Plastic analysis of shear in reinforced concrete

The square yield condition and associated flow rule for concrete are postulated. The state of stress in a kinematical discontinuity (crack) in plain concrete is derived and it is shown that interface shear transfer occurs when the relative displacement rate is not normal to the crack. This is used to analyse the shear of an orthogonally reinforced concrete disc element, including the case when the reinforcement in one direction does not yield. This is also the case for reinforced concrete beams subjected to shear, and the shear strength of a beam with compression flange is derived. The solution is compared with test results, and with the British and the Danish Codes of Practice.