Study On Seismic Performance Of High-rise Reinforced Concrete Chimney Structure

This study is organized to assess the seismic performance of a high-rise reinforced concrete (RC) chimney using the comprehensive nonlinear finite-element analyses. For that purpose, the following contents are included:(1) With the aid of OpenSees, a simplified non-linear finite element model based on distributed plasticity and flexibility approaches element is built. The model efficiency and accuracy are verified through comparison with the available in suit ambient vibration tests results and modal and linear elastic time history analytical results obtained from ABAQUS.(2) The analysis procedures for standard modal pushover analysis (MPA) and modified MPA (MMPA) are outlined. Based on the rationale and analysis procedures for classical modal response spectrum analysis and mMPA and the existing Ry(strength reduction factor)-μ(the displacement ductility ratio)-T(the period of vibration) relations, a modified modal response spectrum analysis (mMRSA) method is proposed. The effectiveness and applicability of these methods for high-rise RC chimney are assessed by comparison of the results for a set of earthquake records with the ones of nonlinear response history analysis (NLRHA). Furthermore, the effects of the higher modes on the seismic demand of RC chimney are also evaluated.(3) Performance-based seismic vulnerability assessment methodology for RC chimney is detailedly presented. The incremental dynamic analysis (IDA) method is comprehensively stated. Four damage limit states are defined in terms of curvature ductility ratio of cross-section based on concrete and longitudinal reinforcement strain levels, using the sectional curvature analysis results of91circular hollow sections. Taking the uncertainties in ground motion realizations into account and based on probabilistic seismic demand model, the fragility curves characterized in terms of peak ground acceleration are developed for the RC chimney at various damage states and the vulnerability performance is assessed.(4) Based on beam-on-nonlinear-Winkler-foundation (BNWF) model, a detailed integral soil-foundation-superstructure model is proposed using the finite element software OpenSees. The nonlinear soil-structure interaction (SSI) modeling techniques are also described in detail. The effects of SSI on the distributed features of seismic demand of the tall RC chimney are studied. Furthermore, the seismic collapse-resisting capability is also evaluated within the probabilistic framework.