The proposed formulation is validated by means of benchmarks. The corrosion rate of steel depends on the concentration of the aggressive agent Bertolini et al. The results of this study showed that the importance of the uncertainty effects associated with the design parameters may significantly vary over time, with different trends depending on the performance indicators. Although member-level performance and reliability assessment procedures are currently well-established, it is widely recognized that a member-oriented approach does not necessarily lead to an efficient utilization of limited resources when making decisions related to the management of existing deteriorating structures or lifeline systems, especially those that may be exposed to extreme events. The recent relevant advances accomplished in the fields of modeling, analysis, design, maintenance and rehabilitation of deteriorating civil structure and infrastructure systems are hence perceived to be at the heart of a modern approach to structural engineering. Over 30 invited participants from several countries attended the Workshop Figure 2. This paper presents a general approach to the probabilistic prediction of the lifetime of reinforced concrete frames with respect to structural collapse.
The goal of the workshop will be to outline methods to advance the implementation of risk-based methods during the design of civil structures and infrastructures. In this way, both the time-variant probability of failure, as well as the expected structural lifetime associated with a prescribed reliability level, are evaluated. . The proposed approach is applied to reinforced concrete bridges exposed to corrosion considering different types of highway networks with detours and re-entry links. A probabilistic approach to the lifetime seismic assessment of deteriorating concrete structures is presented.
In this study the lifetime seismic performance of concrete structures is investigated in both probabilistic and deterministic terms. This is achieved by means of time-variant structural performance indicators, such as robustness and redundancy Frangopol and Curley 1987, Biondini and Restelli 2008, Biondini 2009, Ghosn et al. For this reason, it is of great interest to develop suitable measures of lifetime structural robustness. In this paper the effect of the epistemic uncertainty associated with deterioration modeling on the bridge service life prediction by using a credibility indicator. The assessment of the lifetime seismic bridge performance is therefore obtained by means of probabilistic time-variant nonlinear static analyses of the structural system. All materials contained in this website fall under U. Wind tunnel test of aeroelastic model is the principal means to research the performance of bridge structures in wind flow.
A parametric study aimed to validate the design method is carried out by varying, within the range of practical interest, the main design parameters such as the number of storeys, the mass-over-stiffness ratios and the stiffness characteristics of the columns. The factory, built near the sea shore, is not in use since many years and its build-ings, mostly made by reinforced concrete structures, are severely damaged by deterioration processes mainly related to chloride-induced corrosion of the steel reinforcement Serafini 2011. Seismic design criteria should therefore account for the environmental hazard, especially if bridges are considered, because of the direct exposure of the structure to the atmosphere. The results show a significant reduction of both base shear strength and displacement ductility over the structural lifetime and highlight the importance of a lifetime approach to seismic assessment and design of concrete structures. The seismic performance of concrete structures should be considered time-variant, since in aggressive environments the corrosion phenomena affect the characteristics of both reinforcing steel bars and concrete matrix during lifetime. The proposed approach is applied to a four-span continuous bridge with box cross-section piers exposed to corrosion.
Cyclic experimental tests on both single dissipative connectors and structural sub assemblies consisting of two full scale panels have been performed at the Laboratorio Prove Materiali of Politecnico di Milano to investigate the hysteretic behavior of the devices considering different technological features, restraint conditions, and loading protocols. Martinez y Cabrera 1997-2002 , and Prof. A probabilistic approach to seismic assessment of aging bridge structures and resilience analysis of highway networks is presented. Damage modelling considers uniform and pitting corrosion and includes the reduction of cross-sectional area of corroded bars, the reduction of ductility of reinforcing steel and the deterioration of concrete strength due to splitting cracks, delamination and spalling of the concrete cover. A probabilistic approach to lifetime assessment of seismic resilience of deteriorating concrete structures is presented. In this paper, failure loads and failure times of concrete structures exposed to corrosion are investigated and life-cycle performance indicators, related to redundancy and elapsed times between sequential failures, are proposed. Despite these advances, life-cycle concepts are far from being explicitly addressed in design and assessment codes and effectively implemented into practice.
Truss systems are then analyzed to investigate their robustness. Case study The shear-type reinforced concrete frame shown in Figure 1 is considered Biondini and Frangopol 2013, 2014a. It has been shown that structural configurations of precast buildings involving an interaction between the outer frames and the cladding panels, owing to the panel-to-structure fastening systems, may draw high forces into the diaphragm or lead to strong distortions of the roof deck. An overall measure of lifetime structural quality, able to also take the time-variant structural performance into account, is then obtained through a weighted integration of the quality indices over the expected service life of the structure. The stiffness of the diaphragm usually depends on the mechanical connections of the roof deck only. In particular, the purpose of Task Group 1 is to promote the study, research, and application of scientific principles of safety and reliability in the assessment, prediction, and optimal management of life-cycle performance of structural systems under uncertainty. The different sets have however different structural stiffness, which depends on the adopted prestress levels.
Tali dispositivi sono stati sviluppati sulla base di studi teorici corredati da verifica sperimentale. The results prove that the credibility index is able to recognize, in qualitative and quantitative terms, the most reliable modeling. The objectives were to overview the advances accomplished in the field of life-cycle civil engineering, to promote a better understanding of life-cycle concepts in the structural engineering community, and to discuss methodologies and tools to incorporate life-cycle concepts into structural design codes and standards. Design solutions involving a controlled cladding—structure interaction have been proposed to address this problem. However, this paper will focus on the effects of corrosion in terms of mass loss of the steel bars. For practical purposes, the only form finding phase is therefore not sufficient, but the introduction of additional design criteria, such as structural performance in terms of rigidity and deformability, are needed.
The seismic capacity is assumed as time-variant functionality indicator and the seismic resilience is evaluated based on a suitable analytical representation of the functionality recovery profile. The variation of these performance indicators with respect to the values associated with the undamaged system is used to formulate dimensionless measures of structural robustness. The robustness criterion is formulated by taking the importance of the structure into account. The effects of the damage process are evaluated by using a proper methodology for lifetime assessment of concrete structures exposed to diffusive attacks from environmental aggressive agents. Therefore, the design of these connections cannot rely on the seismic reduction factor used for design of the bare structure.