A risk-targeted decision model for the verification of the seismic performance of RC structures against structural pounding

Abstract

In this study, a novel risk-targeted decision model is introduced to verify the seismic performance of RC structures against structural pounding and then to define the minimum demand for separation gap distance (dg) between adjacent structures at a target probability Pt. The derivations are based on a linear approximation of the seismic hazard function and well-established probabilistic seismic demand models (PSDMs). New performance objectives (POs) dedicated to structural pounding risk are proposed based on engineering demand parameter (EDP) hazard curves and on the separation gap distances (dg: available or acceptable) between adjacent structures. The theoretical background in the context of the risk-targeted decision model is presented, and then the adjustment to the structural pounding risk is introduced. The minimum separation gap distance (dg,minPt) at a target Pt is defined considering a) the demand hazard curve for the maximum displacement (without pounding) at the top contact floor level of the structure (δmax), and b) the acceptable structural pounding PO of an EDP. The proposed risk-targeted decision model is then demonstrated by means of a structural pounding case study of a RC structure. Local and global EDPs at different performance levels are considered and several POs at different dg are compounded. The verification of the seismic performance of the RC structure at a target probability Pt is carried out either with or without considering the structural pounding risk. Numerical examples of the verification and the definition of the dg,minPt at different pounding risk levels (Pt) of the examined RC structure are also presented and discussed. Based on these results, a distinct PO of an EDP was identified. This PO is characterized as a critical level of structural pounding risk at the capacity level of the EDP and is associated with an explicit-critical separation gap distance between the adjacent structures. In a future research study, this PO could be the basis for providing a design solution against structural pounding risk when the estimated minimum separation gap distance at a target Pt between the adjacent structures cannot be implemented. The provided solution through the proposed decision model also indicates that the maximum demand for separation gap distance between the adjacent structures can safely be shifted to smaller values, notwithstanding that pounding risk is increased.