| A three-parameter exponential model is proposed to represent the behavior of the top and seat angles with/without double web-angle connections. Two of the parameters, the initial stiffness and the mechanism moment, are theoretically defined. The shape parameter is determined by the curve-fitting with the test data of connections collected in the data bank at Purdue University and statistically regressed to be represented by a practical linear expression for design. A second-order elastic analysis method for semi-rigid frames is used for the studies of parameter sensitivities and model accuracy in frame behaviors. It is concluded that the proposed connection model used in frame analysis is accurate enough and acceptable for practical design use. An approximate second-order analysis method for the semi-rigid frame design is proposed and verified by the extensive comparisons between the simplified methods and the exact method. |
