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Design of shear reinforcement

Design of shear reinforcement includes:

• design for biaxial shear force,see "Design of shear reinforcement for shear forces"
• design for torsion , see "Design shear reinforcement for torsion"
• design for interaction shear force and torsion, see "Design of shear reinforcement for interaction shear and torsion"

Design is provided according to clause 6.1 - 6.3 in EN 1992-1-1. Design reinforcement for shear and torsion is commonly based on the theory of the concrete truss-model too. In this theory a virtual truss-model is imagined in a concrete beam. This truss-model has a set of vertical (or slightly diagonal), horizontal and diagonal members. The vertical bars are considered to be the stirrups; the horizontal bars are the main reinforcement and the diagonal bars are the concrete struts.

There are the following assumptions:

• The shear forces in both direction are taken into account and design of shear reinforcement is done for resultant of shear forces
• The parameters of plane of equilibrium (value, d, z and h) are recalculated to direction of shear force resultant
• The design shear resistance of the member without shear reinforcement (V_Rd,c) is calculated according to clause 6.2.2(1) in EN 1992-1-1, if section is cracked in flexure, otherwise clause 12.6.3 in EN 1992-1-1 is used
• Design value of maximum shear force will be calculated according to clause 6.2.2(6) (V_Ed,max) and 6.2.3 (3,4) (V_Rd,max) in EN 1992-1-1
• Design value of shear resistance is calculated according to 6.2.3 (3,4) (V_Rd,s) in EN 1992-1-1
• The number of shear link is loaded directly from Design defaults from concrete setting or concrete member data, see "Design Defaults"
• The angle of compression strut can be calculated automatically or defined by user, see "Angle between concrete compression strut and beam axis"
• The torsional cracking moment (T_Rd,c) is calculated according to clause 6.3.2(5) in EN 1992-1-1
• Design value of maximum of torsional resistance moment (T_Rd,max) is calculated according to clause 6.3.2(4) in EN 1992-1-1
• The angle of stirrups for design shear reinforcement for torsion has to be perpendicular
• There are 5 possibilities for calculation thin-walled closed section, see "Equivalent thin-walled closed cross-section"

With the following limitations

• Cross-section with one polygon and one material is taken into account in version SCIA Engineer 15 and later.
• The user(practical) reinforcement is not taken into account.
• Design should be done only in case that the angle between gradient of the strain plane and the resultant of shear forces is not greater than 15 °.
• Inclined compression chord or inclined tensile chord are not taken into account.
• The widths of cross-section for shear checks (value b_w and b_w1) are calculated automatically. There is no possibility for definition of user value in SCIA Engineer 15 and later.

Except of statically required shear reinforcement per meter including detailing provision (A_swm.req), the program calculates provided shear reinforcement (A_swm.prov). It is statically required shear reinforcement, where the spacing of the stirrups in longitudinal direction is rounded to 25 mm

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