Controlled Rocking Steel Frames Paper Earns ASCE Moisseiff Award

The American Society of Civil Engineers (ASCE) has honored Matthew R. Eatherton, Ph.D., P.E., S.E., Xiang Ma, Helmut Krawinkler, Ph.D., Gregory G. Deierlein, P.E., and Jerome F. Hajjar, Ph.D., P.E., with the 2016 Moisseiff Award for their paper, Quasi-Static Cyclic Behavior of Controlled Rocking Steel Frames, published in the November 2014 Journal of Structural Engineering.

The paper describes testing and analysis of a new controlled rocking system, a seismic lateral force resisting system for steel-framed buildings. The experimental program described in this paper is part of a multi-institution, international research project to develop the controlled rocking system.

Conventional seismic lateral force resisting systems are designed to undergo inelastic deformations in primary structural members during a design level earthquake. Structural damage associated with these inelastic deformations may be impractical to repair after an earthquake, especially when coupled with permanent residual drifts. The controlled rocking braced steel-framed system developed in this study provides a new, practical and viable alternative structural design strategy, which has the ability to virtually eliminate residual drifts and concentrate the significant inelastic deformations in replaceable structural fuse elements.

The controlled rocking system uses braced steel frames, column-uplifting mechanisms, high-strength post-tensioning and replaceable energy-dissipating fuses to enhance seismic performance.

The paper describes quasi-static cyclic tests of half-scale rocking frames that were conducted to investigate the behavior of the system and its components, validate analysis models, establish seismic performance limit states and develop and evaluate construction details. Design parameters investigated include alternate frame configurations, fuse characteristics, capacity for self-centering, overturning moment resistance and initial post-tensioning stress.

The tests demonstrate that the controlled rocking system can satisfy the performance goals of maintaining elastic response of the rocking braced frame and post-tensioning up to drift ratios of 2.5%, confining inelastic response to replaceable shear fuses and achieving near-zero residual drift when the lateral forces are removed.

The Moisseiff Award is given to the author(s) of an important paper published by ASCE, dealing with the broad field of structural design, including applied mechanics, as well as the theoretical analysis or construction improvement of engineering structures, such as bridges and frames, of any structural material.

Deierlein and Eatherton were also honored with AISC achievement awards at the 2016 NASCC: The Steel Conference for their outstanding contributions to the structural steel industry.