Ultimate capacity of core structures subjected to axial force, biaxial bending and torsional loads

The tall building represent the economic means ofproviding large numbers of people with modern housing in bigcities considering the scarcity of land and the cost ofexpanding or creating new cities, with all their requirementsof other services.One of the primary considerations in structural planningand analysis of tall buildings is the transfer of vertical andhorizontal loads which may be caused by wind, earthquake orblast from the superstructure to foundations.Core structures in tall building frequently take theform of thin-walled sections which ally the advantages ofcomparatively low weight with heigh strength, particularly intorsion.Core structures may be of either open cross section orpartially closed by lintel beams at flour levels, because thecore must have regular large openings for acess to the liftsand stairs, usually its cross section considered as opensection.Core structure have been used increasingly in recentyears primarily due to their large bending stiffness againsthorizontal loading [1]. However, in presence of wind, the coreviII be subjected to torsional forces in case of, the location