| A study was performed to investigate the reduced beam section (RBS) beam-to-column moment connection without continuity plates. The study involved three main tasks: (1) analyzing the results from four full-scale cyclic experimental tests of the RBS moment connection without continuity plates; (2) performing analytical parametric studies using nonlinear finite element models with buckling modes to evaluate the connection behavior; and, (3) using the results of the experimental and analytical studies to assess current design provisions and to develop design guidelines for the connection without continuity plates.; The four tested column specimens consisted of two matched pairs of W14x283 and W18x211 sections. Each column specimen was connected to a single W30x132 beam representing an exterior connection. The top flanges of the beam were braced near the RBS to simulate a floor slab condition. The bottom flanges of the beams were unbraced. The cyclic testing concluded that the W14x283 column specimens were able to perform adequately, while the W18x211 column specimens were at point of instability.; Nonlinear finite element analysis of the tested connections established a correlation between the measured and computed responses of the connections. With this correlation, the mechanics of the connection were subject to further study. The analytically computed connection behavior was expanded to include additional beam and column sections, with continuity plates at the level of each beam flange, with no continuity plates, and with continuity plates only at the level of the beam bottom flange. The stability of the RBS and the connecting column flange twist potential was found to be influenced by the thickness of the column web, where thinner, deeper column web sections are more prone to allow for instability and local flange twisting.; Both the experimental and finite element results indicate that the RBS moment connection can be used in some specific situations without one or both continuity plates in the column. Based on the stability of the RBS, a procedure for determining when the connection may be used without continuity plates is presented. By eliminating one or both continuity plates, material and labor cost reductions can provide an economic benefit to steel moment frame construction. |
