Resumo This paper presents the results of reinforced concrete columns strengthened by addition of a self-compacting concrete overlay at the compressed and at the tensioned face of the member, with and without addition of longitudinal steel bars. Eight columns were submitted to loading with an initial eccentricity of 60 mm. These columns had 120 mm x 250 mm of rectangular cross section, 2000 mm in length and four longitudinal reinforcement steel bars with 10 mm in diameter. Reference columns P1 and P2 were tested to failure without any type of rehabilitation. Columns P3 to P8 were loaded to a predefined load (close to the initial yield point of tension reinforcement), then unloaded and strengthened for a subsequent test until failure. Results showed that the method of rehabilitation used was effective, increasing the loading capacity of the strengthened pieces by 2 to 5 times the ultimate load of the reference column. Este artigo apresenta os resultados de pilares de concreto armado reforçados por meio da adição de camadas de concreto auto-adensável, tanto na face tracionada quanto na face comprimida, com ou sem adição de barras de aço longitudinais. Oito pilares foram submetidos a um carregamento com excentricidade inicial de 60mm. Estes pilares possuíam seção transversal retangular de 120 mm x 250 mm, comprimento de 2000 mm, e armadura longitudinal constituída por quatro barras de 10 mm de diâmetro. Os pilares de refer-ência, P1 e P2, foram ensaiados até a ruptura sem nenhum tipo de reabilitação. Os pilares P3 à P8 foram inicialmente submetidos a um pré-carregamento que provocava na armadura longitudinal, tensões próximas a do escoamento do aço. Em seguida, estas peças foram descarregadas e reforçadas. Após o concreto do reforço atingir resistência adequada, estes pilares foram ensaiados até a ruptura. Os resultados mostraram que o método de reforço estudado foi eficiente, pois dependendo da face do pilar em que se aplicava a camada de reforço, as peças reabilitadas apresentaram uma capacidade de carga de 2 a 5 vezes maior que a dos pilares não reforçados. Palavras-chave: pilar; concreto armado; reforço; excentricidade; concreto auto-adensável.
ResumoThis article presents the study of reinforced concrete columns strengthened using a partial jacket consisting of a 35mm self-compacting concrete layer added to its most compressed face and tested in combined compression and uniaxial bending until rupture. Wedge bolt connectors were used to increase bond at the interface between the two concrete layers of different ages. Seven 2000 mm long columns were tested. Two columns were cast monolithically and named PO (original column) e PR (reference column). The other five columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and other columns had a 155 mm by 250mm cross section after the strengthening procedure. Results show that the ultimate resistance of the strengthened columns was more than three times the ultimate resistance of the original column PO, indicating the effectiveness of the strengthening procedure. Detachment of the new concrete layer with concrete crushing and steel yielding occurred in the strengthened columns.Este artigo apresenta um estudo do comportamento de pilares de concreto armado reforçados por encamisamento parcial, com o uso de uma camada de 35 mm de concreto auto adensável na face mais comprimida submetidos à flexo-compressão até à ruptura. Foram utilizados parafusos conectores como armadura de ligação entre as duas camadas de concreto de diferentes idades. Foram ensaiados 7 pilares de 2000 mm de altura, sendo 2 peças concretadas monoliticamente nomeadas de PO (pilar original) e PR (pilar de referência). Os outros 5 pilares foram reforçados utilizando uma camada de 35 mm de concreto moldada na face submetida a maior compressão. O pilar PO tinha uma seção transversal retangular de 120x 250 mm e as demais colunas 155 x 250 mm após executado o reforço. Os resultados alcançados mostram que os pilares reforçados atingiram uma resistência de aproximadamente três vezes maior com relação ao pilar PO, demostrando eficiência da técnica utilizada. Os pilares apresentaram o desplacamento da camada de reforço nas cargas finais, com tendências ao esmagamento do concreto e escoamento do aço.Palavras-chave: pilares, reforço, concreto, parafusos.
The scope of this research is the recycling of polymers from mobile phones hulls discarded and the performance evaluation when they are submitted to the Recycling Cycle of Materials (RCM). The studied material was the ABS/PC blend in a 70/30 proportion. Different compositions were evaluated adding virgin material, recycled material and using the copolymer SBS as impact modifier. In order to evaluate the properties of material's composition, the samples were characterized by TGA, FTIR, SEM, IZOD impact strength and tensile strength tests. At the first stage, the presented results suggest the composition containing 25% of recycled material and 5% of SBS combines good mechanical performance to the higher content of recycled material and lower content of impact modifier providing major benefits to recycling plans. Five cycles (RCM) were applied in the second stage; they evidenced a decrease trend considering the impact strength. At first and second cycle the impact strength was higher than reference material (ABS/PC blend) and from the fourth cycle it was lower. The superiority impact strength in the first and second cycles can be attributed to impact modifier effect. The thermal tests and the spectrometry didn't show the presence of degradation process in the material and the TGA curves demonstrated the process stability. The impact surface of each sample was observed at SEM. The microstructures are not homogeneous presenting voids and lamellar appearance, although the outer surface presents no defects, demonstrating good moldability. The present work aims to assess the life cycle of the material from the successive recycling processes.
This study evaluates seven flat slabs made with reinforced concrete. There are three reference slabs, one of them doesn’t present any shear reinforcement. Four slabs have a new model of shear reinforcement of stud type, internally anchored to the flexural reinforcements. That reinforcement has an additional element, called on this study by the name: anti-cracking pins. The main objective of the research is to find the ideal spacing between these pins to achieve a failure mode and a failure load similar to the reference slabs that have conventional studs. For that, are evaluated: vertical displacements, rotation, shear reinforcement deformation, load capacity and failure mode. The slabs with the new stud have a load gain of 40% to 106% compared to the slab without studs LRef. The slab L-5-13 presented a load and a failure mode similar to the slab of reference, LRef-AC.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.