Digital twin approach for enhancing urban resilience:A cycle between virtual space and the real world

Construction of disaster-resilient cities has attracted considerable attention.However,traditional methods of studying urban disaster resilience through experimental approaches are often constrained by various limitations,such as testing sites,costs and ethical considerations.To address these constraints,this paper proposes incor-porating digital twin concepts into urban disaster resilience research.By establishing a connection between the physical realm of the city and its virtual counterpart,this approach utilizes digital simulations to overcome the limitations of experimental methods and enables dynamic deduction and control of the disaster process.This pa-per delves into three key aspects encompassing the acquisition of data from reality to the virtual space,disaster simulation within the virtual space,and translation of virtual insights into effective disaster prevention strate-gies in reality.It provides a comprehensive summary of relevant research endeavors from the authors’research group and showcases the effectiveness and potential of the proposed techniques.These findings serve as refer-ences for pre-disaster planning,real-time emergency assessments,post-disaster rescue operations,and accident investigations for buildings and cities.

Theoretical study on the confine-stiffening effect and fractal cracking of square concrete filled steel tubes in tension loads

Tension stress in steel-concrete composite is widely observed in engineering design.Based on an experimental program on tension performance of three square concrete-filled tubes(SCFT),the tension theory of SCFT is proposed using a mechanics-based approach.The tension stiffening effect,the confining strengthening effect and the confining stiffening effect,observed in tests of SCFTs are included in the developed tension theory model.Subsequently,simplified constitutive models of steel and concrete are proposed for the axial tension performance of SCFT.Based on the MSC.MARC software,a special fiber beam-column element is proposed to include the confining effect of SCFTs under tension and verified.The proposed analytical theory,effective formulas,and equivalent constitutive laws are extensively verified against three available tests reported in the literature on both global level(e.g.,load-displacement curves)and strain level.The experimental verification proves the accuracy of the proposed theory and formulations in simulating the performance of SCFT members under tension with the capability to accurately predict the tensile strength and stiffness enhancements and realistically simulate the fractal cracking phenomenon.