Effect of wet-dry cycles on the bond behaviour of concrete elements strengthened with NSM CFRP laminate strips

The near-surface mounted (NSM) strengthening technique is capable of effectively increase the bearing capacity of structural concrete elements. This technique which basically consists of placing FRP reinforcements inside small grooves cut in the concrete cover, has been widely investigated in terms of structural performance and ability to improve the flexural and shear behaviour of reinforced concrete beams and columns. However, little research has been carried out concerning to the NSM long-term performance and durability. Motivated by the need of increasing the knowledge on the expected durability of the NSM technique using CFRP laminates, this paper presents an experimental program in which direct pull-out tests are carried out for evaluating the bond behaviour of specimens aged through wet-dry cycles. A total of 30 specimens are tested, analysing the effect of the bond length, the groove width, the groove depth and the aging effect on the bond behaviour. Digital image correlation method is also used to identify the bond resistant mechanism developed in an element strengthened using NSM technique. Finally, using the experimental results, an analytical–numerical strategy is applied to establish the local bond stress–slip relationship.This work was supported by FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT - Portuguese Foundation for Science and Technology under the project CutInDur PTDC/ECM/112396/2009. The third author acknowledge the grant SFRH/BD/80338/2011 provided by FCT. Finally, the authors also like to thank all the companies that have been involved supporting and contributing for the development of this study, mainly S&P Clever Reinforcement Iberica Lda. and SECIL

An alternative system for measuring displacements in bridges by using displacement transducers

One of the most important controlling parameters in bridges are the vertical displacements. Measuring deflections is not only valuable at the early stages of the construction, but during the service lifetime of the structure also. Furthermore, vertical displacements are one of the most important indicators of the healthy state of the bridges among other structural health monitoring parameters used in the assessment of the structural response of the bridges and for foreseeing eventual damage or deterioration issues. Bridges are often placed over watercourses or over accidentally terrain and normally load tests are carried out before starting its use with the purpose of evaluating the structural response. Measuring vertical displacements are always a challenge and many technics have been developed during the past few years. The present paper introduces a new system based on the use of LVDTs that enables the measurement of vertical displacements in structures when the access to reference points are limited. Also, this system offers a simple application and can be easily placed on site for measuring vertical displacements with both high sampling frequency rates and resolution

Establishing erosion susceptibility – different techniques for decision-making in different stages

O trabalho avaliou alternativas de produção de cartas de suscetibilidade á erosão considerando diferentes combinações de pesos para os atributos do meio físico, segundo quatro diferentes técnicas de análise. Os atributos considerados foram landform, declividade do terreno, solo, substrato rochoso e ocupação do solo. Foram avaliadas as alternativas de pesos iguais para os atributos tratados, pesos diferentes de acordo com a visão de autor que havia trabalhado previamente na área, pesos diferentes definidos a partir de outros trabalhos da literatura, e pesos diferentes definidos com base no processo analítico hierárquico (AHP). A área estudada compreendeu a Bacia do Prosa localizada a cidade de Campo Grande – Mato Grosso do Sul, Brasil. Os resultados mostraram que as alternativas avaliadas podem ser utilizadas em conjunto ou em diferentes etapas de estudos visando o planejamento urbano.We evaluated and discussed alternatives to erosion susceptibility chart production due to different weights for physical environment attributes, using four techniques. Considered attributes were landform, terrain steepness, soil, rock and land use and occupation. The following attributes combinations were discussed: equal weights for physical environment attributes, different weights according to an expert in Prosa Basin, different weights according to other researchers, and different weights obtained through an analytical hierarchical process (AHP). Studied area comprises Prosa Basin in Campo Grande (Mato Grosso do Sul, Brazil). Results show that the considered alternatives can be used as a group or in different stages to support urban planning.Asociación de Universidades Grupo Montevide

Establishing erosion susceptibility: different techniques for different stages in a decision - making process

We evaluated and discussed alternatives to erosion susceptibility chart production according to different weights for physical environment attributes. Four techniques were used: landform, terrain steepness, soil, rock, land use and occupation. The following combinations of attributes were discussed: equal weights for physical environment attributes, different weights according to an expert in Prosa Basin, different weights according to other researchers, and different weights obtained through an analytical hierarchical process (AHP). The studied area comprises Prosa Basin in Campo Grande (Mato Grosso do Sul, Brazil). Results show that the considered alternatives can be used as a group or in different stages to support urban planning.O trabalho avaliou alternativas de produção de cartas de suscetibilidade à erosão considerando diferentes combinações de pesos para os atributos do meio físico, segundo quatro diferentes técnicas de análise. Os atributos considerados foram landforms, declividade do terreno, solo, substrato rochoso e ocupação do solo. Foram avaliadas as alternativas de pesos iguais para os atributos tratados, pesos diferentes de acordo com a visão de autor que havia trabalhado previamente na área, pesos diferentes definidos a partir de outros trabalhos da literatura, e pesos diferentes definidos com base no processo analítico hierárquico (AHP). A área estudada compreendeu a Bacia do Prosa localizada a cidade de Campo Grande – Mato Grosso do Sul, Brasil. Os resultados mostraram que as alternativas avaliadas podem ser utilizadas em conjunto ou em diferentes etapas de estudos visando o planejamento urbano.Es revisado por: http://sedici.unlp.edu.ar/handle/10915/26632Comité de Medio Ambient

