal Contribution Factor could be a meaningful parameter to be implemented in a professional
structural design software and used in conjunction with the common modal participating
mass ratios to identify the number of modes to be included in the analyses
A “direct five-step procedure” for the preliminary seismic design of buildings with added viscous dampers
Full text linkIn the present work a direct procedure for the preliminary seismic design of building structures with added dampers is described which represents the simplification of the so-called “five-step procedure” originally developed in 2010 by some of the authors. The procedure is applicable to yielding frame structures with a generic along-the-height distribution of inter-storey viscous dampers. It is aimed at guiding the structural engineer through the sizing of both viscous dampers and structural elements making use of an equivalent static analysis approach. First, the peak structural response under earthquake excitation is reduced by imposing an overall reduction factor accounting for both the ductility demand and the viscous damping provided by the added dampers. Second, linear damping coefficients are calculated in order to reduce the structural response according to the selected target damping ratio. Then, analytical formulas allow the estimation of peak velocities and forces in the dissipative devices, and an energy criterion is used to identify the non-linear mechanical characteristics of the actual manufactured viscous dampers. Finally, the internal actions in the structural elements are estimated through the envelope of two equivalent static analyses (ESA). At this initial stage of the research, the procedure appears suitable for the preliminary design phase, while correction factors for the higher modes contributions need to be applied to improve its accuracy, especially for high-rise buildings. A numerical verification of the final behaviour of the system by means of non-linear time-history analyses is recommended. An applicative example is finally developed to highlight the soundness of the procedure
A Simplified Approach to the Analysis of Torsional Effects in Eccentric Systems: the Alpha Method
No full textEccentric structures, characterized by non coincident center of mass and center of stiffness, when subjected to dynamic excitation, develop a coupled lateral-torsional response that may increase the local peak dynamic response of such a structure: this behaviour becomes particularly important for seismic isolated structures for which large displacements are developed in the isolators. The coupled lateral-torsional response can be estimated only through a three-dimensional analysis which is specifically carried out for a single structure subjected to a determined dynamic input. In this paper the authors present the analytical formulation of a simplified method which allows to understand, predict and govern the global trend of one-storey eccentric structures to develop a torsional response to dynamic inputs through the identification of a system key parameter named “alpha”. This parameter can be easily used to effectively estimate the maximum rotational response of a given eccentric system under a dynamic excitation through a simple linear elastic analysis of the “equivalent” non-eccentric system. Moreover, the results of the analysis in the non-linear field show that the linear elastic value of “alpha” acts as an upper bound for the corresponding value of elastic-perfectly plastic systems. In summary, this paper proposes a physically-based general theory which frames the problem of torsional phenomena of one-storey eccentric systems subjected to dynamic inputs and immediately allows the quantification of the system torsional response and the identification of the structural parameters governing it
SSHM and DSHM for a better knowledge and risk prevention of historical buildings: The cases of the Two Towers in Bologna and the Cathedral in Modena
No full textIn the last recent years, structural monitoring has acquired an increasing importance in the diagnosis and control of buildings, especially for historical buildings whose preservation is essential to the safeguard of cultural heritage. The aim of this study is to introduce a standardized approach for the interpretation of the large amount of data acquired from a monitoring system of historic buildings. This approach is based on the definition of specific reference quantities (extrapolated from the recorded time series) able to characterize the main features of the structural response and the preliminary identification of the order of magnitudes of these quantities. These reference quantities may be collected in a database and may become fundamental for comparing the response of similar buildings. This type of analysis has been applied to the data obtained from the Static Structural Health Monitoring (SSHM) system of two significant Italian monuments: the Cathedral of Modena and the Two Towers of Bologna (Asinelli and the Garisenda Towers), North Italy. This paper provides, also, the preliminary results of the experimental data as obtained from the Dynamic Structural Health Monitoring (DSHM) of the Asinelli Tower conducted by the Italian National Institute of Geophysics and Volcanology (INGV)
A comprehensive study on the seismic response of one-storey asymmetric systems
No full textThe non-linear seismic response of in-plan asymmetric systems has been extensively studied since the 1980s. Nevertheless, most of the research effort has been devoted to the study of specific asymmetric buildings and, even though relevant progresses have been achieved in the understanding of the complex translational-to-torsional coupled response of such systems, a complete understanding of the seismic behaviour of in-plan asymmetric buildings is still missing. In this paper a systematic study of the seismic response of linear and non-linear one-storey asymmetric structures is presented. A mixed analytical–numerical approach, the so-called “alpha” method, is used to investigate the non-linear seismic response of a wide range of in-plan asymmetric structures with the aim of providing general trends of behavior
EFFECT OF THE GRAIN SLIDING ON THE SEISMIC BEHAVIOR OF CIRCULAR SILOS: A THEORETICAL FORMULATION
Full text linkEarthquakes frequently cause damage or collapse in silos, provoking significant financial loss and even loss of life. The effect of lateral seismic loads can damage the upper portion of the silo if the material contained can oscillate inside the silo during the ground motion. The contribution of the grain sliding in terms of wall stresses is not
explicitly accounted neither in current design codes nor in scientific literature. In the present paper, the effect of the horizontal sliding of the grain layers is accounted in
terms of additional overpressures, wall shear and bending moment during dynamic excitation and compared with theoretical formulations, code provisions and
experimental evidence. Shaking table tests suggest that the grain sliding may be relevant in the evaluation of the wall base bending moment and that ACI 313-97 and
Eurocode 8 provisions appear overly conservative. Finally, a design recommendation is drawn for reducing the effect of the seismic actions on the silo wall
Application of the Equivalent Static Analysis procedure for the seismic design of buildings with added viscous dampers
No full textMost of the actual seismic design procedures for structures equipped with viscous dampers requires the development of non-linear time-history analyses, which, even though of quite common use among the researchers, still represent a challenge for professional engineers. The paper describes a simple Equivalent Static Analysis procedure for the seismic design of building structures equipped with added viscous damper. The procedure, which is based on the fundamentals of the dynamics of multi-storey frame structures with added viscous dampers, is aimed at estimating the maximum forces in the viscous dampers as well as the peak internal actions in the structural members. The simplified procedure is applied for the design of a 3-storey reference steel frame analysed by other researchers
- …
