Response of semirigid steel frames to cyclic and earthquake loads

This paper presents the experimental results from a large research project dealing with the seismic behavior of semirigid steel frames. The investigation focuses on the performance of steel frames with semirigid connections comprised of top, seat, and web angles in comparison with fully rigid alternatives. The experimental program includes monotonic, cyclic, and pseudodynamic tests. Results from eight tests on two-story frames are discussed, and the effects of connection stiffness and capacity on frame response are assessed. In addition, a comparison between the behavior of frames with bolted semirigid and fully welded rigid connections is carried out under realistic seismic loading conditions. It is shown that the type of the bolted connection used in this study exhibits sufficient ductility and stable hysteretic behavior and that connection yielding is a viable alternative to the weak-beam strong-column design. It is also indicated that with appropriate design and careful consideration of the dynamic characteristics of semirigid frames, adequate response to earthquake loads may be achieved, even in areas of high seismicity.