Faculdade de Engenharia Civil - FEC/ITEC

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2788

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Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Influence of the cable´s layout on the shearing resistance of prestressed concrete beams
(Universidade Federal do Pará, 2016-10) SOUZA JUNIOR, Orivaldo de Azevedo; OLIVEIRA, Dênio Ramam Carvalho de
Little information on experimental investigations regarding the influence of the prestressing forces in the shear resistance of prestressed beams is found in the technical literature. Thus, it was experimentally evaluated the shear resistance of six post-tensioned prestressed concrete beams with cross section of (150 x 450) mm2, total length of 2400 mm and concrete’s compressive resistance of 30 MPa, with the variables of this work being the layout of the prestressing cable, straight or parabolic, and the stirrups geometric rate. Verticals displacement, steel and concrete’s strains and a comparison of the experimental loads with the estimates of ACI 318, EUROCODE 2 and NBR 6118: 2014 codes are presented and discussed. The results showed that the cable’s parabolic layout increased the beams’ shear resistance in up to 16% when compared to beams with straight cables.
Acesso aberto (Open Access)
Influence of the column rectangularity index and of the boundary conditions in the punching resistance of slab-column connections
(Universidade Federal do Pará, 2015-06) PAIVA, Odilson da Silva de; FERREIRA, Maurício de Pina; OLIVEIRA, Dênio Ramam Carvalho de; LIMA NETO, Aarão Ferreira; TEIXEIRA, Marcelo Rassy
Experimental evidence indicates that both the column rectangularity index and the boundary conditions of the connection may affect the ultimate punching resistance. This paper presents general aspects of these topics and, through the analysis of experimental results of tests on 131 slabs, evaluates the accuracy and suitability of recommendations presented by ABNT NBR 6118, Eurocode 2, ACI 318 and fib Model Code 2010. Experimental results showed that the security level of normative estimates trend to reduce as the column rectangularity increases, and in some cases, the punching resistance was overestimated. Finally, adjustments are suggested in equations presented by NBR 6118 and MC2010 in order to eliminate this trend of unsafe results.
Acesso aberto (Open Access)
Lajes lisas nervuradas de concreto armado ao cisalhamento
(Universidade Federal do Pará, 2011-10) SOUZA, Shirley do Socorro Melo de; OLIVEIRA, Dênio Ramam Carvalho de
The structural systems with waffle flat slabs are the most used in Brazil when the main requirement is flexible "layouts" and long spans with reasonable economy. However, few studies have been developed in Brazil regarding the behavior of these slabs when the flexural resistance is satisfactory and the shear in the ribs and punching resistances become competitive. This work shows the experimental analysis of 8 two-way reinforced concrete waffle flat slabs under centered load. The dimensions of the slabs were the same and equal to 1800 mm x 1800 mm x 140 mm. The ribs were 80 mm (height) by 50 mm (width) and the compressive concrete strength was approximately 40 MPa. The experimental results were compared to those estimated by the Brazilian code NBR 6118:2003. It was verified that the resistance of the ribs is not satisfactorily estimated by the code, which excessively underestimates the results for ribs with and without shear reinforcement.
Acesso aberto (Open Access)
Punching strength of reinforced concrete flat slabs without shear reinforcement
(Universidade Federal do Pará, 2012-10) SACRAMENTO, Paulo Victor Prazeres; FERREIRA, Maurício de Pina; OLIVEIRA, Dênio Ramam Carvalho de; MELO, Guilherme Sales Soares de Azevedo
Punching strength is a critical point in the design of flat slabs and due to the lack of a theoretical method capable of explaining this phenomenon, empirical formulations presented by codes of practice are still the most used method to check the bearing capacity of slab-column connections. This paper discusses relevant aspects of the development of flat slabs, the factors that influence the punching resistance of slabs without shear reinforcement and makes comparisons between the experimental results organized in a database with 74 slabs carefully selected with theoretical results using the recommendations of ACI 318, EUROCODE 2 and NBR 6118 and also through the Critical Shear Crack Theory, presented by Muttoni (2008) and incorporated the new fib Model Code (2010).

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