Survey on major worldwide regulations on seismic base isolation of buildings

Base isolation solutions are efficient alternatives for seismic protection of buildings and for enhancing resilient capacity. Currently, seismic isolation is focused principally on the critical infrastructure of public health, transportation, education, etc. Despite these considerations, the current worldwide implementation of this technology is still insufficient. A crucial step to be taken into the promotion of any earthquake-resistant construction technique is the development of design codes that, although being inspired in the major international regulations, account for the local seismic effects, among other factors. With the aim of assisting code developers, this work analyzes and compares the code requirements for seismic base isolation in Japan, China, Russia, Italy, USA, and Chile. Two prototype seismically isolated hospital buildings located in high and medium seismicity zones (Los Angeles and New Mexico, respectively) were analyzed and designed with the examined codes. It is concluded that there are high differences among some of their requirements even though the technology used is the same.Peer ReviewedPostprint (published version

Novel trends on the assessment and management of maritime infrastructures: Outcomes from GIIP project

Climatic conditions, load, fatigue, aging and other factors causes a deterioration in civil infrastructures. As a consequence, repair and maintenance work actions are needed, being the former considered as more expensive than the latter ones. Indeed, an accurate method for measuring corrosion is a fundamental prerequisite for the detection of damaged areas and for planning an effective repairing of concrete maritime structures. In this article a comparation between two surrogate models, Markov Chains and Neuronal Networks, is presented and applied to predict the results of corrosion sensors of an infrastructure data set. The proposed methodology benefits from current monitoring practice and have the objective to develop a modular decision support system for the integrated asset management, taking into account operational, economic and environmental criteria. The results could contribute to the possibility of adapting these degradation models to aggressive environments and repaired structures, thus generating accurate maintenance strategies, and reducing costs. This methodology is part of the ongoing study “GIIP- Intelligent Port Infrastructure Management”

Degradation models for application in bridge management systems

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2017.São apresentados os resultados de uma pesquisa que teve como objetivo propor um modelo de previsão da degradação, baseada numa análise determinística e estocástica, para contribuir no acompanhamento das Obras de Arte Especiais – OAEs do Brasil, sob responsabilidade do Departamento Nacional de Infraestrutura de Transporte – DNIT, e para banco de dados similares. No banco de dados do DNIT consta o inventário de quatro mil quinhentos e trinta e uma OAEs, com uma vistoria realizada entre 2012 a 2016 para todas as obras do inventario. Devido ao número insuficiente de registros históricos para o desenvolvimento de um modelo de previsão da degradação das OAEs, foram testados os modelos de degradação utilizando-se o banco de dados do Departamento de Transporte de Nevada (NDOT), obtido durante um ano de estágio desenvolvido na Universidade de Nevada, Las Vegas (USA). Foi realizado um estudo comparativo dos modelos de degradação, e após a calibragem dos modelos de previsão com o banco de dados de NDOT, foi determinado o modelo de degradação mais apropriado para as OAEs sob responsabilidade do DNIT e banco de dados similares, visando proporcionar apoio na tomada de decisões e garantir um desempenho eficiente das estruturas. Foi determinado que a Regressão de Potência é o método de cálculo mais apropriado para a estimação das curvas de degradação das OAEs no Brasil, sob responsabilidade do DNIT. Podendo-se utilizar esta regressão de maneira individual para cada uma das OAEs, uma vez sejam realizadas mais inspeções nas estruturas.The objective of this research was to propose a degradation prediction model, based on a deterministic and stochastic analysis, to contribute to the accompaniment of the Brazil Bridges, under the responsibility of the National Department of Transport Infrastructure - DNIT, and other similar databases. In the DNIT database there is an inventory of four thousand five hundred and thirty-one bridges, but only one inspection was carried out between 2012 and 2016. Due to the insufficient number of historical records for the development of a model for predicting the degradation of bridges, the models of degradation were tested using the database of the Department of Transportation of Nevada (NDOT), obtained during a year of internship developed at the University of Nevada, Las Vegas (USA). A comparative study of the degradation models was carried out, and after the calibration of the forecast models with the NDOT database, the most appropriate degradation model was determined for the bridges under the responsibility of DNIT and similar databases, aiming to provide support in decision-making and ensure efficient performance of structures. It was determined that the Power Regression is the most appropriate calculation method for the estimation of the degradation curves of OAEs in Brazil, under the responsibility of DNIT. This regression can be used individually for each of the OAEs, once more inspections are performed on the structures

Experimental and numerical study of stress acting the mortar of ceramic façade and fatigue due to thermal-mechanical action

