Design Procedure for Seismic Retrofit Using Stud-Type Dampers Considering the Strength and Stiffness of Surrounding Frames


Abstract eng:
Stud-type dampers that are installed in a limited length of beam span are useful for building structures with many openings, but its performance is affected significantly by the deformation of surrounding frames. This study proposes a seismic retrofit design procedure for existing steel frames using stud-type dampers in consideration of the interaction between the damper and surrounding frame. As a stud-type damper, slitted steel shear wall stiffened by plywood panels is used. It is thinner than a shear wall with conventional stiffeners, light enough to carry by hand, easy to construct, and highly cost efficient. Furthermore, the strength and stiffness of the shear wall can be controlled independently by the adjustment of slit arrangement, namely spacing and length. The procedure of proposed seismic retrofit design is as follows: (a) The damper size is determined based on the location of openings and installation position applicable for a damper in the existing frame. (b) The maximum strength of the damper is derived to prevent shear yielding, bending yielding or lateral buckling of existing steel beam connected to the damper. When the damper width increases, the upper limit of damper strength also increases. (c) The number and layout of the dampers are determined in consideration of the desired base shear coefficient of the frame retrofitted with dampers. (d) The required stiffness of the damper is estimated to obtain sufficient energy dissipation. When the damper strength is fixed, the equivalent viscous damping ratio increases with the damper stiffness and then reaches a constant value. The stiffness that has 0.8 times the maximum achievable damping ratio is chosen as the minimum value. (e) The steel plate thickness and slit arrangement of the damper are determined considering the above design conditions. (f) If a feasible slitted steel plate is not obtained, the damper size, layout or strength should be re-examined. Cyclic loading test is conducted to examine the validity of proposed design procedure and the performance of retrofit strategy. The specimen was a single-story, single-bay steel frame in which a slitted steel shear wall was installed as a studtype damper in the middle of beam span, and with a scale ratio of 0.6. The damper yielded at a shear angle of 0.24 %, then the beam ends yielded near the beam-to-column connection at 1.0 %. The test shows that the design procedure is proven effective, because the beam did not yield or buckle at sections close to the damper. The damper had stable hysteresis behavior until the shear angle of 9 % (equivalent to the story drift angle of 3%) and sufficient energy dissipation with the equivalent viscous damping ratio of approximately 0.18.

Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
Rights:
Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2017-01-18, last modified 2017-01-18


Original version of the author's contribution as presented on USB, paper 2417.:
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