A risk‐based life cycle cost strategy for optimal design and evaluation of control methods for nonlinear structures

Abstract

Summary The lack of direct correspondence between control objectives and hazard risks over the lifetime of systems is a key shortcoming of current control techniques. This along with the inability to objectively analyze the benefits and costs of control solutions compared with conventional methods has hindered widespread application of control systems in seismic regions. To address these gaps, this paper offers 2 new contributions. First, it introduces risk‐based life cycle–cost (LCC) optimal control algorithms, where LCC is incorporated as the performance objective in the control design. Two strategies called risk‐based linear quadratic regulator and unconstrained risk‐based regulator are subsequently proposed. The considered costs include the initial cost of the structure and control system, LCC of maintenance, and probabilistically derived estimates of seismic‐induced repair costs and losses associated with downtime, injuries, and casualties throughout the life of the structure. This risk‐based framework accounts for uncertainties in both system properties and hazard excitations and uses outcrossing rate theory to estimate fragilities for various damage states. The second contribution of this work is a risk‐based probabilistic framework for LCC analysis of existing and proposed control strategies. The proposed control designs are applied to the nonlinear model of a 4‐story building subjected to seismic excitations. Results show that these control methods reduce the LCC of the structure significantly compared with the status quo option (benefits of up to $1 351 000). The advancements offered in this paper enhance the cost‐effectiveness of control systems and objectively showcase their benefits for risk‐informed decision making.

Seismic Damage Assessment of Steel Buildings considering Viscoelastic Dampers in Near-Field Earthquake

“…Seismic loads are initially contractual in nature, and the seismic design forces designed by the regulations are generally much smaller than the forces applied to the structure during an earthquake (Figure 1). e energy incoming to the structure depends on both seismic characteristics such as frequency, intensity, and periodicity of strong motions and structural characteristics such as ductility, damping, periodicity, and hysteresis behavior [15]. In determining the input energy to structures, it is generally assumed that the periodicity of the structure is about the dominant periodicity of the earth.…”

Life‐cycle cost optimization of semiactive magnetorheological dampers for the seismic control of steel frames

“…The references of Table 1 present the expected loss ratios for buildings under the earthquake excitations. Because these ratios are dimensionless, they have been used in different sites (e.g., previous studies [2][3][4][5][6][7] ).…”

“…[ 1 ] Therefore, in recent studies, the life‐cycle cost has been the seismic optimization goal of designing the control system for retrofitting (or seismic design) the structures. [ 2–9 ] Mitropoulou and Lagaros [ 3 ] investigated the performance and cost of seismic isolators using life‐cycle cost analysis. They showed that although the seismic isolator system is expensive, the life‐cycle cost is less than its fixed counterpart.…”

Multi‐hazard typhoon and earthquake collapse fragility models for transmission towers: An active learning reliability approach using gradient boosting classifiers

“…While susceptibility to a single hazard type and multiple exposures to the same hazard type 8,11 poses risks to the built environment, there is the possibility to experience multiple hazards of different types. The likelihood of multi‐hazard exposures varies geographically and with the type of hazards.…”