Seismic Evaluation of a Large Network of Bridges by Simplified Automated Procedures and Consequent System Identifications by Dynamic Tests

This work presents the seismic evaluation of a large network of infrastructures located in the Veneto Region in the North-East of Italy. A large bridge database was subject to investigation, and simplified automated seismic valuation methods were developed in order to estimate the behavior of different types of structures located in seismic zones. In particular, analyses of infrastructures insistent in seismic zones, including surveys, investigations, seismic evaluation and seismic hazard assessment of the infrastructure in reference to parametric study of the structural vulnerability have been carried out. After estimating the safety factor of each structure based on the most vulnerable structural element, the key infrastructures on which execute system identification and simulate the response through numerical models were distinguished. In fact, the second step of this study is the structural identification of highly damaged bridges where a straightforward procedure has been applied. Static and modal parameters have been estimated for masonry arch bridges, concrete arch and continuous bridges, reticular and box girder steel bridges. The structural identification was used not only for calibration purposes but also for short and long term structural health monitoring (SHM) and damage detection. The SHM systems revealed good efficiency by maintaining the analyzed bridges open to traffic and constantly controlled

Seismic vulnerability assessment of clustered historical centers: fragility curves based on local collapse mechanisms analyses

open5noProtection and preservation of minor historical centres against earthquakes effects are not trivial tasks, particularly in the cases, quite common, of complex aggregate buildings. The paper aims at evaluating the seismic vulnerability of historical clustered buildings on a urban scale, through the analysis of local collapse mechanisms, carried out with a parametric approach. This procedure is applied to four historical centres of L’Aquila province struck by the 2009 earthquake. The identification of the significant parameters is related to the definition of representative typologies within the city centres. Each typology is characterized by recurring features, mainly recognizable with a survey performed outside the buildings. After the identification of the relevant aspects, local mechanisms of collapse analyses are carried out, by varying the parameters between defined range of values, in order to take into account possible uncertainties in the data collection. A set of fragility curves for each identified typology is defined and the obtained results are compared to the damage data gathered in the post-earthquake phase for the buildings. This approach allows for possible extensions to buildings that may be included in the typology categories here defined.openTaffarel, S.; Caliman, M.; Valluzzi, M.R; da Porto, F.; Modena, C.Taffarel, Sabrina; Caliman, M.; Valluzzi, MARIA ROSA; DA PORTO, Francesca; Modena, Claudi

Seismic vulnerability assessment on a territorial scale based on a Bayesian approach

Italian historical centres are mostly characterized by aggregate buildings. As defined by the Italian codes (Norme Tecniche per le Costruzioni 2008 and Circolare n. 617), the analysis of the most representative local mechanisms of collapse must be performed in order to assess their vulnerability. In this article, the out-of-plane local mechanisms of collapse analysis is implemented by applying a new method of analysis based on a probabilistic approach. Usually information which are necessary for the implementation of the local mechanisms analyses are affected by uncertainty or are missing, therefore in lots of cases it is only possible to hypothesize them on the basis of the other buildings information collected during the on-site survey. In this context, the implementation of a Bayesian approach allows to deduce buildings lacking information (i.e. wall thickness and interstorey height) starting from certain collected data (i.e. facades height). The historical centre of Timisoara (Romania) is selected as the case study for the implementation of this new method of analysis, given the extension of the on-site survey already carried out in the area (information about more than 200 structural units have been collected) and the seismic vulnerability assessment on an urban scale already performed by applying a traditional method. Results obtained by adopting the two approaches are then compared and a validation and a calibration of the new one is carried out

Fatigue Damage Estimation in Existing Railway Steel Bridges by Detailed Loading History Analysis

Fatigue life estimation of metal historical bridges is a key issue for managing cost-effective decisions regarding rehabilitation or replacement of existing infrastructure. Because of increasing service loads and speeds, this type of assessment method is becoming relevant. Hence there is a need to estimate how long these structures could remain in service. In this paper a method to estimate fatigue damage in existing steel railway bridges by detailed loading history analysis is presented. The procedure is based on the assumption that failure probability is a function of the number of predicted future trains and the probability of failure is related to the probability of reaching the critical crack length

The application of a Bayesian approach to assess the seismic vulnerability of historical centers

The seismic vulnerability of historical centers at a territorial scale cannot be assessed performing detailed analysis which are usually adopted at the single building scale. In fact, a traditional complete survey would be extremely time-consuming and not sustainable for this purpose. The approach described in this paper is based on the idea that it is possible to infer quantities which cannot be directly detected from buildings outside inspection starting from parameters that can be measured. In order to achieve this purpose, a Bayesian approach is applied, updating initial hypotheses when new data become available. In this context, the procedure herein proposed aims at applying a probabilistic approach instead of a deterministic one to define facades inter-storey height starting from buildings height knowledge. In order to validate the method, for out of plane local mechanisms of collapse (walls overturning), horizontal loads multiplier \uf0610 values are calculated and compared to results obtained by using data collected on-site

Selected Papers from the 10th International Conference on Structural Analysis of Historical Constructions (SAHC 2016)

info:eu-repo/semantics/publishedVersio

Efficiency of alternative intensity measures for the seismic assessment of monolithic free-standing columns

open4siThis paper deals with the dynamic response of a free-standing ancient column in the Roman Agora of Thessaloniki, Greece as a means to shed more light on the complex behaviour of rocking bodies under seismic excitation. Numerical analyses utilizing discrete element method were carried out with the use of multiple seismic records selected based on the disaggregation of the seismic hazard for the region of interest. To identify their impact on structural performance, earthquake Intensity Measures, such as Peak Ground Acceleration and Peak Ground Velocity are examined for the case of a column that sustained no visible permanent deformations during the Ms = 6.5 Thessaloniki earthquake of 1978. The analysis revealed a weak correlation of PGA and PGV with the response results and a significant influence of the mean frequency (fm) of the seismic motion. No coupling was found between the maximum displacement of the top during the oscillation and the permanent post-seismic deformations. The complementarity of both earthquake Intensity Measures in the structural vulnerability assessment is also depicted.openPappas, Athanasios; Sextos, Anastasios; da Porto, Francesca; Modena, ClaudioPappas, Athanasios; Sextos, Anastasios; DA PORTO, Francesca; Modena, Claudi

Evaluation of primary stability of single implants placed in fresh extraction sockets: a clinical trial

ABSTRACTDental implants have been used for the last 20 years. With the latest modern developments, however, minimally invasive protocols and immediate implants are currently used. The aim of this study was to evaluate the primary stability of a new implant design. Thirty immediate implants were placed and they all achieved successful osseointegration. Primary stability was reached with all the implants after the first apical threads. Within the limitations of the present study, the immediate implant approach seems to be a predictable treatment option, especially in conjunction with a specifically designed implant system