O sistema de revestimento em fachadas vem alcançando grande escala de utilização no Brasil devido às vantagens no seu uso, como, proteger os elementos estruturais, isolamento térmico, segurança ao fogo, estanqueidade, regularização da superfície, entre outras vantagens. O clima, a localização e outros fatores atuantes na obra civil, fazem com que se apresentem manifestações patológicas no sistema de revestimento, devido principalmente ao choque térmico, já que a exposição à variação térmica cria gradientes internos de temperatura e estes gradientes por sua vez provocam tensões térmicas que podem causar trincas e possivelmente a falha do sistema de revestimento, sendo as tensões e deformações de origem termo-mecânica as consideradas nesta pesquisa, posto que elas geram o desplacamento do revestimento cerâmico. Como este sistema de revestimento cerâmico que é composto por diferentes materiais, faz-se necessário se manter um equilíbrio entre as tensões atuantes no sistema e tensões resistentes para ter-se uma integridade da fachada. Este trabalho procura avaliar o comportamento da argamassa colante quando sob fadiga, traçando para isso a curva experimental de Wöhler ou curva S-N. As tensões térmicas alternadas que agem no sistema podem provocar a ruptura por fadiga. Desta forma, os limites de resistência à fadiga tanto à compressão quanto à tração são importantes valores para serem conhecidos. Tais valores foram obtidos neste trabalho e valem, respectivamente, 5,06 MPa e 1,69 MPa. Conclui-se ainda que a argamassa colante, dentro do sistema de revestimento e nos transientes térmicos aqui estudados, não apresenta risco de ruptura por fadiga termo-mêcanica. ______________________________________________________________________________ ABSTRACTCeramic facade coating system is mostly use in Brazil. It protects the structural elements supporting the building, provides thermal insulation, fire protection, tightness, surface adjustment, among other advantages. However, the weather variation may be a source of some pathological manifestations in facade coating systems due to change in the weather temperature conditions. In tropical countries, rainstorms are very common and induce thermal shocks on ceramic facades. The exposure to thermal shocks creates in the facade internal temperature gradients and such gradients generate thermal stresses that can create cracks and progressively cause the failure of large pieces of the ceramic coating system. Such thermal stresses and strains may generate the peeling of the ceramic coating system and may bring danger to people on the sidewalk of the building. To keep the integrity of the ceramic facade, different materials composing the ceramic coating system must maintain the equilibrium between the stresses acting on the coating system and the materials strength. This study searches to evaluate the fatigue behavior of mortar. For this, the experimental Wöhler S-N curve is obtained. The alternating thermal stresses on the system may produce fatigue failure; therefore, the fatigue strength limits in compression and in tension are important parameters to be known. These values were obtained in this work and are, respectively, 5.06 MPa and 1.69 MPa. In conclusion, the mortar within the coating system and under the thermal transients studied here shows no fatigue failure risk

Stochastic degradation model analysis for prestressed concrete bridges

Bridges in the road infrastructure represent a critical and strategic asset, due to their functionality, is vital for the economic and social development of the countries. Currently, approximately 50% of construction industry expenditures in most developed countries are associated with repairs, maintenance, and rehabilitation of existing structures, and are expected to increase in the future. In this sense, it is necessary to monitor the behaviour of bridges and obtain indicators that represent the evolution of the state of service over time. Therefore, degradation models play a crucial role in determining asset performance that will define cost-effective and efficient planned maintenance solutions to ensure continuous and correct operation. Of these models, Markov chains stand out for being stochastic models that consider the uncertainty of complex phenomena and are the most used for structures in general due to their practicality, easy implementation, and compatibility. In this context, this research develops degradation models of a database of 414 prestressed concrete bridges continuously monitored from 2000 to 2016 in the state of Indiana, USA. Degradation models were developed from a rating system of the state of the deck, the superstructure, and the substructure. Finally, the database is identified and divided from cluster analysis, into classes that share similar deterioration trends to obtain a more accurate prediction that can facilitate the decision processes of bridge management systems.This project received funding to carry out this publication of the European Union's Portugal 2020 research and innovation program under the I&D project “GIIP - Intelligent Management of Port Infrastructures”, with POCI-01-0247-FEDER039890. The sole responsibility for the content of this publication lies with the authors. It does not necessarily reflect the opinion of the European Union

Bridge deterioration models for different superstructure types using Markov chains and two-step cluster analysis

Bridges deteriorate due to different causes such as ageing and climatic conditions. As a consequence, repair actions are considered more expensive than maintenance. Therefore, the prediction of maintenance at the bridge network level is particularly complex due to the considerable level of heterogeneity spanning various bridge types and functions. Consequently, in this article an analytical deterioration model called ‘two-step cluster analysis’ is presented and applied to predict the results of a homogeneous data set. This model had been used in different fields including civil engineering but not for superstructure deterioration forecasting. Variables that interfere with the performance of the structure were considered, such as geometry, volume of traffic, among others. The results show that deterioration drop rapidly if repair treatments were not performed. Variations of up to 20.9% at 50 years between the degradation of the database and the analysis of groups, demonstrates the importance of grouping within the analysis of the database, since the late maintenance can affect the life of the bridge. Preventive actions could significantly mitigate the deterioration process. The applied methodology benefits from current bridge inspection practice and produces a probabilistic rating that is consistent with the Markov approach for model deterioration and grouping variables.This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme – COMPETE and by national funds through the FCT Foundation for Science and Technology within the scope of the project POCI-01-0145- FEDER-007633

From quality control to decision-making on the management of bridges and structures: what's next?

The process of managing a stock of existing bridges and structures is extremely complex and challenging. At the same time, it is considered as one of the most relevant and important fields for civil engineers, involving academics, researchers, consultants, contractors, and owners. Indeed, in the recent years, several national and international R&D funded projects raised this topic, and many international associations, such as EuroStruct, IABSE& fib, started commissions and task groups on this field. This work consists on an overview of the most recent matters on this field, covering the whole cycle, from the quality control, addressing extreme events, to the decision making process. Also, it will be given a focus on the recent developments on the assessment and forecasting the performance of bridge and other structures. Finally, an overview will be made for different types of structures, specifically those related to transport infrastructures.The authors would like to acknowledge COST TU1406 Research Project: Quality specifications for roadway bridges, standardization at a European level (tu1406.eu), and now, to EuroStruct – European Association for the Quality Control of Bridges and Structures (eurostruct.org). Also, they would like to acknowledge the international R&D projects SAFEWAY - GIS-based infrastructure management system for optimized response to extreme events on terrestrial transport networks (safeway-project.eu), SIRMA – Strengthening Infrastructure Risk Management in the Atlantic Area (sirma-project.eu), and the national R&D projects InfraCrit (management system for critical infrastructures) and GIIP (management system for port infrastructures)