Moment–rotation model of semi-rigid connections with angles

A 2-parameter log model to describe the non-linear M–θ relationship of semi-rigid connections is proposed. The proposed model accurately describes the moment–rotation behavior of nearly all connections by controlling shape parameters α and n. To overcome the disadvantage that the shape parameters have very little physical meaning, the semi-analytic approach that optimum values of α and n, agreeing rather well with experimental curves, are derived in terms of initial stiffness (ki) and plastic stiffness (kp) from statistical regression analysis is applied to this paper. The analytic formulations of ki and kp are developed for double web angle connection and top and seat angle connection respectively.