Coauthored Publications with: Lúcio

Journal Article

Bras, A, Gião R, Lúcio V, Chastre C.  2013.  Development of an injectable grout for concrete repair and strengthening. Cement and Concrete Composites. AbstractWebsite

This paper deals with the coupled effect of temperature and silica fume addition on rheological, mechanical behaviour and porosity of grouts based on CEMI 42.5R, proportioned with a polycarboxylate-based high range water reducer. Preliminary tests were conducted to focus on the grout best able to fill a fibrous network since the goal of this study was to develop an optimized grout able to be injected in a mat of steel fibers for concrete strengthening. The grout composition was developed based on criteria for fresh state and hardened state properties. For a CEMI 42.5R based grout different high range water reducer dosages (0, 0.2%, 0.4%, 0.5%, 0.7%) and silica fume (SF) dosages (0, 2%, 4%) were tested (as replacement of cement by mass). Rheological measurements were used to investigate the effect of polycarboxylates (PCE) and SF dosage on grout properties, particularly its workability loss, as the mix was to be injected in a matrix of steel fibers for concrete jacketing. The workability behaviour was characterized by the rheological parameters yield stress and plastic viscosity (for different grout temperatures and resting times), as well as the procedures of mini slump cone and funnel flow time. Then, further development focused only on the best grout compositions. The cement substitution by 2% of SF exhibited the best overall behaviour and was considered as the most promising compared to the others compositions tested. Concerning the fresh state analysis, a significant workability loss was detected if grout temperature increased above 35°C. Below this temperature the grout presented a self-levelling behaviour and a life time equal to 45 minutes. In the hardened state, silica fumes increased not only the grout’s porosity but also the grout’s compressive strength at later ages, since the pozzolanic contribution to the compressive strength does not occur until 28 days and beyond.
Gião, R, Lúcio V, Chastre C.  2019.  Gravity load effects on the behaviour of reinforced concrete beam critical zones subjected to cyclic loads, 2019/02/15/. Engineering Structures. 181:503-518. AbstractWebsite

The aim of the present study was to proceed to a numerical analysis of the gravity load effects on the behaviour of reinforced concrete beam critical zones when subjected to cyclic loads. A parametric study to assess the influence of different levels of gravity load on RC beam critical zones subjected to cyclic loading was carried out. For this purpose, assuming the level of gravity load as a variable parameter, a nonlinear numerical model of a beam-column connection, previously calibrated with experimental data, was used. In order to evaluate the gravity load effects in the global response, a numerical study of a RC frame system is also presented. The numerical results are analysed in terms of global hysteretic response, accumulated energy dissipation and equivalent viscous damping ratio. In this numerical study, it was observed that the hysteretic response depends on the load path. In the presence of higher gravity load levels, the structure hysteretic behaviour exhibits higher damage levels, associated to a failure mechanism corresponding to the formation of four span plastic hinges. Thus, the proper test procedure should involve the imposition of a reverse cyclic displacement history starting each cycle from the gravity load effects.

Magazine Article

Chastre, C, Lúcio V.  2014.  Evolução histórica, desenvolvimento atual e potencial futuro das torres de concreto pré-moldado para suporte de aerogeradores. Revista Concreto IBRACON, 75. :p.90-100.revista_concreto_ibracon_75_-_pg.90-100_-_fina.pdf
Lúcio, V, Chastre C.  2014.  Precast concrete wind tower structures. Historic development, current development and future potential, June 2014. CPI - Concrete Plant International, 3. :110-115., Number 3 Abstractcpi_03-2014_p144-149.pdfWebsite

The wind energy production is a growing industry and the energy produced is renewable and environmentally cleaner than most of the energy production systems. The supports of the wind energy generators may be built with precast concrete elements. The precast solutions for these structures are competitive in comparison to other structural systems. The evolution of the technology for wind energy production shows a clear need for larger wind turbines and longer blades and, consequently, taller towers. The experience also shows that precast concrete solutions increase their competitiveness as the tower height increases. Offshore wind farms have some advantages in relation to onshore ones, which explains recent investments in this area. Also in this case, the durability of concrete in the sea when compared to steel, gives advantages to precast concrete in relation to other structural solutions. This paper shows the evolution of the supports of the wind energy generators and the advantages of the use of precast concrete towers.

Thesis

Chastre Rodrigues, C.  1993.  Comportamento da Ligação Aço-Resina-Betão em Elementos Estruturais, 1993. Departamento de Engenharia Civil, Instituto Superior Técnico. MSc, Lisboa: Universidade Técnica de Lisboa Abstract1993_-_msc-_ist_-_carlos_chastre_-_comportamento_da_ligacao_aco-resina-betao_em_elementos_estruturais.pdf

The present work studies the behaviour of bonded steel plates to reinforced concrete elements, which can be used in the strengthening of concrete structural elements. Metallic expansion bolts can be added.The objective of this dissertation is to investigate the behaviour to monotonic actions and particularly to cyclic loading of steel-epoxy-concrete connection with expansion bolts. This cyclic action is of particular interest due to the strong seismicity of the Portuguese territory.The research is mainly based in experimental analysis. The caracterization of the materials was carried out. Six models of the steel-epoxy connection were tested with monotonic loading. Twenty six models of steel-epoxy-concrete bond were submitted either to monotonic or to cyclic actions.Besides the type of action, other parameters were studied in the steel-epoxy-concrete connection models.These were the bond geometry area, the type of concrete, the type of epoxy and connection - with or without metallic expansion bolts.A parametric study with a numerical model of finite elements, as well as a global analysis of the experimental tests of the steel-epoxy-concrete connection was carried out.