Local deformation‐based design of minimal‐disturbance arm damper for retrofitting steel moment‐resisting frames

Abstract

Summary This paper presents a design approach for seismic rehabilitation of frames having a beam‐collapse mechanism using a technique termed minimal‐disturbance seismic rehabilitation. This technique pursues enhancing the seismic performance of buildings with the intention of improving the continuity of business. It minimizes obstruction of the visual and physical space of building users and the use of heavy construction equipment and work requiring fire permit (welding/cutting). The developed design approach is simple to use. Yet it leads to designs that limit the beams' plastic rotations to allowable values, while minimizing the number of locations where devices are installed and the devise dimensions. Furthermore, the effectiveness of the design approach and the rehabilitation technique is numerically studied through retrofitting a four‐story steel moment‐resisting frame. Copyright © 2017 John Wiley & Sons, Ltd.

Minimal-Disturbance Arm Damper Retrofitting: Evaluation of Retrofit Effect Using Multi-Span Steel Frame Specimens

“…The beam-column strength ratio was around 1.8 in all the stories. The further details of the steel frame are described in the previous studies [1,2]. In experimental design, a one-story four span substructure boxed in Figure 2…”

“…A technique named minimal disturbance arm damper (MDAD) protects the beam ends from fracture with the moderate increase of the stiffness and strength of the entire frame, while reducing the installation time by using light-weight steel members with only bolt connections. Lavan et al [2] proposed a design procedure of MDAD that explicitly considers the unique feature of MDAD in directly reducing beam-end local deformation. As a nature of retrofitting, the performance of retrofit cannot be evaluated solely by the testing of retrofit techniques and devices.…”

“…The use of a multi-span specimen that enables to observe the influence of the retrofitting on force-resisting mechanism is more suitable. In case of MDAD, the previous researches [1,2] evaluated the devise behavior through component-level tests and the retrofit impact to steel moment-resisting frames in numerical simulations. However, the numerical simulation holds many assumptions and the effect of MDAD retrofit on existing frame has not been closely examined yet.…”

Multiple-Damage State Retrofit of Steel MRFs with Composite Beams Using a Minimal-Disturbance Arm Damper

“…The present research develops a retrofit procedure to control both the story drift and member ductility, offering an efficient frame upgrade that meets the multiple performance requirements of PBSD and overcomes the deficiencies of current retrofit methods for MRFs. The retrofit system, named the Minimal-Disturbance Arm Damper (MDAD) (Lavan et al 2017), is designed to enhance the seismic performance of steel MRFs with composite beams by adequately increasing story strength and stiffness and reducing plastic deformation demands at beam ends under positive bending. The basic behavior and design procedures of MDAD, which delay yielding and reduce plastic rotation under positive bending, have been verified through tests and numerical simulations (Kurata et al 2016).…”