FEM-based numerical strategy for analysis of composite modular floor prototype for emergency housing applications

The paper presents the numerical modelling of a temporary residential floor prototype composed of three jointed composite floor sandwich panels made of glass fiber reinforced polymer (GFRP) skins, a polyurethane foam core (PU) and pultruded U-shaped GFRP profiles working as ribs. Panels are supported on a GFRP pultruded frame structure. A 3D nonlinear finite element model is developed considering geometrical and material nonlinearities and adherent surfaces interaction. The model is coherently validated with experimental results, showing its capability to capture the mechanical performance of a single panel (which includes the possibility of local instability on the GFRP skin), two and three panels working together, and the whole prototype. A series of parametric studies are then conducted using the numerical model developed. Those studies aim to (i) assess the influence that ribs on the panel stiffness and on the shear stresses distribution through the sandwich panel’s components, (ii) the flexibility of the designed connections between jointed panels and frame structure, and (iii) the influence of geometry in the modular housing.This work is part of the research project ClickHouse – Development of a prefabricated emergency house prototype made of composites materials, involving the company ALTO – Perfis Pultrudidos, Lda., CERis/Instituto Superior Técnico and ISISE/University of Minho, supported by FEDER funds through the Operational Program for Competitiveness Factors – COMPETE and the Portuguese National Agency of Innovation (ADI) – project no. 38967. Special thanks are given to company ALTO – Perfis Pultrudidos, Lda., who manufactured all the elements (GFRP profiles and sandwich panels) involved in the research. The numerical model was performed in collaboration with the Department of Construction Engineering of the Universitat Politècnica de València

Comparação do Fechamento do Balanço de Energia para dias de Vento Forte e Fraco nas Regiões de Paraíso do Sul e Cruz Alta- RS

O presente estudo utiliza duas regiões de culturas agrícolas diferentes: Paraíso do Sul, região de várzea natural de rio, na qual ocorre cultivo de arroz irrigado; Cruz Alta, região do planalto médio do RS, com cultivo de milho. O objetivo deste trabalho é estimar as componentes do balanço de energia junto à superfície usando dados experimentais dos fluxos superficiais de calor e de radiação para ambas as regiões e verificar a influência da velocidade do vento, forte ou fraco, no fechamento do balanço de energia no período de um ano para ambos os sítios experimentais

Caracterização experimental do comportamento mecânico de painéis sandwich com lâminas de GFRP e núcleo de poliuretano

Neste trabalho apresentam-se os resultados de um programa experimental realizado no piso da laje de um protótipo destinado a habitações de emergência em materiais compósitos. Este piso é constituído por painéis sandwich, com lâminas de GFRP e núcleo de poliuretano, apoiados em vigas e pilares em perfis pultrudidos em GFRP. O trabalho realizado tem como objetivo fundamental o estudo do comportamento estrutural do piso, incluindo a determinação de parâmetros modais dos painéis sanduíche analisados

Recent contributions from UMinho and Empa on durability issues of flexural strengthening of RC slab with EB CFRP laminates

Common research activities in the field of durability of prestressed externally bonded reinforcement (EBR) for reinforced concrete (RC) structures were carried out at both the University of Minho (UMinho) and the Swiss Federal Laboratories for Materials Science and Technology (Empa). The research includes the study of the durability of (i) the constituent materials (concrete, epoxy and CFRP laminate) and (ii) large-scale RC slabs strengthened with prestressed CFRP laminates with two different anchorage systems (mechanical anchorage and the gradient anchorage), when subjected to different environmental conditions. The main achievements for a better understanding of the durability of RC elements strengthened with prestressed EBR-FRPs are presented in this paper. Finally, the effect of polymer sealings and asphalt application at high temperatures on CFRP/epoxy/concrete connections is also briefly discussed.This work was supported by the following programs: FEDER (European Funds for Regional Development) funds through the Operational Program for Competitiveness Factors – COMPETE, Operational Program for Competitiveness and Internationalization (POCI) and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects CutInDur FCOMP-01-0124-FEDER-014811 (PTDC/ECM/112396/2009), FRPreDur FCOMP-01-0124-FEDER-028865 (FCT reference PTDC/ECM-EST/2424/2012), FRPLongDur POCI-01-0145-FEDER-016900 (FCT reference PTDC/ECM-EST/1282/2014) and POCI-01- 0145-FEDER-007633. From the Swiss side, The Swiss Road Authorities (FEDRO) and the Swiss National Science Foundation are kindly thanked for their financial support (AGB2012/001 and SNSF No.124401). The authors also like to thank: S&P Clever Reinforcement Ibérica Lda, S&P Clever Reinforcement Company (Switzerland), Tecnipor - Gomes & Taveira Lda., Vialam – Indústrias Metalúrgicas e Metalomecânicas, Lda, Hilti Portugal-Produtos e Serviços, Lda.info:eu-repo/semantics/publishedVersio