According to this standard, the effective area in this context would be that obtained by the ratio V/ζ máx, where Vis the shear force in the section and ζ máx is the maximum shear stress in the section obtained with Jourávski expression.
#Shear area calculator concrete beam code#
For the calculation of V sw, Merta proposes model that takes into account the curved stirrup sand divides the contribution of the reinforcement into two parts: the vertical component of force in the stirrup crossing this hear crack and over an additional portion due to radial forces that a rise due to the adhesion between the steel and concrete.Ī useful concept introduced by Merta & Kolbitsch and Li is the effective area (A ef) for shear force, also called "shear area" in one of the works.Ī similar concept is used by the Brazilian code of steel structures, NBR8800 (2010). For determining the value of V c, the above author presents expressions in which the influence of the main variables were empirically determined based on the results of 44 testing circular beams reinforced only with longitudinal rebars, ie, without the use of stirrups.
Merta, presents analytical model for determining the shear strength of reinforced concrete beams of circular section. The presented results suggests that the application of the expressions of AASHTO (2007)may lead to safe values of shear strength of reinforced concrete circular cross-section beams as shown in the item 4 of this study. The cited authors used the American Standard AASHTO LFRD Bridge Design Specifications, 2007 ,to estimate the resistance of the tested beams. The tested beams had a diameter of 25cm and were reinforced with different longitudinal and transverse arrangements ( Figure 3). , present the test results of sixteen circular beams. However, the application of the Brazilian Standard expression for circular cross-section beams presents some problems, such as: (a) the applicability of the expression used for the determination of V Rd2, the shear strength design related to the concrete failure by diagonal compression (b) the definition of the value of b w for the calculation of V c, the parcel of shear force resisted for complementary mechanisms to truss (c) doubts related to the efficiency of circular stirrups in shear strength when determining V sw, the portion of the shear force resisted by shear reinforcement.Īttempts to cover this subject are found in literature, ,. The determination of shear strength of these elements on Ultimate Limit States must be made by the expression given on item 17.4 of NBR 6118. Utilization of circular cross-section beams for shallow tunnels has also been verified in recent projects.(Maffei, )( Figure 2). Reinforced concrete circular cross-section beams are often used in infrastructure works, such as retaining structures for excavations ( Figure 1). Keywords: shear reinforced concrete circular section retaining walls. The proposed adequation is based on extensive bibliographic review and practical experience with a great number of infrastructure elements, such as anchored retaining pile walls, where the use of circular reinforced concrete members is frequent. The actual expressions are most suitable to rectangular cross-section and some misleading occurs when applied to circular sections at determination of VRd2, Vc and Vsw, as consequence of bw (beam width) and d (effective depth) definitions as well as the real effectiveness of circular stirrups. São Paulo, SP - BrasilĪ proposed adequation of NBR 6118, Item 7.4, related to shear strength of reinforced concrete beams is presented with aims to application on circular cross-section. IIIMaffei Engenharia, Address: Rua Moura Brasil, 183. Luciano Gualberto - Travessa 3 no 380 - Cidade Universitária - Butantã, CEP 05.508-010, São Paulo-SP, Brasil IIUniversidade de São Paulo, Escola Politécnica, Departamento de Estruturas e Geotécnica, Address: Av. IUniversidade de São Paulo, Escola Politécnica, Departamento de Estruturas e Geotécnica, Address: Av. Shear strength of reinforced concrete circular cross-section beams
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