Abstract
Este artigo apresenta um estudo analítico de uma recente técnica de reforço de lajes lisas de concreto armado contra o fenômeno da punção. Trata-se da utilização de mantas de Polímeros Reforçados com Fibra de Carbono (PRFC) como armadura de cisalhamento. O sistema, denominado Stitch, foi idealizado por Sissakis (2002) [1] e consiste em se formar um laço completo entre dois furos subsequentes como pontos de costura . O objetivo deste artigo é avaliar a aplicação de adaptações das principais normas, nacional e internacionais, de dimensionamento à punção de lajes com pilar interno, sem a atuação de momentos fletores e associadas às limitações do ACI 440 2R:2008 [6], a qual trata do reforço de estruturas com PRFC. Os Resultados mostram que a NBR 6118:2007 [4] apresentou o menor grau de dispersão, com alguns resultados contra a segurança. O ACI 318:2011 possui uma tendência mais conservadora, e o EUROCODE 2:2004 [4] e Model Code (2010) [5] possuem resultados intermediários, com esse ligeiramente mais conservador que aquele.
Highlights
Uncertainties regarding structural safety – like suspicions of project and execution error, doubts about the stability due to apparently pathological demonstrations and changes of service loads – are situations that justify an intervention with the strengthening of a structure
As the current standards do not deal with strengthening to shear with carbon fiber reinforced polymer (CFRP) reinforcement, it was assessed the application of the code’s required from by ACI 318 (2011) [2], by Eurocode 2 (2004) [3] by ABNT NBR 6118 (2007) [4] and by Model Code (2010) [5], associated to the limitations of ACI 440.2R (2008) [6] which provides guidance for the selection, design, and installation of Fiber Reinforced Polymers (FRP) systems for concrete structures
Punching strengthening in flat plates of reinforced concrete with carbon fiber reinforced polymer (CFRP) Figure 2 – Punching shear surface the columns and, lately, these ones discharge them on the foundations (Figure 1 (a))
Summary
Uncertainties regarding structural safety – like suspicions of project and execution error, doubts about the stability due to apparently pathological demonstrations and changes of service loads – are situations that justify an intervention with the strengthening of a structure. The objective of this research is to evaluate the safety, economy and the accuracy of the application of some of the main project regulations in the slab punching resistance in reinforced concrete strengthened to punching with CFRP. An adjustment suggested by Sissakis (2002) [1] will be adopted so that these regulations can be used in the case studied, with CFRP reinforcement, in which the deformation limits of ACI 440.2R is considered. This last code deals only with the strengthening of reinforced concrete structures using fiber-reinforced polymers. Will be evaluated the dispersion and the conservatism level of each case
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