Damping-Enhanced Seismic Strengthening of RC Columns for Multiple Performance Objectives

Abstract

In this paper, the damping effect of a damping-enhanced strengthening methodology was evaluated with a 1/5-scale reinforced concrete column and full-size columns. As a damping component, constrained viscoelastic (VE) layers with their constraining layer anchored into the footing of a column or a bent cap is a new concept that has recently been introduced by the authors. An emphasis was placed on the analytical derivation of the VE layer effects on circular column responses and modeling of the VE layers with discrete springs in a finite element model of a highway bridge. The accuracy of the complex spring model was validated with an analytical solution under harmonic loading. The effect of single versus double curvatures on the damping effect was investigated in detail using the out-of-plane and in-plane motions of a three-column bent that represents a three-span regular highway bridge in the New Madrid Seismic Zone in the central United States. Both operational and safety performance objectives were considered under moderate and large earthquakes, respectively. The enhanced damping component will be used to reduce the bridge response under a moderate earthquake event for a limited damage performance level while the strengthening component is to ensure that the bridge system remains intact after a large earthquake event for a structural safety performance level. The numerical solutions from the proposed finite element model are in excellent agreement with the analytical results. Based on the numerical studies on full-scale columns, a VE layer covering the lower 40% of three columns of the bent can reduce the out-of-plane acceleration and displacement of the column by 44% and the inplane responses by approximately 40%. In comparison with the retrofit scheme at both ends of the columns, retrofitting one end of the columns with the same 40% VE coverage can further reduce the elastic response from 25% to 40%.

Meeting Name

5th National Seismic Conference on Bridges and Highways: Innovation in Earthquake Engineering for Highway Structures (2006: Sep. 18-20, San Francisco, CA)

Department(s)

Civil, Architectural and Environmental Engineering

Keywords and Phrases

Analysis; Columns; Dislocation (Geology); Earthquake resistant design; Earthquakes; Finite element method; Mathematical models; Mechanical loads; Methodology; Performance; Reinforced concrete; Resistance (Mechanics); Safety; Seismicity; Strengthening (Maintenance); Validation; Viscoelastic materials

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Publication Date

01 Sep 2006

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