Computational and Hybrid Simulation of High Performance Fiber Reinforced Concrete Coupled Wall Systems.

Abstract

High performance fiber reinforced concretes (HPFRCs) are characterized by pseudo-ductile tensile strain-hardening behavior, large energy absorption prior to crack localization and confined-like compressive response. These properties imply that HPFRCs have the potential to serve as highly damage tolerant and energy absorbing materials under severe loading conditions. A structural system that could significantly benefit from the use of HPFRC is reinforced concrete (RC) coupled wall systems (CWSs). Therefore, the overall objective of this work is to investigate, through computational and hybrid simulation techniques, the seismic behavior of RC CWSs in which HPFRC is used to replace regular concrete in vulnerable regions of the structure.

In order to simulate the hysteretic behavior of HPFRC structural components under random displacement reversals, an inelastic HPFRC material model is developed. Two 18-story CWSs, one RC and the other containing HPFRC in the coupling beams and wall plastic hinge zones, are designed and their seismic responses investigated. The latter system is designed with less reinforcing steel and reduced detailing than the former in recognition of the beneficial effects of HPFRC. Comparisons between the seismic performances of both systems indicate that the HPFRC system has an enhanced energy dissipation pattern and less post-event damage than the RC system despite the reduction in reinforcement quantity and detailing.

In addition to conventional computational simulation, hybrid simulation is also employed to model the seismic behavior of HPFRC CWSs. A strategy for estimating the tangent stiffness of structures during hybrid simulation is proposed. It is shown that when the strategy is combined with the widely used Operator Splitting Method (OSM) for hybrid simulation, the simulation accuracy is enhanced compared to the traditional OSM. A new conditionally stable algorithm, called Full Operator Method (FOM) is also developed. It is shown that FOM has enhanced accuracy compared to OSM and that it is possible to modify FOM into an unconditionally stable algorithm for cases where the estimated tangent stiffness is larger than the real tangent stiffness. Hybrid simulation of an 18-story prototype with FOM indicates that the new technique is able to model seismic behavior of CWSs with reasonable accuracy.