Mathematical Model for Moment-Rotation Curve of High Strength Steel Endplate Connections

Abstract:

In order to predict the moment-rotation (M-θ) curve of high strength steel endplate connections at ambient temperature, in fire and after fire, a calculation method for initial stiffness, post-yield stiffness, ultimate flexural resistance and shape parameter is proposed based on the four parameter exponential function, the concept of component method, and equivalent T-stubs. The prediction of moment-rotation curve is then obtained by substituting calculation results into the four parameter exponential function. Moreover, the calculation results and predicted moment-rotation curves are compared with the test results of Q690 and Q960 high strength steel endplate connections at ambient temperature, in fire and after fire. The comparisons demonstrate that the calculation values of flexural resistance are in good agreement with the test values, particularly the relative errors of Q960 are within 5%. Besides, the calculation values of initial stiffness are closer to the test results than those of EN 1993—1?8. Moreover, the predicted moment-rotation curves of Q960 are consistent with the test results and those of Q690 are relatively conservative.

Key words:high strength steel;endplate connection;moment-rotation curve;mathematical model