http://hdl.handle.net/10362/1746 DEC_CL 2013-05-18T13:23:45Z http://hdl.handle.net/10362/7046 Title: Robustness of corroded reinforced concrete structures Authors: Cavaco, Eduardo S. Abstract: The deterioration of existing structures has been a growing concern in the last decade. Signi cant attention has been paid to the deterioration of bridges, since signi cant costs in repair and replacement are expected in the next decades. At the same time structural robustness seems to be an emergent concept related to the structural response to damage. At the present time, robustness is not well de ned and much controversy still remains around this subject. This report intends to be a contribution to the de nition of structural robustness especially in the analysis of reinforced concrete structures subjected to corrosion. To achieve this, rst of all, several proposed robustness de nitions and indicators and misunderstood concepts will be analyzed and compared. From this point and regarding a concept that could be applied to most type of structures and damage scenarios, a robustness de nition is proposed. To illustrate the proposed concept, some example of corroded reinforced concrete structures will be analyzed using nonlinear analysis numerical methods based on a continuum strong discontinuities approach and isotropic damage models for concrete. Finally the robustness of the presented examples will be assessed and compared. Description: Short Term Scienti c Mission, COST ACTION TU-0601 2009-01-01T00:00:00Z http://hdl.handle.net/10362/6211 Title: Probabilistic maintenance and optimization strategies for deteriorating civil infrastructures Authors: Frangopol, D. M.; Neves, L. C. Abstract: In developed countries, civil infrastructures are one of the most significant investments of governments, corporations, and individuals. Among these, transportation infrastructures, including highways, bridges, airports, and ports, are of huge importance, both economical and social. Most developed countries have built a fairly complete network of highways to fit their needs. As a result, the required investment in building new highways has diminished during the last decade, and should be further reduced in the following years. On the other hand, significant structural deteriorations have been detected in transportation networks, and a huge investment is necessary to keep these infrastructures safe and serviceable. Due to the significant importance of bridges in the serviceability of highway networks, maintenance of these structures plays a major role. In this paper, recent progress in probabilistic maintenance and optimization strategies for deteriorating civil infrastructures with emphasis on bridges is summarized. A novel model including interaction between structural safety analysis,through the safety index, and visual inspections and non destructive tests, through the condition index, is presented. Single objective optimization techniques leading to maintenance strategies associated with minimum expected cumulative cost and acceptable levels of condition and safety are presented. Furthermore, multi-objective optimization is used to simultaneously consider several performance indicators such as safety, condition, and cumulative cost. Realistic examples of the application of some of these techniques and strategies are also presented. 2004-09-01T00:00:00Z http://hdl.handle.net/10362/5047 Title: The thickness of the transport layer in stratified geomorphic flows Authors: Leal, J. B.; Ferreira, Rui M. L.; Cardoso, António H. Abstract: This paper is aimed at the development of a model for the thickness of the transport layer in stratified geomorphic flows such as sheet-flows or immature debris flows occurring, for instance, as a consequence of dam failure. These are flows with high geomorphic potential, occurring at or generating high shear stresses, whose ultimate driving mechanism is gravity. The micromechanical characteristics of the sediment and viscous flow-grain interactions are of paramount importance in the definition of the constitutive equations that relate stresses and shear rates within the flow. The model was derived from the granular flow theory based on Chapman-Enskog’s dense gas kinetic theory. A 2DV conceptual model was employed to render the flow structure in a flow in the absence of longitudinal pressure gradients. The 2DV model was further simplified to obtain an implicit formula for the thickness of the transport layer. The role of the flux of fluctuating particle energy and of the granular temperature is clarified. Results of the simplified formula are discussed and compared with the result of the complete model. Solutions of hyperbolic instantaneous dam-break problems over mobile beds, incorporating the present model of the transport layer thickness, are presented. Description: River Flow 2010 2010-01-01T00:00:00Z http://hdl.handle.net/10362/5043 Title: Experimental dam-break waves profile analysis: horizontal mobile bed Authors: Leal, J. B.; Ferreira, R. M. L.; Cardoso, A. H. Description: River Flow, Vol. 2 2008-01-01T00:00:00Z